Turbine dosing system with bypass output and delivery

Abstract

A turbine for a turbocharger is provided, including: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine body flow; a turbine wheel chamber configured to receive the turbine body flow from the turbine inlet passage, 5, the turbine wheel chamber configured to receive a turbine wheel, the turbine wheel being supported for rotation; a turbine outlet passage configured to receive the turbine body flow from the turbine wheel chamber, the turbine outlet passage being at least partially defined by a turbine outlet passage surface, and the turbine outlet passage defining a centerline; an auxiliary channel configured to receive a portion of the turbine body flow, the portion of the turbine body flow received by the auxiliary channel defining an auxiliary flow; and a dosing module configured to deliver a spray of an after-treatment fluid into the turbine outlet passage; wherein the auxiliary channel is configured to direct the auxiliary flow in an auxiliary flow layer along the turbine outlet channel surface.

Description

Background Art

[0001] Turbochargers are used in internal combustion engine systems to increase the pressure of the intake air entering the engine to a pressure above atmospheric pressure. This is called "boosting." By increasing the pressure of the intake air entering the engine, more oxygen is available in the engine to support the combustion of a larger amount of fuel, thereby increasing the amount of power produced by the engine.

[0002] A turbocharger includes a compressor and a turbine. The compressor includes a compressor wheel configured to impart energy to an incident fluid flow, and the turbine includes a turbine wheel configured to extract energy from the incident fluid flow. The compressor impeller and the turbine impeller are attached to opposite ends of the turbocharger shaft so that both rotate synchronously. The compressor receives intake air from the atmosphere and delivers the intake air to the intake manifold of the internal combustion engine. The turbine receives exhaust gas from the exhaust manifold of the internal combustion engine and delivers the exhaust gas to the aftertreatment system. During use, exhaust gas exiting the internal combustion engine travels through the turbine, causing the turbine impeller to rotate. The rotation of the turbine impeller drives the compressor impeller, which is used to compress the intake air as it is delivered to the intake manifold.

[0003] Exhaust gas from internal combustion engines contains substances that are harmful to the environment. Most countries have vehicle emissions standards that limit the amount of these substances that internal combustion engine systems are allowed to emit. Therefore, modern internal combustion engine systems include exhaust aftertreatment systems designed to remove harmful substances from the exhaust gas.

[0004] Typically, an exhaust aftertreatment system will include a particulate filter and one or more catalytic reducers. The particulate filter removes heavy combustion products, such as soot, from the exhaust. The catalytic reducer removes harmful substances such as nitrogen oxides (NOx) from the exhaust. The catalytic reducer typically includes a large number of narrow passages made of materials selected to support the chemical reaction that removes NOx from the exhaust. The narrow passages provide a large surface area for the catalytic reaction to occur. There are several types of catalytic reducers on the market, such as two-way catalytic reducers, three-way catalytic reducers, diesel oxidation catalytic reducers (DOCs), and selective catalytic reducers (SCRs). DOCs and SCRs are typically used in diesel engine systems. Specifically, for SCRs, in order for the SCR reaction to work, an exhaust aftertreatment fluid must be mixed with the exhaust before the exhaust enters the catalytic reducer. The exhaust aftertreatment fluid is typically a mixture of approximately 30% to 35% urea (CO(NH2)2) by volume and approximately 65% ​​to 70% deionized water (H2O) by volume. Exhaust aftertreatment fluids are commonly referred to as Diesel Exhaust Fluid (DEF) and are commonly available under the registered trademark AdBlue.

[0005] Conventionally, DEF is mixed with exhaust gas in a decomposition chamber. DEF is injected into the decomposition chamber using a dosing module. Within the decomposition chamber, heat is transferred from the exhaust gas to the DEF, causing the water within the DEF to evaporate and the urea to thermally decompose into the reducing agents ammonia (NH3) and isocyanic acid (HNCO) required to support the SCR reaction.

[0006] Compared to the width of a standard exhaust duct, a typical decomposition chamber has a relatively large cross-sectional area. Exhaust gas entering the decomposition chamber expands, resulting in a decrease in exhaust velocity and an increase in exhaust pressure. This rapid expansion of the exhaust gas causes the formation of turbulent eddies. DEF is then injected into the decomposition chamber, where the turbulent eddies promote mixing of the DEF with the exhaust gas. Heat exchange between the exhaust gas and DEF decomposes the urea in the DEF into a reductant, which is then transferred to the SCR.

[0007] If the exhaust and DEF are not mixed sufficiently, the heat exchange between the DEF and the exhaust will not be sufficient to decompose the DEF into the required reductants. In addition, poor mixing means that the reductants are not evenly distributed in the flow, and therefore some passages of the catalytic reducer will not receive enough reductants to support the SCR reaction. In order to ensure sufficient mixing, the decomposition chamber typically includes a mixing plate that is configured to generate additional turbulence. However, the additional turbulence caused by the mixing plate and the fluid friction applied to the exhaust by the mixing plate create back pressure on the exhaust in the decomposition chamber. This back pressure is transmitted upstream and acts to increase the pumping work required by the internal combustion engine and thus reduces the overall efficiency of the engine system.

[0008] In turbocharged engine systems, the exhaust gas exiting the turbine wheel typically has very high velocities and exhibits pronounced directional characteristics, such as high swirl around the turbine axis. Consequently, the flow regime in the immediate vicinity of the turbine wheel outlet is typically laminar and poorly mixed. This makes the turbine outlet an unsuitable location for locating a dosing module. Furthermore, the narrow geometry of the turbine outlet passageway means that any injected aftertreatment fluid is likely to impact the surfaces defining the turbine outlet. To support adequate mixing and reduce the risk of impact, the decomposition chamber and dosing module are typically positioned downstream of the turbine outlet passageway and at a distance from the turbine itself to allow for turbulent flow. However, as the exhaust gas exits the turbine wheel, it loses energy due to duct friction and transient heat dissipation. Consequently, when the decomposition chamber is located further away from the turbine, less heat is available to initiate the decomposition of the DEF.

[0009] Furthermore, when the aftertreatment fluid is injected into the exhaust, some of it may impact one or more surfaces of the network, risking solidification and forming a blockage in the turbine outlet passage. This blockage can increase the back pressure of the internal combustion engine, thereby increasing pumping work and reducing the power output of the engine system.

[0010] The amount of nitrogen oxides (NOx) produced by an internal combustion engine will vary depending on the operating conditions of the engine. When more NOx is produced, a greater mass of reducing agent is required to support the SCR reaction in order to sufficiently reduce the NOx content in the exhaust gas to below an acceptable level. However, if too much DEF is introduced into the exhaust gas stream, there is an increased risk that the DEF may impinge on surfaces of the exhaust gas aftertreatment system and solidify. Therefore, it is known to adjust the amount of DEF delivered to the exhaust gas stream by a dosing module in proportion to the amount of nitrogen oxides contained in the stream. Typically, such exhaust gas aftertreatment systems are provided with a sensor configured to measure the nitrogen oxide content in the exhaust gas stream.

[0011] However, sensors that are capable of detecting the presence of NOx also detect the presence of other substances, particularly ammonia (NH3) and isocyanic acid (HNCO), and are unable to detect the amount of NOx separately from the other substances. Therefore, the reading from such a sensor is typically proportional to the overall combined amount of NOx, ammonia, and isocyanic acid in the exhaust gas. Therefore, in many cases, if the reducing agent from the decomposed DEF reaches the NOx sensor, the sensor reading will not accurately reflect the actual NOx content in the exhaust gas produced by the engine. One solution to this problem is to provide additional sensors that are configured to sense the presence of ammonia (NH3) and isocyanic acid (HNCO) and to subtract the readings of these sensors from the reading of the NOx sensor. However, due to the increased number of sensors, this arrangement is more expensive to manufacture and more complicated to operate. In addition, it has been found that ammonia condensed on the sensor surface may cause damage to the sensor.

[0012] Aftertreatment fluids such as DEF are typically injected into the exhaust as a spray of droplets. By spraying the aftertreatment fluid, the aftertreatment fluid can be distributed throughout the exhaust. However, even if the aftertreatment fluid is sprayed, it tends to follow the streamlines of the exhaust and therefore does not mix evenly with the exhaust until it has dissipated over the length of the pipe. However, in some engine systems, the pipe may not provide sufficient distance for the aftertreatment fluid to be fully mixed before entering any downstream aftertreatment components (such as SCR). Therefore, there is a need to improve the mixing of the aftertreatment fluid in the pipe downstream of the aftertreatment fluid injection point.

[0013] When an aftertreatment fluid is injected, it typically consists of droplets of a range of sizes. Larger droplets have greater mass than smaller droplets and therefore carry greater momentum. Consequently, larger droplets are more likely to impact the walls of the exhaust pipe. Droplets deposited on the pipe walls can lead to the formation of solid deposits, which can cause backpressure on the engine and reduce overall power output. Therefore, it is necessary to prevent the formation of deposits in the pipes downstream of the aftertreatment fluid injection point. Summary of the Invention

[0014] It is an object of the present invention to obviate or mitigate one or more disadvantages of the prior art, whether described herein or elsewhere.

[0015] According to a first aspect of the present invention, a turbine for a turbocharger is provided, comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine main flow; a turbine impeller chamber configured to receive the turbine main flow from the turbine inlet passage, the turbine impeller chamber configured to accommodate a turbine impeller, the turbine impeller being supported for rotation about a turbine axis; a turbine outlet passage configured to receive the turbine main flow from the turbine impeller chamber; a distribution module configured to deliver a spray of an aftertreatment fluid to a spray region of the turbine outlet passage, the turbine main flow traveling through the spray region; and an auxiliary channel configured to receive a portion of the turbine main flow, the portion of the turbine main flow received by the auxiliary channel defining an auxiliary flow; wherein the auxiliary channel is configured to guide the auxiliary flow into the spray region of the turbine outlet passage.

[0016] The term "turbine bulk flow" encompasses the main flow of exhaust gas passing through the turbine. Mostly, this is the exhaust gas received by the turbine from the internal combustion engine, and this exhaust gas flows from the turbine inlet, through the turbine wheel chamber, and into the turbine outlet, and then travels downstream to the exhaust aftertreatment system, which includes one or more catalytic reducers (e.g., DOC or SCR reducers).

[0017] The term "auxiliary flow" covers the exhaust flow that passes through the auxiliary channel until it completely merges with the main turbine flow and is fluidically indistinguishable. Those skilled in the art will recognize that even when both flows flow through the turbine outlet channel, the auxiliary flow can be distinguished from the main turbine flow by their different flow characteristics. Flow characteristics that can be used to distinguish the auxiliary flow from the main turbine flow include velocity, pressure, temperature, Reynolds number, density, etc. For example, the auxiliary channel can adjust the flow direction of the auxiliary flow within the auxiliary channel. The momentum of the auxiliary flow causes the auxiliary flow to continue to flow in the same direction after entering the turbine outlet channel until sufficient momentum is exchanged with the main turbine flow, the auxiliary flow mixes with the main turbine flow and begins to flow in the same direction as the main turbine flow. At this point, the auxiliary flow and the main turbine flow may become difficult to distinguish from each other.

[0018] The term "spray zone" encompasses the spatial region within the turbine outlet into which the after-treatment fluid is sprayed by the distribution module. Specifically, the spray zone can be a region in which the velocity component of the after-treatment fluid in the spray direction defined by the distribution module is greater than the velocity component in the direction of the turbine's main flow. In other words, the spray zone encompasses the region in which the momentum and behavior of the after-treatment fluid are more influenced by the forces imparted to the after-treatment fluid by the distribution module than by the forces imparted to the after-treatment fluid by the turbine's main flow.

[0019] The term "auxiliary passage" encompasses a passage that is separate from the turbine inlet passage, the turbine wheel chamber, and the turbine outlet passage, and that is capable of receiving exhaust gas from a first location in the turbine and conveying the exhaust gas to a second location in the turbine within the turbine outlet. The portion of the turbine from which the auxiliary passage inlet receives exhaust gas can be essentially any portion of the turbine that receives exhaust gas but does not form part of the auxiliary passage. For example, this can include one or more of the turbine inlet passage, the turbine wheel chamber, the turbine outlet passage, or a wastegate (i.e., bypass) passage.

[0020] The auxiliary passageway being "configured to direct the auxiliary flow into the spray region" encompasses substantially any arrangement of the auxiliary passageway, turbine outlet passageway, and spray region in which the auxiliary flow is caused to pass through the spray region before merging with and becoming indistinguishable from the main turbine flow. That is, the geometry of the auxiliary passageway, turbine outlet, and / or spray region is selected such that the auxiliary flow, having traveled through the auxiliary passageway, fluidically interacts with the after-treatment fluid injected into the spray region by the dosing module at or before the auxiliary flow fully merges and / or mixes with the main turbine flow.

[0021] Since the auxiliary flow is separated from the main flow of the turbine, the auxiliary flow can be adjusted by the auxiliary channel so that the auxiliary flow has fluid properties that are separate from the main flow of the turbine. For example, the geometry of the auxiliary channel can be selected to adjust the direction and speed of the auxiliary flow. Therefore, the auxiliary channel can adjust the auxiliary flow so that the momentum of the auxiliary flow carries the auxiliary flow into the spray area. As the auxiliary flow enters the spray area, the auxiliary flow exchanges momentum with the spray of the after-treatment fluid and the main flow of the turbine. This momentum exchange can be used to provide one or more beneficial effects. In other words, in addition to the energy of the main flow of the turbine and the energy of the after-treatment fluid spray itself, the auxiliary flow will also introduce additional energy into the spray area, and this energy can be used to provide one or more specific beneficial effects.

[0022] Depending on how the auxiliary flow interacts with the main flow of the turbine and the after-treatment fluid in the spray area, various beneficial effects may occur. For example, the auxiliary flow can be delivered in such a way that the auxiliary flow applies high shear forces at the nozzle of the distribution module to keep the nozzle clean from being affected by the after-treatment fluid and thereby reduce the risk of deposits forming at the nozzle. In another example, the auxiliary flow can be delivered in such a way that the momentum of the auxiliary flow is used to carry the after-treatment fluid further into the turbine outlet channel and thereby promote a more uniform distribution of the after-treatment fluid across the entire width of the turbine outlet channel. In yet another example, the auxiliary flow can be delivered in such a way that turbulence is generated within the turbine outlet channel to promote better heat transfer from the exhaust gas to the after-treatment fluid, causing the after-treatment fluid to decompose at a faster rate. Other possible beneficial effects will be apparent from the description.

[0023] The distribution module can include a nozzle configured to generate the spray of the aftertreatment fluid, and the nozzle can be substantially aligned with the side wall of the turbine outlet channel or located radially outside the side wall. In some embodiments, the nozzle can be positioned substantially flush with the side wall of the turbine outlet channel. The term "substantially flush" covers the fact that the distribution module is roughly or precisely aligned with the inner surface of the turbine outlet channel that defines the periphery of the turbine outlet channel. In such embodiments, the nozzle does not protrude into the turbine outlet channel. Therefore, the nozzle does not obstruct the flow through the turbine outlet channel and thus avoids applying back pressure to the internal combustion engine.

[0024] The nozzle of the distribution module can be configured to produce a spray of the after-treatment fluid and can therefore be referred to as a spray generating nozzle or an atomizing nozzle. As described in the introduction, the geometry within the turbine outlet channel is very narrow. When the distribution module including the spray generating nozzle is mounted on the side wall of the turbine outlet, the sprayed after-treatment fluid tends to impact the opposite wall of the turbine outlet. The fluid after impact may solidify, thereby causing blockage, and therefore the side wall of the turbine outlet has historically been considered an unsuitable location for placing the nozzle of the distribution module. However, in this case, since the auxiliary channel delivers the auxiliary flow to the spray of the after-treatment fluid, the auxiliary flow introduces additional energy into the after-treatment fluid. For example, this energy can be used to increase heat transfer to the after-treatment fluid, thereby improving decomposition and reducing the solidification of the after-treatment fluid after impact. Therefore, the use of the auxiliary flow allows the nozzle of the distribution module to be located in a position that was previously impossible.

[0025] The distribution module can be configured to deliver the aftertreatment fluid along a spray direction, and the auxiliary channel can be configured to guide the auxiliary flow into the spray area along an auxiliary flow direction that is approximately normal to the spray direction. The term "spray direction" encompasses the overall or average direction along which the aftertreatment fluid is sprayed from the nozzle. For example, this can be along the longitudinal centerline of the spray area. The term "approximately normal to the spray direction" encompasses a flow with a larger velocity component in a direction orthogonal to the spray direction, but some angular misalignment can be allowed, as described below.

[0026] Because the auxiliary flow is delivered in a direction roughly normal to the spray direction, the auxiliary flow and the after-treatment fluid have higher velocity components in directions orthogonal to each other. Consequently, the auxiliary flow can exert shear forces on the after-treatment fluid in the spray area. This shear force causes the droplets in the spray to break into smaller droplets, thereby increasing the surface area available for heat exchange between the two fluids and promoting faster decomposition of the after-treatment fluid. Furthermore, the shear force introduces turbulence into the spray area, thereby improving mixing of the after-treatment fluid and the exhaust gas, and further increasing the amount of heat exchange between the two fluids.

[0027] The auxiliary flow direction can be tilted at an angle of up to about 30° relative to the normal to the spray direction. "Normal to the spray direction" encompasses an axis lying in a plane orthogonal to the spray direction. In an alternative embodiment, the auxiliary flow direction can be tilted at an angle of up to about 30° relative to the normal to the spray direction.

[0028] It has been found that when the auxiliary flow is inclined within one of the above ranges relative to the normal to the spray direction, the shear force exerted by the auxiliary flow on the after-treatment fluid is sufficient to cause the after-treatment fluid droplets to break up and also introduce sufficient turbulence into the flow to provide improved mixing.

[0029] The dosing module may comprise a nozzle, and the auxiliary channel may be configured to direct the auxiliary flow past the nozzle in a direction generally normal to the spray direction. The term "passing the nozzle" encompasses the auxiliary flow being sufficiently close to the nozzle such that the auxiliary flow generates shear forces on the nozzle.

[0030] During use, droplets of after-treatment fluid may coalesce at the nozzles of the dosing module. If the exhaust gas near the nozzles is not hot enough, ammonia decomposed from the after-treatment fluid will solidify and potentially form deposits that could block or restrict the flow of after-treatment fluid from the nozzles. However, because the auxiliary airflow is directed through the nozzles in a direction roughly orthogonal to the spray direction, it applies shear forces to the nozzles, which act to blow away any droplets that do form at the nozzles. As a result, the nozzles remain clean and the risk of deposit formation is reduced.

[0031] The dispensing module can be configured to convey the post-treatment fluid in a spray direction, and the auxiliary channel can be configured to guide the auxiliary flow into the spray area in an auxiliary flow direction opposite to the spray direction. The term "opposite to the spray direction" encompasses flows in which a velocity component of the flow acting in a direction opposite to the spray direction is greater than a velocity component normal to the spray direction. The direction opposite to the spray direction can include a direction directly opposite to the spray direction or a direction inclined at an angle relative to the direction directly opposite to the spray direction.

[0032] In some cases, the after-treatment fluid delivered to the turbine outlet channel by the distribution module may impact the wall of the turbine outlet channel on the side of the channel opposite the distribution module. The after-treatment fluid after impact may coalesce into large droplets, which may form solid deposits on the wall of the turbine outlet channel. In this arrangement, since the auxiliary flow is delivered in a direction opposite to the spray direction, the momentum of the auxiliary flow and the momentum of the after-treatment fluid act in opposite directions. Therefore, the auxiliary flow can prevent the after-treatment fluid from impacting the wall of the turbine outlet channel. In addition, the momentum exchange between the auxiliary flow and the after-treatment fluid causes the droplets of the after-treatment fluid to break up, thereby increasing the available heat exchange area between the exhaust gas and the after-treatment fluid. The relatively large momentum exchange also generates a large amount of turbulence, which improves the mixing of the after-treatment fluid and the exhaust gas in the spray area. As a result, more heat is exchanged from the exhaust gas to the after-treatment fluid, ensuring that as much of the after-treatment fluid as possible is decomposed into the required reducing agent. This helps to reduce the risk of deposits forming from aftertreatment fluid pooling on surfaces in the turbine outlet passages and also ensures that the reductant is thoroughly and evenly mixed into the bulk turbine flow.

[0033] The auxiliary flow can be oriented in an upstream direction relative to the main turbine flow, and the auxiliary flow direction can be angularly tilted at an angle of between about 50° and about 90° relative to the opposite direction of the spray direction. The term "opposite direction of the spray direction" encompasses a direction directly opposite the spray direction. In alternative embodiments, the auxiliary flow direction can be angularly tilted at an angle of between about 55° and about 80°, or between about 60° and about 70° relative to the opposite direction of the spray direction.

[0034] Because the auxiliary flow is delivered upstream and in the opposite direction of the spray, it has a significant velocity component in the opposite direction of both the after-treatment fluid and the main turbine flow. Consequently, significant turbulence is generated within the spray region. This turbulence promotes the breakup of the after-treatment fluid into smaller droplets and enhances mixing. This results in a faster and more complete breakdown of the after-treatment fluid into the reducing agent.

[0035] The auxiliary flow may be oriented in a downstream direction relative to the main turbine flow, and the auxiliary flow direction may be angularly inclined at an angle of between about 30° and about 90° relative to the opposite direction of the spray direction. In alternative embodiments, the auxiliary flow direction may be angularly inclined at an angle of between about 40° and about 80°, or at an angle of between about 45° and about 70°, or at an angle of about 55° relative to the opposite direction of the spray direction.

[0036] Because the auxiliary flow is delivered counter-directionally to the spray direction, it has a larger velocity component opposite to that of the aftertreatment fluid. This results in droplet breakup of the aftertreatment fluid, leading to increased heat exchange and faster, more complete decomposition. However, because this flow is oriented downstream relative to the main turbine flow, the amount of turbulence generated by the confluence of the main turbine flow and the auxiliary flow in the turbine outlet passage is reduced. Consequently, sufficient turbulence is provided to promote mixing of the aftertreatment fluid and exhaust gas in the spray region, while ensuring that the amount of turbulence does not increase to a level that could significantly hinder flow through the turbine outlet passage and reduce engine system efficiency.

[0037] The auxiliary channel may include an auxiliary channel outlet configured to deliver the auxiliary flow to the turbine outlet channel, and the turbine may further include a barrier member configured to substantially cover the auxiliary channel outlet from the perspective of the distribution module in the spray direction. Thus, the barrier member forms a barrier to prevent the after-treatment fluid from entering the auxiliary channel outlet. Thus, the chance of the after-treatment fluid solidifying and forming solid deposits in the auxiliary channel is reduced or eliminated.

[0038] The auxiliary channel can be configured to guide the auxiliary flow into the turbine outlet channel along an auxiliary flow direction facing the center line of the turbine outlet channel; and the distribution module can be configured to transport the after-treatment fluid along a spray direction facing the center line. The auxiliary channel can be configured to transport the auxiliary flow along the auxiliary flow direction normal to the center line. In some embodiments, the auxiliary channel can be configured to transport the auxiliary flow along an auxiliary flow direction inclined relative to the center line, for example, transporting the auxiliary flow along an auxiliary flow direction inclined to about 45° in an upstream direction or a downstream direction. The distribution module can be configured to transport the after-treatment fluid along a spray direction normal to the center line. In some embodiments, the distribution module can be configured to transport the after-treatment fluid along a spray direction inclined relative to the center line, for example, transporting the after-treatment fluid along a spray direction inclined to about 45° in an upstream direction or a downstream direction.

[0039] The auxiliary channel can be configured to direct the auxiliary flow into the turbine outlet channel along an auxiliary flow direction facing downstream relative to the main turbine flow surface, and the auxiliary flow direction can be inclined at an angle of at least about 45° relative to the centerline of the turbine outlet channel. The "centerline" of the turbine outlet channel encompasses a line defined by the centroid of the turbine outlet channel along the flow direction of the exhaust gas. In the simplest form, the centerline can be a straight line coaxial with the turbine axis. However, in some embodiments, the turbine outlet channel can include complex geometries resulting in a bent, curved, stepped, or inclined centerline.

[0040] The inclination between the auxiliary flow direction and the centerline encompasses the minimum angle between the auxiliary flow direction and the centerline at the point where the auxiliary flow is introduced into the turbine outlet passage. For example, the auxiliary passage may include an auxiliary outlet defining a centroid, and the angle of the auxiliary flow direction may be measured at the centroid of the auxiliary passage outlet relative to a line parallel to the centerline. If the centerline is not straight, the angle may be measured relative to a tangent to the centerline. The centerline position at which the tangent is taken may be the position at which the normal to the centerline passes through the centroid of the auxiliary passage outlet.

[0041] During operation, the velocity of the turbine main flow through the turbine outlet passage is very high. Therefore, if aftertreatment fluid is injected into the turbine outlet in the absence of auxiliary flow, the aftertreatment fluid will be carried downstream by the turbine main flow before it can spread across the entire width of the turbine outlet passage. As a result, only a portion of the turbine main flow will carry the aftertreatment fluid, and the SCR reaction will only occur in a small portion of the SCR reducer (because the reductant required to support the SCR reaction is not present).

[0042] However, when the auxiliary flow direction is inclined in the downstream direction relative to the centerline of the turbine outlet channel, the auxiliary flow contains a velocity component that is normal to the flow direction of the main turbine flow (i.e., one of the substantially orthogonal components of the velocity vector of the auxiliary flow). Due to the normal component of velocity, when the auxiliary flow enters the turbine outlet channel, the auxiliary flow not only travels in the downstream direction, but also travels across part or all of the width of the turbine outlet channel. When the auxiliary flow travels through the spray area, the auxiliary flow will transfer part of its momentum to the after-treatment fluid to carry the after-treatment fluid across a larger proportion of the width of the turbine outlet channel. In other words, the auxiliary flow is used to "pick up" the after-treatment fluid in the spray area and carry the after-treatment fluid across a larger range of the width of the turbine outlet channel. Therefore, the after-treatment fluid is distributed more evenly across the turbine outlet channel and is not concentrated in a localized portion of the main turbine flow.

[0043] It will be appreciated that because the auxiliary flow and the main turbine flow face in a downstream direction, the two fluid flows can merge with relatively minimal turbulence. Minimizing turbulence between the auxiliary flow and the main turbine flow can reduce backpressure on the turbine and internal combustion engine, which could otherwise adversely affect engine performance.

[0044] The extent to which the auxiliary flow and aftertreatment fluid are carried across the width of the turbine outlet passage will depend on the magnitude of the normal component of the auxiliary flow velocity relative to the velocity of the main turbine flow. It has been found that for most turbocharger operating conditions, an angle of at least about 45° is required to significantly increase the penetration of the aftertreatment fluid across the main turbine flow.

[0045] The auxiliary flow direction can be inclined at an angle in the range of about 45° to about 90° relative to the center line, or at an angle in the range of about 45° to about 60°. Generally speaking, the greater the angle between the auxiliary flow direction and the center line, the farther the aftertreatment fluid is carried across the turbine outlet channel. If the angle is too gentle, the aftertreatment fluid may not be able to penetrate the entire range of the channel. However, if the angle is too steep, the aftertreatment fluid may impact the wall of the turbine outlet channel opposite to the distribution module. The aftertreatment fluid may solidify into a deposit that restricts flow through the turbine outlet channel. It has been found that by keeping the angle between the auxiliary flow direction and the center line within the above range, a balance between these two factors can be found so that the aftertreatment fluid is more evenly distributed across the turbine outlet channel, but the impact on the wall of the turbine outlet channel is minimized.

[0046] The auxiliary channel can be configured to direct the auxiliary flow into the turbine outlet channel along an auxiliary flow direction facing upstream relative to the main turbine flow, and the auxiliary flow direction can be inclined at an angle of at least about 45° relative to the centerline of the turbine outlet channel. Because the auxiliary flow and the main turbine flow face in substantially opposite directions, a relatively large amount of turbulence is generated at the point where the two fluid flows meet. This can be used to increase turbulence in the spray region and thereby provide improved mixing of the aftertreatment fluid with the exhaust gas. Generally, when the auxiliary flow direction faces upstream relative to the main turbine flow, the smaller the angle between the auxiliary flow direction and the centerline, the more opposite the direction of the auxiliary flow and the direction of the main turbine flow are to each other. This results in increased turbulence at the point where the two fluid flows meet. If the turbulence in the turbine outlet channel is too high, this may cause flow restriction that hinders the main turbine flow. It has been found that a minimum angle of about 45° between the auxiliary flow direction and the centerline is necessary to keep the amount of turbulence generated below an acceptable level.

[0047] The auxiliary flow direction can be inclined relative to the centerline at an angle in the range of about 45° to about 90°. If the angle between the auxiliary flow direction and the centerline is too shallow when the auxiliary flow direction faces upstream relative to the main turbine flow, excessive turbulence may result. However, if the angle is too steep, the aftertreatment fluid may be prevented from fully penetrating the entire width of the turbine outlet passage. It has been found that an angle between the auxiliary flow direction and the centerline in the range of about 45° to about 60° provides a good balance between these two factors.

[0048] The distribution module may define a spray direction, and the turbine outlet passage may define a centerline, and the spray direction may be oriented generally normal to the centerline. That is, the distribution module is oriented such that it injects the aftertreatment fluid in a direction generally normal to the centerline.

[0049] Since the aftertreatment fluid is directed in a direction generally normal to the centerline, the momentum of the aftertreatment fluid can carry the aftertreatment fluid across the width of the turbine outlet passage, thereby evenly distributing the aftertreatment fluid across the turbine outlet passage.

[0050] The dosing module may define a spray direction, and the spray direction may be oriented upstream relative to the turbine body flow. That is, the dosing module is oriented so that it injects the aftertreatment fluid in a direction having a velocity component upstream relative to the turbine body flow.

[0051] Since the aftertreatment fluid is injected upstream, it carries a momentum component that opposes the momentum of the main turbine flow. This increases the collision amplitude between the main turbine flow and the aftertreatment fluid, causing the aftertreatment fluid to break up into smaller droplets. Smaller droplets have a larger surface area for heat exchange and are therefore able to more quickly break down the desired reductant.

[0052] The spray direction can be tilted at an angle of up to about 90° relative to the normal to the centerline. "Normal to the centerline" refers to a line perpendicular to the centerline, such as a line perpendicular to the centerline at a point on the centerline. If the centerline is curved, the normal is a line perpendicular to a tangent to the centerline at a point on the centerline.

[0053] Generally, as the angle between the spray direction and the centerline increases in the upstream direction, the collision amplitude increases accordingly. Therefore, the spray direction can be oriented up to 90° relative to the centerline, facing directly in the opposite direction of the turbine's main flow. However, this reduces the extent to which aftertreatment fluid is carried across the turbine's outlet passage. It has been found that a balance between these two factors is achieved when the spray direction is tilted from about 10° to about 45° relative to the centerline.

[0054] The dosing module may define a spray direction, and the spray direction may be oriented downstream relative to the turbine main flow. That is, the dosing module is oriented so that it injects the aftertreatment fluid into the turbine outlet passage in a generally downstream direction relative to the direction of the turbine main flow.

[0055] Because the spray direction is generally oriented downstream, the momentum of the aftertreatment fluid acts in the same direction as the momentum of the main turbine flow, and therefore the two fluid streams can merge with less flow disturbance. Therefore, adding the aftertreatment fluid does not add additional turbulence to the main turbine flow. This is useful, for example, for keeping the overall amplitude of turbulence in the main flow below an acceptable level so that it does not restrict flow through the turbine outlet channel. For example, the auxiliary flow can be introduced into the turbine outlet channel in a manner configured to generate a relatively large amount of turbulence (e.g., facing upstream). In this case, the main turbine flow may already be turbulent enough so that thorough mixing will occur once the aftertreatment fluid is injected.

[0056] The spray direction can be tilted up to about 90° relative to the normal to the centerline. Generally, as the angle between the spray direction and the centerline increases in the downstream direction, less turbulence is generated. Therefore, the spray direction can be oriented up to 90° relative to the centerline, so that it directly faces the main turbine flow. However, this reduces the extent to which aftertreatment fluid is carried across the turbine outlet passage. It has been found that a balance between these two factors is achieved when the spray direction is tilted up to about 45° relative to the centerline.

[0057] The auxiliary passage can be configured to allow the auxiliary flow to be delivered to the turbine outlet passage during all operating conditions of the turbine when receiving exhaust gas from the internal combustion engine. For example, the auxiliary passage can be substantially free of any structure configured to selectively restrict, reduce, or prevent flow along the auxiliary passage. In one embodiment, the auxiliary passage can be substantially free of valves, and in particular, free of a wastegate valve. In another embodiment, the auxiliary passage can include a valve, such as a wastegate valve, however, the valve can be configured so that leakage through the valve is always permitted.

[0058] Since the auxiliary flow is allowed to be delivered to the turbine outlet passage under all operating conditions of the turbine, this ensures that there is always an auxiliary flow that can provide one or more beneficial effects.

[0059] The auxiliary channel can define a cross-section perpendicular to the direction of the auxiliary flow, and the size of the narrowest part of the cross-section can be set so that the mass flow rate of the auxiliary flow does not exceed about 5% of the mass flow rate of the exhaust gas delivered from the engine to the turbine inlet channel. Therefore, the flow rate of the auxiliary flow is large enough so that the auxiliary flow can affect the aftertreatment fluid and the main turbine flow in the turbine outlet channel, but the flow rate of the auxiliary flow is small enough so that the auxiliary flow does not reduce the overall efficiency of the turbine. Generally, the smaller the auxiliary flow, the higher the efficiency of the turbine. Preferably, the size of the cross-section of the auxiliary channel is set so that the mass flow rate of the auxiliary flow does not exceed about 1% or about 2% of the mass flow rate of the exhaust gas delivered to the turbine inlet channel.

[0060] The auxiliary passage may include: an auxiliary passage inlet positioned in the turbine inlet passage; and an auxiliary passage outlet positioned in the turbine outlet passage. In other words, the auxiliary passage may bypass the turbine wheel. When the auxiliary flow originates from the turbine inlet passage, the auxiliary flow typically has a higher pressure and temperature than the main turbine flow in the turbine outlet passage, and thus can provide more energy for interaction with the aftertreatment fluid.

[0061] The auxiliary passage can include a valve configured to control flow through the auxiliary passage. In this manner, the auxiliary passage can function as a wastegate passage. The valve can be configured to allow a small amount of leakage when the valve is in a closed configuration. The leakage can be large enough to support specific interactions with the turbine bulk flow and aftertreatment fluid in the turbine outlet passage, such as nozzle cleaning, while being small enough not to negatively impact turbine performance.

[0062] The valve may be configured such that the auxiliary flow is allowed to pass through the valve during all operating conditions of the turbine. In this way, the auxiliary flow is always able to influence the aftertreatment fluid and the turbine main flow in the turbine outlet passage.

[0063] The valve can be configured such that the auxiliary flow passing through the valve always accounts for at least about 0.1% of the mass flow of exhaust gas delivered from the engine to the turbine inlet passage. The greater the amount of auxiliary flow allowed, the greater the effect of the auxiliary flow on the aftertreatment fluid in the turbine outlet passage and the turbine main flow. In alternative embodiments, the valve can be configured such that the auxiliary flow passing through the valve always accounts for at least about 0.2%, about 0.5%, about 1%, about 2%, or about 5% of the mass flow of exhaust gas delivered from the engine to the turbine inlet passage.

[0064] In addition to the auxiliary passage, the turbine may also include a wastegate arrangement, which may include: a wastegate passage fluidly connecting the turbine inlet passage and the turbine outlet passage so that exhaust gas traveling through the wastegate passage does not travel through the turbine wheel chamber; and a wastegate valve configured to selectively allow or prevent fluid flow through the wastegate passage. The term "wastegate passage" encompasses a fluid-carrying passage that is configured to provide fluid flow communication between the turbine inlet passage and the turbine outlet passage while bypassing the turbine wheel and the turbine wheel chamber. The flow through the wastegate passage may be referred to as wastegate flow. The wastegate arrangement may be independent of and in addition to the auxiliary passage arrangement. That is, the turbine may include an auxiliary passage and a wastegate passage that are separate from each other.

[0065] The wastegate passage can be configured to direct the wastegate flow into the spray region of the turbine outlet passage. By doing so, when the auxiliary flow is directed into the spray region of the turbine outlet passage, the wastegate device can affect the aftertreatment fluid and the main turbine flow in the same manner as described above. It should be understood that the wastegate device can deliver the wastegate flow in a manner corresponding to any of the configurations described herein related to the auxiliary flow. For example, the wastegate device can be used to support nozzle cleaning of a dosing module, increase turbulence in the turbine outlet passage, prevent aftertreatment fluid from impacting the walls of the turbine outlet passage, and the like.

[0066] The wastegate passage may fluidly merge with the auxiliary passage such that the wastegate passage is in fluid communication with the turbine outlet passage via the auxiliary passage. That is, the wastegate passage is in direct fluid communication with the auxiliary passage such that, during use, when the wastegate valve is open, exhaust gas passes through the wastegate passage into the auxiliary passage and then continues to flow toward the turbine outlet passage.

[0067] Compared to an arrangement in which the wastegate and auxiliary passages are completely separate, this arrangement can be more compact and easier to manufacture. Furthermore, in this arrangement, the wastegate flow merges with the auxiliary flow and becomes part of it. Typically, the wastegate flow has a much greater flow rate than the auxiliary flow, and thus the wastegate flow can effectively be "added" to the auxiliary flow, increasing the magnitude of the benefit provided by the auxiliary flow. This is particularly beneficial when the auxiliary flow does not originate from a location upstream of the turbine outlet, as in this arrangement, the wastegate flow would have a higher pressure than the auxiliary flow.

[0068] The dosing module may be configured to deliver the after-treatment fluid to the turbine outlet passage via the auxiliary passage. That is, the nozzle of the dosing module may be positioned within the auxiliary passage such that, during use, the dosing module delivers the after-treatment fluid to the auxiliary passage, the after-treatment fluid traveling through the auxiliary passage and into the turbine outlet passage.

[0069] The auxiliary passage may include an auxiliary passage inlet configured to receive exhaust gas from the turbine outlet passage and an auxiliary passage outlet configured to deliver exhaust gas to the turbine outlet passage.

[0070] The auxiliary passage may include an outlet portion extending from the nozzle to the auxiliary passage outlet, the outlet portion may define an outlet axis, and the outlet axis may be tilted relative to the centerline of the turbine outlet passage at an angle of up to about 70°. In alternative embodiments, the outlet axis may be tilted relative to the centerline at an angle between about 20° and about 70°, between about 30° and about 60°, between about 40° and about 50°, or at an angle of about 45°. The relative angle between the outlet axis and the centerline may be measured at the centroid of the auxiliary passage outlet.

[0071] Due to the momentum carried by the mixture of auxiliary flow and aftertreatment fluid traveling through the outlet portion of the auxiliary channel, the likelihood of aftertreatment fluid impacting the wall of the turbine outlet channel opposite the auxiliary channel outlet increases as the angle between the outlet axis and the centerline increases. Aftertreatment fluid that impacts the wall of the turbine outlet may not be hot enough to evaporate and may result in the formation of deposits. Although this can be mitigated by reducing the angle between the outlet axis and the centerline, if the angle is too small, the length of the auxiliary channel must be increased and, therefore, the auxiliary channel outlet must be placed further downstream (and possibly outside the preferred distance from the turbine wheel outlet inducer as discussed below). It has been found that when the angle between the outlet axis and the centerline is within the above-mentioned range, this reduces the risk of aftertreatment fluid impacting the wall of the turbine outlet channel while keeping the auxiliary channel compact.

[0072] The auxiliary passage may include an inlet portion extending from an auxiliary passage inlet to the nozzle, the inlet portion may define an inlet axis, and wherein the inlet axis may be tilted relative to a centerline of the turbine outlet passage at an angle between about 20° and about 70°. In alternative embodiments, the inlet axis may be tilted relative to the centerline at an angle between about 30° and about 60°, between about 40° and about 50°, or at an angle of about 45°. The relative angle between the inlet axis and the centerline may be measured at the centroid of the auxiliary passage inlet.

[0073] As the angle of the auxiliary passage's inlet axis increases, the momentum change required for the exhaust to enter the auxiliary passage increases, creating flow resistance. However, if the inlet axis angle is too small, the auxiliary passage must be made longer. It has been found that when the angle between the inlet axis and the centerline is within the aforementioned range, this reduces the momentum change required for the exhaust to enter the auxiliary passage while maintaining a compact overall length.

[0074] The cross-sectional area of ​​the outlet portion of the auxiliary channel may increase along the outlet axis from the nozzle of the dosing module to the auxiliary channel outlet. That is, the second portion of the auxiliary channel comprises a diverging side that diverges outwardly in the direction of the auxiliary channel outlet.

[0075] The distribution module will produce a fine spray of atomized post-treatment fluid, which is ejected from the end of the distribution module in a cone shape. In some embodiments, the outlet portion of the auxiliary channel expands at an angle approximately equal to or greater than the spray cone angle of the nozzle. For example, the spray cone angle can be about 45° to about 50°, and the outlet portion can expand at an angle of about 60°. In such an embodiment, since the outlet portion of the auxiliary channel expands at the same or higher rate as the spray cone, this reduces the risk of the post-treatment fluid impacting the auxiliary channel wall. However, if the outlet portion expands at too steep an angle, the auxiliary flow will slow down, causing the auxiliary flow to lose the potential energy that affects the flow in the turbine outlet channel. Therefore, in an alternative embodiment, the spray cone angle can be the same as described above, while the outlet portion of the auxiliary channel expands at a more gentle angle, for example, about 5° to 10°. Although the post-treatment fluid may impact the wall of the outlet portion, the velocity of the auxiliary flow will remain high, so that the shear force will clean any impacted post-treatment fluid from the wall to avoid deposit formation.

[0076] The turbine outlet passage may define a diffuser portion, and the distribution module may be oriented so that the spray area is located within the diffuser portion. The term "diffuser portion" encompasses a portion of the turbine outlet passage, wherein the cross-sectional area of ​​the turbine outlet passage increases along the centerline of the turbine outlet passage. The diffuser portion may be, for example, a diffuser having a straight axis with frustoconical walls that taper outwardly relative to the turbine body flow. Such an axial diffuser may be axially aligned with the turbine axis. However, in alternative embodiments, substantially any expansion geometry may be used to define the diffuser portion. For example, the diffuser portion may include one or more bends.

[0077] In such an arrangement, the purpose of the diffuser section is to decelerate and increase the pressure of the turbine main flow according to the Bernoulli principle. Since the turbine outlet is connected to the atmosphere, the exhaust pressure downstream of the turbine outlet will be approximately atmospheric pressure. By using a diffuser, the pressure of the main flow immediately downstream of the turbine impeller can be reduced, thereby increasing the pressure difference on the turbine impeller and allowing more energy to be extracted from the turbine main flow. Due to the expansion of the turbine main flow, turbulence will naturally be generated in the diffuser section. By aligning the distribution module relative to the diffuser section so that the spray area is positioned within the diffuser section, natural turbulence can be utilized to provide improved mixing of the aftertreatment fluid, and thus promote faster and more complete decomposition. In addition, the expanded diameter of the diffuser section reduces the amount of aftertreatment fluid that impacts the wall, and therefore reduces the risk of deposit formation. In addition, the diffuser enables the distributor to naturally tilt downstream, and thus improves the integration of the distributor with the turbine housing components.

[0078] The turbine may include a turbine wheel having an outlet inducer portion, the outlet inducer portion defining an outlet inducer diameter, and the distribution module may be oriented such that at least a portion of the spray region is positioned within about 10 outlet inducer diameters from the turbine wheel relative to the centerline of the turbine outlet passage. The term "exit inducer portion" encompasses the portion of the turbine wheel that serves as the turbine wheel outlet (i.e., at the distal end of the turbine wheel from the perspective of the main turbine flow flowing therethrough). The term "exit inducer diameter" encompasses the diameter of the outlet inducer portion at the distalmost portion of the turbine wheel from the perspective of the main turbine flow. It has been found that the main flow maintains a relatively high velocity until at least about 4 or 5 outlet inducer diameters downstream of the turbine wheel. Therefore, in alternative embodiments, the spray region may be positioned within a range of no more than about 5, about 3, or about 2 outlet inducer diameters from the turbine wheel relative to the centerline, such that the aftertreatment fluid interacts with the main flow in the high velocity region.

[0079] As the turbine body flow exits the turbine wheel, its temperature is at its hottest relative to any location downstream. Generally speaking, the hotter the turbine body flow, the more heat is available for heat exchange with the aftertreatment fluid, thereby promoting decomposition into the desired reductants. Positioning and orienting the distribution module so that the spray area is closer to the turbine wheel ensures that more heat is provided, resulting in faster and more complete decomposition of the aftertreatment fluid. Experimental results have shown that when the spray area is farther from the turbine wheel along the centerline than approximately 10 inducer diameters, heat dissipates from the turbine body flow, and the decomposition rate decreases.

[0080] The turbine may include a housing having a mounting structure to which the dosing module is mounted and which may define an aperture through which a nozzle of the dosing module passes. The housing may be essentially any solid body that forms part of a structure defining a turbine inlet passage, a turbine wheel passage, a turbine outlet passage, auxiliary passages, and / or any other passages that may be present (e.g., a wastegate passage, an exhaust gas recirculation passage, etc.) as appropriate. In particular, the housing may be part of an assembly of various housing components that define portions of the various passages of the turbine as described above.

[0081] This enables the dosing module to deliver the aftertreatment fluid to the turbine outlet passage as the nozzle passes through the hole in the housing.

[0082] The aperture may be positioned no more than about 10 inducer diameters from the turbine wheel relative to a centerline of the turbine outlet passage.

[0083] According to a second aspect of the present invention, a method for operating a turbine for a turbocharger is provided, which includes: receiving exhaust gas from an internal combustion engine into a turbine inlet channel, the exhaust gas received by the turbine inlet channel defining a turbine main flow; receiving the turbine main flow from the turbine inlet channel into a turbine impeller chamber, the turbine impeller chamber being configured to accommodate a turbine impeller, the turbine impeller being supported to rotate about a turbine axis; receiving the turbine main flow from the turbine impeller chamber into a turbine outlet channel; using a dosing module to deliver an after-treatment fluid to a spray region of the turbine outlet channel, the turbine main flow traveling through the spray region; receiving a portion of the turbine main flow into an auxiliary channel, the portion of the turbine main flow received by the auxiliary channel defining an auxiliary flow; and guiding the auxiliary flow into the spray region of the turbine outlet channel.

[0084] The dosing module may be configured to deliver the after-treatment fluid in a spray direction, and the method may further include directing the auxiliary flow into the spray region in an auxiliary flow direction that is generally normal to the spray direction.

[0085] The auxiliary flow direction may be angled at an angle of up to about 30° relative to the normal to the spray direction.

[0086] The dosing module may include a nozzle, and the method may further include directing the auxiliary flow through the nozzle in a direction generally normal to the spray direction.

[0087] The dosing module may be configured to deliver the after-treatment fluid in a spray direction, and wherein the method may further include directing the auxiliary flow into the spray area in an auxiliary flow direction opposite to the spray direction.

[0088] The method may further include orienting the auxiliary flow direction in an upstream direction relative to the main turbine flow and tilting the auxiliary flow direction relative to an opposite direction of the spray direction by an angle of approximately 45°.

[0089] The method may further include orienting the auxiliary flow direction in a downstream direction relative to the turbine main flow and tilting the auxiliary flow direction relative to an opposite direction of the spray direction by an angle of approximately 45°.

[0090] The auxiliary channel may include an auxiliary channel outlet configured to deliver the auxiliary flow to the turbine outlet channel, and the method may further include shielding the auxiliary channel outlet from the after-treatment fluid using a barrier member, the barrier member being configured to substantially cover the auxiliary channel outlet from the perspective of the distribution module in the spray direction.

[0091] The auxiliary passage may be configured to direct the auxiliary flow into the turbine outlet passage in an auxiliary flow direction facing a centerline of the turbine outlet passage; and may further include directing the aftertreatment fluid in a spray direction facing the centerline.

[0092] The method may further include directing the auxiliary flow into the turbine outlet passage in an auxiliary flow direction facing downstream relative to the turbine main flow, and the auxiliary flow direction may be inclined at an angle of at least about 45° relative to a centerline of the turbine outlet passage.

[0093] The auxiliary flow direction may be inclined at an angle in a range of about 45° to about 90° relative to the centerline.

[0094] The method may further include directing the auxiliary flow into the turbine outlet passage in an auxiliary flow direction facing upstream relative to the turbine main flow, and the auxiliary flow direction may be inclined at an angle of at least about 45° relative to a centerline of the turbine outlet passage.

[0095] The auxiliary flow direction may be inclined at an angle in a range of about 45° to about 90° relative to the centerline.

[0096] The dosing module may define a spray direction and the turbine outlet passage may define a centerline, and the method may include orienting the spray direction substantially normal to the centerline.

[0097] The dosing module may define a spray direction, and the method may include orienting the spray direction upstream relative to the turbine body flow direction.

[0098] The spray direction may be inclined at an angle of up to about 90° relative to the normal to the centerline.

[0099] The dosing module may define a spray direction, and the method may include orienting the spray direction flow downstream relative to the turbine body.

[0100] The spray direction may be inclined at an angle of up to about 90° relative to the normal to the centerline.

[0101] The auxiliary passage may be configured to allow delivery of the auxiliary flow to the turbine outlet passage during all operating conditions of the turbine when receiving exhaust gas from the internal combustion engine.

[0102] The auxiliary passage may define a cross section perpendicular to the direction of the auxiliary flow, and the narrowest portion of the cross section may be sized such that the mass flow of the auxiliary flow does not exceed approximately 5% of the mass flow of exhaust gas delivered from the engine to the turbine inlet passage.

[0103] The auxiliary passage may include: an auxiliary passage inlet positioned in the turbine inlet passage; and an auxiliary passage outlet positioned in the turbine outlet passage.

[0104] The auxiliary passage may include a valve configured to control flow through the auxiliary passage.

[0105] The valve may be configured such that the auxiliary flow is allowed to pass through the valve during all operating conditions of the turbine.

[0106] The valve may be configured such that the auxiliary flow through the valve always represents at least about 1% of the mass flow of exhaust gas delivered from the engine to the turbine inlet passage.

[0107] The turbine may also include a wastegate device, which may include: a wastegate passage, which fluidly connects the turbine inlet passage and the turbine outlet passage so that exhaust gas passing through the wastegate passage does not pass through the turbine impeller chamber; and a wastegate valve, which is configured to selectively allow or prevent fluid flow through the wastegate passage.

[0108] The wastegate passage may be configured to direct wastegate flow into the spray region of the turbine outlet passage.

[0109] The wastegate passage may fluidly merge with the auxiliary passage such that the wastegate passage is in fluid communication with the turbine outlet passage via the auxiliary passage.

[0110] The distribution module may be configured to deliver the aftertreatment fluid to the turbine outlet passage via the auxiliary passage.

[0111] The auxiliary passage may include an auxiliary passage inlet configured to receive exhaust gas from the turbine outlet passage and an auxiliary passage outlet configured to deliver exhaust gas to the turbine outlet passage.

[0112] The auxiliary passage may include an outlet portion extending from the nozzle to the auxiliary passage outlet, the outlet portion may define an outlet axis, and the outlet axis may be inclined relative to a centerline of the turbine outlet passage by an angle of up to about 70°.

[0113] The auxiliary passage may include an inlet portion extending from an auxiliary passage inlet to the nozzle, the inlet portion may define an inlet axis, and the inlet axis may be inclined at an angle between about 20° and about 70° relative to a centerline of the turbine outlet passage.

[0114] The cross-sectional area of ​​the outlet portion of the auxiliary channel may increase along the outlet axis from the nozzle of the dosing module to the auxiliary channel outlet.

[0115] The turbine outlet passage may define a diffuser portion, and the dosing module may be oriented such that the spray region is located within the diffuser portion.

[0116] The turbine may include a turbine wheel having an outlet inducer portion defining an outlet inducer diameter, and the dosing module may be oriented such that at least a portion of the spray area is positioned within approximately 10 outlet inducer diameters of the turbine wheel relative to a centerline of the turbine outlet passage.

[0117] The turbine may include a housing having a mounting structure to which the dosing module is mounted, and the housing may define a bore through which a nozzle of the dosing module passes.

[0118] The aperture may be positioned relative to a centerline of the turbine outlet passage within a range of no more than about 10 inducer diameters from the turbine wheel.

[0119] According to a third aspect of the present invention, a turbine for a turbocharger is provided, comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine main flow; a turbine impeller chamber configured to receive the turbine main flow from the turbine inlet passage, the turbine impeller chamber configured to accommodate a turbine impeller, the turbine impeller being supported for rotation; a turbine outlet passage configured to receive the turbine main flow from the turbine impeller chamber A chamber receives the turbine main flow, the turbine outlet channel is at least partially defined by a turbine outlet channel surface, and the turbine outlet channel defines a centerline; an auxiliary channel, the auxiliary channel is configured to receive a portion of the turbine main flow, the portion of the turbine main flow received by the auxiliary channel defines an auxiliary flow; and a distribution module, the distribution module is configured to deliver a spray of after-treatment fluid into the turbine outlet channel; wherein the auxiliary channel is configured to guide the auxiliary flow along the turbine outlet channel surface in an auxiliary flow layer.

[0120] The creation of an auxiliary flow layer, which encompasses the layer of fluid flowing over the turbine outlet passage surface and exerts shear on the surface, offers a number of distinct advantages.

[0121] First, the auxiliary flow layer can act as a fluid barrier that substantially inhibits the after-treatment fluid from reaching the surface of the turbine outlet channel. In this context, it should be understood that the fluid barrier covers the fluid interaction between the auxiliary flow and the after-treatment fluid, wherein momentum is exchanged between the two fluids in such a way that the after-treatment fluid is deflected away from the surface of the turbine outlet channel. In particular, the auxiliary flow exerts a shear force on the after-treatment fluid, thereby preventing the after-treatment fluid from contacting the surface of the turbine outlet channel or substantially reducing the amount of after-treatment fluid that can contact the surface of the turbine outlet channel. The shear force can further cause the droplets of the after-treatment fluid to break up, thereby reducing their relative mass and making the droplets more easily deflected. Therefore, the auxiliary flow layer acts as a "cushion" that inhibits the after-treatment fluid from contacting the surface of the turbine outlet channel. Therefore, the droplets of the after-treatment fluid are less likely to solidify on the surface of the turbine outlet channel.

[0122] Second, the shearing effect of the auxiliary flow layer acts to "disperse" any aftertreatment fluid that reaches the surface of the turbine outlet passage. In other words, the auxiliary flow layer thins any aftertreatment fluid film that forms on the turbine outlet passage. This "thinning" or "dispersing" effect increases the surface area of ​​the aftertreatment fluid, thereby allowing more heat to be transferred to the aftertreatment fluid. Because more heat is transferred to the aftertreatment fluid, the aftertreatment fluid evaporates more easily. This improves the decomposition of the aftertreatment fluid and reduces the chance of it solidifying and forming a blockage in the turbine outlet passage.

[0123] Third, the shearing action of the auxiliary flow layer also serves to strip aftertreatment fluid that has deposited on the turbine outlet passage surfaces, allowing it to be re-entrained in the exhaust. This re-entrainment of the aftertreatment fluid improves its disintegration and makes it less likely to solidify. Finally, the shearing action simply propels the aftertreatment fluid further downstream and toward further aftertreatment components, such as the SCR catalyst.

[0124] As a result of the above-mentioned effects, the use of the auxiliary flow layer makes the turbine outlet channel a suitable location for injecting the after-treatment fluid. In particular, as described above, the risk of after-treatment fluid deposits forming in the turbine outlet channel is reduced, and the turbine outlet channel can therefore be used as a decomposition chamber for receiving and decomposing the after-treatment fluid. This means that the dosing module can be placed closer to the turbine impeller than was previously possible. The temperature of the main turbine flow will be higher near the turbine impeller, and therefore the temperature of the main turbine flow can be used to provide better heat transfer to the after-treatment fluid, so that the after-treatment fluid is decomposed more quickly into the reducing agent required to support the SCR reaction.

[0125] The term "auxiliary flow" encompasses exhaust gas that has already traveled through the auxiliary passage. The momentum of the auxiliary flow is primarily influenced by the geometry and flow conditions within the auxiliary passage. Once the auxiliary flow leaves the auxiliary passage, it dissipates until it completely merges with the main turbine flow. The term "auxiliary passage" encompasses a passage that is separate and distinct from the turbine outlet passage. In some embodiments, the auxiliary passage may be a wastegate passage that bypasses the turbine wheel and includes a wastegate valve. However, in alternative embodiments, the auxiliary passage may not bypass the turbine wheel and / or may not include a wastegate valve.

[0126] The distribution module may include a nozzle in fluid communication with the turbine outlet channel. The nozzle may be configured to produce a spray of after-treatment fluid. The nozzle may be positioned on a side of the turbine outlet channel opposite the auxiliary flow layer. Optionally, during use, the auxiliary flow layer may inhibit after-treatment fluid from reaching portions of the turbine outlet channel surface opposite the nozzle. That is, the distribution module nozzle and at least a portion of the auxiliary flow layer are positioned on opposite sides of the turbine outlet channel. Thus, the auxiliary flow layer can "capture" after-treatment fluid dispensed by the nozzle and hinder or prevent it from contacting portions of the turbine outlet channel surface generally opposite the nozzle. The auxiliary flow layer may also apply high shear forces to any fluid that has impacted the turbine outlet channel surface, thereby dispersing the fluid and increasing heat transfer to the fluid after impact, thereby preventing deposits from solidifying. The nozzle may be aligned so that it is substantially flush with the sidewall of the turbine outlet channel. The term "substantially flush" encompasses the distribution module being substantially aligned or precisely aligned with the inner surface of the turbine outlet channel that defines the perimeter of the turbine outlet channel. In such embodiments, the nozzle does not protrude into the turbine outlet channel. Thus, the nozzle does not create an obstruction to the flow through the turbine outlet passage and thus avoids applying back pressure to the internal combustion engine.The spray of aftertreatment fluid may be atomized.

[0127] The auxiliary passage can be configured to direct the auxiliary flow layer downstream in a generally axial direction relative to the centerline. The main turbine flow passes through the turbine outlet passage in a generally axial direction. When the auxiliary passage directs the auxiliary flow layer in a generally axial direction, the momentum of the auxiliary flow layer and the momentum of the main turbine flow act in generally the same direction. Therefore, the two momentums work together to increase shear forces in the auxiliary flow layer.

[0128] The turbine may include a shield structure protruding into the turbine outlet passage, and the shield structure may define a portion of the auxiliary passage.

[0129] The turbine impeller can impart swirl momentum to the main turbine flow, and the swirl momentum of the main turbine flow can define a positive angular direction. The auxiliary channel can be configured to deliver the auxiliary flow to the turbine outlet channel in a direction that induces a swirl in the auxiliary flow layer about the centerline along the positive angular direction. Because the auxiliary channel delivers the auxiliary flow to the turbine outlet channel in a direction that induces a swirl in the same angular direction as the main turbine flow, the swirl momentum of the auxiliary flow is imparted to the swirl momentum of the main turbine flow, thereby increasing the amplitude of the swirl momentum of the main turbine flow. The increased rotational momentum of the combined turbine and auxiliary flow further increases the velocity and shear stress of the auxiliary flow layer. This increases the amount of energy available in the auxiliary flow layer for deflection and decomposition of the aftertreatment fluid, thereby improving the "buffering" effect. Furthermore, when the auxiliary flow has swirl momentum, the auxiliary flow layer acts as a fluid agitator, mixing the main turbine flow more thoroughly. This improves heat transfer to the aftertreatment fluid, ensuring that more aftertreatment fluid is decomposed at a faster rate.

[0130] The increased velocity and shear near the turbine outlet channel surface make the turbine outlet channel a suitable location for injecting aftertreatment fluid. Specifically, aftertreatment fluid injected into the turbine outlet channel is deflected by the high-velocity, high-shear exhaust gas and prevented from reaching the surface of the turbine outlet channel. This reduces the risk of aftertreatment fluid pooling and deposit formation in the turbine outlet channel, allowing the turbine outlet channel to function as a decomposition chamber for receiving and decomposing the aftertreatment fluid.

[0131] To achieve a vortex in a positive direction, the auxiliary channel can be configured to deliver the auxiliary flow in a direction having a directional component that is tangential to the turbine outlet channel surface in a plane normal to the centerline. In other words, the auxiliary flow can have a directional component that is tangential to the turbine outlet channel surface in a plane normal to the centerline. Because the auxiliary flow has a directional component that is tangential to the turbine outlet channel surface, the turbine outlet channel surface induces the auxiliary flow to swirl about the centerline.

[0132] The auxiliary passage may be configured to deliver the auxiliary flow into the turbine outlet passage in a direction between 0° and about 60° relative to a direction normal to the centerline. That is, the auxiliary passage may be configured such that, in the absence of any main turbine flow, the auxiliary flow will enter the turbine outlet passage in a direction that is normal to the turbine axis (or the centerline of the turbine outlet passage) or inclined up to about 60° relative to such normal direction.

[0133] The auxiliary channel can be configured to deliver the auxiliary flow to the turbine outlet channel at a swirl angle between about 30° and about 85°. The term "swirl angle" covers the angle between the velocity vector of the flow during use and the directional component of the velocity vector parallel to the center line. In other words, the velocity vector can define the hypotenuse of a right triangle, the directional component of the velocity vector parallel to the center line can define the adjacent side of the triangle, and the directional component of the velocity vector tangential to the turbine outlet channel surface in a plane normal to the center line can define the opposite side of the triangle. The swirl angle is the angle between the hypotenuse and the adjacent side of the triangle.

[0134] The auxiliary channel can be at least partially defined by an auxiliary channel surface, wherein the auxiliary channel surface and the turbine outlet channel surface define an interface therebetween, and at the interface, the auxiliary channel surface can be substantially tangential to the turbine outlet channel surface. "Substantially tangential" should be understood to mean that the auxiliary channel surface and the turbine outlet channel surface can be completely tangential to each other, or can have some angular offset as described below. When the two surfaces are tangential to each other, this ensures that the auxiliary flow is smoothly delivered to the turbine outlet channel, thereby minimizing flow recirculation or disturbance near the turbine outlet channel surface.

[0135] At the interface, the auxiliary channel surface may be inclined by an angle of up to about 15° relative to the tangent of the turbine outlet channel surface in a plane normal to the centerline. The angle of misalignment may be in a positive or negative direction relative to the tangent of the turbine outlet channel surface. It has been found that flow recirculation and disturbances are minimized when the angular misalignment between the two surfaces is within the above range. Preferably, the auxiliary channel surface is as tangent to the tangent of the turbine outlet channel surface as possible. Alternatively, the auxiliary channel surface may be inclined by up to about 2°, about 5° or about 10° relative to the tangent of the turbine outlet channel surface. As the relative angle between the auxiliary outlet channel surface and the tangent of the turbine outlet channel surface increases, it is preferred for the interface therebetween to transition from one surface to the other as smoothly as possible.

[0136] The turbine may also include a sensor device, the sensor device including a sensor channel having a sensor channel inlet and a sensor channel outlet; the sensor channel inlet may be configured to receive a portion of the turbine main flow from the turbine outlet channel to define a sensor flow, and the sensor channel outlet may be configured to convey the sensor flow to the turbine outlet channel; and the auxiliary channel may be configured to guide the auxiliary flow into the turbine outlet channel so that the auxiliary flow layer passes downstream of the sensor channel outlet. That is, the auxiliary channel may be configured so that the auxiliary flow layer does not pass upstream of the sensor channel outlet. In some embodiments, the sensor channel may be defined by a conduit that extends at least partially into the turbine outlet channel. If the auxiliary flow layer passes upstream of the sensor channel outlet, the auxiliary flow layer will impact the conduit, thereby generating unnecessary additional turbulence and dissipating energy from the auxiliary flow layer. However, when the auxiliary flow layer passes downstream of the sensor channel outlet, the auxiliary flow layer misses the conduit, and thus the flow disturbance to the auxiliary flow layer is minimized.

[0137] The turbine may be configured as a network of exhaust ducts connected to a downstream portion of the turbine outlet channel, the network may include a curved portion configured to receive the turbine main flow from the turbine outlet channel; and the auxiliary channel may be configured to guide the auxiliary flow into the turbine outlet channel so that the auxiliary flow layer passes through the outer top end of the curved portion. Due to the axial momentum of the turbine main flow, any aftertreatment fluid carried by the turbine main flow may impact the outer top end of the curved portion. However, since the auxiliary flow layer is guided past the outer top end of the curved portion, the auxiliary flow layer is able to form a fluid barrier on the outer top end of the curved portion, thereby inhibiting the aftertreatment fluid from contacting the outer top end and forming deposits. The term "outer top end" refers to the inner surface of the radially outermost portion of the curved portion defined by the axis of curvature of the curved portion.

[0138] The auxiliary channel may include an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel so that the thickness of the auxiliary flow layer is between at least about 5% and at most about 25% of the distance defined between the turbine outlet channel surface and the centerline. Alternatively, the thickness of the auxiliary flow layer may be about 10%, 15% or 20% of the distance between the turbine outlet channel and the centerline. As the thickness of the auxiliary flow layer increases, the shear momentum that can be used to deflect the post-treatment fluid and prevent the post-treatment fluid from reaching the auxiliary channel surface increases. It has been found that in order to provide a sufficient amount of shear momentum, the thickness of the auxiliary flow layer should be at least about 5% of the distance from the turbine outlet channel surface to the centerline. However, if the thickness of the auxiliary flow layer increases too much, the auxiliary flow layer will hinder the flow of the turbine body through the turbine outlet channel. It has been found that the thickness of the auxiliary flow layer should therefore not exceed about 25% of the distance from the turbine outlet channel surface to the centerline. When the cross-section of the turbine outlet passage is substantially circular, the distance defined between the turbine outlet passage surface and the centerline may be a radius of the turbine outlet passage surface relative to the centerline.

[0139] The auxiliary channel may include an auxiliary channel outlet, which is configured to deliver the auxiliary flow into the turbine outlet channel so that the width of the auxiliary flow layer can be between about 50% and about 100% of the diameter of the turbine outlet channel defined by the turbine outlet channel surface. Typically, the distribution module spreads the after-treatment fluid in a conical spray area. It should be understood that in order to form an effective fluid barrier to hinder contact between the after-treatment fluid and the turbine outlet channel surface, the auxiliary flow layer must be wide enough so that it can capture the after-treatment fluid that has been spread by the distribution module. The diameter of the turbine outlet channel surface can be taken from a plane normal to the centerline of the centroid of the auxiliary channel outlet.

[0140] The auxiliary channel outlet may define a width and a depth, and the depth may be from about 15% to about 50% of the width, and preferably may be about 25% of the width. Thus, the auxiliary channel opening is long and narrow, giving it a generally "letterbox" shape. When the auxiliary channel is long and narrow, this forms the auxiliary flow layer into a wide "blanket" covering a large area of ​​the turbine outlet channel surface. Furthermore, the narrow depth relative to the width may serve to accelerate the auxiliary flow into the turbine outlet channel. Thus, the shear forces in the auxiliary flow layer are sufficient to provide the aforementioned effects, while the auxiliary flow layer is wide enough to capture as much post-treatment fluid as possible.

[0141] The auxiliary passage may include a wastegate valve configured to selectively allow or prevent the auxiliary flow from passing through the auxiliary passage; the wastegate valve may include a valve opening defining a valve flow area; the auxiliary passage outlet may define an auxiliary flow area in a plane normal to the direction of the auxiliary flow; and the auxiliary flow area may be approximately 1.2 times the valve flow area. Since the auxiliary flow area is larger than the valve flow area, blockage at the auxiliary passage outlet is prevented.

[0142] The auxiliary channel can be configured to receive the portion of the main turbine flow from the turbine inlet channel. This allows the auxiliary flow to bypass the turbine wheel chamber. Because the auxiliary flow is drawn from a location upstream of the turbine wheel, its pressure is higher than that of the main turbine flow. Consequently, more energy is available within the auxiliary flow layer to deflect and break up droplets of the post-treatment fluid, thereby improving the cushioning effect.

[0143] The auxiliary passage may include a valve configured to control the flow of an auxiliary flow through the auxiliary passage. In such embodiments, the auxiliary passage is functionally equivalent to a wastegate passage. When the valve is closed, substantially all of the exhaust gas delivered to the turbine will travel through the turbine wheel as the main turbine flow. Under such conditions, the flow rate of the main turbine flow may be high enough to prevent the aftertreatment fluid from impacting the turbine outlet passage surfaces. This may be assisted by one or more other features of the turbine that act to hinder contact between the aftertreatment fluid and the turbine outlet passage surfaces, such as diffusers, turbulators, etc., which can improve mixing of the aftertreatment fluid with the main turbine flow. When the valve is open, the energy of the main turbine flow will be reduced, and the aftertreatment fluid can therefore more easily impact the turbine outlet passage surfaces. However, because the auxiliary passage delivers the auxiliary flow into the turbine outlet passage as an auxiliary flow layer, the aftertreatment fluid is "buffered" by the auxiliary flow layer and prevented from contacting the turbine outlet passage surfaces.

[0144] The auxiliary passage can be sized so that, when the valve is open, the flow rate of the auxiliary flow through the auxiliary passage is between about 25% and 25% of the flow rate of the main turbine flow received by the turbine inlet passage. To provide an adequate wastegate effect, the auxiliary passage needs to be large enough so that the amount of exhaust gas bypassing the turbine wheel results in a significant decrease in the amount of power generated by the turbine wheel. It has been found that the auxiliary passage should therefore be able to receive at least about 25% to at least about 50% of the total exhaust gas delivered to the turbine.

[0145] The auxiliary channel may include an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel, and the valve may be positioned at the auxiliary channel outlet. During use, when the valve moves between a closed position and an open position, the valve will define an opening of variable size. When the opening is smaller, the auxiliary flow will accelerate through the opening. In a conventional wastegate arrangement, the valve is typically positioned near the inlet of the wastegate channel (rather than near the outlet of the wastegate channel). Therefore, the wastegate flow traveling through the valve will expand in the wastegate channel, causing the wastegate flow to decelerate. However, in this embodiment, by positioning the valve at the auxiliary channel outlet, it is ensured that the auxiliary flow entering the turbine outlet channel has a higher velocity. This further increases the shear momentum of the auxiliary flow in the auxiliary flow layer, thereby improving the "buffering" effect.

[0146] Positioning the valve "at" the auxiliary passage outlet can encompass at least the valve being configured to selectively block the auxiliary passage outlet itself. Additionally or alternatively, the auxiliary passage outlet can define a depth in a plane normal to the centerline, and the valve can be positioned upstream of the auxiliary passage outlet no more than approximately twice such depth.

[0147] In alternative embodiments, the valve may not be located at the auxiliary passage outlet and may, for example, be placed upstream of the auxiliary passage outlet. For example, the valve may be located upstream of the turbine passage outlet by approximately 6, 7, 8, 10, or 15 times the depth of the turbine passage outlet.

[0148] The auxiliary passage may be configured to receive the portion of the turbine body flow from the turbine outlet passage.

[0149] The auxiliary passage can be configured to always allow the auxiliary flow to pass through it. That is, the auxiliary passage can be substantially free of control devices, such as valves, for preventing fluid flow through the auxiliary passage. Thus, the auxiliary passage can be considered "always open." In such an embodiment, the auxiliary flow layer is always present at the turbine passage outlet, thereby providing a "cushioning" effect under all operating conditions of the turbine.

[0150] The auxiliary channel can be sized so that, during use, the flow rate of the auxiliary flow can be about 0.5% to about 2% of the flow rate of the main turbine flow received by the turbine inlet channel. When the auxiliary channel is "always open", a portion of the exhaust gas will always be able to bypass the turbine impeller, and therefore the efficiency of the turbine will decrease. However, it has been found that when the auxiliary flow is sufficiently small compared to the total exhaust gas delivered to the turbine, the efficiency drop of the turbine is minimal or negligible. In alternative embodiments, the auxiliary channel can receive about 1%, 1.5%, 2%, 2.5%, 3%, 4% or 5% of the main turbine flow. Generally, the larger the auxiliary flow is in proportion to the main turbine flow delivered to the turbine by the engine, the more energy can be used to support the "buffer" effect of the auxiliary flow layer.

[0151] The auxiliary channel may include an auxiliary channel outlet and may define a flow area normal to the flow direction of the auxiliary flow through the auxiliary channel, and the flow area may narrow toward the auxiliary channel outlet. As the flow area narrows toward the auxiliary channel outlet, the auxiliary flow accelerates as it passes through the auxiliary channel outlet. This results in higher shear forces in the auxiliary flow layer, thereby inhibiting the aftertreatment fluid from reaching the turbine outlet channel surface.

[0152] The auxiliary passage may include a plurality of auxiliary passage outlets configured to deliver the auxiliary flow into the turbine outlet passage.

[0153] The auxiliary passage may include a first branch and a second branch, the first branch may define the auxiliary passage outlet, and the second branch may define a second auxiliary passage outlet, the second auxiliary passage outlet may be positioned on a side of the turbine outlet passage generally opposite the auxiliary passage outlet.

[0154] The auxiliary channel outlets may be equidistantly distributed around the center line.

[0155] The auxiliary channel may include a plenum chamber and a plurality of branches fluidly connected to the plenum chamber, the plenum chamber may be configured to receive the auxiliary flow from the auxiliary channel inlet, and the branches may be configured to deliver the auxiliary flow to the auxiliary channel outlet.

[0156] Each of the branches may be configured to deliver the secondary flow to the turbine outlet passage in a direction that may induce a vortex in the secondary flow layer about the centerline.

[0157] The auxiliary channel may include: a first auxiliary channel branch, which is configured to receive a first auxiliary flow portion and guide the first auxiliary flow portion into the turbine outlet channel as a first auxiliary flow layer; and a second auxiliary channel branch, which is configured to receive a second auxiliary flow portion and guide the second auxiliary flow portion into the turbine outlet channel as a second auxiliary flow layer.

[0158] The first auxiliary channel branch can be configured to guide the first auxiliary flow layer downstream relative to the center line in a generally axial direction into the turbine outlet channel; and the second auxiliary channel branch can be configured to guide the second auxiliary flow layer downstream relative to the center line in a generally axial direction into the turbine outlet channel.

[0159] The first auxiliary channel branch can be configured to guide the first auxiliary flow layer into the turbine outlet channel along a direction inducing a vortex in the first auxiliary flow layer around the center line along a positive angle direction; and the second auxiliary channel branch can be configured to guide the second auxiliary flow layer into the turbine outlet channel along a direction inducing a vortex in the second auxiliary flow layer around the center line along the positive angle direction.

[0160] The first auxiliary channel branch can be configured to guide the first auxiliary flow layer into the turbine outlet channel downstream in a substantially axial direction relative to the center line; and the second auxiliary channel branch can be configured to guide the second auxiliary flow layer into the turbine outlet channel in a direction that induces a vortex in the second auxiliary flow layer around the center line in the positive angle direction.

[0161] The turbine outlet passage may define a diffuser portion, and the turbine outlet passage surface may be a surface of the diffuser portion.

[0162] The turbine may include a housing assembly having a turbine housing defining the turbine inlet passage and the turbine wheel chamber, and a connection adapter defining the turbine outlet passage surface and at least a portion of the turbine outlet passage.

[0163] The third aspect of the present invention may be embodied in a turbocharger.

[0164] According to a fourth aspect of the present invention, a method for operating a turbine for a turbocharger is provided, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet channel, the exhaust gas received by the turbine inlet channel defining a turbine main flow; receiving the turbine main flow from the turbine inlet channel into a turbine impeller chamber, the turbine impeller chamber being configured to accommodate a turbine impeller, the turbine impeller being supported for rotation; receiving the turbine main flow from the turbine impeller chamber into a turbine outlet channel, the turbine outlet channel being at least partially defined by a turbine outlet channel surface, the turbine outlet channel defining a centerline; receiving a portion of the turbine main flow into an auxiliary channel, the portion of the turbine main flow received by the auxiliary channel defining an auxiliary flow; delivering a spray of an after-treatment fluid into the turbine outlet channel using a dosing module; and guiding the auxiliary flow along the turbine outlet channel surface in an auxiliary flow layer.

[0165] The distribution module may include a nozzle connected to the turbine outlet channel fluid, and the nozzle may be configured to produce a spray of after-treatment fluid; and the nozzle may be positioned on a side of the turbine outlet channel opposite to the auxiliary flow layer, so that during use, the auxiliary flow layer can inhibit the after-treatment fluid from reaching the portion of the turbine outlet channel surface opposite to the nozzle.

[0166] The secondary channel may be configured to direct the secondary flow layer in a generally axial direction downstream relative to the centerline.

[0167] The turbine may include a shield structure protruding into the turbine outlet passage, and the shield structure may define a portion of the auxiliary passage.

[0168] The turbine wheel may impart swirl momentum to the turbine main flow, the swirl momentum of the turbine main flow may define a positive angular direction, and the auxiliary channel may be configured to deliver the auxiliary flow to the turbine outlet channel in a direction that may induce the auxiliary flow layer to swirl about the centerline along the positive angular direction.

[0169] The auxiliary passage may be configured to deliver the auxiliary flow into the turbine outlet passage in a direction between 0° and about 60° relative to a direction normal to the centerline.

[0170] The auxiliary passage may be configured to deliver the auxiliary flow to the turbine outlet passage at a swirl angle of between about 30° and about 85°.

[0171] The auxiliary passage may be at least partially defined by an auxiliary passage surface, the auxiliary passage surface and the turbine outlet passage surface may define an interface therebetween, and the auxiliary passage surface may be generally tangential to the turbine outlet passage surface at the interface.

[0172] At the interface, the secondary duct surface may be inclined at an angle of up to about 15° relative to a tangent to the turbine outlet duct surface in a plane normal to the centerline.

[0173] The turbine may further include a sensor device comprising a sensor channel having a sensor channel inlet and a sensor channel outlet; the sensor channel inlet may be configured to receive a portion of the turbine main flow from the turbine outlet channel to define a sensor flow, and the sensor channel outlet may be configured to deliver the sensor flow to the turbine outlet channel; and the auxiliary channel may be configured to guide the auxiliary flow into the turbine outlet channel so that the auxiliary flow layer passes downstream of the sensor channel outlet.

[0174] The turbine can be configured to be connected to a network of exhaust ducts downstream of the turbine outlet channel, the network may include a curved portion configured to receive the turbine main flow from the turbine outlet channel; and the auxiliary channel can be configured to guide the auxiliary flow into the turbine outlet channel so that the auxiliary flow layer passes through the outer top end of the curved portion.

[0175] The auxiliary channel may include an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel so that the thickness of the auxiliary flow layer may be between at least about 5% and at most about 25% of the distance defined between the turbine outlet channel surface and the centerline.

[0176] The auxiliary channel may include an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that a width of the auxiliary flow layer may be between about 50% and about 100% of a diameter of the turbine outlet channel defined by the turbine outlet channel surface.

[0177] The auxiliary channel outlet may define a width and a depth, and the depth may be about 15% to about 50% of the width, and preferably may be about 25% of the width.

[0178] The auxiliary channel may include a wastegate valve configured to selectively allow or prevent the auxiliary flow from traveling through the auxiliary channel; the wastegate valve may include a valve opening that defines a valve flow area; the auxiliary channel outlet may define an auxiliary flow area in a plane normal to the direction of the auxiliary flow; the auxiliary flow area may be approximately 1.2 times the valve flow area.

[0179] The auxiliary passage may be configured to receive the portion of the turbine body flow from the turbine inlet passage.

[0180] The auxiliary passage may include a valve configured to control a flow rate of the auxiliary flow through the auxiliary passage.

[0181] The auxiliary passage may be sized such that when the valve is open, the flow rate of the auxiliary flow through the auxiliary passage may be between at least about 25% of the flow rate of the turbine main flow received by the turbine inlet passage.

[0182] The auxiliary passage may include an auxiliary passage outlet configured to deliver the auxiliary flow into the turbine outlet passage, and the valve may be positioned at the auxiliary passage outlet.

[0183] The auxiliary passage may be configured to receive the portion of the turbine body flow from the turbine outlet passage.

[0184] The auxiliary channel may be configured such that the auxiliary flow is always allowed to pass through the auxiliary channel.

[0185] The auxiliary passage may be sized such that, during use, the flow rate of the auxiliary flow may be about 0.5% to about 2% of the flow rate of the main turbine flow received by the turbine inlet passage.

[0186] The auxiliary channel may include an auxiliary channel outlet and may define a flow area normal to a flow direction of the auxiliary flow through the auxiliary channel, and the flow area may narrow toward the auxiliary channel outlet.

[0187] The auxiliary passage may include a plurality of auxiliary passage outlets configured to deliver the auxiliary flow into the turbine outlet passage.

[0188] The auxiliary passage may include a first branch and a second branch, the first branch may define the auxiliary passage outlet, and the second branch may define a second auxiliary passage outlet, the second auxiliary passage outlet may be positioned on a side of the turbine outlet passage generally opposite the auxiliary passage outlet.

[0189] The auxiliary channel outlets may be equidistantly distributed around the center line.

[0190] The auxiliary channel may include a plenum chamber and a plurality of branches fluidly connected to the plenum chamber, the plenum chamber may be configured to receive the auxiliary flow from the auxiliary channel inlet, and the branches may be configured to deliver the auxiliary flow to the auxiliary channel outlet.

[0191] Each of the branches may be configured to deliver the secondary flow to the turbine outlet passage in a direction that may induce a vortex in the secondary flow layer about the centerline.

[0192] The auxiliary channel may include: a first auxiliary channel branch, which is configured to receive a first auxiliary flow portion and guide the first auxiliary flow portion into the turbine outlet channel as a first auxiliary flow layer; and a second auxiliary channel branch, which is configured to receive a second auxiliary flow portion and guide the second auxiliary flow portion into the turbine outlet channel as a second auxiliary flow layer.

[0193] The first auxiliary channel branch can be configured to guide the first auxiliary flow layer downstream relative to the center line in a generally axial direction into the turbine outlet channel; and the second auxiliary channel branch can be configured to guide the second auxiliary flow layer downstream relative to the center line in a generally axial direction into the turbine outlet channel.

[0194] The first auxiliary channel branch can be configured to guide the first auxiliary flow layer into the turbine outlet channel along a direction that can induce the first auxiliary flow layer to vortex around the center line along a positive angle direction; and the second auxiliary channel branch can be configured to guide the second auxiliary flow layer into the turbine outlet channel along a direction that can induce the second auxiliary flow layer to vortex around the center line along the positive angle direction.

[0195] The first auxiliary channel branch can be configured to guide the first auxiliary flow layer into the turbine outlet channel downstream in a substantially axial direction relative to the center line; and the second auxiliary channel branch can be configured to guide the second auxiliary flow layer into the turbine outlet channel in a direction that can induce the second auxiliary flow layer to vortex around the center line in the positive angle direction.

[0196] The turbine outlet passage may define a diffuser portion, and the turbine outlet passage surface may be a surface of the diffuser portion.

[0197] The turbine may include a housing assembly having a turbine housing defining the turbine inlet passage and the turbine wheel chamber, and a connection adapter defining the turbine outlet passage surface and at least a portion of the turbine outlet passage.

[0198] According to a fifth aspect of the present invention, there is provided a post-treatment system for an internal combustion engine system, comprising: a decomposition chamber, the decomposition chamber being configured to receive a main flow from the internal combustion engine, the decomposition chamber being at least partially defined by a decomposition chamber surface, and the decomposition chamber defining a center line; an auxiliary channel, the auxiliary channel being configured to receive a portion of the main flow, the portion of the main flow received by the auxiliary channel defining an auxiliary flow; and a distribution module, the distribution module being configured to deliver a spray of the after-treatment fluid into the decomposition chamber; wherein the auxiliary channel is configured to guide the auxiliary flow along the decomposition chamber surface in an auxiliary flow layer.

[0199] Therefore, the main difference between this aspect of the invention and the previous (fourth) aspect of the invention for a turbine for a turbocharger is that the auxiliary flow layer is formed in the decomposition chamber instead of in the turbine outlet channel. Apart from this difference, it should be understood that the working principle and advantages of this aspect of the invention are the same as or equivalent to the previous aspects of the invention. In particular, the decomposition chamber of this aspect can be considered to be equivalent to the turbine outlet channel of the previous aspect, the decomposition chamber surface of this aspect can be considered to be equivalent to the auxiliary channel surface of the previous aspect, the auxiliary channel of this aspect can be considered to be equivalent to the auxiliary channel of the previous aspect, and the distribution module of this aspect can be considered to be equivalent to the distribution module of the previous aspect. Since the basic operating principles are the same, it should be understood that this aspect can include any optional features of the above-mentioned previous aspects. Nevertheless, additional optional features of this aspect are set forth below.

[0200] The distribution module may include a nozzle connected to the decomposition chamber fluid, and the nozzle may be configured to produce the spray of the post-treatment fluid; and the nozzle may be positioned on a side of the decomposition chamber opposite to the auxiliary flow layer, so that during use, the auxiliary flow layer can inhibit the post-treatment fluid from reaching the portion of the decomposition chamber surface opposite to the nozzle.

[0201] The secondary channel may be configured to direct the secondary flow layer in a generally axial direction downstream relative to the centerline.

[0202] The auxiliary channel may be configured to deliver the auxiliary flow to the decomposition chamber in a direction that may induce a vortex of the auxiliary flow layer about the centerline.

[0203] The auxiliary channel may be configured to deliver the auxiliary flow to the decomposition chamber in a tangential direction relative to a surface of the decomposition chamber in a plane normal to the centerline.

[0204] The internal combustion engine system may include a turbine having a turbine wheel, and the auxiliary passage may receive the auxiliary flow from a position upstream of the turbine wheel. In other words, the auxiliary passage may function as a wastegate passage. The auxiliary passage may include a valve device configured to control flow through the auxiliary passage.

[0205] The turbine can impart vortex momentum to the main flow, the vortex momentum of the main flow can define a positive angular direction, and the auxiliary channel can be configured to deliver the auxiliary flow to the decomposition chamber in a direction that can induce the auxiliary flow layer to swirl around the center line along the positive angular direction.

[0206] The swirl momentum imparted by the turbine to the turbine body flow may define a first swirl angle, and the auxiliary passage may be configured to deliver the auxiliary flow to the decomposition chamber at a second swirl angle that is equal to or steeper than the first swirl angle.

[0207] The auxiliary channel may be configured to deliver the auxiliary flow to the decomposition chamber at a swirl angle between about 30° and about 85°.

[0208] The auxiliary channel may be at least partially defined by an auxiliary channel surface, the auxiliary channel surface and the decomposition chamber surface may define an interface therebetween, and the auxiliary channel surface may be substantially tangential to the decomposition chamber surface at the interface.

[0209] At the interface, the auxiliary channel surface may be inclined at an angle of up to about 15° relative to a tangent line to the decomposition chamber surface in a plane normal to the centerline.

[0210] The decomposition chamber may further include a sensor device comprising a sensor channel having a sensor channel inlet and a sensor channel outlet; the sensor channel inlet may be configured to receive a portion of the main flow from the decomposition chamber to define a sensor flow, and the sensor channel outlet may be configured to deliver the sensor flow to the decomposition chamber; and the auxiliary channel may be configured to guide the auxiliary flow into the decomposition chamber so that the auxiliary flow layer may pass downstream of the sensor channel outlet.

[0211] The decomposition chamber may include a curved portion, and the auxiliary channel may be configured to guide the auxiliary flow into the decomposition chamber such that the auxiliary flow layer passes over an outer top end of the curved portion.

[0212] The auxiliary channel may include an auxiliary channel outlet configured to deliver the auxiliary flow into the decomposition chamber so that the thickness of the auxiliary flow layer may be between at least about 5% and at most about 25% of the distance defined between the decomposition chamber surface and the centerline.

[0213] The auxiliary channel may include an auxiliary channel outlet configured to deliver the auxiliary flow into the decomposition chamber such that a width of the auxiliary flow layer may be between about 50% and about 100% of a diameter of the turbine outlet channel defined by the decomposition chamber surface.

[0214] The auxiliary channel outlet may define a width and a depth, and the depth may be about 15% to about 50% of the width, and preferably may be about 25% of the width.

[0215] The auxiliary passage may include a valve configured to control a flow rate of the auxiliary flow through the auxiliary passage.

[0216] The auxiliary channel may include an auxiliary channel outlet configured to deliver the auxiliary flow into the decomposition chamber, and the valve may be positioned at the auxiliary channel outlet.

[0217] The auxiliary channel may include an auxiliary channel outlet and may define a flow area normal to a flow direction of the auxiliary flow through the auxiliary channel, and the flow area may narrow toward the auxiliary channel outlet.

[0218] The auxiliary channel may include a plurality of auxiliary channel outlets configured to deliver the auxiliary flow into the decomposition chamber.

[0219] The auxiliary channel outlets may be equidistantly distributed around the center line.

[0220] The auxiliary channel may include a plenum chamber and a plurality of branches fluidly connected to the plenum chamber, the plenum chamber may be configured to receive the auxiliary flow from the auxiliary channel inlet, and the branches may be configured to deliver the auxiliary flow to the auxiliary channel outlet.

[0221] Each of the branches may be configured to deliver the secondary flow to the turbine outlet passage in a direction that may induce a vortex in the secondary flow layer about the centerline.

[0222] The auxiliary channel may include: a first auxiliary channel branch, which is configured to receive a first auxiliary flow portion and guide the first auxiliary flow portion into the decomposition chamber in a first auxiliary flow layer; and a second auxiliary channel branch, which is configured to receive a second auxiliary flow portion and guide the second auxiliary flow portion into the decomposition chamber in a second auxiliary flow layer.

[0223] The first auxiliary channel branch can be configured to guide the first auxiliary flow layer downstream relative to the center line along a generally axial direction into the decomposition chamber; and the second auxiliary channel branch can be configured to guide the second auxiliary flow layer downstream relative to the center line along a generally axial direction into the decomposition chamber.

[0224] The first auxiliary channel branch can be configured to guide the first auxiliary flow layer into the decomposition chamber along a direction that can induce the first auxiliary flow layer to swirl around the center line along a positive angle direction; and the second auxiliary channel branch can be configured to guide the second auxiliary flow layer into the decomposition chamber along a direction that can induce the second auxiliary flow layer to swirl around the center line along the positive angle direction.

[0225] The first auxiliary channel branch can be configured to guide the first auxiliary flow layer into the decomposition chamber in a substantially axial direction downstream relative to the center line; and the second auxiliary channel branch can be configured to guide the second auxiliary flow layer into the decomposition chamber in a direction that can induce the second auxiliary flow layer to vortex around the center line in the positive angle direction.

[0226] According to a sixth aspect of the present invention, a turbine for a turbocharger is provided, comprising: a turbine inlet passage, the turbine inlet passage being configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine main flow; a turbine impeller chamber, the turbine impeller chamber being configured to receive the turbine main flow from the turbine inlet passage, the turbine impeller chamber accommodating a turbine impeller, the turbine impeller being supported for rotation; a turbine outlet passage, the turbine outlet passage being configured to receive the turbine main flow from the turbine impeller chamber a main turbine flow, and the turbine outlet passage defines a center line; an auxiliary passage, the auxiliary passage being configured to receive a portion of the turbine main flow, the portion of the turbine main flow received by the auxiliary passage defining an auxiliary flow, and wherein the turbine impeller is configured to discharge the turbine main flow into the turbine outlet passage so that the turbine main flow swirls around the center line in a positive angular direction; and wherein the auxiliary passage is configured to guide the auxiliary flow into the turbine outlet passage in a negative angular direction opposite to the positive angular direction.

[0227] Because the auxiliary flow is directed at an angle opposite to the natural vortex motion of the main turbine flow, the auxiliary flow and the main turbine flow collide with each other, resulting in a large amount of turbulence in the turbine outlet passage. The increased turbulence leads to improved mixing of the main turbine flow, the auxiliary flow, and the aftertreatment fluid, thereby transferring a larger amount of heat to the aftertreatment fluid at a faster rate. As a result, the water component of the aftertreatment fluid evaporates more fully and faster, and the urea component is more quickly decomposed into the reductant required to support the SCR reaction. In addition, the improved mixing distributes the decomposed reductant more evenly throughout the main turbine flow downstream of the turbine, ensuring that substantially all downstream SCR catalyst devices have sufficient reductant to support the required reaction.

[0228] The term "auxiliary flow" encompasses exhaust gas that has already traveled through the auxiliary passage. The momentum of the auxiliary flow is primarily influenced by the geometry and flow conditions within the auxiliary passage. Once the auxiliary flow leaves the auxiliary passage, it dissipates until it completely merges with the main turbine flow. The term "auxiliary passage" encompasses a passage that is separate and distinct from the turbine outlet passage. In some embodiments, the auxiliary passage may be a wastegate passage that bypasses the turbine wheel and includes a wastegate valve. However, in alternative embodiments, the auxiliary passage may not bypass the turbine wheel and / or may not include a wastegate valve.

[0229] The turbine may further comprise a distribution module configured to deliver a spray of after-treatment fluid into the turbine outlet passage.The turbine may comprise a distribution module mount configured to receive a distribution module.

[0230] The auxiliary flow can collide with the main turbine flow within the turbine outlet passage to create a turbulent region, and the distribution module can include a nozzle configured to generate the spray of the after-treatment fluid, the nozzle being oriented to direct the after-treatment fluid into the turbulent region. Since the after-treatment fluid is directed into the turbulent region, it is delivered directly to the location within the turbine outlet passage where maximum mixing occurs. This accelerates the rate of decomposition of the after-treatment fluid.

[0231] The vortex momentum imparted to the main turbine flow by the turbine impeller can define a first vortex angle, and the auxiliary channel can be configured to deliver the auxiliary flow to the turbine outlet channel at a second vortex angle, which can be equal to the first vortex angle or steeper in magnitude than the first vortex angle. That is, although the vortex angle of the main turbine flow and the vortex angle of the auxiliary flow will be inclined in different directions relative to the centerline, the inclination amplitude of the second vortex angle is equal to or greater than the inclination amplitude of the second vortex angle. Since the second vortex angle is equal to or greater than the first vortex angle in magnitude, this means that the auxiliary flow has sufficient momentum to act in the negative angle direction to cause turbulence in the turbine outlet channel.

[0232] The auxiliary passage may be configured to deliver the auxiliary flow to the turbine outlet passage in a direction between 0° and about 60° relative to a direction that may be orthogonal to the centerline.

[0233] The auxiliary channel may be at least partially defined by an auxiliary channel surface. The auxiliary channel surface and the turbine outlet channel surface may define an interface therebetween. At the interface, the auxiliary channel surface may be substantially tangential to the turbine outlet channel surface. In this manner, the momentum of the auxiliary flow directly opposes the momentum of the main turbine flow, thereby generating maximum turbulence.

[0234] The auxiliary channel can be configured to receive the portion of the main turbine flow from the turbine inlet channel. This bypasses the turbine wheel chamber. Because the auxiliary flow is drawn from a location upstream of the turbine wheel, its pressure is higher than that of the main turbine flow. Consequently, more energy is used to generate turbulence, ensuring complete decomposition of the aftertreatment fluid.

[0235] The auxiliary passage may include a valve configured to control the flow rate of the auxiliary flow passing through the auxiliary passage. The valve may be, for example, a wastegate valve.

[0236] The auxiliary passage can be sized so that, when the valve is open, the flow rate of the auxiliary flow through the auxiliary passage can be between at least about 25% and about 50% of the flow rate of the main turbine flow received by the turbine inlet passage. To provide an adequate wastegate effect, the auxiliary passage needs to be large enough so that the amount of exhaust gas bypassing the turbine wheel results in a significant decrease in the amount of power generated by the turbine wheel. It has been found that the auxiliary passage should therefore be able to receive at least about 25% to at least about 50% of the total exhaust gas delivered to the turbine.

[0237] The auxiliary passage may be configured to receive the portion of the turbine body flow from the turbine outlet passage.

[0238] The auxiliary passage can be configured to always allow the auxiliary flow to pass through it. That is, the auxiliary passage can be substantially free of control devices, such as valves, for preventing fluid flow through the auxiliary passage. Thus, the auxiliary passage can be considered "always open." In such an embodiment, the auxiliary flow always collides with the main turbine flow at the turbine passage outlet under all operating conditions of the turbine to generate turbulence.

[0239] The auxiliary passage can be sized so that, during use, the flow rate of the auxiliary flow can be approximately 0.1% to approximately 2% of the flow rate of the main turbine flow received by the turbine inlet passage. When the auxiliary passage is "always open," a portion of the exhaust gas will always be able to bypass the turbine wheel, and thus the efficiency of the turbine will decrease. However, it has been found that when the auxiliary flow is sufficiently small compared to the total exhaust gas delivered to the turbine, the decrease in turbine efficiency is minimal or negligible. In alternative embodiments, the auxiliary passage can receive approximately 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 4% or 5% of the main turbine flow. Generally, the larger the auxiliary flow is in proportion to the main turbine flow delivered by the engine to the turbine, the more energy can be used to support improved turbulence generation and improved mixing in the turbine outlet passage.

[0240] The auxiliary passage may include an auxiliary passage outlet configured to deliver the auxiliary flow into the turbine outlet passage.

[0241] The turbine outlet passage may define a diffuser section. The diffuser section causes the turbine bulk flow to expand and decelerate, thereby causing turbulent eddies to form in the turbine outlet passage. The turbulent eddies improve mixing, supporting faster decomposition of the reductant and improving distribution of the reductant throughout the turbine bulk flow.

[0242] The auxiliary channel outlet is defined by the surface of the diffuser section. Because the auxiliary channel outlet is located within the diffuser section, the auxiliary flow collides with the main turbine flow within the diffuser section. Consequently, the turbulent flow generated by the diffuser section and the turbulent region resulting from the collision of the auxiliary flow with the main turbine flow occur at the same location within the turbine outlet channel. This increases the magnitude of turbulent mixing, further improving the decomposition rate and evenly distributing the reducing agent throughout the main turbine flow.

[0243] The auxiliary passage may include a plurality of auxiliary passage outlets configured to deliver the auxiliary flow into the turbine outlet passage.

[0244] The turbine may include a housing assembly having a turbine housing defining the turbine inlet passage and the turbine wheel chamber, and a connection adapter defining the turbine outlet passage surface and at least a portion of the turbine outlet passage.

[0245] The sixth aspect of the present invention may be embodied in a turbocharger.

[0246] According to a seventh aspect of the present invention, a method for operating a turbine for a turbocharger is provided, which includes: receiving exhaust gas from an internal combustion engine into a turbine inlet channel, the exhaust gas received by the turbine inlet channel defining a turbine main flow; receiving the turbine main flow from the turbine inlet channel into a turbine impeller chamber, the turbine impeller chamber accommodating a turbine impeller, the turbine impeller being supported for rotation; receiving the turbine main flow from the turbine impeller chamber into a turbine outlet channel, the turbine outlet channel defining a centerline; receiving a portion of the turbine main flow into an auxiliary channel, the portion of the turbine main flow received by the auxiliary channel defining an auxiliary flow; using the turbine impeller to discharge the turbine main flow into the turbine outlet channel so that the turbine main flow swirls around the centerline in a positive angular direction; and guiding the auxiliary flow into the turbine outlet channel in a negative angular direction opposite to the positive angular direction.

[0247] The method may further include delivering a spray of after-treatment fluid into the turbine outlet passage using a dosing module.

[0248] The auxiliary flow may collide with the turbine main flow within the turbine outlet passage to create a turbulent region, and the dosing module may include a nozzle configured to generate the spray of after-treatment fluid, the nozzle being oriented to direct the after-treatment fluid into the turbulent region.

[0249] The swirl momentum imparted to the turbine body flow by the turbine wheel may define a first swirl angle, and the auxiliary passage may be configured to deliver the auxiliary flow to the turbine outlet passage at a second swirl angle, which may be equal to the first swirl angle or steeper in magnitude than the first swirl angle.

[0250] The auxiliary passage may be configured to deliver the auxiliary flow to the turbine outlet passage in a direction between 0° and about 60° relative to a direction normal to the centerline.

[0251] The auxiliary passage may be at least partially defined by an auxiliary passage surface, the auxiliary passage surface and the turbine outlet passage surface may define an interface therebetween, and the auxiliary passage surface may be generally tangential to the turbine outlet passage surface at the interface.

[0252] The auxiliary passage may be configured to receive the portion of the turbine body flow from the turbine inlet passage.

[0253] The auxiliary passage may include a valve configured to control a flow rate of the auxiliary flow through the auxiliary passage.

[0254] The auxiliary passage may be sized such that when the valve is open, the flow of the auxiliary flow through the auxiliary passage may be between at least about 25% and about 50% of the flow of the turbine main flow received by the turbine inlet passage.

[0255] The auxiliary passage may be configured to receive the portion of the turbine body flow from the turbine outlet passage.

[0256] The auxiliary channel may be configured such that the auxiliary flow is always allowed to pass through the auxiliary channel.

[0257] The auxiliary passage may be sized such that, during use, the auxiliary flow may have a flow rate of about 0.1% to about 2% of the flow rate of the main turbine flow received by the turbine inlet passage.

[0258] The auxiliary passage may include an auxiliary passage outlet configured to deliver the auxiliary flow into the turbine outlet passage.

[0259] The turbine outlet passage may define a diffuser portion.

[0260] The auxiliary channel outlet may be defined by a surface of the diffuser portion.

[0261] The auxiliary passage may include a plurality of auxiliary passage outlets configured to deliver the auxiliary flow into the turbine outlet passage.

[0262] The turbine may include a housing assembly having a turbine housing defining the turbine inlet passage and the turbine wheel chamber, and a connection adapter defining the turbine outlet passage surface and at least a portion of the turbine outlet passage.

[0263] According to an eighth aspect of the present invention, a turbine for a turbocharger is provided, comprising: a turbine inlet channel configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet channel defining a turbine main flow; a turbine impeller chamber configured to receive the turbine main flow from the turbine inlet channel, the turbine impeller chamber configured to accommodate a turbine impeller, the turbine impeller being supported for rotation; a turbine outlet channel configured to receive the turbine main flow from the turbine impeller chamber, the turbine outlet channel being configured to receive the turbine main flow from the turbine impeller chamber, The turbine outlet passage extends along a centerline and is at least partially defined by a first surface of a partition wall; a distribution module configured to deliver a spray of an aftertreatment fluid into the turbine outlet passage; and an auxiliary passage configured to receive a portion of the turbine main flow, the portion of the turbine main flow received by the auxiliary passage defining an auxiliary flow, the auxiliary passage being at least partially defined by a second surface of the partition wall; wherein the partition wall is configured to provide thermal connectivity from the auxiliary passage to the first surface via the second surface.

[0264] The term "turbine main flow" encompasses the main flow of exhaust gas passing through the turbine. For the most part, this is the exhaust gas received by the turbine from the internal combustion engine, and this exhaust gas flows from the turbine inlet, through the turbine wheel chamber and into the turbine outlet, and then travels downstream to the exhaust aftertreatment system including one or more catalytic reducers (such as DOC or SCR reducers).

[0265] The term "auxiliary passage" encompasses a passage that is separate from the turbine inlet passage, the turbine wheel chamber, and the turbine outlet passage, and that is capable of receiving exhaust gas from a first location of the turbine and conveying the exhaust gas to a second location. The second location may be a location within the turbine outlet. The portion of the turbine's auxiliary passage inlet from which the exhaust gas is received may be essentially any portion of the turbine that receives the exhaust gas but does not form part of the auxiliary passage. For example, this may include one or more of the turbine inlet passage, the turbine wheel chamber, the turbine outlet passage, or a wastegate (i.e., bypass) passage.

[0266] The term "auxiliary flow" encompasses the exhaust gas flow travelling through the auxiliary passage. The term "dividing wall" encompasses the structure that separates the auxiliary flow in the auxiliary passage from the main turbine flow in the turbine outlet passage.

[0267] As used herein, the term "centerline" encompasses the line defined by the centroid of the cross-section of the turbine outlet passage along the direction of exhaust gas flow. That is, the centerline of the turbine outlet passage is an imaginary line drawn along the turbine outlet passage that always lies at the center of the geometry of the exhaust gas flowing through the turbine outlet passage. Typically, though not always, the centerline will be an extension of the turbine axis, which may deviate from the turbine axis depending on the geometry of the turbine outlet passage. The turbine axis is the axis about which the turbine wheel is configured to rotate.

[0268] As used herein, the term "distribution module" encompasses any device configured to introduce an aftertreatment fluid into the turbine outlet passage. The aftertreatment fluid may be a fluid required to support chemical reactions in the exhaust aftertreatment process. For example, the aftertreatment fluid may be DEF used in an SCR process. The aftertreatment fluid may include a reducing agent (i.e., a reducing agent). The term "nozzle" refers to the portion of the distribution module from which the aftertreatment fluid exits the distribution module. In other words, the aftertreatment fluid is ejected from that portion of the distribution module.

[0269] The term "thermal communication" encompasses the transfer of thermal energy from a source location to a heat sink location. For example, this may include transfer by conduction or convective heat transfer.

[0270] During use, when the aftertreatment fluid is injected into the turbine outlet channel, the aftertreatment fluid may impact the first surface. The aftertreatment fluid is typically at a lower temperature than the main turbine flow and therefore forms a heat sink that drives heat transfer from the first surface to the aftertreatment fluid. The first surface is heated by two sources. First, the first surface is heated by convective heat transfer from the main turbine flow passing through the turbine outlet channel. Second, the first surface is heated by the auxiliary flow passing through the auxiliary channel; and specifically by convective heat transfer from the auxiliary flow to the second surface and conductive heat transfer from the second surface through the material of the partition wall to the first surface. Therefore, the first surface and the second surface ensure that there is a larger surface area available for capturing heat from the main flow and the auxiliary flow so that the heat can be transferred to the converging aftertreatment fluid (for example, compared to the case without the auxiliary channel). As a result, the amount of heat transferred to the aftertreatment fluid after the impact increases, causing the temperature of the aftertreatment fluid to rise until the aftertreatment fluid evaporates. Therefore, the formation of deposits in the turbine outlet channel is reduced or prevented.

[0271] Because the dividing wall and the first surface can mitigate the formation of solid deposits, the aftertreatment fluid can be injected closer to the turbine wheel than previously thought possible. Injecting the aftertreatment fluid closer to the turbine wheel can improve mixing and breakup of the aftertreatment fluid and thereby eliminate the need for any auxiliary mixing baffles or the like downstream.

[0272] The first surface may be disposed on a side of the partition wall opposite the second surface. Specifically, the first surface may be parallel to the second surface and face in a direction opposite to the second surface. Since the first and second surfaces are located on opposite sides of the partition wall, a direct heat conduction path from the second surface to the first surface is provided, thereby improving heating of the first surface.

[0273] The dividing wall may define a thickness between the first surface and the second surface, the turbine including a turbine wheel having an inducer portion, the inducer portion defining an inducer diameter, and the thickness of the dividing wall being approximately 5% of the inducer diameter. Thus, the dividing wall is relatively thin compared to the flow area of ​​the turbine wheel and the turbine outlet passage. Consequently, the first surface is in close proximity to the second surface, thereby improving conductive heat transfer from the second surface to the first surface.

[0274] The auxiliary passage can be configured to receive the auxiliary flow from the turbine outlet passage. The auxiliary passage receives a portion of the main turbine flow from the turbine outlet passage, increasing the amount of thermal energy that can be recovered from the main turbine flow and used to heat the first surface of the dividing wall. Thus, the rate of heat transfer to the dividing wall can be increased, resulting in a temperature of the first surface sufficiently high to cause evaporation of any aftertreatment fluid impinging on the surface.

[0275] The auxiliary passage may be configured to receive the auxiliary flow from the turbine inlet passage. As the main turbine flow travels from the turbine inlet passage through the turbine wheel chamber to the turbine outlet passage, the energy of the main turbine flow decreases because the main turbine flow performs work on the turbine wheel, causing the turbine wheel to rotate. This decrease in energy of the main turbine flow is generally observed as a decrease in temperature and pressure. Therefore, the temperature of the main turbine flow in the turbine inlet passage is higher than the temperature of the main turbine flow in the turbine outlet passage.

[0276] Because the auxiliary flow is received from the turbine inlet channel, the temperature of the auxiliary flow is higher than the temperature of the main turbine flow in the turbine outlet channel. Thus, the heat transferred to the first surface of the dividing wall is increased (at least compared to the alternative embodiment in which the auxiliary flow is received from the turbine outlet channel). In other words, because the auxiliary flow bypasses the turbine wheel, the auxiliary flow contains more energy, which can be extracted by the second surface of the dividing wall and used to heat the aftertreatment fluid collected on the first surface.

[0277] The auxiliary passage may include a valve arrangement configured to selectively allow, prevent, and / or regulate the flow of the auxiliary flow through the auxiliary passage. In this way, the auxiliary passage may function as a wastegate passage for selectively bypassing a portion of the turbine main flow around the turbine wheel.

[0278] The auxiliary passage can be configured to always allow flow through the auxiliary passage. That is, the auxiliary passage can be substantially free of valves or closures that would obstruct auxiliary flow through the auxiliary passage. However, in some embodiments, the auxiliary passage can include valves or closures, as long as the valves or closures can be controlled so that at least some leakage exists therethrough under all operating conditions of the turbine.

[0279] The turbine may include a turbine wheel having an outlet guide vane, the outlet guide vane defining an outlet guide vane diameter, and the dosing module may include a nozzle configured to inject a spray of aftertreatment fluid into the turbine outlet passage, and the nozzle of the dosing module may be spaced apart from the outlet guide vane of the turbine wheel by a distance of up to about 10 outlet guide vane diameters along the centerline of the turbine outlet passage. As used herein, the term "outlet guide vane" encompasses a portion of the turbine wheel that is configured to discharge exhaust gas into the turbine outlet passage. The spacing of the nozzle from the outlet guide vane of the turbine wheel may be measured from the most downstream portion of the tip of the blades of the turbine wheel to the most upstream portion of the nozzle as viewed from the centerline. Preferably, the nozzle of the distribution module is spaced apart from the outlet guide of the turbine impeller along the centerline of the turbine outlet channel by at most about 2, 3, 4 or 5 times the outlet guide diameter, and the nozzle of the distribution module is spaced apart from the outlet guide of the turbine impeller along the centerline by at least about 0.5, 1 or 2 times the outlet guide diameter.

[0280] Because the nozzle is located within a distance of up to approximately 10 inducer diameters from the turbine wheel, the location at which the after-treatment fluid is injected is relatively close to the turbine wheel. This ensures that the after-treatment fluid is delivered to a region of the turbine main flow in the turbine outlet passage that has relatively high energy, particularly relatively high turbulent kinetic energy, and a high temperature compared to downstream locations. Delivering the after-treatment fluid to a region of the turbine main flow with relatively high turbulent kinetic energy promotes mixing of the after-treatment fluid with the turbine main flow, and similarly, the relatively high temperature promotes decomposition of the delivered after-treatment fluid.

[0281] Furthermore, as the auxiliary flow travels through the auxiliary passage, the rate of heat transfer to the dividing wall decreases, and thus the temperature of the first surface of the dividing wall decreases along the length of the centerline. Thus, by delivering the aftertreatment fluid close to the turbine wheel, any impact of the aftertreatment fluid on the dividing wall generally occurs at the hottest region of the first surface of the dividing wall, meaning that the evaporation rate of any aftertreatment fluid impacting the first surface of the dividing wall is greater than at locations further downstream.

[0282] The nozzle can be positioned substantially flush with the sidewall of the turbine outlet passage, or radially outward of the sidewall. In some embodiments, the nozzle can be positioned substantially flush with the sidewall of the turbine outlet passage. The term "substantially flush" encompasses the distribution module being roughly aligned or precisely aligned with the inner surface of the turbine outlet passage, thereby defining the perimeter of the turbine outlet passage. In such embodiments, the nozzle does not protrude into the turbine outlet passage. As a result, the nozzle does not impede flow through the turbine outlet passage, thereby avoiding back pressure on the internal combustion engine.

[0283] The distribution module can be configured to deliver an atomized spray of the after-treatment fluid into the turbine outlet channel in a direction facing the first surface. In particular, the nozzle of the distribution module can generally face the first surface of the partition wall. The distribution module can produce a fine spray of atomized after-treatment fluid, which is ejected from the nozzle of the distribution module in a cone shape. The cone can have a top at the nozzle of the distribution module and extend generally toward the first surface of the partition wall. The partition wall can define a distal end relative to the turbine impeller, and the nozzle of the distribution module can be positioned between the turbine impeller and the distal end of the partition wall, with the nozzle being oriented to face the first surface of the partition wall.

[0284] The first surface of the dividing wall is heated by heat energy transferred from the main turbine flow in the turbine outlet passage and from the auxiliary flow. Directing the atomized spray of aftertreatment fluid in a direction facing the first surface of the dividing wall improves the likelihood that any aftertreatment fluid that impinges on the inner surface of the turbine will impinge on the first surface and thereby be vaporized.

[0285] That is, the aftertreatment fluid can be delivered to the turbine outlet channel in a direction that is substantially deviated from the direction of the turbine main flow. For example, the aftertreatment fluid can be delivered in a direction that is substantially perpendicular to the direction of the turbine main flow in the turbine outlet channel. This not only causes the aftertreatment fluid that impacts the partition wall to impact the hotter first surface of the partition wall (the advantages of which are described above), but also causes the delivered aftertreatment fluid to penetrate the turbine main flow, so that the aftertreatment fluid and the turbine main flow are more evenly mixed. In addition, since the aftertreatment fluid can be delivered to the turbine outlet channel in a direction that is substantially perpendicular to the turbine main flow, the momentum exchange between the aftertreatment fluid and the turbine main flow can be greater, which leads to improved mixing of the aftertreatment fluid and the turbine main flow.

[0286] The auxiliary channel can define an auxiliary channel outlet configured to deliver the auxiliary flow to the turbine outlet channel, and the auxiliary channel outlet can be located at least about 0.5 times the outlet guide diameter downstream of the nozzle along the center line. Since the partition wall is located downstream of the nozzle, the first surface of the partition wall is able to capture the aftertreatment fluid that has been sprayed into the turbine outlet channel by the nozzle. In other words, the partition wall covers the area where the aftertreatment fluid may impact. Any aftertreatment fluid that impacts the first surface of the partition wall will be heated and evaporated by the partition wall. In an alternative embodiment, the auxiliary channel outlet can be positioned at a position at least about 1 or 2 times the outlet guide diameter from the nozzle, and at a position about 5 or about 10 times the outlet guide diameter from the nozzle. The distance between the nozzle and the auxiliary channel outlet can be measured between their respective geometric centers.

[0287] The turbine may include a surface that at least partially defines the turbine outlet passage, and the nozzle may be substantially aligned with or located radially outward of the surface in a radial direction relative to the centerline. In other words, the nozzle is aligned with one of the surfaces defining the turbine outlet passage such that the nozzle does not protrude into the turbine outlet passage. Thus, the nozzle does not obstruct flow through the turbine outlet passage.

[0288] The surface may be a surface of a partition wall, for example a first surface.

[0289] The term "aligned" encompasses the fluid injection portion of the nozzle being substantially flush with the surface. Those skilled in the art will appreciate that this alignment need not be absolute, and a small amount of misalignment can be tolerated, as long as the nozzle of the distribution module does not protrude into the turbine outlet passage in a manner that causes significant obstruction to flow. The term "radially outward" encompasses the fluid injection portion of the nozzle being spaced apart from the surface.

[0290] The dividing wall may extend circumferentially about the centerline. In particular, the dividing wall may be generally annular or frusto-conical and arranged concentrically about the centerline. The dividing wall may be a continuous wall formed as a single, unitary structure. The dividing wall may be a sleeve disposed within the turbine housing.

[0291] The partition wall may be supported by a pair of elongated support columns, and the auxiliary channel may be at least partially defined between the support columns. The support columns serve to concentrate the energy of the auxiliary flow to a specific location, so that the auxiliary flow can be used to heat a specific portion of the partition wall.

[0292] The support struts can be positioned on a side of the turbine outlet passage opposite the distribution module, and the auxiliary passage can be defined between the support struts on a side of the turbine outlet passage opposite the distribution module. The portion of the dividing wall most likely to be impacted by after-treatment fluid is the portion opposite the distribution module. Because the struts define the auxiliary passage opposite the distribution module, this ensures that the portion of the dividing wall opposite the distribution module is sufficiently hot to evaporate any impacted after-treatment fluid.

[0293] The auxiliary channel may define an annular nozzle. The term "annular nozzle" encompasses a channel in the shape of an annulus having a generally decreasing cross-sectional area in the direction of flow. As the auxiliary flow travels through the nozzle, the velocity of the auxiliary flow will generally increase and the pressure of the flow will generally decrease due to the reduction in the cross-sectional area of ​​the auxiliary channel. This increases the velocity. The accelerated auxiliary flow may be reintroduced into the turbine outlet channel to provide a high shear layer close to the surface of the turbine outlet channel. The high shear layer may remove solid deposits formed on the surface of the turbine outlet channel and may also displace post-treatment fluid that has been deposited on the surface. Providing a high shear layer makes the turbine outlet channel a suitable location for conveying post-treatment fluid because the risk of post-treatment fluid pooling and deposit formation in the turbine outlet channel is mitigated.

[0294] The turbine outlet passage may include a diffuser portion, which is at least partially defined by the partition wall. That is, the turbine outlet passage may include a diffuser, for example defined by one or more tapered portions of the turbine housing and / or the partition wall. As used herein, the term "diffuser" encompasses an expansion passage, wherein the cross-sectional area of ​​the passage increases along the length of the passage. As the cross-sectional area of ​​the diffuser increases (i.e., as the wall defining the turbine outlet passage expands), the velocity of the turbine body flow decreases and the pressure increases. The increase in pressure can be used to improve the efficiency of the turbine. It will be understood that the cross-sectional area of ​​the diffuser portion can increase linearly or nonlinearly along its length.

[0295] The diffuser portion may be aligned with the turbine axis and extend symmetrically about the turbine axis. That is, the diffuser may be an axial diffuser. The diffuser may comprise a generally circular cross-section defined by the conical wall of the turbine outlet passage.

[0296] The diffuser portion may define a centerline defined by the centroid of the turbine outlet passage. The centerline may be offset from the turbine axis such that the centerline of the diffuser portion is offset from the turbine axis. The diffuser portion may include a generally circular cross-section despite the offset.

[0297] The distribution module can be configured to deliver the after-treatment fluid to the diffuser section. As explained above, as the turbine body flow travels through the diffuser section, the turbine body flow generally decreases in velocity and increases in pressure. Delivering the after-treatment fluid to the region of reduced turbine body flow velocity in the turbine outlet passage allows the after-treatment fluid to penetrate the turbine body flow and more evenly mix with the turbine body flow in the turbine outlet passage.

[0298] Furthermore, depending on the geometry of the diffuser section and the flow conditions of the turbine main flow, the diffuser section can promote a turbulent region in the turbine main flow. This delivers the aftertreatment fluid into the turbulent region of the turbine main flow, promoting mixing of the aftertreatment fluid with the turbine main flow and also reducing the impact of the aftertreatment fluid on surfaces in the turbine outlet passage.

[0299] The turbine may include a support structure disposed in the auxiliary passage and configured to support the partition wall. That is, the support structure may be, for example, a post, a fin, an arm, a blade, a baffle, or any other suitable type of structure suitable for supporting the partition wall and separating the partition wall from the turbine housing. The support structure may extend from a surface of the turbine housing that at least partially defines the outermost surface of the auxiliary passage to an innermost surface of the auxiliary passage (e.g., a second surface of the partition wall). The support structure may be aerodynamically shaped to minimize disturbance of the auxiliary flow in the auxiliary passage.

[0300] The turbine may comprise a plurality of support structures. In the case where the auxiliary passage is a substantially annular passage, the plurality of support structures may be equally spaced circumferentially around the centre line.

[0301] The distribution module may include a nozzle, and the support structure may be configured to shield the nozzle from the auxiliary flow and / or the main turbine flow. That is, the support structure may be configured to deflect the auxiliary flow and / or the main turbine flow away from the nozzle. For example, the support structure may substantially surround the nozzle to prevent the auxiliary flow or the main turbine flow from passing through the nozzle by blocking or obstructing the nozzle from contacting the auxiliary flow and / or the exhaust gas of the turbine outlet flow.

[0302] The aftertreatment fluid is delivered as an atomized spray from a nozzle in the distribution module to the turbine outlet passage. The atomized spray of aftertreatment fluid typically emerges from the nozzle in a cone-like pattern, with the tip of the cone located at the nozzle. Shielding the nozzle allows the cone to develop, thereby promoting uniform mixing of the aftertreatment fluid with the bulk turbine flow in the turbine.

[0303] The nozzle may be shielded from the turbine main flow and / or auxiliary flow by a wall of the turbine housing. For example, the wall of the turbine housing may define a recessed portion, and the nozzle may be disposed in the recessed portion such that the recessed portion shields the nozzle.

[0304] The dosing module may comprise a nozzle positioned to be in fluid communication with the auxiliary channel so that, in use, the auxiliary stream may pass through the nozzle of the dosing module. It is known that when the after-treatment fluid is discharged from the dosing module, residues of the after-treatment fluid may remain at or near the nozzle and may result in the formation of solid deposits which clog the nozzle. One benefit of having the auxiliary stream passing through the nozzle is that it provides a cleaning effect because, due to the relatively high temperature of the auxiliary stream, the stream may cause the after-treatment fluid that may have been deposited around the nozzle to evaporate, and furthermore, the auxiliary stream may be configured to remove solid deposits that have formed near the nozzle, both of which may alleviate the situation where the nozzle becomes clogged and is unable to deliver the after-treatment fluid as an atomised spray.

[0305] Another benefit of the secondary flow passing through the nozzle is that as the after-treatment fluid exits the nozzle, it can exchange momentum with the secondary flow before entering the turbine outlet passage. This momentum exchange can be used to provide beneficial effects, such as ensuring that the after-treatment fluid is carried across a greater lateral extent of the turbine outlet passage.

[0306] The turbine outlet passage may include a curved portion defining a top end, and the distribution module may include a nozzle configured to deliver an aftertreatment fluid into the turbine outlet passage, the nozzle being positioned at the top end of the curved portion or upstream of the top end of the curved portion. The term "curved portion" encompasses an axis whose centerline deviates from a straight line such that the main flow of the turbine changes direction. Examples of curved portions include, but are not limited to, arcuate paths, stepped portions, and dog-leg bends. In other words, a curved portion is an area in the passage that causes the main flow of the turbine to change direction. Including a curved portion may be necessary due to packaging requirements of the engine compartment.

[0307] Turbulent kinetic energy dissipates around bends in pipes. Therefore, it is beneficial to position the nozzle so that it is not downstream of the top of the bend. This ensures that the post-treatment fluid is injected into an area with sufficient turbulent kinetic energy to ensure adequate mixing.

[0308] The first surface may define a surface of the curved portion, and the nozzle may face the first surface. Because the distribution module faces (i.e., is generally opposite) the first surface, and the first surface defines a portion of the curved portion, aftertreatment flow that does not mix with the turbine body flow will impinge on the hot first surface rather than on a cooler downstream surface.

[0309] The auxiliary channel may include an auxiliary channel outlet configured to deliver a portion of the auxiliary flow to the turbine outlet channel at a position downstream of the nozzle of the dosing module, and the dividing wall may include an auxiliary orifice configured to deliver a portion of the auxiliary flow to the turbine outlet channel at a position aligned with the nozzle or at a position upstream of the nozzle. The term "auxiliary orifice" encompasses slots, holes, openings, etc. in the dividing wall and is suitable for providing a fluid path from the auxiliary channel to a turbine outlet channel separate from the auxiliary channel outlet.

[0310] The dividing wall may comprise a plurality of auxiliary apertures and / or a plurality of auxiliary channel outlets.

[0311] The auxiliary orifice can be configured to deliver a portion of the auxiliary flow into the turbine outlet passage, specifically into a region of the main turbine flow with relatively low turbulent kinetic energy. This region of the main turbine flow with relatively low turbulent kinetic energy can be referred to as a "recirculation zone." Delivering a portion of the auxiliary flow into the recirculation zone of the main turbine flow results in momentum exchange between the delivered auxiliary flow and the main turbine flow, and increases the turbulent kinetic energy of the main turbine flow. Consequently, turbulence in the turbine outlet passage is increased, and a recirculation zone is avoided.

[0312] The turbine may further include a turbine housing assembly, which may include: a turbine housing defining the turbine inlet passage, the turbine wheel chamber, and at least a portion of the turbine outlet passage; and a connection adapter defining at least a portion of the turbine outlet passage and at least a portion of the auxiliary passage, the connection adapter being connectable to the turbine housing at a first interface; the connection adapter being configured to support the divider wall so as to extend along the centerline; and the divider wall being configured to extend axially along the centerline through the first interface. The term "interface" encompasses a mechanical joint between two components. Such an interface may result in a localized surface discontinuity between the components, which presents a risk of after-treatment fluid pooling and deposit formation. However, when the divider wall extends across the first interface, it shields the first interface from the impact of the after-treatment fluid. In other words, the divider wall forms a barrier to block the after-treatment fluid and prevents it from reaching the first interface. Thus, the risk of pooling and deposit formation at the first interface can be reduced or avoided.

[0313] The turbine housing assembly may further include a downpipe adapter configured to connect to a downpipe, the downpipe adapter may define at least a portion of the auxiliary channel and / or the turbine outlet channel, and the downpipe adapter is coupled to the connection adapter at a second interface; and the partition wall extends axially along the centerline through the second interface. The term "downpipe adapter" encompasses a component disposed between the connection adapter and a downstream conduit (e.g., a downpipe). As explained above with respect to the first interface, the second interface may have surface discontinuities, which risk causing post-treatment fluid collection and deposit formation. However, when the partition wall extends across the second interface, the partition wall acts as a barrier preventing post-treatment fluid from reaching the second interface. Thus, post-treatment fluid collection and deposit formation at the second interface are reduced or avoided.

[0314] The auxiliary passage may be a first auxiliary passage, and the auxiliary flow may be a first auxiliary flow, and the turbine may further include a second auxiliary passage, the second auxiliary passage being configured to receive a portion of the turbine main flow from the turbine inlet passage, the portion of the turbine main flow received by the second auxiliary passage defining a second auxiliary flow, and the second auxiliary passage being configured to deliver the second auxiliary flow to the turbine outlet passage. The term "second auxiliary passage" encompasses a passage that is separate from the first auxiliary passage, the turbine inlet passage, the turbine wheel chamber, and the turbine outlet passage, and that is capable of receiving exhaust gas from the turbine inlet passage and delivering the exhaust gas to the turbine outlet passage.

[0315] Because the second auxiliary channel receives a portion of the turbine's main flow from the turbine inlet channel, the energy of the second auxiliary channel is greater than that of the main flow in the turbine outlet channel. This energy difference can be exploited to provide specific beneficial effects. For example, the second auxiliary channel can be delivered to the turbine outlet channel in a manner that increases the turbulent kinetic energy of the main flow in the turbine outlet channel. As another example, the second auxiliary channel can be delivered in a manner that provides a cleaning effect around the nozzle area. The second auxiliary channel can be functionally equivalent to a wastegate channel.

[0316] The second auxiliary channel may include a second auxiliary channel outlet, which may be aligned with the nozzle of the distribution module relative to the center line or positioned upstream of the nozzle of the distribution module, and the second auxiliary channel outlet may be configured to guide the second auxiliary flow along the first surface of the partition wall in a second auxiliary flow layer. Since the second auxiliary flow does not travel through the turbine impeller, the temperature of the second auxiliary flow is generally higher than the temperature of the turbine main flow in the turbine outlet channel. Therefore, guiding the second auxiliary flow along the first surface of the partition wall in a second auxiliary flow layer promotes heat transfer to the first surface, thereby further increasing the temperature of the first surface. The second auxiliary flow layer can be provided along the area where the post-treatment fluid may impact the first surface.

[0317] In addition, the second auxiliary flow layer can form a fluid barrier that substantially inhibits the post-treatment fluid from reaching the first surface. In this context, it should be understood that the fluid barrier covers the fluid interaction between the second auxiliary flow layer and the post-treatment fluid, in which momentum is exchanged between the two fluids in a manner that causes the post-treatment fluid to be deflected away from the first surface of the partition wall. In particular, the second auxiliary flow layer exerts a shear force on the post-treatment fluid, thereby preventing the post-treatment fluid from contacting the first surface of the partition wall or substantially reducing the amount of the post-treatment fluid that can contact the first surface of the partition wall. The shear force can further cause the droplets of the post-treatment fluid to break apart, thereby reducing their relative mass and making the droplets more easily deflected. Therefore, the second auxiliary flow layer acts as a "cushion", inhibiting the post-treatment fluid from contacting the first surface of the partition wall.

[0318] This "buffering" effect makes the turbine outlet channel a suitable location for injecting after-treatment fluid. In particular, after-treatment fluid injected into the turbine outlet channel will be deflected by the second auxiliary flow layer and prevented from reaching the first surface of the partition wall. Therefore, the risk of after-treatment fluid collecting and forming deposits in the turbine outlet channel is reduced, and the turbine outlet channel can therefore be used as a decomposition chamber for receiving and decomposing the after-treatment fluid. This means that the dosing module can be placed closer to the turbine impeller than was previously possible. The temperature of the turbine main flow will be higher near the turbine impeller, and therefore the higher temperature of the turbine main flow can be used to provide improved heat transfer to the after-treatment fluid, so that the after-treatment fluid is decomposed more quickly into the reducing agent required to support the SCR reaction.

[0319] The nozzle of the distribution module can be positioned on a side of the turbine outlet passage opposite the second auxiliary flow layer, such that, during use, the second auxiliary flow layer inhibits the after-treatment fluid from reaching the portion of the first surface of the dividing wall opposite the nozzle. In other words, the nozzle of the distribution module and at least a portion of the second auxiliary flow layer are arranged on opposite sides of the turbine outlet passage. Thus, the second auxiliary flow layer is able to "capture" the after-treatment fluid dispensed by the nozzle and hinder or prevent the after-treatment fluid from contacting the portion of the turbine outlet passage surface generally opposite the nozzle.

[0320] The second auxiliary channel can be configured to guide the second auxiliary flow into the turbine outlet channel in a direction that induces the second auxiliary flow to swirl around the centerline in the turbine outlet channel in the same angular direction as the main turbine flow in the turbine outlet channel. Since the second auxiliary channel guides the second auxiliary flow into the turbine outlet channel in a direction that induces a swirl in the same angular direction as the main turbine flow, the swirl momentum of the second auxiliary flow will be imparted to the swirl momentum of the main turbine flow, thereby increasing the amplitude of the swirl momentum of the main turbine flow. The rotational momentum of the combination of the main turbine flow and the second auxiliary flow increases, further increasing the velocity and shear stress of the second auxiliary flow layer. This increases the amount of energy available in the second auxiliary flow layer for deflection and separation of the after-treatment fluid, and thus improves the "buffering" effect. In addition, when the second auxiliary flow has swirl momentum, the second auxiliary flow layer acts as a fluid agitator, which mixes the main turbine flow more thoroughly. This improves heat transfer to the after-treatment fluid, thereby ensuring that more after-treatment fluid is decomposed at a faster rate.

[0321] The increased velocity and shear near the first surface of the dividing wall make the turbine outlet channel a suitable location for injecting the after-treatment fluid. Specifically, after-treatment fluid injected into the turbine outlet channel is deflected by the high-velocity, high-shear exhaust gas and prevented from reaching the first surface of the dividing wall. This reduces the risk of after-treatment fluid pooling and deposit formation in the turbine outlet channel, allowing the turbine outlet channel to function as a decomposition chamber for receiving and decomposing the after-treatment fluid.

[0322] To achieve a vortex in the positive direction, the second auxiliary channel can be configured to deliver the second auxiliary flow in a direction having a directional component tangential to the surface of the turbine outlet channel in a plane normal to the centerline. In other words, the second auxiliary flow can have a directional component tangential to the surface of the turbine outlet channel in a plane normal to the centerline. Because the second auxiliary flow has a directional component tangential to the surface of the turbine outlet channel, the turbine outlet channel induces the second auxiliary flow to swirl about the centerline.

[0323] The second auxiliary passage may include a second auxiliary passage valve device configured to selectively allow, prevent, and / or regulate the flow of the second auxiliary flow through the second auxiliary passage. Thus, the second auxiliary passage may function as a wastegate passage for selectively bypassing a portion of the turbine main flow around the turbine wheel.

[0324] Additionally or alternatively, the second auxiliary passage can be configured such that flow is always permitted therethrough. In particular, the second auxiliary passage can be substantially free of valves or closures. Alternatively, the second auxiliary passage can include one or more valves or closures configured to provide at least some leakage therethrough under all operating conditions of the turbine.

[0325] While only first and second auxiliary passages are described, it will be appreciated that the turbine may include any number of auxiliary passages, wherein different auxiliary passages may be configured to condition the respective flows within each passage to provide different or additional beneficial effects.

[0326] The turbine may further include a controller configured to selectively activate the dosing module to deliver aftertreatment fluid to the turbine outlet passage. Specifically, the controller may be configured to activate the dosing module based on a temperature of the first surface or a time since engine ignition. Specifically, the controller may be configured to activate the dosing module when the first surface reaches a predetermined temperature.

[0327] According to a ninth aspect of the present invention, there is provided a method for operating a turbine for a turbocharger, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet passage, the exhaust gas received by the turbine inlet passage defining a turbine main flow; receiving the turbine main flow from the turbine inlet passage into a turbine impeller chamber, the turbine impeller chamber being configured to accommodate a turbine impeller, the turbine impeller being supported for rotation; receiving the turbine main flow from the turbine impeller chamber into a turbine outlet passage, the turbine outlet passage extending along a centerline and being at least partially defined by a first surface of a partition wall; delivering an atomized spray of an aftertreatment fluid into the turbine outlet passage using a dosing module including a nozzle; receiving a portion of the turbine main flow into an auxiliary passage, the portion of the turbine main flow received by the auxiliary passage defining an auxiliary flow, the auxiliary passage being at least partially defined by a second surface of the partition wall; wherein the partition wall is configured to provide thermal connectivity from the auxiliary passage to the first surface via the second surface.

[0328] The first surface may be provided on a side of the partition wall opposite to the second surface.

[0329] The dividing wall may define a thickness between the first surface and the second surface, the turbine may include a turbine wheel having an inducer portion defining an inducer diameter, and the thickness of the dividing wall may be approximately 5% of the inducer diameter.

[0330] The auxiliary passage may be configured to receive the auxiliary flow from the turbine outlet passage.

[0331] The auxiliary passage may be configured to receive the auxiliary flow from the turbine inlet passage.

[0332] The auxiliary passage may include a valve arrangement configured to selectively allow, prevent and / or regulate flow of the auxiliary fluid through the auxiliary passage.

[0333] The auxiliary channel may be configured such that flow is always permitted through the auxiliary channel.

[0334] The turbine may include a turbine impeller having an outlet inducer, the outlet inducer defining an outlet inducer diameter, and the dosing module may include a nozzle configured to inject the atomized spray of the aftertreatment fluid into the turbine outlet passage, and the nozzle of the dosing module may be spaced apart from the outlet inducer of the turbine impeller along the centerline of the turbine outlet passage by a distance of up to about 10 times the outlet inducer diameter.

[0335] The nozzle may be substantially aligned with or radially outward of a sidewall of the turbine outlet passage. In some embodiments, the nozzle may be positioned substantially flush with a sidewall of the turbine outlet passage.

[0336] The distribution module may be configured to deliver the atomized spray of after-treatment fluid into the turbine outlet passage in a direction facing the first surface.

[0337] The auxiliary passage may define an auxiliary passage outlet configured to deliver the auxiliary flow into the turbine outlet passage, and the auxiliary passage outlet may be located at least about 0.5 outlet inducer diameters downstream from the nozzle along the centerline.

[0338] The turbine may include a surface at least partially defining the turbine outlet passage, and the nozzle may be substantially aligned with or located radially outward of the surface in a radial direction relative to the centerline.

[0339] The dividing wall may extend circumferentially about the centerline.

[0340] The partition wall may be supported by a pair of elongated support columns, and the auxiliary channel may be at least partially defined between the support columns.

[0341] The support struts may be positioned on a side of the turbine outlet passage opposite the distribution module, and the auxiliary passage may be defined between the support struts on a side of the turbine outlet passage opposite the distribution module.

[0342] The secondary channel may define an annular nozzle.

[0343] The turbine outlet passage may include a diffuser portion defined at least in part by the dividing wall.

[0344] The distribution module may be configured to deliver an aftertreatment fluid into the diffuser portion.

[0345] The turbine may include a support structure provided in the auxiliary passage and configured to support the partition wall.

[0346] The distribution module may include a nozzle, and the support structure may be configured to shield the nozzle from the auxiliary flow and / or the turbine body flow.

[0347] The dosing module may comprise a nozzle positioned in fluid communication with the auxiliary channel such that, in use, the auxiliary flow may pass through the nozzle of the dosing module.

[0348] The turbine outlet passage may include a curved portion defining a top end, and the distribution module may include a nozzle configured to deliver the aftertreatment fluid into the turbine outlet passage, the nozzle may be positioned at the top end of the curved portion or upstream of the top end of the curved portion.

[0349] The first surface may define a surface of the curved portion, and the nozzle may face the first surface.

[0350] The auxiliary channel may include an auxiliary channel outlet, which is configured to deliver a portion of the auxiliary flow to the turbine outlet channel at a position downstream of the nozzle of the distribution module, and the partition wall may include an auxiliary orifice, which is configured to deliver a portion of the auxiliary flow to the turbine outlet channel at a position aligned with the nozzle or at a position upstream of the nozzle.

[0351] The method may also include a turbine housing assembly, which may include: a turbine housing, the turbine housing defining the turbine inlet passage, the turbine wheel chamber and at least a portion of the turbine outlet passage; and a connection adapter, the connection adapter defining at least a portion of the turbine outlet passage and at least a portion of the auxiliary passage, the connection adapter being connectable to the turbine housing at a first interface; the connection adapter being configured to support the partition wall to extend along the centerline; and the partition wall being extendable axially along the centerline through the first interface.

[0352] The turbine housing assembly may further include a downtube adapter configured to connect to a downtube, the downtube adapter may define at least a portion of the turbine outlet passage and / or the auxiliary passage, and the downtube adapter may be coupled to the connection adapter at a second interface; and the partition wall may extend axially along the centerline through the second interface.

[0353] The auxiliary channel may be a first auxiliary channel, and the auxiliary flow may be a first auxiliary flow, and the turbine may further include a second auxiliary channel configured to receive a portion of the turbine main flow from the turbine inlet channel, the portion of the turbine main flow received by the second auxiliary channel may define a second auxiliary flow, and the second auxiliary channel may be configured to deliver the second auxiliary flow to the turbine outlet channel.

[0354] The second auxiliary channel may include a second auxiliary channel outlet, which may be aligned with the nozzle of the distribution module relative to the center line or positioned upstream of the nozzle, and the second auxiliary channel outlet may be configured to guide the second auxiliary flow along the first surface of the partition wall in a second auxiliary flow layer.

[0355] The second auxiliary passage may include a second auxiliary passage valve arrangement configured to selectively allow, prevent and / or regulate flow of a second auxiliary fluid through the second auxiliary passage.

[0356] The method may further include a controller configured to selectively activate the dosing module to deliver aftertreatment fluid into the turbine outlet passage.

[0357] The step of delivering an atomized spray of aftertreatment fluid into the turbine outlet passage may be performed as a function of time from engine ignition and / or a temperature of the first surface.

[0358] According to the tenth aspect of the present invention, a turbine for a turbocharger is provided, which includes: a turbine inlet channel, the turbine inlet channel being configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet channel defining a turbine main flow; a turbine impeller chamber, the turbine impeller chamber being configured to receive the turbine main flow from the turbine inlet channel, the turbine impeller chamber accommodating a turbine impeller, the turbine impeller being supported to rotate around a turbine axis; a turbine outlet channel, the turbine outlet channel being configured to receive the turbine main flow from the turbine impeller chamber; a distribution module, the distribution module being configured to deliver an atomized spray of an after-treatment fluid into the turbine outlet channel; an auxiliary channel, the auxiliary channel being configured to receive a portion of the turbine main flow from a position upstream of the turbine outlet channel, the portion of the turbine main flow received by the auxiliary channel defining an auxiliary flow; and an exhaust gas sensor, the exhaust gas sensor being located in the auxiliary channel; wherein the exhaust gas sensor is configured to sense one or more physical parameters of the auxiliary flow.

[0359] Since the turbine impeller extracts energy from the main turbine flow, the pressure of the main turbine flow upstream of the turbine outlet channel is generally higher than the pressure of the main turbine flow in the turbine outlet channel. In this way, the main turbine fluid flows out of the turbine impeller chamber and carries the aftertreatment fluid. Therefore, the aftertreatment fluid and any reducing agent (such as ammonia (NH3)) decomposed from the aftertreatment fluid will not generally pass through the upstream of the turbine outlet channel. In the present invention, since the auxiliary channel receives the auxiliary flow from the upstream position of the turbine outlet channel, the presence of the aftertreatment fluid or reducing agent in the auxiliary flow is almost completely eliminated. Therefore, the auxiliary flow will not be contaminated by the aftertreatment fluid or reducing agent, and therefore the auxiliary flow can provide an accurate representation of the real physical properties of the exhaust gas generated by the internal combustion engine. In this way, a more accurate reading of the physical parameters measured by the exhaust gas sensor can be obtained.

[0360] In the context of the present invention, a "physical parameter" of the exhaust gas encompasses essentially any quantifiable property of the exhaust gas. This may include, for example, temperature, pressure, velocity, mass, volume flow, mass flow, etc. In particular, such a "physical parameter" may include the chemical composition of the exhaust gas, and more particularly, may include the absolute or relative concentration of a particular chemical component in the exhaust gas.

[0361] In the context of the present invention, a "position upstream of the turbine outlet passage" encompasses essentially any fluid position of the turbine from which fluid may flow to the turbine outlet passage (rather than out of the auxiliary passage itself).

[0362] In the context of the present invention, the exhaust gas sensor being located in the auxiliary flow passage encompasses the exhaust gas sensor having a sensing portion configured to interact with the auxiliary flow, wherein the sensing portion is exposed to the auxiliary flow in the auxiliary passage. In other words, the exhaust gas sensor is positioned within the auxiliary passage such that the exhaust gas sensor is able to detect a parameter of the auxiliary flow as the auxiliary flow flows through the auxiliary passage.

[0363] The exhaust gas sensor may be configured to measure the concentration of nitrogen oxides (NOx) in the auxiliary flow. That is, the sensor may be a NOx sensor. The turbine may be used in an exhaust gas aftertreatment system including an SCR catalyst device. Since the exhaust gas sensor is configured to measure the concentration of NOx in the auxiliary flow, the amount of aftertreatment fluid required to reduce NOx to an acceptable level can be calculated and the operation of the dosing module controlled accordingly. The exhaust gas sensor may be configured to sense the presence of substances other than NOx in the auxiliary flow, for example, the exhaust gas sensor may sense the presence of ammonia (NH3) and isocyanic acid (HNCO).

[0364] The auxiliary passage may be sized to receive at least about 0.1% of the turbine body flow received by the turbine inlet passage.

[0365] That is, the proportion of the auxiliary passage is such that at least about 0.5% of the total exhaust gas delivered from the internal combustion engine to the turbine is able to pass through the auxiliary passage. The remaining exhaust gas (i.e., the remaining turbine main flow) will pass through the turbine wheel chamber and enter the turbine outlet passage. Alternatively, the auxiliary passage can be sized to receive at least about 0.2%, 0.3%, 0.4%, 0.5%, 1%, 1.5%, 2% or 5% of the turbine main flow received by the turbine inlet passage. The relative proportion of the exhaust gas received by the auxiliary passage can be determined based on mass flow and / or volume flow. Since the auxiliary passage receives at least about 0.5% of the turbine main flow received by the turbine inlet passage, the exhaust gas sensor can obtain a sufficient amount of auxiliary flow to accurately measure one or more physical parameters of the auxiliary flow.

[0366] The auxiliary channel can be sized to receive up to approximately 10% of the turbine main flow received by the turbine inlet channel. In other words, the proportion of the auxiliary channel allows up to approximately 10% of the total exhaust gas delivered from the internal combustion engine to the turbine to pass through the auxiliary channel. The remaining exhaust gas (i.e., the remaining turbine main flow) will pass through the turbine wheel chamber and enter the turbine outlet channel. Alternatively, the auxiliary channel can be sized to receive up to approximately 1%, 1.5%, 2%, or 5% of the turbine main flow received by the turbine inlet channel. The relative proportion of exhaust gas received by the auxiliary channel can be determined based on mass flow and / or volume flow. It should be understood that since the auxiliary flow is received from a position upstream of the turbine outlet channel, the auxiliary flow will bypass at least a portion of the turbine impeller. This will reduce the amount of power generated by the turbine impeller. However, since the auxiliary channel receives up to approximately 10% of the turbine main flow received by the turbine inlet channel, the amount of power loss is reduced.

[0367] The auxiliary channel may be configured such that the auxiliary flow is always allowed to flow through the auxiliary channel during all operating conditions of the turbine. That is, the auxiliary channel may be substantially free of valves and / or closures configured to prevent the auxiliary flow from passing along the auxiliary channel. In other words, the auxiliary channel may include an auxiliary channel inlet connected to a position upstream of the turbine outlet channel and an auxiliary channel outlet connected to the turbine outlet channel, and the auxiliary channel may be configured such that flow from the auxiliary channel inlet to the auxiliary channel outlet is always allowed regardless of the operating conditions of the engine. Since flow is always allowed through the auxiliary channel, this ensures a constant supply of auxiliary flow to the exhaust gas sensor under all operating conditions of the engine. Therefore, the flow to the exhaust gas sensor is not interrupted, and therefore the readings produced by the exhaust gas sensor are more reliable.

[0368] The auxiliary passage may include a valve assembly configured to control the flow of the auxiliary flow through the auxiliary passage. Specifically, the auxiliary passage may be a wastegate passage having a wastegate valve. In such an embodiment, the exhaust gas sensor may be positioned within an existing wastegate arrangement, and thus the auxiliary passage does not need to be embodied in a passage that is separate and additional to the wastegate passage. When the auxiliary passage is configured to always allow flow through the auxiliary passage, the valve assembly may be configured to allow some leakage across the valve when in its closed position. Alternatively, the valve assembly may be controlled so that it is not fully closed.

[0369] The valve assembly can define an open configuration and a closed position, in which, in the open configuration, the auxiliary flow can be allowed to pass through the valve assembly, and in the closed position, the auxiliary flow can be substantially blocked by the valve assembly, and the valve assembly can include a leakage channel configured to allow leakage from one side of the valve assembly to the other side when the valve is in the closed configuration. The leakage hole can be considered to form part of the auxiliary channel. It should be understood that in the closed configuration, the valve assembly can substantially block the auxiliary flow by blocking a majority of the auxiliary flow (for example, approximately 90%, 95%, 98%, 98.5%, 99%, 99.5%, 99.6%, 99.7%, 99.8% or 99.9% of the auxiliary flow can be blocked by the valve assembly). The leakage channel can be located within the valve itself, for example, within the valve member, or can be located within a portion of the turbine housing that houses the valve assembly.

[0370] The auxiliary passage may be configured to deliver the auxiliary flow to the turbine outlet passage. In other words, the auxiliary passage may be configured to deliver the auxiliary flow to the turbine main flow at a position of the turbine outlet passage downstream of the turbine wheel chamber.

[0371] The auxiliary passage may be configured to deliver the auxiliary flow to the turbine inlet passage.

[0372] The dosing module may comprise a nozzle configured to generate the spray of the post-treatment fluid. For example, the nozzle may be an atomising nozzle.

[0373] The turbine outlet passage may be at least partially defined by a surface, and the turbine outlet passage may define a centerline, and the nozzle may be substantially aligned with the surface, or may be located radially outside the surface relative to the centerline. That is, the nozzle of the distribution module does not protrude into the turbine outlet passage. An inherent property of the turbine outlet passage is that it is defined by the surface of a housing component (e.g., a turbine housing, a connection adapter, a diffuser, etc.). The term "aligned" encompasses the fluid injection portion of the nozzle being substantially flush with the surface. It will be understood by those skilled in the art that such alignment need not be absolute, and a small amount of misalignment can be tolerated, as long as the nozzle of the distribution module does not protrude into the turbine outlet passage in a manner that causes a significant obstruction to the main flow of the turbine. Because the nozzle is substantially aligned with the surface, the turbine outlet passage is substantially free of obstructions that impede the flow of exhaust gas.

[0374] The turbine may include a turbine wheel having an outlet inducer, the outlet inducer defining an outlet inducer diameter, the turbine outlet passage may define a centerline, and the nozzle may be spaced apart from the outlet inducer of the turbine wheel along the centerline of the turbine outlet passage by a distance of up to about 10 times the outlet inducer diameter. The term "outlet inducer" encompasses the portion of the turbine wheel that serves as the turbine wheel outlet. In other words, at the distal end of the turbine wheel from the perspective of the main turbine flow passing through the turbine wheel. From the perspective of the main turbine flow, the term "outlet inducer diameter" encompasses the diameter of the outlet inducer at the distalmost portion of the turbine wheel. In alternative embodiments, the nozzle may be positioned relative to the turbine wheel along the centerline of the turbine outlet passage by no more than about 5 times, about 3 times, or about 2 times the outlet inducer diameter.

[0375] As the turbine body flow exits the turbine wheel, its temperature is at its hottest relative to any location downstream. Generally speaking, the hotter the turbine body flow, the more heat is available for heat exchange with the aftertreatment fluid, thereby promoting decomposition into the desired reductants. Positioning and orienting the distribution module so that the spray area is closer to the turbine wheel ensures greater heat capture, resulting in faster and more complete decomposition of the aftertreatment fluid. Experiments have shown that when the spray area is farther from the turbine wheel along the centerline than approximately 10 inducer diameters, heat dissipates from the turbine body flow, and the decomposition rate decreases.

[0376] The auxiliary channel can be configured to deliver the auxiliary flow to the turbine outlet channel upstream of the nozzle. That is, the auxiliary channel can include an auxiliary channel outlet configured to deliver the auxiliary flow to the turbine outlet channel, and the auxiliary channel outlet can be positioned upstream of the nozzle relative to the centerline. When the auxiliary flow rejoins the main turbine flow in the turbine outlet channel, the auxiliary flow will disturb the main turbine flow, thereby causing turbulence. Having some turbulence in the main turbine flow is generally beneficial because it can improve the mixing of the after-treatment fluid and the exhaust gas. This in turn increases the rate of heat transfer to the after-treatment fluid, thereby causing the after-treatment fluid to decompose into the reducing agent required for the SCR reaction more quickly. Since the auxiliary flow is delivered to the turbine outlet channel upstream of the nozzle, turbulence can be established or promoted at a location upstream of the nozzle. Therefore, when the nozzle injects the after-treatment fluid into the turbine outlet channel, the after-treatment fluid will enter an area of ​​turbulence and, therefore, the after-treatment fluid will decompose more quickly.

[0377] The auxiliary channel can be configured to direct the auxiliary flow through the nozzle. During use, post-treatment fluid may pool at the nozzle. If the post-treatment fluid cools, it may solidify and clog the nozzle. However, when the auxiliary fluid is directed through the nozzle, the auxiliary flow removes the pooled post-treatment fluid, thereby keeping the nozzle clean.

[0378] The auxiliary passage can be configured to receive the auxiliary flow from the turbine inlet passage. In particular, the auxiliary passage can include an auxiliary passage inlet in direct fluidic communication with the turbine inlet passage. Because the auxiliary flow is received from the turbine inlet passage and conveys the aftertreatment fluid within the turbine outlet passage, the likelihood of aftertreatment fluid entering the auxiliary passage and distorting measurements by the exhaust gas sensor is further reduced and / or eliminated.

[0379] The turbine inlet passage may include a first volute and a second volute, and the auxiliary passage may be configured to receive the auxiliary flow from the first volute. That is, the auxiliary passage may include an auxiliary passage inlet communicating with the first volute. Specifically, the auxiliary passage may be configured to receive the auxiliary flow only from the first volute and not from the second volute. Because the auxiliary passage receives the auxiliary flow only from the first volute, any flow disturbance caused by the auxiliary flow in the turbine inlet passage is confined to the first volute.

[0380] The tenth aspect of the present invention may be embodied in a turbocharger.

[0381] According to an eleventh aspect of the present invention, an exhaust aftertreatment system is provided, comprising: a turbine or turbocharger according to the aforementioned aspects of the present invention; and a catalyst device configured to receive a turbine body flow downstream of the turbine outlet passage. Specifically, the catalyst device may be a selective catalytic reduction (SCR) catalyst device.

[0382] The system may also include a controller that communicates with the exhaust gas sensor and may be configured to determine the measurement results of the one or more physical parameters of the auxiliary flow sensed by the exhaust gas sensor; the controller may also be configured to generate a control signal based on the measurement results of the one or more physical parameters, and the dosing module may communicate with the controller to receive the control signal, and the dosing module is operable to adjust the delivery rate of the after-treatment fluid to the turbine outlet channel based on the control signal. In the context of the present invention, "communication" may include, for example, electrical communication, optical communication, wireless communication, etc. The term "adjustment" covers the fact that the dosing module is configured to adjust the delivery rate of the after-treatment fluid. For example, this may include increasing or decreasing the delivery rate, or stopping delivery altogether. Since the delivery rate of the after-treatment fluid is adjusted based on the output of the exhaust gas sensor, excessive delivery of the after-treatment fluid can be avoided, thereby reducing the risk of deposit formation.

[0383] According to the twelfth aspect of the present invention, a method for operating a turbine for a turbocharger is provided, which includes: receiving exhaust gas from an internal combustion engine into a turbine inlet channel, the exhaust gas received by the turbine inlet channel defining a turbine main flow; receiving the turbine main flow from the turbine inlet channel into a turbine impeller chamber, the turbine impeller chamber accommodating a turbine impeller, the turbine impeller being supported to rotate around a turbine axis; receiving the turbine main flow from the turbine impeller chamber into a turbine outlet channel; receiving a portion of the turbine main flow into an auxiliary channel, the portion of the turbine main flow received by the auxiliary channel defining an auxiliary flow; using a dosing module to deliver an atomized spray of an after-treatment fluid to the turbine outlet channel; and sensing one or more physical parameters of the auxiliary flow using an exhaust gas sensor connected to the auxiliary flow fluid.

[0384] The exhaust gas sensor may be configured to measure a concentration of nitrogen oxides (NOx) in the secondary flow.

[0385] The auxiliary passage may be sized to receive at least about 0.1% of the turbine body flow received by the turbine inlet passage.

[0386] The auxiliary passage may be sized to receive at most about 10% of the turbine body flow received by the turbine inlet passage.

[0387] The auxiliary passage may be configured such that the auxiliary flow is always allowed to flow through the auxiliary passage during all operating conditions of the turbine.

[0388] The auxiliary passage may include a valve assembly configured to control flow of the auxiliary fluid through the auxiliary passage.

[0389] The valve assembly may define an open configuration and a closed position, wherein in the open configuration, the auxiliary flow is allowed to pass through the valve assembly, and in the closed position, the auxiliary flow is substantially blocked by the valve assembly, and the valve assembly may include a leakage channel, which is configured to allow leakage from one side of the valve assembly to the other side when the valve is in the closed configuration.

[0390] The auxiliary passage may be configured to deliver the auxiliary flow to the turbine outlet passage.

[0391] The auxiliary passage may be configured to deliver the auxiliary flow to the turbine inlet passage.

[0392] The dosing module may include a nozzle configured to generate the spray of after-treatment fluid.

[0393] The turbine outlet passage may be at least partially defined by a surface, with the turbine outlet passage defining a centerline, and the nozzle may be substantially aligned with the surface or may be located radially outward of the surface relative to the centerline.

[0394] The turbine may include a turbine wheel having an outlet inducer, the outlet inducer defining an outlet inducer diameter, the turbine outlet passage may define a centerline, and the nozzle may be spaced apart from the outlet inducer of the turbine wheel along the centerline of the turbine outlet passage by a distance of up to about 10 outlet inducer diameters.

[0395] The auxiliary passage may be configured to deliver the auxiliary flow into the turbine outlet passage upstream of the nozzle.

[0396] The auxiliary channel may be configured to direct the auxiliary flow through the nozzle.

[0397] The auxiliary passage may be configured to receive the auxiliary flow from the turbine inlet passage.

[0398] The turbine inlet passage may include a first volute and a second volute, and the auxiliary passage may be configured to receive the auxiliary flow from the first volute.

[0399] The method may also include: using a controller to determine measurement results of the one or more physical parameters of the auxiliary flow sensed by the exhaust gas sensor; and using the controller to generate a control signal based on the measurement results of the one or more physical parameters of the auxiliary flow; using the dosing module to adjust the delivery rate of the aftertreatment fluid to the turbine outlet channel based on the control signal.

[0400] According to a thirteenth aspect of the present invention, an exhaust aftertreatment system is provided, which includes a turbine, the turbine being configured to receive an exhaust flow from an internal combustion engine, the turbine comprising: a turbine inlet channel, the turbine inlet channel being configured to receive exhaust gas from the internal combustion engine, the exhaust gas received by the turbine inlet channel defining a main flow; a turbine impeller chamber, the turbine impeller chamber being configured to receive the main flow from the turbine inlet channel, the turbine impeller chamber being configured to accommodate a turbine impeller, the turbine impeller being supported to rotate about a turbine axis; a turbine outlet channel, the turbine outlet channel being configured to receive the main flow from the turbine inlet channel The turbine wheel chamber receives the main flow; and a distribution module, the distribution module is configured to deliver a spray of after-treatment fluid to the turbine outlet channel; an exhaust channel, the exhaust channel is configured to receive the main flow from the turbine outlet channel; and an auxiliary channel, the auxiliary channel is configured to receive a portion of the main flow, the portion of the main flow received by the auxiliary channel defining an auxiliary flow; wherein the exhaust channel includes a predicted after-treatment fluid concentration area, and wherein the auxiliary channel is configured to deliver the auxiliary flow to the exhaust channel to the predicted after-treatment fluid concentration area.

[0401] In this context, the term "aftertreatment fluid" encompasses the fluid injected into the turbine outlet passage by the distribution module, as well as any products produced by this fluid (e.g., as a result of heating). Aftertreatment fluid is commonly referred to as diesel exhaust fluid (DEF) and comprises a mixture of urea and water. During use, urea decomposes into ammonia and isocyanic acid, but other products may also be formed. In this context, such reducing agents are also included within the meaning of aftertreatment fluid.

[0402] The after-treatment fluid concentration area covers a spatial region in the exhaust passage that has a high concentration of after-treatment fluid relative to the exhaust gas. In this context, a high concentration of after-treatment fluid covers a spatial region in which the concentration of the after-treatment fluid in the spatial region is higher than the expected concentration of the after-treatment fluid in the exhaust passage when the after-treatment fluid is evenly distributed. The concentration of the after-treatment fluid can be quantified as a volume fraction (expressed in parts per million), a mole fraction, or any other suitable measure of the main flow in the exhaust passage. Such after-treatment fluid concentration areas are undesirable because the after-treatment fluid is not fully mixed with the exhaust gas to support the conversion of NOx contained in the exhaust gas by the catalyst device located further downstream. For example, in the after-treatment fluid concentration area, the urea content of the after-treatment fluid may not have been decomposed. Even if the urea has been decomposed, due to the presence of the after-treatment fluid concentration area, the urea will not be evenly distributed over the entire width of the exhaust passage. This may result in some parts of the downstream catalyst device receiving insufficient reductant supply to support the conversion of NOx.

[0403] The predicted aftertreatment fluid concentration area encompasses a theoretical spatial region of the exhaust passage where the aftertreatment fluid concentration area is expected to exist when no auxiliary flow is delivered to the exhaust passage. That is, the predicted aftertreatment fluid concentration area does not define the aftertreatment fluid concentration area itself, but rather defines the location of the possible aftertreatment fluid concentration area when no auxiliary flow is delivered to the exhaust passage. The predicted aftertreatment fluid concentration area can be calculated, for example, using computational fluid dynamics and / or determined through real-world testing in an engine test cell.

[0404] During use, as the auxiliary flow is delivered to the exhaust passage and into the predicted aftertreatment fluid concentration area, it exchanges momentum with the aftertreatment fluid in the predicted aftertreatment fluid concentration area, resulting in a more even distribution of the aftertreatment fluid across the width of the exhaust passage. Consequently, urea decomposition is increased, and the resulting reductant is evenly dispersed across the width of the exhaust passage. This ensures that all portions of the downstream catalyst device receive a sufficient amount of reductant to support NOx conversion.

[0405] The exhaust passage may define a centerline and may include a non-linear portion that causes a change in the momentum of the main flow, the turbine may include a turbine wheel having an outlet guide vane that defines an outlet guide vane diameter; and the auxiliary passage may be configured to deliver the auxiliary flow to the predicted aftertreatment fluid concentration area at a location along the centerline within approximately 5 outlet guide vane diameters of the non-linear portion. In this context, "non-linearity" encompasses any feature of the exhaust passage that differs from a straight pipe section and that induces a measurable change in the momentum of the main flow. This includes, but is not limited to, changes in pipe width, tapered and stepped pipe sections, bends, the presence of turbulators or blunt bodies in the main turbine flow, etc. Because such non-linear portions cause changes in the momentum of the main flow, it has been found that such non-linear portions increase the chance of forming an aftertreatment fluid concentration area. For example, such non-linear portions may result in stagnant or recirculation areas where aftertreatment fluid can collect. When the auxiliary flow is introduced into the exhaust channel within about 5 times the diameter of the outlet deflector of the non-straight portion, the auxiliary flow is able to exchange momentum with the after-treatment fluid at a location where an after-treatment fluid concentration area may occur. In an alternative embodiment, the auxiliary channel can be configured to deliver the auxiliary flow to the predicted after-treatment fluid concentration area at a location within about 3 times, about 2 times, or about 1 times the diameter of the outlet deflector from the bend along the center line. In other alternative embodiments, the auxiliary channel can be configured to deliver the auxiliary flow to the predicted after-treatment fluid concentration area at the non-straight portion. Generally, the closer the auxiliary flow is delivered to the non-straight portion, the greater the possibility that the auxiliary flow will disperse the after-treatment fluid. The auxiliary flow can be delivered upstream or downstream of the non-straight portion.

[0406] The non-linear portion may include a bend. Because a bend changes the momentum direction of the main flow, it has been found that aftertreatment fluid concentration areas are likely to occur at bends in the exhaust passage. In particular, the aftertreatment fluid concentration area may occur slightly downstream of the bend.

[0407] The exhaust passage may include a curved portion having an inner curved surface and an outer curved surface, the inner curved surface defining an inner curvature radius, the outer curved surface defining an outer curvature radius, the outer curvature radius being larger than the inner curvature radius, a portion of the predicted after-treatment fluid concentration area being able to overlap at least a portion of the outer curved surface; and the auxiliary passage may be configured to deliver the auxiliary flow to the portion of the predicted after-treatment fluid concentration area that overlaps the outer curved surface. In this context, the term "overlapping" encompasses the spatial region of the predicted after-treatment fluid concentration area distributed over a portion of the exhaust passage wall defining the outer curved surface. Typically, due to the momentum of the after-treatment fluid upstream of the bend, the predicted after-treatment fluid concentration area will be formed along at least a portion of the outer surface of the bend because the after-treatment fluid does not change direction until acted upon by the outer surface. Therefore, the outer surface of the curved portion of the exhaust passage is a suitable location for delivering the auxiliary flow.

[0408] The auxiliary passage may include an auxiliary passage outlet configured to deliver the auxiliary flow to the exhaust passage, and the auxiliary passage outlet may be defined by an opening formed in the outer curved surface.

[0409] The outer curved surface can define a proximal end and a distal end relative to the direction of the main flow, and the auxiliary channel outlet can be located at the distal end of the outer curved surface. Due to the momentum of the post-treatment fluid upstream of the bend, the predicted post-treatment fluid concentration area is more likely to form on and cover the outer surface at the distal end of the bend (rather than at the proximal end of the bend). Therefore, the distal end of the outer curved surface is a suitable location for introducing the auxiliary flow.

[0410] The bend can define a centerline having an inlet vector and an outlet vector, and the outlet vector can be inclined at an angle of at least about 30° relative to the inlet vector. That is, the bend can be a bend having a width of at least about 30°. In alternative embodiments, the outlet vector can be inclined at an angle of at least about 45°, about 60°, about 75°, or about 90° relative to the inlet vector. Generally, the greater the change in direction around a bend, the more likely it is that a post-treatment fluid concentration zone will form. Therefore, it is beneficial to introduce auxiliary flows at bends with greater curvature.

[0411] The exhaust channel may define a centerline; and the auxiliary channel may be configured to deliver the auxiliary flow to the exhaust channel along an auxiliary flow direction, and the auxiliary flow direction may be inclined at least about 15° relative to the centerline. The auxiliary flow direction covers the direction vector of the auxiliary flow at the outlet of the auxiliary channel. In alternative embodiments, the auxiliary flow direction may be inclined at an angle of at least about 30°, about 45°, about 60°, about 75° or about 90° relative to the centerline. Generally, the steeper the relative angle between the auxiliary flow direction and the centerline, the greater the turbulence generated by the momentum exchange between the auxiliary flow and the main flow. The increase in turbulence in the main flow will have the effect of dispersing the post-treatment fluid and thereby reduce the formation or continuation of the post-treatment fluid concentration area.

[0412] The auxiliary flow direction can face upstream relative to the direction of the main flow. The auxiliary flow direction can be inclined upstream at an angle of at least about 15°, about 30°, about 45°, about 60°, or about 75°. When the auxiliary flow faces upstream, the difference in magnitude between the momentum of the main flow and the momentum of the auxiliary flow increases, thereby increasing turbulence formation and improving the dispersion of the post-treatment fluid.

[0413] The auxiliary flow direction can face downstream relative to the direction of the main flow. The auxiliary flow direction can be tilted downstream at an angle of at least about 15 °, about 30 °, about 45 °, about 60 ° or about 75 °. When the auxiliary flow faces downstream, the amplitude difference between the momentum of the main flow and the momentum of the auxiliary flow can be reduced. Therefore, the angle of introduction can be changed to generate enough turbulence to improve the dispersion of the post-treatment fluid, but the turbulence should not be too large because it can cause obstruction to the main flow.

[0414] The geometry of the predicted post-treatment fluid concentration area may be determined using a computational model.

[0415] The predicted after-treatment fluid concentration region may include a spatial region in which the concentration of the after-treatment fluid in the spatial region is at least approximately 50% higher than the expected concentration of the after-treatment fluid in the exhaust passage when the after-treatment fluid is uniformly distributed. In other words, the after-treatment fluid concentration region includes a spatial region in which the concentration of the after-treatment fluid in the spatial region is at least approximately 50% higher than the average concentration of the after-treatment fluid in the entire exhaust passage. In alternative embodiments, the after-treatment fluid concentration region may include a spatial region in which the concentration of the after-treatment fluid in the spatial region is at least approximately 100%, approximately 150%, or approximately 200% higher than the average concentration of the after-treatment fluid in the entire exhaust passage.

[0416] The predicted post-treatment fluid concentration area can include a spatial region in which the concentration of the post-treatment fluid in the spatial region is at least about 2.25% of the volume of the main flow. It has been found that if the post-treatment fluid is completely evenly distributed throughout the main flow, the relative concentration of the post-treatment fluid is about 1.5% of the volume of the main flow. Therefore, in the context of the present invention, the high concentration area can cover a spatial region in which the concentration of the post-treatment fluid is at least 2.25% of the volume of the main flow. In alternative embodiments, the predicted post-treatment fluid concentration area can include a spatial region in which the concentration of the post-treatment fluid is at least about 3%, about 3.5%, about 4% or about 5% of the volume of the main flow.

[0417] The auxiliary passage may receive the auxiliary flow from a location upstream of the turbine outlet passage. For example, the auxiliary passage may receive the auxiliary flow from the turbine inlet passage, the auxiliary flow from leakage on blades of the turbine wheel within the turbine wheel chamber, or the auxiliary flow from leakage around nozzle vanes in a variable geometry mechanism.

[0418] The auxiliary passage may include a valve configured to allow, prevent, or regulate the flow of the auxiliary flow. The valve may be a wastegate valve, and the auxiliary passage may be a wastegate passage. The auxiliary passage may be sized to receive a sufficient amount of the auxiliary flow to provide a wastegate effect for the turbine. For example, the auxiliary passage may be sized to provide a flow rate of the auxiliary flow that is at least approximately 20%, or approximately 50%, of the flow rate of the main flow delivered by the internal combustion engine to the turbine inlet passage.

[0419] The auxiliary passage can be configured to always allow the auxiliary flow to pass through the auxiliary passage. In such an embodiment, the auxiliary passage can be sized so that the flow rate of the auxiliary flow is small compared to the main flow, so that the auxiliary flow does not adversely affect the power generated by the turbine. For example, the auxiliary passage can be sized so that the flow rate of the auxiliary flow is at most about 1%, about 2%, about 5%, or about 10% of the flow rate of the main flow delivered by the internal combustion engine to the turbine inlet passage.

[0420] According to a fourteenth aspect of the present invention, an exhaust aftertreatment system is provided, which includes a turbine, the turbine being configured to receive an exhaust flow from an internal combustion engine, the turbine comprising: a turbine inlet channel, the turbine inlet channel being configured to receive exhaust gas from the internal combustion engine, the exhaust gas received by the turbine inlet channel defining a main flow; a turbine impeller chamber, the turbine impeller chamber being configured to receive the main flow from the turbine inlet channel, the turbine impeller chamber accommodating a turbine impeller, the turbine impeller being supported to rotate about a turbine axis, the turbine having an outlet guide vane defining an outlet guide vane diameter; a turbine outlet channel, the turbine outlet channel configured to receive the main flow from the turbine wheel chamber; and a distribution module, the distribution module being configured to deliver a spray of after-treatment fluid to the turbine outlet channel; an exhaust channel, the exhaust channel being configured to receive the main flow from the turbine outlet channel, the exhaust channel defining a centerline and including a non-straight portion; and an auxiliary channel, the auxiliary channel being configured to receive a portion of the main flow, the portion of the main flow received by the auxiliary channel defining an auxiliary flow; wherein the auxiliary channel is configured to deliver the auxiliary flow to the exhaust channel at a position along the centerline within approximately 5 times the diameter of the outlet guide vane from the non-straight portion.

[0421] The non-linear portion may include a curved portion.

[0422] The curved portion may include an inner curved surface and an outer curved surface, the inner curved surface defining an inner curved radius, the outer curved surface defining an outer curved radius, the outer curved radius may be greater than the inner curved radius, the auxiliary channel may include an auxiliary channel outlet configured to deliver the auxiliary flow to the exhaust channel; and the auxiliary channel outlet may be defined by an opening formed in the outer curved surface.

[0423] The outer curved surface may define a proximal end and a distal end relative to the direction of the bulk flow, and the auxiliary channel outlet may be positioned at the distal end of the outer curved surface.

[0424] The bend may define a centerline having an entry vector and an exit vector, and the exit vector may be inclined at an angle of at least about 30° relative to the entry vector.

[0425] The auxiliary passage may be configured to deliver the auxiliary flow to the exhaust passage along an auxiliary flow direction, and the auxiliary flow direction may be inclined at least about 15° relative to the centerline.

[0426] The auxiliary flow direction may face upstream relative to the direction of the main flow.

[0427] The auxiliary flow direction may face downstream relative to the direction of the main flow.

[0428] According to a fifteenth aspect of the present invention, an exhaust aftertreatment system is provided, which includes a turbine, wherein the turbine is configured to receive an exhaust flow from an internal combustion engine, and the turbine includes: a turbine inlet channel, wherein the turbine inlet channel is configured to receive exhaust gas from the internal combustion engine, and the exhaust gas received by the turbine inlet channel defines a main flow; a turbine impeller chamber, wherein the turbine impeller chamber is configured to receive the main flow from the turbine inlet channel, and the turbine impeller chamber is configured to accommodate a turbine impeller, and the turbine impeller is supported to rotate around a turbine axis; a turbine outlet channel, wherein the turbine outlet channel is configured to receive the main flow from the turbine impeller chamber chamber to receive the main flow; and a distribution module, the distribution module is configured to deliver a spray of after-treatment fluid to the turbine outlet channel; an exhaust channel, the exhaust channel is configured to receive the main flow from the turbine outlet channel; and an auxiliary channel, the auxiliary channel is configured to receive a portion of the main flow, the portion of the main flow received by the auxiliary channel defining an auxiliary flow; wherein the inner surface of the exhaust channel includes a predicted after-treatment fluid impact risk area, and wherein the auxiliary channel is configured to guide the auxiliary flow with an auxiliary flow layer along the portion of the inner surface that defines the predicted after-treatment fluid impact risk area.

[0429] In this context, the term "aftertreatment fluid" encompasses the fluid injected into the turbine outlet passage by the distribution module, as well as any products produced by that fluid (e.g., as a result of heating). Aftertreatment fluid is commonly referred to as diesel exhaust fluid (DEF) and comprises a mixture of urea and water. During use, urea decomposes into the products ammonia and isocyanic acid. Such reducing agents are also encompassed within the meaning of aftertreatment fluid.

[0430] "After-treatment fluid impact risk zones" encompass areas on the inner surface of the exhaust duct where there is a higher risk of after-treatment fluid impact. That is, after-treatment fluid impact risk zones include areas where the momentum of the after-treatment fluid within the exhaust duct will cause the after-treatment fluid to collide with the exhaust duct walls. In these areas, the walls will be covered to some extent by a layer of after-treatment fluid after impact. A high after-treatment fluid impact risk zone can be defined as any theoretical or observed area on the inner surface of the exhaust duct where the after-treatment fluid concentration is higher than the average concentration of after-treatment fluid on the inner surface of the exhaust duct as a whole. Additionally or alternatively, the presence of an after-treatment fluid impact risk zone can be determined based on theoretical or observed wall film thickness of the after-treatment fluid on the inner surface of the exhaust conduit. The presence of such after-treatment fluid impact risk zones can be determined using computational fluid dynamics and / or through real-world modeling in an engine test cell. Such after-treatment fluid impact risk zones are undesirable because after-treatment fluid impacting the exhaust duct walls may solidify and cause blockage.

[0431] The predicted aftertreatment fluid impact risk zone encompasses a theoretical area on the inner surface of the exhaust passageway where the aftertreatment fluid impact risk zone is expected to exist when no auxiliary flow is delivered to the exhaust passageway. In other words, the predicted aftertreatment fluid impact risk zone does not define the aftertreatment fluid impact risk zone itself, but rather the location of the possible aftertreatment fluid impact risk zone when no auxiliary flow is delivered to the exhaust passageway. For example, computational fluid dynamics can be used to calculate the predicted aftertreatment fluid impact risk zone.

[0432] The "auxiliary flow layer" encompasses a fast-moving, high-shear layer of exhaust gas that passes over the inner surface of the exhaust duct. The auxiliary flow layer helps reduce the amount of after-treatment fluid that impacts the inner surface of the exhaust duct in several ways. First, the auxiliary flow layer forms a fluid barrier, significantly inhibiting after-treatment fluid from reaching the predicted after-treatment fluid impact risk zone on the inner surface. Second, the auxiliary flow layer applies shear forces to the after-treatment fluid, which serve to "disperse" any impacted after-treatment fluid, causing it to form a wider and thinner layer on the inner surface of the exhaust duct. This increases heat transfer to the impacted after-treatment fluid, causing it to evaporate more quickly and preventing it from forming solid deposits. Finally, the high shear forces applied by the auxiliary flow layer to the impacted after-treatment fluid serve to re-entrain after-treatment fluid that has collected on the inner surface. As a result of these combined properties, the auxiliary flow layer reduces the risk of after-treatment fluid impact at the after-treatment fluid impact risk zone during use. In this way, deposit formation within the exhaust duct can be mitigated or completely avoided.

[0433] The exhaust passage may define a centerline and may include a non-linear portion that causes a change in momentum of the bulk flow, and the non-linear portion may be at least partially defined by a portion of the interior surface including the after-treatment fluid impingement risk zone.

[0434] The non-linear portion may include a curved portion of the exhaust passage.

[0435] The curved portion may include an inner curved surface and an outer curved surface, the inner curved surface defining an inner curved radius, the outer curved surface defining an outer curved radius, the outer curved radius may be greater than the inner curved radius, and the outer curved surface may include a portion of the inner surface defining the predicted post-treatment fluid impact risk zone.

[0436] The auxiliary passage may include an auxiliary passage outlet configured to deliver the auxiliary flow to the exhaust passage, and the auxiliary passage outlet may be defined by an opening formed in the outer curved surface.

[0437] The outer curved surface can define a proximal end and a distal end relative to the direction of the main flow, and the auxiliary channel outlet can be located at the distal end of the outer curved surface. Due to the momentum of the post-treatment fluid upstream of the bend, the predicted post-treatment fluid concentration area is more likely to form on and cover the outer surface at the distal end of the bend (rather than at the proximal end of the bend). Therefore, the distal end of the outer curved surface is a suitable location for introducing the auxiliary flow.

[0438] The bend can define a centerline having an inlet vector and an outlet vector, and the outlet vector can be inclined at an angle of at least about 30° relative to the inlet vector. That is, the bend can be a bend having a width of at least about 30°. In alternative embodiments, the outlet vector can be inclined at an angle of at least about 45°, about 60°, about 75°, or about 90° relative to the inlet vector. Generally, the greater the change in direction around a bend, the more likely it is that a post-treatment fluid concentration zone will form. Therefore, it is beneficial to introduce auxiliary flows at bends with greater curvature.

[0439] Computational models may be used to determine the geometry of the predicted post-treatment fluid concentration area.

[0440] The predicted aftertreatment fluid impact risk zone may include an area of ​​the inner surface of the exhaust passage where an impact rate of aftertreatment fluid by mass may be approximately 50% or more higher than an average impact rate of aftertreatment fluid by mass of the surface of the exhaust passage as a whole.

[0441] The auxiliary passage may receive the auxiliary flow from a location upstream of the turbine outlet passage. For example, the auxiliary passage may receive the auxiliary flow from the turbine inlet passage, the auxiliary flow from leakage on blades of the turbine wheel within the turbine wheel chamber, or the auxiliary flow from leakage around nozzle vanes in a variable geometry mechanism.

[0442] The auxiliary passage may include a valve configured to allow, prevent, or regulate the flow of the auxiliary flow. The valve may be a wastegate valve, and the auxiliary passage may be a wastegate passage. The auxiliary passage may be sized to receive a sufficient amount of the auxiliary flow to provide a wastegate effect for the turbine. For example, the auxiliary passage may be sized to provide a flow rate of the auxiliary flow that is at least approximately 20%, or approximately 50%, of the flow rate of the main flow delivered by the internal combustion engine to the turbine inlet passage.

[0443] The auxiliary passage can be configured to always allow the auxiliary flow to pass through the auxiliary passage. In such an embodiment, the auxiliary passage can be sized so that the flow rate of the auxiliary flow is small compared to the main flow, so that the auxiliary flow does not adversely affect the power generated by the turbine. For example, the auxiliary passage can be sized so that the flow rate of the auxiliary flow is at most about 1%, about 2%, about 5%, or about 10% of the flow rate of the main flow delivered by the internal combustion engine to the turbine inlet passage.

[0444] According to a sixteenth aspect of the present invention, an exhaust aftertreatment system is provided, which includes a turbine, the turbine being configured to receive an exhaust flow from an internal combustion engine, the turbine comprising: a turbine inlet channel, the turbine inlet channel being configured to receive exhaust from the internal combustion engine, the exhaust received by the turbine inlet channel defining a main flow; a turbine impeller chamber, the turbine impeller chamber being configured to receive the main flow from the turbine inlet channel, the turbine impeller chamber being configured to accommodate a turbine impeller, the turbine impeller being supported to rotate around a turbine axis; a turbine outlet channel, the turbine outlet channel being configured The invention provides a method of receiving the main flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of the after-treatment fluid to the turbine outlet channel; an exhaust channel configured to receive the main flow from the turbine outlet channel, the exhaust channel including a non-straight portion defined by an inner surface of the exhaust channel; and an auxiliary channel configured to receive a portion of the main flow, the portion of the main flow received by the auxiliary channel defining an auxiliary flow; wherein the auxiliary channel is configured to guide the auxiliary flow along the inner surface of the non-straight portion in an auxiliary flow layer.

[0445] The auxiliary passage may receive the auxiliary flow from a location upstream of the turbine outlet passage. For example, the auxiliary passage may receive the auxiliary flow from the turbine inlet passage, the auxiliary flow from leakage on blades of the turbine wheel within the turbine wheel chamber, or the auxiliary flow from leakage around nozzle vanes in a variable geometry mechanism.

[0446] The non-linear portion may include a curved portion of the exhaust passage.

[0447] The curved portion may include an inner curved surface and an outer curved surface, the inner curved surface defining an inner curved radius, the outer curved surface defining an outer curved radius, the outer curved radius may be greater than the inner curved radius, the outer curved surface may include the inner surface; and the auxiliary channel may be configured to guide the auxiliary flow layer along the outer curved surface.

[0448] The auxiliary passage may include an auxiliary passage outlet configured to deliver the auxiliary flow to the exhaust passage; and the auxiliary passage outlet may be defined by an opening formed in the outer curved surface.

[0449] The outer curved surface may define a proximal end and a distal end relative to the direction of the bulk flow, and the auxiliary channel outlet may be positioned at the distal end of the outer curved surface.

[0450] The bend may define a centerline having an entry vector and an exit vector, and the exit vector may be inclined at an angle of at least about 30° relative to the entry vector.

[0451] According to the seventeenth aspect of the present invention, an exhaust aftertreatment system is provided, which includes: a turbine, the turbine being configured to receive an exhaust flow from an internal combustion engine, the turbine including: a turbine inlet channel, the turbine inlet channel being configured to receive exhaust from the internal combustion engine, the exhaust received by the turbine inlet channel defining a main flow; a turbine impeller chamber, the turbine impeller chamber being configured to receive the main flow from the turbine inlet channel, the turbine impeller chamber being configured to accommodate a turbine impeller, the turbine impeller being supported to rotate around a turbine axis; a turbine outlet channel, the turbine outlet channel being configured to receive the main flow from the turbine impeller chamber; and a distribution module, the distribution module a block configured to deliver a spray of aftertreatment fluid into the turbine outlet channel; an exhaust channel configured to receive the main flow from the turbine outlet channel; and an auxiliary channel configured to receive a portion of the main flow, the portion of the main flow received by the auxiliary channel defining an auxiliary flow; wherein the exhaust channel is at least partially defined by a first surface of a partition wall, and the auxiliary channel is at least partially defined by a second surface of the partition wall, the partition wall being configured to provide thermal connectivity from the auxiliary channel to the first surface via the second surface; and wherein at least a portion of the first surface of the partition wall includes an aftertreatment fluid impact risk area.

[0452] During use, when the aftertreatment fluid is injected into the turbine outlet channel, the aftertreatment fluid may impact the first surface. The aftertreatment fluid is typically at a lower temperature than the turbine main flow and therefore forms a heat sink that drives heat from the first surface to the aftertreatment fluid. The first surface is heated by two sources. First, the first surface is heated by convective heat transfer from the main flow traveling through the exhaust channel. Second, the first surface is heated by the auxiliary flow traveling through the auxiliary channel; and in particular by convective heat transfer from the auxiliary flow to the second surface and conductive heat transfer from the second surface through the material of the partition wall to the first surface. Therefore, the first surface and the second surface ensure that there is a larger surface area available for capturing heat from the main flow and the auxiliary flow so that heat can be transferred to the aftertreatment fluid (for example, compared to the case without the auxiliary channel). As a result, the amount of heat transferred to the aftertreatment fluid after the impact increases, causing the temperature of the aftertreatment fluid to rise until the aftertreatment fluid evaporates. Therefore, the formation of deposits in the exhaust channel is reduced or prevented.

[0453] The first surface may be disposed on a side of the partition wall opposite the second surface. Specifically, the first surface may be parallel to the second surface and face in a direction opposite to the second surface. Since the first and second surfaces are located on opposite sides of the partition wall, a direct heat conduction path from the second surface to the first surface is provided, thereby improving heating of the first surface.

[0454] The dividing wall can define a thickness between the first surface and the second surface. The turbine includes a turbine wheel having an outlet inducer portion, the outlet inducer portion defining an outlet inducer diameter, and the thickness of the dividing wall can be approximately 1% to approximately 10% of the outlet inducer diameter. Thus, the dividing wall is relatively thin compared to the geometry of the turbine and exhaust passage. Because the dividing wall is thin, heat conduction through the dividing wall is improved. In some embodiments, the thickness of the dividing wall can be up to approximately 40% of the outlet inducer diameter.

[0455] The exhaust passage may include a non-linear portion defined at least in part by a portion of the first surface including the after-treatment fluid impingement risk zone.

[0456] The non-linear portion may include a curved portion.

[0457] The curved portion may include an inner curved surface and an outer curved surface, the inner curved surface defining an inner curved radius, the outer curved surface defining an outer curved radius, the outer curved radius may be greater than the inner curved radius, and the outer curved surface may include a portion of the first surface defining the post-treatment fluid impact risk zone.

[0458] The auxiliary passage may include an auxiliary passage outlet configured to deliver the auxiliary flow to the exhaust passage; and the auxiliary passage outlet may be defined by an opening formed in the outer curved surface.

[0459] The outer curved surface may define a proximal end and a distal end relative to the direction of the bulk flow, and the auxiliary channel outlet may be positioned at the distal end of the outer curved surface.

[0460] The geometry of the post-treatment fluid impact risk zone may be determined using a computational model. Alternatively, the post-treatment fluid impact risk zone may be determined by physical inspection, such as by observing evidence of post-treatment fluid impact (eg, surface pitting, etc.).

[0461] The predicted aftertreatment fluid impact risk zone may include an area of ​​the inner surface of the exhaust passage where an impact rate of aftertreatment fluid by mass may be approximately 50% or more higher than an average impact rate of aftertreatment fluid by mass of the surface of the exhaust passage as a whole.

[0462] The auxiliary passage may receive the auxiliary flow from a location upstream of the turbine outlet passage. For example, the auxiliary passage may receive the auxiliary flow from the turbine inlet passage, the auxiliary flow from leakage on blades of the turbine wheel within the turbine wheel chamber, or the auxiliary flow from leakage around nozzle vanes in a variable geometry mechanism.

[0463] The auxiliary passage may include a valve configured to allow, prevent, or regulate the flow of the auxiliary flow. The valve may be a wastegate valve, and the auxiliary passage may be a wastegate passage. The auxiliary passage may be sized to receive a sufficient amount of the auxiliary flow to provide a wastegate effect for the turbine. For example, the auxiliary passage may be sized to provide a flow rate of the auxiliary flow that is at least approximately 20%, or approximately 50%, of the flow rate of the main flow delivered by the internal combustion engine to the turbine inlet passage.

[0464] The auxiliary passage can be configured to always allow the auxiliary flow to pass through the auxiliary passage. In such an embodiment, the auxiliary passage can be sized so that the flow rate of the auxiliary flow is small compared to the main flow, so that the auxiliary flow does not adversely affect the power generated by the turbine. For example, the auxiliary passage can be sized so that the flow rate of the auxiliary flow is at most about 1%, about 2%, about 5%, or about 10% of the flow rate of the main flow delivered by the internal combustion engine to the turbine inlet passage.

[0465] According to an eighteenth aspect of the present invention, an exhaust aftertreatment system is provided, which includes a turbine, the turbine being configured to receive an exhaust flow from an internal combustion engine, the turbine comprising: a turbine inlet channel, the turbine inlet channel being configured to receive exhaust gas from the internal combustion engine, the exhaust gas received by the turbine inlet channel defining a main flow; a turbine impeller chamber, the turbine impeller chamber being configured to receive the main flow from the turbine inlet channel, the turbine impeller chamber being configured to accommodate a turbine impeller, the turbine impeller being supported to rotate around a turbine axis; a turbine outlet channel, the turbine outlet channel being configured to receive the main flow from the turbine impeller chamber; and a distribution channel. module, the distribution module is configured to deliver a spray of after-treatment fluid into the turbine outlet channel; an exhaust channel, the exhaust channel is configured to receive the main flow from the turbine outlet channel, the exhaust channel defines a bend; and an auxiliary channel, the auxiliary channel is configured to receive a portion of the main flow, the portion of the main flow received by the auxiliary channel defines an auxiliary flow; wherein the bend of the exhaust channel is at least partially defined by a first surface of a partition wall, and the auxiliary channel is at least partially defined by a second surface of the partition wall, and the partition wall is configured to provide thermal connectivity from the auxiliary channel to the first surface via the second surface.

[0466] The first surface may be provided on a side of the partition wall opposite to the second surface.

[0467] The dividing wall may define a thickness between the first surface and the second surface, the turbine may include a turbine wheel having an outlet inducer portion, the outlet inducer portion defining an outlet inducer diameter, and the thickness of the dividing wall may be approximately 1% to approximately 10% of the outlet inducer diameter.

[0468] The curved portion may include an inner curved surface defining an inner curved radius and an outer curved surface defining an outer curved radius, the outer curved radius may be greater than the inner curved radius, and the outer curved surface may include the first surface of the partition wall.

[0469] The auxiliary passage may include an auxiliary passage outlet configured to deliver the auxiliary flow to the exhaust passage; and the auxiliary passage outlet may be defined by an opening formed in the outer curved surface.

[0470] The outer curved surface may define a proximal end and a distal end relative to the direction of the bulk flow, and the auxiliary channel outlet may be positioned at the distal end of the outer curved surface.

[0471] According to the nineteenth aspect of the present invention, a turbine for a turbocharger is provided, comprising: a turbine inlet channel configured to receive exhaust gas from an internal combustion engine; a turbine wheel chamber configured to receive exhaust gas from the turbine inlet channel, the turbine wheel chamber configured to accommodate a turbine wheel, the turbine wheel being supported to rotate about a turbine axis; a turbine outlet channel configured to receive exhaust gas from the turbine wheel chamber; an auxiliary channel comprising: an auxiliary channel inlet configured to receive exhaust gas from the turbine outlet channel; and an auxiliary channel outlet configured to deliver exhaust gas from the auxiliary channel to the turbine outlet channel. In particular, the exhaust gas received by the turbine outlet channel can pass through the turbine wheel accommodated in the turbine wheel chamber.

[0472] As used herein, the term "auxiliary passage" encompasses any fluid-carrying structure capable of routing exhaust gas from an auxiliary passage inlet to an auxiliary passage outlet. The terms "auxiliary passage inlet" and "auxiliary passage outlet" encompass openings of the auxiliary passage that define a corresponding fluid interface with the turbine outlet passage. The "auxiliary passage inlet" and "auxiliary passage outlet" may be defined by the turbine outlet passage, and in particular may be openings formed in a wall defining the turbine outlet passage. The term "turbine outlet passage" encompasses a structure configured to receive exhaust gas that has traveled through the turbine impeller at a position immediately downstream of the turbine impeller.

[0473] The exhaust flow in the auxiliary passage (also referred to as the auxiliary flow) is separate from the flow through the turbine outlet passage (also referred to as the main turbine flow). The auxiliary passage allows the auxiliary flow to be conditioned so that it has different properties from the main turbine flow. For example, the auxiliary passage can be configured to alter the direction, velocity, pressure, turbulence, etc. of the exhaust flowing through it.

[0474] Under normal conditions, the flow conditions in the turbine outlet channel are generally not suitable for injecting the after-treatment fluid. However, the reconditioned exhaust flow through the auxiliary channel can be used for one or more fluid applications in the auxiliary channel outlet to support improved decomposition at the injection site of the after-treatment fluid. For example, by using an auxiliary channel, a distribution module can be provided to inject the after-treatment fluid into the turbine outlet channel, and the auxiliary channel can guide the exhaust flow into the after-treatment fluid to induce turbulence and improve mixing. Additionally or alternatively, the auxiliary channel can guide the flow through the nozzle of the distribution module to clean the nozzle. Additionally or alternatively, the momentum of the auxiliary flow can be used to increase the momentum of the injected after-treatment fluid, so that the after-treatment fluid can be dissipated over substantially the entire cross-sectional area of ​​the turbine outlet channel, thereby providing increased uniformity of the flow of the after-treatment fluid across the turbine outlet channel. In yet another alternative or additional embodiment, the auxiliary channel can be used to form a narrow layer of fast-moving fluid on the surface of the turbine outlet channel where after-treatment fluid impact may occur, so as to avoid the accumulation of deposits on the surface of the turbine outlet. Other applications of the auxiliary flow will become apparent from the description.

[0475] It should be understood that in order for the auxiliary channel to regulate the auxiliary flow to provide the aforementioned beneficial functions, exhaust gas must be supplied to the auxiliary channel. Advantageously, the auxiliary channel inlet is positioned within the turbine outlet channel so that exhaust gas that has already passed through the turbine wheel is supplied to the auxiliary channel inlet. This prevents the main turbine flow from being divided before the turbine wheel, allowing the turbine wheel to extract the maximum possible amount of work from the main turbine flow. In contrast, if the auxiliary channel inlet were positioned before the turbine wheel, the mass flow to the turbine wheel would be reduced, and less work would be extracted from the exhaust gas, thereby reducing turbine efficiency. It has also been found that positioning the auxiliary channel inlet within the turbine outlet channel results in a simpler and more compact arrangement, as this eliminates the need for casting or machining a duct bypassing the turbine wheel. Furthermore, since the auxiliary channel inlet is positioned within the turbine outlet channel, this ensures that the auxiliary flow originates close to the turbine wheel. Consequently, less energy is lost to friction compared to locations downstream of the turbine outlet channel.

[0476] The auxiliary passage inlet may be located at a position in the turbine outlet passage that is fluidically upstream of the auxiliary passage outlet relative to flow through the turbine outlet passage. For example, the auxiliary passage inlet may define a centroid, the auxiliary passage outlet may define a centroid, and the centroid of the auxiliary passage inlet may be upstream of the auxiliary passage outlet relative to exhaust flow through the turbine outlet passage. The term "centroid" encompasses the geometric center of an inlet or outlet, including, for example, the geometric center of an opening forming the auxiliary inlet and the auxiliary outlet.

[0477] Because the auxiliary channel inlet is located upstream of the auxiliary channel outlet, it is positioned closer to the turbine wheel than the auxiliary channel outlet. Therefore, the exhaust gas in the turbine outlet channel near the auxiliary channel inlet experiences less loss due to duct friction or transient energy loss than the exhaust gas at the auxiliary channel outlet. Consequently, the fluid entering the auxiliary channel has relatively higher energy and is more suitable for conditioning through the auxiliary channel.

[0478] The turbine wheel may include an outlet inducer defining an outlet inducer diameter, the turbine outlet passage may define a centerline; and the auxiliary passage inlet may be spaced apart from the outlet inducer of the turbine wheel along the centerline of the turbine outlet passage by a distance of up to about 5 times the outlet inducer diameter. As used herein, the term "centerline" encompasses a line defined by the centroid of the cross-section of the turbine outlet passage along the direction of exhaust gas flow. That is, the centerline of the turbine outlet passage is an imaginary line drawn along the turbine outlet passage that is always located at the center of the geometry of the exhaust gas flowing through the turbine outlet passage. Typically, although not always, the centerline will be an extension of the turbine axis, which may deviate from the turbine axis depending on the geometry of the turbine outlet passage.

[0479] As used herein, the term "exit inducer" encompasses a portion of a turbine wheel configured to discharge exhaust gas into a turbine outlet passage. The spacing between the auxiliary passage inlet and the outlet inducer of the turbine wheel, as viewed from the centerline, can be measured from the downstream-most portion of the turbine wheel blade tips to the upstream-most portion of the auxiliary passage inlet.

[0480] Because the auxiliary channel inlet is located within approximately 5 outlet guide diameters of the turbine wheel, the auxiliary channel inlet is positioned relatively close to the turbine wheel. This ensures that the exhaust gas entering the auxiliary channel has relatively high energy because it does not lose any energy due to duct friction, transient heat losses, etc. In addition, this facilitates a compact layout. Generally, the auxiliary channel inlet should be positioned as close to the turbine wheel as possible while remaining downstream of the turbine wheel. This may be determined by factors such as manufacturing tolerances. Preferably, the auxiliary channel inlet is spaced apart from the outlet guide by at most 3 outlet guide diameters or at most 1 outlet guide diameter.

[0481] The auxiliary channel outlet can be spaced apart from the outlet guide vane of the turbine wheel along the geometric centerline of the turbine outlet channel by a distance of up to about 10 times the outlet guide vane diameter. Since the auxiliary channel outlet is located within about 10 times the outlet guide vane diameter of the turbine wheel, the auxiliary channel inlet is positioned relatively close to the turbine wheel. Therefore, applications using the auxiliary flow can be positioned close to the turbine wheel. This is particularly advantageous where the turbine outlet also serves as a decomposition chamber for the exhaust aftertreatment fluid, because the exhaust flow through the auxiliary channel can be used to alleviate one or more problems associated with injecting the aftertreatment fluid close to the turbine wheel. For example, as discussed above, the auxiliary channel can be used to clean the nozzle of the dosing module, improve the decomposition of the reductant, prevent the formation of deposits on the walls of the turbine outlet, etc. Preferably, the auxiliary channel outlet is positioned closer to the turbine wheel to provide a compact arrangement. For example, within about 1, 3 or 5 times the outlet guide vane diameter.

[0482] The turbine may include a turbine housing that at least partially defines a turbine inlet, a turbine wheel chamber, and a turbine outlet passage, and the auxiliary passage may be at least partially defined by the turbine housing. That is, the turbine housing may include at least a portion of the auxiliary passage. As used herein, the term "turbine housing" encompasses a structure that is configured to accommodate and guide exhaust gas into and out of the turbine wheel. For example, the turbine housing may define a radial inlet volute and an axial outlet. The turbine housing may define the entire geometry of the auxiliary passage from the auxiliary passage inlet to the auxiliary passage outlet. Alternatively, the turbine housing may define only a portion of the auxiliary passage, such as one or more surfaces defining a portion of the auxiliary passage. In such an embodiment, the geometry of the remainder of the auxiliary passage may be defined by one or more additional components (e.g., connection adapters, inserts, baffles, etc.) that are separate from the turbine housing.

[0483] Since the auxiliary passage is at least partially defined by the turbine housing, the turbine housing and the auxiliary passage can be manufactured as a single integral component, and thus the ease of manufacture and assembly is increased.

[0484] The turbine may include a turbine housing and a connection adapter, wherein the turbine housing defines a turbine inlet and a turbine wheel chamber, the connection adapter may at least partially define a turbine outlet passage, and the auxiliary passage may be at least partially defined by the connection adapter. That is, the connection adapter may define at least a portion of the turbine outlet passage. The remainder of the turbine outlet passage may be defined by the turbine housing. Alternatively, the connection adapter may define substantially the entire turbine outlet passage. The connection adapter may be connected to the turbine housing, for example, using fasteners, clips, V-belts, or the like. The connection adapter may include at least a portion or all of the auxiliary passage. That is, the connection adapter may include one or more surfaces that define the geometry of the auxiliary passage.

[0485] Because the connection adapter defines the auxiliary channel and the turbine outlet channel separately from the turbine housing, the auxiliary channel and the turbine outlet channel may include complex geometries that would be impossible or cost-prohibitive to manufacture if the auxiliary channel and the turbine outlet channel were part of the turbine housing.

[0486] The turbine may also include a distribution module comprising an atomizing nozzle configured to deliver an after-treatment fluid to the turbine outlet passage. As used herein, the term "distribution module" encompasses any device configured to introduce an after-treatment fluid into the turbine outlet structure. The after-treatment fluid may be a fluid required to support chemical reactions during exhaust gas after-treatment. For example, the after-treatment fluid may be DEF used in an SCR process. The term "nozzle" encompasses the portion of the distribution module from which the after-treatment fluid exits the distribution module. In other words, the portion of the distribution module from which the after-treatment fluid is ejected. The distribution module may be a self-atomizing distribution module configured to produce a fine spray or mist of the after-treatment fluid ejected from the distribution module's nozzle. If the distribution module is self-atomizing, no additional components are required to atomize the after-treatment fluid. This allows the after-treatment fluid to mix with the exhaust gas immediately upon exiting the distribution module's nozzle. This improves the atomization rate and increases the decomposition rate of urea in the after-treatment fluid.

[0487] The nozzle of the distribution module can be substantially aligned with the surface defining the auxiliary channel or the surface of the turbine outlet channel. In other words, the nozzle of the distribution module does not protrude into the auxiliary channel or the turbine outlet channel. An inherent property of the auxiliary channel or the turbine outlet channel is that these channels will be defined by the surface of a housing component (such as, for example, the turbine housing, the connection adapter, the diffuser, etc.). Therefore, the surface defining the auxiliary channel or the turbine outlet channel encompasses any surface used to accommodate the exhaust gas within the auxiliary channel or the turbine outlet channel. In other words, the surface is the surface that depicts the outermost geometry of the fluid-bearing portion of the auxiliary channel or the turbine outlet channel. The term "aligned" encompasses the fluid injection portion of the nozzle being substantially flush with the surface. Those skilled in the art will understand that this alignment does not need to be absolute and a small amount of misalignment can be tolerated as long as the nozzle of the distribution module does not protrude into the auxiliary channel or the turbine outlet channel in a manner that causes significant obstruction to the flow. Because the nozzle is substantially aligned with the surface, the auxiliary channel or the turbine outlet channel is substantially free of obstructions that hinder the flow of exhaust gas.

[0488] The nozzle of the distribution module can be positioned within the auxiliary channel so that the distribution module can be configured to deliver the after-treatment fluid to the turbine outlet channel through the auxiliary channel. That is, during use, the distribution module delivers the after-treatment fluid to the auxiliary channel, and the after-treatment fluid travels through at least a portion of the auxiliary channel before entering the turbine outlet channel. Because the after-treatment fluid is injected into the auxiliary channel before entering the turbine outlet channel, the after-treatment fluid is able to exchange momentum with the exhaust gas flowing through the auxiliary channel before entering the turbine outlet channel. This momentum exchange can be used to provide beneficial effects, such as cleaning the nozzle of the distribution module, or ensuring that the after-treatment fluid is carried across a larger lateral extent of the turbine outlet channel.

[0489] The auxiliary passage may include an outlet portion extending from the nozzle to the auxiliary passage outlet, the outlet portion may define an outlet axis, and the outlet axis may be inclined relative to the centerline of the turbine outlet passage at an angle of up to about 70°. In alternative embodiments, the outlet axis may be inclined relative to the centerline at an angle between about 20° and about 70°, between about 30° and about 60°, between about 40° and about 50°, or about 45°. The relative angle between the outlet axis and the centerline may be measured at the centroid of the auxiliary passage outlet.

[0490] Due to the momentum carried by the mixture of auxiliary flow and aftertreatment fluid traveling through the outlet portion of the auxiliary channel, the likelihood of aftertreatment fluid impacting the wall of the turbine outlet channel opposite the auxiliary channel outlet increases as the angle between the outlet axis and the centerline increases. Aftertreatment fluid impacting the wall of the turbine outlet may not be hot enough to evaporate and may result in the formation of deposits. While this can be mitigated by reducing the angle between the outlet axis and the centerline, if the angle is too small, the length of the auxiliary channel must be increased and, therefore, the auxiliary channel outlet must be placed further downstream (and possibly outside the preferred distance from the turbine wheel outlet inducer discussed previously). It has been found that when the angle between the outlet axis and the centerline is within the above-mentioned range, this reduces the risk of aftertreatment fluid impacting the wall of the turbine outlet channel while keeping the auxiliary channel compact.

[0491] The auxiliary passage may include an inlet portion extending from an auxiliary passage inlet to a nozzle, the inlet portion may define an inlet axis, and the inlet axis may be tilted relative to a centerline of the turbine outlet passage at an angle between about 20° and about 70°. In alternative embodiments, the inlet axis may be tilted relative to the centerline at an angle between about 30° and about 60°, between about 40° and about 50°, or at an angle of about 45°. The relative angle between the inlet axis and the centerline may be measured at the centroid of the auxiliary passage inlet.

[0492] As the angle of the auxiliary passage's inlet axis increases, the momentum change required for the exhaust to enter the auxiliary passage increases, creating flow resistance. However, if the inlet axis angle is too small, the auxiliary passage must be made longer. It has been found that when the angle between the inlet axis and the centerline is within the aforementioned range, this reduces the momentum change required for the exhaust to enter the auxiliary passage while maintaining a compact overall length.

[0493] The cross-sectional area of ​​the outlet portion of the auxiliary channel increases along the outlet axis from the nozzle of the dosing module to the auxiliary channel outlet. That is, the second portion of the auxiliary channel comprises a diverging side that diverges outwardly in the direction of the auxiliary channel outlet.

[0494] The distribution module will produce a fine spray of atomized post-treatment fluid, which is ejected from the end of the distribution module in a cone shape. In some embodiments, the outlet portion of the auxiliary channel expands at an angle approximately equal to or greater than the spray cone angle of the nozzle. For example, the spray cone angle can be about 45° to about 50°, and the outlet portion can expand at an angle of about 60°. In such an embodiment, since the outlet portion of the auxiliary channel expands at the same or higher rate as the spray cone, this reduces the risk of the post-treatment fluid impacting the auxiliary channel wall. However, if the outlet portion expands at too steep an angle, the auxiliary flow will slow down, causing the auxiliary flow to lose the potential energy that affects the flow in the turbine outlet channel. Therefore, in an alternative embodiment, the spray cone angle can be the same as described above, while the outlet portion of the auxiliary channel expands at a more gentle angle, for example, about 5° to 10°. Although the post-treatment fluid may impact the wall of the outlet portion, the velocity of the auxiliary flow will remain high, so that the shear force will clean any impacted post-treatment fluid from the wall to avoid deposit formation.

[0495] The turbine outlet passage may define a diffuser. That is, the turbine outlet passage may include a diffuser. As used herein, the term "diffuser" encompasses an expansion passage, wherein the cross-sectional area of ​​the passage increases along the length of the passage. As the cross-sectional area of ​​the diffuser increases (i.e., as the walls defining the turbine outlet passage expand), the velocity of the turbine body flow decreases and the pressure increases. The increase in pressure can be used to improve the efficiency of the turbine and / or associated exhaust aftertreatment system. For example, where the turbine includes a dosing module, reducing the velocity of the turbine body flow through the turbine outlet passage may allow the injected aftertreatment fluid to more easily penetrate the turbine body flow in the turbine outlet passage.

[0496] The diffuser can be aligned with the turbine axis and can extend symmetrically about the turbine axis. That is, the diffuser can be an axial diffuser. The diffuser can include a generally circular cross-section defined by the conical walls of the turbine outlet passage. However, in alternative embodiments, substantially any diffuser shape can be used, including asymmetric diffusers, etc.

[0497] The auxiliary channel inlet may include a scoop extending into the turbine outlet channel, and the scoop may be configured to direct the exhaust flow into the auxiliary channel. As used herein, the term "scoop" encompasses any type of obstruction to flow in the turbine outlet channel that is configured to deflect or direct the fluid into the auxiliary channel. The turbine outlet channel may be defined in part by a duct. The scoop may be at least partially defined by the duct, for example by one or more stamped sections protruding into the turbine outlet channel. "Extending into the turbine outlet" encompasses extending at least partially in a radial direction toward the centerline of the turbine outlet channel. The scoop may take the form of a dome-shaped structure, a slat, or any other suitable type of protruding feature configured to deflect or direct the fluid into the auxiliary channel.

[0498] The scoop may create an obstruction to the main flow of exhaust gas traveling through the diffuser and may be configured to encourage exhaust gas to enter the auxiliary inlet and, therefore, the auxiliary outlet. Providing increased exhaust flow through the auxiliary passage ensures that sufficient exhaust gas is available to support the specific beneficial effects provided by the regulated flow of the auxiliary passage.

[0499] The auxiliary channel may include a plurality of auxiliary channel inlets. That is, the auxiliary channel includes at least two auxiliary inlets, and the auxiliary channel is configured to route exhaust gas from the at least two auxiliary inlets to the auxiliary outlet. For example, the auxiliary channel may include a manifold portion connecting the plurality of auxiliary channel inlets to the auxiliary channel outlet. Providing a plurality of auxiliary inlets can increase the mass flow rate of exhaust gas received by the auxiliary channel from the turbine outlet channel. This can increase the volume of auxiliary flow that can be supplied to support downstream applications. At least one or all of the plurality of auxiliary channel inlets may include a scoop to further increase the volume of the auxiliary flow. In addition, the auxiliary channel inlet may disturb the turbine body flow in the turbine channel, thereby causing turbulence in a local area, which may restrict flow through the turbine outlet channel. Providing a plurality of auxiliary channel inlets means that each inlet can be made smaller and thereby cause less turbulence.

[0500] The auxiliary passage inlet may be substantially axially aligned relative to a centerline of the turbine outlet passage. That is, the plurality of auxiliary inlets share a common axial position relative to the centerline. Because the plurality of auxiliary inlets are axially aligned, the inlets receive exhaust gas from a common axial position of the turbine outlet passage that is closer to the turbine wheel than the auxiliary passage outlet.

[0501] The auxiliary passages may be spaced approximately equally about the centerline. A plurality of auxiliary passage inlets may be defined by openings in the surface of the turbine outlet passage, and the auxiliary passage inlets may be arranged around the circumference of the surface. Spacing the auxiliary passage inlets equally reduces overall disturbance to the turbine body flow in the turbine outlet passage.

[0502] The turbine outlet passage may define a perimeter, and the auxiliary passage may extend around the perimeter to provide fluid communication between the plurality of auxiliary passage inlets. The term "perimeter" encompasses the outermost portion of the turbine outlet passage relative to the centerline of the outlet passage. The auxiliary passage may extend around a portion of the perimeter or around the entire perimeter. For example, if the turbine outlet passage has a circular cross-section, the portion of the auxiliary passage may extend in an arc around part or all of the turbine outlet passage. As another example, the portion of the auxiliary passage extending around the perimeter may be a substantially annular conduit.

[0503] The turbine may also include a wastegate device, which includes a wastegate passage and a movable valve member, the wastegate passage being configured to provide fluid communication from the turbine inlet passage to the turbine outlet passage so that exhaust gas traveling through the wastegate passage does not travel through the turbine wheel chamber, and the movable valve member being configured to selectively allow or prevent fluid flow through the wastegate passage by blocking the wastegate passage. In other words, the turbine may be a turbine with a wastegate. The wastegate passage receives a portion of the turbine main flow, and the received portion of the turbine main flow defines a wastegate flow. The wastegate passage differs from the auxiliary passage in that the wastegate passage receives the wastegate flow from a position upstream of the turbine wheel chamber, while the auxiliary passage inlet receives the auxiliary flow from a position downstream of the turbine wheel chamber.

[0504] The movable valve member can be any suitable type of body or component configured to allow and prevent fluid flow through the wastegate passage. By way of example, the valve member can be a flap-type valve member or a rotary valve member. A flap-type valve member can include a flap and an actuator configured to move the flap between a fully open configuration and a closed configuration; the actuator can be manually controlled, pneumatically controlled, and / or electronically controlled. A rotary valve member can be a valve member configured to rotate about a central axis, and rotation of the member regulates the flow of fluid through the passage.

[0505] As the exhaust gas travels through the turbine wheel chamber, the force of the exhaust gas striking the turbine blades causes the turbine wheel to rotate, extracting mechanical work from the exhaust gas. This mechanical work extracted from the exhaust gas results in a corresponding energy loss in the exhaust gas flow. This can be observed as a decrease in pressure, temperature, and / or velocity, for example, between the exhaust gas at the turbine inlet and the exhaust gas at the turbine outlet passage.

[0506] The wastegate passage can be configured to deliver fluid to the turbine outlet passage through the auxiliary passage. That is, the auxiliary passage can be fluidically disposed between the turbine outlet passage and the wastegate passage such that, during use, when the wastegate valve is open, the wastegate flow passes through at least a portion of the auxiliary passage before entering the turbine outlet passage. Because the wastegate flow is received by the auxiliary passage, it can be used to support the same applications as the auxiliary flow (e.g., cleaning of the dosing module nozzle, etc.). Furthermore, because the wastegate flow does not pass through the turbine wheel, it has a higher internal energy than the auxiliary flow and thus provides increased energy to support the auxiliary flow's applications.

[0507] The movable valve member can also be configured to selectively prevent fluid communication from the auxiliary channel inlet via the auxiliary channel to the auxiliary channel outlet. Since the wastegate flow travels through the auxiliary channel, the wastegate flow can replace the auxiliary flow to support the same applications as the auxiliary flow (for example, cleaning of the distribution module nozzle, etc.). When the wastegate is open, it may be preferred that all exhaust gas after leaving the turbine wheel chamber travels through the turbine outlet channel, rather than a portion of the gas being diverted away from the turbine outlet channel along the auxiliary channel. Preventing the flow from traveling through the auxiliary inlet to the auxiliary outlet when not required can reduce disturbances to the main turbine flow in the turbine outlet channel, thereby reducing energy losses when the main turbine flow flows through the turbine outlet channel.

[0508] In a first configuration of the wastegate arrangement, the valve member can be positioned such that fluid flow is permitted from the auxiliary inlet via the auxiliary passage to the auxiliary outlet, and fluid flow is permitted from the turbine inlet passage via the wastegate passage to the turbine outlet passage. In other words, in the first configuration, both the wastegate passage and the auxiliary passage are open to allow fluid flow. In this first configuration, both the wastegate flow and the auxiliary flow can be used in the same manner to provide benefits in the turbine outlet passage.

[0509] In a second configuration of the wastegate arrangement, the valve member can be positioned such that fluid flow from the auxiliary inlet via the auxiliary passage to the auxiliary outlet is permitted, and fluid flow from the turbine inlet via the wastegate passage to the turbine outlet passage is prevented. That is, in the second configuration, the wastegate is closed and the auxiliary passage is open.

[0510] In a third configuration of the wastegate arrangement, the valve member can be positioned such that fluid flow from the auxiliary inlet via the auxiliary passage to the auxiliary outlet is prevented, while fluid flow from the turbine inlet via the wastegate passage to the turbine outlet passage is permitted. That is, in the third configuration, the wastegate passage is open while the auxiliary passage is closed. In this configuration, wastegate flow can be used to support applications that would otherwise use the auxiliary flow.

[0511] In a fourth configuration of the wastegate arrangement, the valve member can be positioned such that fluid flow from the auxiliary inlet via the auxiliary passage to the auxiliary outlet is blocked, and fluid flow from the turbine inlet via the wastegate passage to the turbine outlet passage is blocked. That is, in the fourth configuration, both the wastegate passage and the auxiliary passage can be closed. Closing both the wastegate passage and the auxiliary passage ensures maximum turbine power output and minimizes flow disturbances in the turbine outlet passage.

[0512] The terms “wastegate assembly” and “wastegate device” may be used interchangeably.

[0513] The turbine outlet passage may further include: a first portion located upstream of the auxiliary passage inlet, the first portion defining a first flow area; and a second portion located downstream of the auxiliary passage inlet and upstream of the auxiliary passage outlet, the second portion defining a second flow area, which may be smaller than the first flow area. The term "flow area" encompasses the area of ​​the turbine outlet passage perpendicular to the direction of exhaust gas flow. Because the second flow area is smaller than the first flow area, the second portion of the turbine outlet passage exerts back pressure on the first portion of the turbine outlet passage, thereby forcing the turbine body flow into the auxiliary passage inlet. The second portion of the turbine outlet passage may be defined by a restriction of the turbine outlet passage, such as a narrower diameter of the turbine outlet passage downstream of the auxiliary passage inlet and / or the presence of one or more protrusions, baffles, or scoops extending from a wall of the turbine outlet passage into the turbine outlet passage. In such an embodiment, the turbine outlet passage may be a substantially straight outlet passage, may include a diverging diffuser, or may have any other suitable geometry.

[0514] The second flow area may be between about 5% and about 15% smaller than the first flow area, and is preferably about 10% smaller than the first flow area.

[0515] Generally, as the second flow area decreases in size, the backpressure exerted by the second portion of the turbine outlet passage on the main turbine flow increases, causing the main turbine flow to enter the auxiliary passage inlet. It has been found that when the second flow area is approximately 5% smaller than the first flow area, this promotes sufficient intake of the main turbine flow by the auxiliary passage inlet. However, if the second flow area is too small, excessive backpressure is generated. This increases the pumping work of the engine and, therefore, reduces the overall efficiency of the engine system. It has been found that when the second flow area is no more than approximately 15% smaller than the first flow area, the amount of backpressure generated by the second portion of the turbine outlet passage is sufficient to increase flow through the auxiliary passage, but not so great as to significantly affect the overall efficiency of the engine system.

[0516] The auxiliary passage may be located externally to the turbine outlet passage. The term "externally" may encompass embodiments in which the turbine outlet passage includes an inner surface defining a terminal end of the turbine outlet passage, and in which at least a portion or all of the auxiliary passage is located outside of the inner surface relative to a central axis of the turbine outlet passage. Thus, in such embodiments, the auxiliary passage does not impede flow through the turbine outlet passage. In such embodiments, the auxiliary passage inlet and the auxiliary passage outlet may be defined by openings in a sidewall of the turbine outlet passage.

[0517] According to the twentieth aspect of the present invention, a method for operating a turbine for a turbocharger is provided, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet passage; receiving exhaust gas from the turbine inlet passage into a turbine impeller chamber, the turbine impeller chamber being configured to accommodate a turbine impeller, the turbine impeller being supported to rotate about a turbine axis; receiving exhaust gas from the turbine impeller chamber into a turbine outlet passage; and receiving a portion of the exhaust gas from the turbine outlet passage into an auxiliary passage via an auxiliary passage inlet; and delivering the exhaust gas from the auxiliary passage to the turbine outlet passage via an auxiliary passage outlet.

[0518] The auxiliary passage inlet may be located at a position in the turbine outlet passage that is fluidly upstream of the auxiliary passage outlet relative to flow through the turbine outlet passage.

[0519] The turbine wheel may include an inducer defining an inducer diameter, the turbine outlet passage may define a centerline, and the auxiliary passage inlet may be spaced apart from the inducer of the turbine wheel along the centerline of the turbine outlet passage by a distance of up to about 5 inducer diameters.

[0520] The auxiliary passage outlet may be spaced apart from the inducer of the turbine wheel along a geometric centerline of the turbine outlet passage by a distance of at most about 10 inducer diameters.

[0521] The turbine may include a turbine housing at least partially defining a turbine inlet, a turbine wheel chamber, and a turbine outlet passage, and the auxiliary passage may be at least partially defined by the turbine housing.

[0522] The turbine may include a turbine housing defining a turbine inlet and a turbine wheel chamber, and a connection adapter at least partially defining a turbine outlet passage, and the auxiliary passage may be at least partially defined by the connection adapter.

[0523] The method may further include delivering the after-treatment fluid to the turbine outlet passage using a distribution module having an atomizing nozzle.

[0524] The nozzle of the dosing module may be substantially aligned with a surface defining the auxiliary passage or a surface of the turbine outlet passage.

[0525] The nozzle of the dosing module may be positioned within the auxiliary passage such that the dosing module is configured to deliver the aftertreatment fluid through the auxiliary passage to the turbine outlet passage.

[0526] The auxiliary passage may include an outlet portion extending from the nozzle to an outlet of the auxiliary passage, the outlet portion may define an outlet axis, and the outlet axis may be inclined relative to a centerline of the turbine outlet passage by an angle of up to about 70°.

[0527] The auxiliary passage may include an inlet portion extending from an auxiliary passage inlet to the nozzle, the inlet portion may define an inlet axis, and the inlet axis may be inclined at an angle of between about 20° and about 70° relative to a centerline of the turbine outlet passage.

[0528] The cross-sectional area of ​​the outlet portion of the auxiliary channel increases along the outlet axis from the nozzle of the dosing module to the auxiliary channel outlet.

[0529] The turbine outlet passage may define a diffuser.

[0530] The diffuser may be aligned with the turbine axis and may extend symmetrically about the turbine axis.

[0531] The auxiliary passage inlet may include a scoop extending into the turbine outlet passage, and the scoop may be configured to direct exhaust gas flow into the auxiliary passage.

[0532] The auxiliary channel may include a plurality of auxiliary channel inlets.

[0533] The auxiliary passage inlet may be substantially axially aligned relative to a centreline of the turbine outlet passage.

[0534] The auxiliary channels may be spaced generally equally about the centerline.

[0535] The turbine outlet passage may define a perimeter, and the auxiliary passage may extend about the perimeter to provide fluid communication between the plurality of auxiliary passage inlets.

[0536] The turbine may also include a wastegate device, which includes a wastegate passage and a movable valve member, the wastegate passage being configured to provide fluid communication from the turbine inlet passage to the turbine outlet passage so that exhaust gas traveling through the wastegate passage does not travel through the turbine impeller chamber, and the movable valve member being configured to selectively allow or prevent fluid flow through the wastegate passage by blocking the wastegate passage.

[0537] The wastegate passage may be configured to deliver fluid through the auxiliary passage to the turbine outlet passage.

[0538] The movable valve member may also be configured to selectively prevent fluid communication from the auxiliary passage inlet to the auxiliary passage outlet via the auxiliary passage.

[0539] In a first configuration of the wastegate arrangement, the valve member may be positioned such that fluid flow is permitted from the auxiliary inlet via the auxiliary passage to the auxiliary outlet, and fluid flow is permitted from the turbine inlet passage via the wastegate passage to the turbine outlet passage.

[0540] In a second configuration of the wastegate arrangement, the valve member may be positioned such that fluid flow from the auxiliary inlet via the auxiliary passage to the auxiliary outlet is permitted and fluid flow from the turbine inlet via the wastegate passage to the turbine outlet passage is prevented.

[0541] In a third configuration of the wastegate arrangement, the valve member may be positioned such that fluid flow from the auxiliary inlet via the auxiliary passage to the auxiliary outlet is prevented and fluid flow from the turbine inlet via the wastegate passage to the turbine outlet passage is permitted.

[0542] In a fourth configuration of the wastegate arrangement, the valve member may be positioned such that fluid flow from the auxiliary inlet via the auxiliary passage to the auxiliary outlet is prevented, and fluid flow from the turbine inlet via the wastegate passage to the turbine outlet passage is prevented.

[0543] The terms “wastegate assembly” and “wastegate device” may be used interchangeably.

[0544] The turbine outlet channel may further include a first portion upstream of the auxiliary channel inlet, which may define a first flow area, and a second portion downstream of the auxiliary channel inlet and upstream of the auxiliary channel outlet, which may define a second flow area, which may be smaller than the first flow area.

[0545] The second flow area may be between about 5% and about 15% smaller than the first flow area, and is preferably about 10% smaller than the first flow area.

[0546] The auxiliary passage may be located outside the turbine outlet passage.In such an embodiment, the auxiliary passage inlet and the auxiliary passage outlet may be defined by openings in the sidewalls of the turbine outlet passage.

[0547] According to the twenty-first aspect of the present invention, a turbine for a turbocharger is provided, the turbine comprising: a turbine inlet channel, the turbine inlet channel being configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet channel defining a turbine main flow; a turbine impeller chamber, the turbine impeller chamber being configured to receive the turbine main flow from the turbine inlet channel, the turbine impeller chamber being configured to accommodate a turbine impeller, the turbine impeller being supported to rotate around a turbine axis; a turbine outlet channel, the turbine outlet channel being configured to receive the turbine main flow from the turbine impeller chamber a turbine wheel chamber receiving the turbine main flow; and an auxiliary passage configured to receive a portion of the turbine main flow from a first position of the turbine located upstream of the turbine outlet passage, the portion of the turbine main flow received by the auxiliary passage defining an auxiliary flow, the auxiliary passage further configured to deliver the auxiliary flow to the turbine main flow at a second position of the turbine located downstream of the turbine wheel chamber; wherein the turbine is configured such that the auxiliary flow is always allowed to flow from the first position of the turbine to the second position of the turbine.

[0548] The term "auxiliary passage" encompasses any fluid carrying passage that is configured to carry fluid separately from the turbine inlet passage, the turbine wheel chamber and the turbine outlet passage. This may include the use of conduits, channels, cutouts, perforations, grooves, recesses, passages and the like. A "first position of the turbine that is located upstream of the turbine outlet passage" encompasses, for example, a position within the turbine wheel chamber or within the turbine inlet passage. A "second position of the turbine that is located downstream of the turbine wheel chamber" encompasses, for example, a position within the turbine outlet passage. The auxiliary passage being arranged "such that the auxiliary flow bypasses at least a portion of the turbine wheel chamber" encompasses an arrangement in which the auxiliary passage accommodates the auxiliary flow such that the auxiliary flow does not pass through the turbine wheel or at least a portion of the turbine wheel chamber.

[0549] Since the auxiliary passage is configured to receive the auxiliary flow from a first location of the turbine upstream of the turbine outlet passage and to deliver the auxiliary flow to the main turbine flow at a second location of the turbine downstream of the turbine wheel chamber, the auxiliary flow bypasses at least a portion of the turbine wheel in use.

[0550] The turbine being "configured such that auxiliary flow is always permitted to flow from a first position of the turbine to a second position of the turbine" encompasses the auxiliary passage being arranged such that, under all operating conditions of the turbine, exhaust gas is permitted to flow from an inlet of the auxiliary passage (which receives exhaust gas from the turbine wheel chamber or the turbine inlet passage) to an outlet of the auxiliary passage (which delivers fluid to the turbine outlet passage). That is, the auxiliary passage is arranged such that, regardless of the operating condition of the turbine (e.g., regardless of the actuation state of a variable geometry mechanism or a wastegate), at least some flow is always permitted through the auxiliary passage. For example, this may include the auxiliary passage being substantially free of valves or closures configured to prevent flow through the auxiliary passage.

[0551] Under normal conditions, the flow conditions in the turbine outlet channel are generally not suitable for injecting the after-treatment fluid. However, the reconditioned exhaust flow through the auxiliary channel can be used for one or more fluid applications in the auxiliary channel outlet to support improved decomposition at the injection site of the after-treatment fluid. For example, by using an auxiliary channel, a distribution module can be provided to inject the after-treatment fluid into the turbine outlet channel, and the auxiliary channel can guide the exhaust flow into the after-treatment fluid to induce turbulence and improve mixing. Additionally or alternatively, the auxiliary channel can guide the flow through the nozzle of the distribution module to clean the nozzle. Additionally or alternatively, the momentum of the auxiliary flow can be used to increase the momentum of the injected after-treatment fluid, so that the after-treatment fluid can be dissipated over substantially the entire cross-sectional area of ​​the turbine outlet channel, thereby providing increased uniformity of the flow of the after-treatment fluid across the turbine outlet channel. In yet another alternative or additional embodiment, the auxiliary channel can be used to form a narrow layer of fast-moving fluid on the surface of the turbine outlet channel where after-treatment fluid impact may occur, so as to avoid the accumulation of deposits on the surface of the turbine outlet. Other applications of the auxiliary flow will become apparent from the description.

[0552] It should be understood that in order for the auxiliary channel to regulate the auxiliary flow to provide the above-mentioned beneficial functions, exhaust gas must be supplied to the auxiliary channel. When the turbine main flow travels through the turbine impeller chamber, the force of the exhaust gas impacting the turbine blades causes the turbine impeller to rotate, thereby extracting mechanical work from the turbine main flow. Mechanical work results in a corresponding energy loss in the turbine main flow. Therefore, the turbine main flow upstream of the turbine outlet channel has higher energy than the turbine main flow downstream of the turbine impeller chamber. As described above, the higher energy of the turbine main flow at the first position of the turbine can be used to influence the exhaust flow at the second position of the turbine.

[0553] Furthermore, because the auxiliary passage always allows fluid to flow through it, the turbine does not experience any operating conditions that would prevent flow through the auxiliary passage. This means that the auxiliary passage can always operate to deliver flow to the turbine's secondary position. Therefore, regardless of which application is supported by the auxiliary flow, it will be maintained under all operating conditions of the turbine.

[0554] The auxiliary passage can receive at least approximately 0.1% of the main turbine flow received by the turbine inlet passage. In other words, the geometry of the auxiliary passage is selected so that, regardless of turbine operating conditions, at least approximately 0.1% of the main turbine flow received by the turbine inlet can pass through the auxiliary passage. This can be measured, for example, by comparing the mass flow of the main turbine flow received by the turbine inlet with the mass flow of the auxiliary flow. The main turbine flow received by the turbine inlet is the total amount of incident exhaust gas delivered to the turbine from the internal combustion engine. This can be achieved by controlling the cross-sectional area of ​​the auxiliary passage.

[0555] Even relatively small amounts of auxiliary flow can be used to support beneficial effects at the turbine outlet. For example, an auxiliary flow of approximately 0.1% of the main turbine flow is sufficient to support cleaning of the nozzles of the dosing module. In other embodiments, the auxiliary flow can be at least approximately 0.2%, 0.3%, 0.4%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, or 5% of the main turbine flow. Generally, the greater the ratio of auxiliary flow to main turbine flow, the more energy available to support the specific application of the auxiliary flow in the second position of the turbine.

[0556] The auxiliary passage may receive at most about 10% of the turbine main flow received by the turbine inlet passage.That is, the geometry of the auxiliary passage is selected so that at most about 10% of the turbine main flow may travel through the auxiliary passage.

[0557] If the mass flow rate of the auxiliary flow increases as a proportion of the main turbine flow, the work extracted from the main turbine flow by the turbine wheel decreases. Consequently, increasing the auxiliary flow results in a corresponding decrease in turbine wheel efficiency and a reduction in the power output of the internal combustion engine. It has been found that if the auxiliary flow exceeds approximately 10% of the main turbine flow, the corresponding drop in turbine efficiency is often too high to tolerate. Preferably, the flow through the auxiliary passage should be kept as low as possible to support the beneficial effects and not too high. It has been found that auxiliary flow mass flows of up to approximately 0.2%, 0.3%, 0.4%, 0.5%, 1%, 1.5%, 2%, or 2.5% of the main turbine flow can adequately support nozzle cleaning of the dosing module without significantly negatively impacting turbine efficiency. Specifically, turbine efficiency at a 1% to 2% leakage may only drop by approximately 1% to 2%. In most applications, such a small drop in efficiency is tolerable. However, in other embodiments, the auxiliary flow may comprise up to about 3%, 4%, or 5% of the main turbine flow.

[0558] The first location may be the turbine inlet passage, and wherein the auxiliary passage may define an auxiliary passage inlet in direct fluid communication with the turbine inlet passage. That is, the auxiliary passage inlet is positioned so that exhaust gas may flow directly from the turbine inlet passage to the auxiliary passage.

[0559] Because the exhaust gas contained within the turbine inlet passage does not pass through the turbine wheel, the exhaust gas within the turbine inlet passage has high energy compared to the exhaust gas at any location further downstream. By coupling the auxiliary pass...

Claims

1. A turbine for a turbocharger, comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine body flow; a turbine wheel chamber configured to receive the turbine body flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation; a turbine outlet passage configured to receive the turbine body flow from the turbine wheel chamber, the turbine outlet passage being at least partially defined by a turbine outlet passage surface, and the turbine outlet passage defining a centerline; an auxiliary passage configured to receive a portion of the turbine main body flow, the portion of the turbine main body flow received by the auxiliary passage defining an auxiliary flow; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; Wherein, the auxiliary passage is configured to guide the auxiliary flow along the turbine outlet passage surface in an auxiliary flow layer.

2. The turbine according to claim 1, wherein: The dosing module includes a nozzle in fluid communication with the turbine outlet passage, the nozzle being configured to produce a spray of aftertreatment fluid; and wherein the nozzle is positioned on a side of the turbine outlet passage opposite the auxiliary flow layer such that, during use, the auxiliary flow layer inhibits aftertreatment fluid from reaching a portion of the turbine outlet passage surface opposite the nozzle.

3. A turbine according to any one of claims 1 or 2, wherein: The secondary passage is configured to direct the secondary flow layer in a generally axial direction downstream relative to the centerline.

4. The turbine according to any one of claims 1 to 3, wherein: The turbine includes a shield structure protruding into the turbine outlet passage, the shield structure defining a portion of the auxiliary passage.

5. A turbine according to any one of claims 1, 2 or 4, wherein: The turbine wheel imparts a swirl momentum to the turbine body flow, the swirl momentum of the turbine body flow defining a positive angular direction, and wherein the auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage in a direction that induces a swirl of the auxiliary flow layer about the centerline along the positive angular direction.

6. The turbine according to any one of claims 1 to 5, wherein: The auxiliary passage is configured to deliver the auxiliary flow into the turbine outlet passage in a direction between 0° and about 60° relative to a direction normal to the centerline.

7. The turbine according to claim 6, wherein: The auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage at a swirl angle between about 30° and about 85°.

8. A turbine according to any one of claims 5 to 7, wherein: The auxiliary passage is at least partially defined by an auxiliary passage surface, wherein the auxiliary passage surface and the turbine outlet passage surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the turbine outlet channel surface.

9. The turbine according to claim 8, wherein: At the interface, the secondary duct surface is inclined at an angle of up to about 15° relative to a tangent to the turbine outlet duct surface in a plane normal to the centerline.

10. A turbine according to any one of claims 5 to 9, wherein: The turbomachine further includes a sensor arrangement including a sensor passage having a sensor passage inlet and a sensor passage outlet; wherein the sensor passage inlet is configured to receive a portion of the turbine body flow from the turbine outlet passage to define a sensor flow, and the sensor passage outlet is configured to deliver the sensor flow to the turbine outlet passage; and The auxiliary passage is configured to guide the auxiliary flow into the turbine outlet passage so that the auxiliary flow layer passes downstream of the sensor passage outlet.

11. A turbine according to any one of claims 5 to 10, wherein: the turbine being configured to be connected to a network of exhaust conduits downstream of the turbine outlet passage, the network including a curved portion configured to receive the turbine body flow from the turbine outlet passage; and The auxiliary passage is configured to guide the auxiliary flow into the turbine outlet passage so that the auxiliary flow layer passes through the outer tip of the curved portion.

12. A turbine according to any one of claims 1 to 11, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that the thickness of the auxiliary flow layer is between at least about 5% and at most about 25% of a distance defined between the turbine outlet channel surface and the centerline.

13. A turbine according to any one of claims 1 to 12, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that a width of the auxiliary flow layer is between about 50% and about 100% of a diameter of the turbine outlet channel defined by the turbine outlet channel surface.

14. A turbine according to any one of claims 12 or 13, wherein: The secondary channel outlet defines a width and a depth, and wherein the depth is about 15% to about 50% of the width, and preferably about 25% of the width.

15. A turbine according to any one of claims 13 or 14, wherein: The auxiliary passage includes a wastegate valve configured to selectively allow or prevent the auxiliary flow from traveling through the auxiliary passage; The wastegate valve includes a valve opening defining a valve flow area; The auxiliary passage outlet defines an auxiliary flow area in a plane normal to the direction of the auxiliary flow; and The auxiliary flow area is approximately 1.2 times the valve flow area.

16. A turbine according to any one of claims 1 to 15, wherein: The auxiliary passage is configured to receive the portion of the turbine body flow from the turbine inlet passage.

17. A turbine according to any one of claims 1 to 16, wherein: The auxiliary passage includes a valve configured to control a flow rate of an auxiliary stream through the auxiliary passage.

18. The turbine according to claim 17, wherein: The auxiliary passage is sized such that when the valve is open, a flow rate of the auxiliary flow through the auxiliary passage is between at least about 25% of a flow rate of the main turbine flow received by the turbine inlet passage.

19. A turbine according to claim 17 or 18, wherein: The auxiliary passage includes an auxiliary passage outlet configured to deliver the auxiliary flow into the turbine outlet passage, and wherein the valve is positioned at the auxiliary passage outlet.

20. A turbine according to any one of claims 1 to 14, wherein: The auxiliary passage is configured to receive the portion of the turbine body flow from the turbine outlet passage.

21. A turbine according to claim 16 or 20, wherein: The auxiliary channel is configured such that an auxiliary flow is always allowed to pass through the auxiliary channel.

22. The turbine according to claim 21, wherein: The auxiliary passage is sized such that, during use, the flow rate of the auxiliary flow is about 0.5% to about 2% of the flow rate of the main turbine flow received by the turbine inlet passage.

23. A turbine according to any one of claims 1 to 22, wherein: The auxiliary channel includes an auxiliary channel outlet and defines a flow area normal to a flow direction of an auxiliary flow through the auxiliary channel, and wherein the flow area narrows toward the auxiliary channel outlet.

24. A turbine according to any one of claims 1 to 23, wherein: The auxiliary passage includes a plurality of auxiliary passage outlets configured to deliver the auxiliary flow into the turbine outlet passage.

25. The turbine according to claim 24, wherein: The auxiliary passage includes a first branch defining the auxiliary passage outlet and a second branch defining a second auxiliary passage outlet, wherein the second auxiliary passage outlet is positioned on a side of the turbine outlet passage generally opposite the auxiliary passage outlet.

26. The turbine of claim 24, wherein: The auxiliary channel outlets are equidistantly distributed around the center line.

27. A turbine according to any one of claims 1 to 26, wherein: The auxiliary channel includes a plenum and a plurality of branches fluidly connected to the plenum, wherein the plenum is configured to receive the auxiliary flow from an inlet of the auxiliary channel, and the branches are configured to deliver the auxiliary flow to an outlet of the auxiliary channel.

28. A turbine according to claim 27, wherein: Each of the branches is configured to deliver the secondary flow to the turbine exit passage in a direction that induces a swirl in the secondary flow layer about the centerline.

29. A turbine according to any one of claims 1 to 28, wherein: The auxiliary channel comprises: a first auxiliary channel branch configured to receive a first auxiliary flow portion and direct the first auxiliary flow portion into the turbine outlet channel as a first auxiliary flow layer; and A second auxiliary channel branch is configured to receive a second auxiliary flow portion and direct the second auxiliary flow portion into the turbine outlet channel in a second auxiliary flow layer.

30. The turbine of claim 28, wherein: The first auxiliary passage branch is configured to direct the first auxiliary flow layer downstream relative to the centerline in a generally axial direction into the turbine exit passage; and The second auxiliary channel branch is configured to guide the second auxiliary flow layer downstream in a substantially axial direction relative to the centerline into the turbine outlet channel.

31. The turbine of claim 29, wherein: the first auxiliary passage branch being configured to direct the first auxiliary flow layer into the turbine exit passage in a direction inducing a vortex of the first auxiliary flow layer about the centerline in a positive angular direction; and Wherein, the second auxiliary channel branch is configured to guide the second auxiliary flow layer into the turbine outlet channel in a direction that induces a vortex of the second auxiliary flow layer about the centerline in the positive angle direction.

32. The turbine of claim 29, wherein: The first auxiliary passage branch is configured to direct the first auxiliary flow layer downstream relative to the centerline in a generally axial direction into the turbine exit passage; and Wherein, the second auxiliary channel branch is configured to guide the second auxiliary flow layer into the turbine outlet channel in a direction that induces a vortex of the second auxiliary flow layer about the centerline in the positive angle direction.

33. A turbine according to any one of claims 1 to 32, wherein: The turbine outlet passage defines a diffuser portion, and wherein the turbine outlet passage surface is a surface of the diffuser portion.

34. A turbine according to any one of claims 1 to 33, wherein: The turbine includes a housing assembly having: a turbine housing defining the turbine inlet passage and the turbine wheel chamber; and A connection adapter defines at least a portion of the turbine outlet passage and the turbine outlet passage surface.

35. A turbocharger comprising a turbine according to any one of claims 1 to 34.

36. A method of operating a turbine for a turbocharger, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet passage, the exhaust gas received by the turbine inlet passage defining a turbine body flow; receiving the turbine body flow from the turbine inlet passage into a turbine wheel chamber configured to house a turbine wheel supported for rotation; receiving the turbine body flow from the turbine wheel chamber into a turbine outlet passage, the turbine outlet passage being at least partially defined by a turbine outlet passage surface, the turbine outlet passage defining a centerline; receiving a portion of the main turbine flow into an auxiliary passage, the portion of the main turbine flow received by the auxiliary passage defining an auxiliary flow; delivering a spray of aftertreatment fluid into the turbine outlet passage using a dosing module; as well as The secondary flow is directed along the turbine outlet passage surface in a secondary flow layer.

37. The method of claim 36, wherein: The dosing module includes a nozzle in fluid communication with the turbine outlet passage, the nozzle being configured to produce a spray of aftertreatment fluid; and wherein the nozzle is positioned on a side of the turbine outlet passage opposite the auxiliary flow layer such that, during use, the auxiliary flow layer inhibits aftertreatment fluid from reaching a portion of the turbine outlet passage surface opposite the nozzle.

38. The method according to any one of claims 36 or 37, wherein: The secondary passage is configured to direct the secondary flow layer in a generally axial direction downstream relative to the centerline.

39. The method according to any one of claims 36 to 38, wherein: The turbine includes a shield structure protruding into the turbine outlet passage, the shield structure defining a portion of the auxiliary passage.

40. The method of any one of claims 36, 37 or 39, wherein: The turbine wheel imparts a swirl momentum to the turbine body flow, the swirl momentum of the turbine body flow defining a positive angular direction, and wherein the auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage in a direction that induces a swirl of the auxiliary flow layer about the centerline along the positive angular direction.

41. The method according to any one of claims 36 to 40, wherein: The auxiliary passage is configured to deliver the auxiliary flow into the turbine outlet passage in a direction between 0° and about 60° relative to a direction normal to the centerline.

42. The method according to claim 41, wherein: The auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage at a swirl angle between about 30° and about 85°.

43. The method according to any one of claims 40 to 42, wherein: The auxiliary passage is at least partially defined by an auxiliary passage surface, wherein the auxiliary passage surface and the turbine outlet passage surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the turbine outlet channel surface.

44. The method of claim 43, wherein: At the interface, the secondary duct surface is inclined at an angle of up to about 15° relative to a tangent to the turbine outlet duct surface in a plane normal to the centerline.

45. The method according to any one of claims 40 to 44, wherein: The turbomachine further includes a sensor arrangement including a sensor passage having a sensor passage inlet and a sensor passage outlet; wherein the sensor passage inlet is configured to receive a portion of the turbine body flow from the turbine outlet passage to define a sensor flow, and the sensor passage outlet is configured to deliver the sensor flow to the turbine outlet passage; and The auxiliary passage is configured to guide the auxiliary flow into the turbine outlet passage so that the auxiliary flow layer passes downstream of the sensor passage outlet.

46. ​​The method according to any one of claims 40 to 45, wherein: the turbine being configured to be connected to a network of exhaust conduits downstream of the turbine outlet passage, the network including a curved portion configured to receive the turbine body flow from the turbine outlet passage; and The auxiliary passage is configured to guide the auxiliary flow into the turbine outlet passage so that the auxiliary flow layer passes through the outer tip of the curved portion.

47. The method according to any one of claims 36 to 46, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that the thickness of the auxiliary flow layer is between at least about 5% and at most about 25% of a distance defined between the turbine outlet channel surface and the centerline.

48. The method according to any one of claims 36 to 47, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that a width of the auxiliary flow layer is between about 50% and about 100% of a diameter of the turbine outlet channel defined by the turbine outlet channel surface.

49. The method according to any one of claims 47 or 48, wherein: The secondary channel outlet defines a width and a depth, and wherein the depth is about 15% to about 50% of the width, and preferably about 25% of the width.

50. The method of any one of claims 48 or 49, wherein: The auxiliary passage includes a wastegate valve configured to selectively allow or prevent the auxiliary flow from traveling through the auxiliary passage; The wastegate valve includes a valve opening defining a valve flow area; The auxiliary passage outlet defines an auxiliary flow area in a plane normal to the direction of the auxiliary flow; and The auxiliary flow area is approximately 1.2 times the valve flow area.

51. The method of any one of claims 36 to 50, wherein: The auxiliary passage is configured to receive the portion of the turbine body flow from the turbine inlet passage.

52. The method of any one of claims 36 to 51, wherein: The auxiliary passage includes a valve configured to control a flow rate of an auxiliary stream through the auxiliary passage.

53. The method of claim 52, wherein: The auxiliary passage is sized such that when the valve is open, a flow rate of the auxiliary flow through the auxiliary passage is between at least about 25% of a flow rate of the main turbine flow received by the turbine inlet passage.

54. The method of claim 52 or 53, wherein: The auxiliary passage includes an auxiliary passage outlet configured to deliver the auxiliary flow into the turbine outlet passage, and wherein the valve is positioned at the auxiliary passage outlet.

55. The method of any one of claims 36 to 49, wherein: The auxiliary passage is configured to receive the portion of the turbine body flow from the turbine outlet passage.

56. The method of claim 55, wherein: The auxiliary channel is configured such that an auxiliary flow is always allowed to pass through the auxiliary channel.

57. The method of claim 56, wherein: The auxiliary passage is sized such that, during use, the flow rate of the auxiliary flow is about 0.5% to about 2% of the flow rate of the main turbine flow received by the turbine inlet passage.

58. The method of any one of claims 36 to 57, wherein: The auxiliary channel includes an auxiliary channel outlet and defines a flow area normal to a flow direction of an auxiliary flow through the auxiliary channel, and wherein the flow area narrows toward the auxiliary channel outlet.

59. The method of any one of claims 36 to 58, wherein: The auxiliary passage includes a plurality of auxiliary passage outlets configured to deliver the auxiliary flow into the turbine outlet passage.

60. The method of claim 59, wherein: The auxiliary passage includes a first branch defining the auxiliary passage outlet and a second branch defining a second auxiliary passage outlet, wherein the second auxiliary passage outlet is positioned on a side of the turbine outlet passage generally opposite the auxiliary passage outlet.

61. The method of claim 60, wherein: The auxiliary channel outlets are equidistantly distributed around the center line.

62. The method of any one of claims 36 to 61, wherein: The auxiliary channel includes a plenum and a plurality of branches fluidly connected to the plenum, wherein the plenum is configured to receive the auxiliary flow from an inlet of the auxiliary channel, and the branches are configured to deliver the auxiliary flow to an outlet of the auxiliary channel.

63. The method of claim 62, wherein: Each of the branches is configured to deliver the secondary flow to the turbine exit passage in a direction that induces a swirl in the secondary flow layer about the centerline.

64. The method of any one of claims 36 to 58, wherein: The auxiliary channel comprises: a first auxiliary channel branch configured to receive a first auxiliary flow portion and direct the first auxiliary flow portion into the turbine outlet channel as a first auxiliary flow layer; and A second auxiliary channel branch is configured to receive a second auxiliary flow portion and direct the second auxiliary flow portion into the turbine outlet channel in a second auxiliary flow layer.

65. The method of claim 64, wherein: The first auxiliary passage branch is configured to direct the first auxiliary flow layer downstream relative to the centerline in a generally axial direction into the turbine exit passage; and The second auxiliary channel branch is configured to guide the second auxiliary flow layer downstream in a substantially axial direction relative to the centerline into the turbine outlet channel.

66. The method of claim 65, wherein: the first auxiliary passage branch being configured to direct the first auxiliary flow layer into the turbine exit passage in a direction inducing a vortex of the first auxiliary flow layer about the centerline in a positive angular direction; and Wherein, the second auxiliary channel branch is configured to guide the second auxiliary flow layer into the turbine outlet channel in a direction that induces a vortex of the second auxiliary flow layer about the centerline in the positive angle direction.

67. The method of claim 66, wherein: The first auxiliary passage branch is configured to direct the first auxiliary flow layer downstream relative to the centerline in a generally axial direction into the turbine exit passage; and Wherein, the second auxiliary channel branch is configured to guide the second auxiliary flow layer into the turbine outlet channel in a direction that induces a vortex of the second auxiliary flow layer about the centerline in the positive angle direction.

68. The method of any one of claims 36 to 67, wherein: The turbine outlet passage defines a diffuser portion, and wherein the turbine outlet passage surface is a surface of the diffuser portion.

69. The method of any one of claims 36 to 68, wherein: The turbine includes a housing assembly having: a turbine housing defining the turbine inlet passage and the turbine wheel chamber; and A connection adapter defines the turbine outlet passage surface and at least a portion of the turbine outlet passage.

70. A turbine for a turbocharger, comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine body flow; a turbine wheel chamber configured to receive the turbine body flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the turbine body flow from the turbine wheel chamber; a distribution module configured to deliver a spray of aftertreatment fluid into a spray region of the turbine outlet passage through which the turbine body flow travels; and An auxiliary channel, the auxiliary channel comprising: - an auxiliary passage inlet configured to receive a portion of the turbine main body flow from the turbine outlet passage, the portion of the turbine main body flow received by the auxiliary passage defining an auxiliary flow; and - an auxiliary channel outlet configured to convey the auxiliary flow from the auxiliary channel to the turbine outlet channel, wherein the auxiliary channel outlet is configured to direct the auxiliary flow into the spray region of the turbine outlet channel.

71. A turbine according to claim 70, wherein: The dosing module comprises a nozzle, and the auxiliary channel is configured to direct the auxiliary flow through the nozzle in a direction substantially normal to the spraying direction.

72. The turbine according to claim 70, wherein: The dosing module is configured to deliver the post-treatment fluid in a spray direction, and the auxiliary channel is configured to guide the auxiliary flow into the spray region in an auxiliary flow direction opposite to the spray direction.

73. A turbine according to claim 72, wherein: The auxiliary flow is oriented in an upstream direction relative to the main turbine flow, and wherein the auxiliary flow direction is angularly inclined at an angle between about 50° and about 90° relative to an opposite direction of the spray direction.

74. The turbine according to claim 72, wherein: The auxiliary flow is oriented in a downstream direction relative to the main turbine flow, and wherein the auxiliary flow direction is angularly inclined at an angle between about 30° and about 90° relative to an opposite direction of the spray direction.

75. The turbine according to claim 70, wherein: The auxiliary passage is configured to direct the auxiliary flow into the turbine outlet passage in an auxiliary flow direction facing downstream relative to the turbine main body flow, and The auxiliary flow direction is inclined at an angle of at least about 45° relative to a centerline of the turbine outlet passage.

76. The turbine according to claim 70, wherein: The auxiliary passage is configured to direct the auxiliary flow into the turbine outlet passage in an auxiliary flow direction facing upstream relative to the turbine main body flow, and The auxiliary flow direction is inclined at an angle of at least about 45° relative to a centerline of the turbine outlet passage.

77. A turbine according to any one of claims 70 to 76, wherein The nozzle of the dosing module is positioned within the auxiliary passage such that the dosing module is configured to deliver aftertreatment fluid to the turbine outlet passage via the auxiliary passage.

78. A turbine according to claim 77, wherein: The auxiliary passage includes an outlet portion extending from the nozzle to the auxiliary passage outlet, the outlet portion defining an outlet axis, and wherein the outlet axis is inclined at an angle of up to about 70° relative to a centerline of the turbine outlet passage.

79. A turbine according to claim 77 or 78, wherein: The auxiliary passage includes an inlet portion extending from an auxiliary passage inlet to the nozzle, the inlet portion defining an inlet axis, and wherein the inlet axis is inclined at an angle between about 20° and about 70° relative to a centerline of the turbine outlet passage.

80. A method of operating a turbine for a turbocharger, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet passage, the exhaust gas received by the turbine inlet passage defining a turbine bulk flow; receiving the turbine body flow from the turbine inlet passage into a turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; receiving the turbine body flow from the turbine wheel chamber into a turbine outlet passage; delivering an aftertreatment fluid using a dosing module into a spray region of the turbine outlet passage through which the turbine body flow travels; receiving a portion of the turbine main body flow from the turbine outlet passage into an auxiliary passage through an auxiliary passage inlet, the portion of the turbine main body flow received by the auxiliary passage defining an auxiliary flow; as well as The auxiliary flow is directed into the spray region of the turbine outlet channel through an auxiliary channel outlet.

81. The method of claim 80, wherein: The dosing module comprises a nozzle, and the auxiliary channel is configured to direct the auxiliary flow through the nozzle in a direction substantially normal to the spraying direction.

82. The method of claim 80, wherein: The dosing module is configured to deliver the post-treatment fluid in a spray direction, and the auxiliary channel is configured to guide the auxiliary flow into the spray region in an auxiliary flow direction opposite to the spray direction.

83. The method of claim 82, wherein: The auxiliary flow is oriented in an upstream direction relative to the main turbine flow, and wherein the auxiliary flow direction is angularly inclined at an angle between about 50° and about 90° relative to an opposite direction of the spray direction.

84. The method of claim 82, wherein: The auxiliary flow is directed in a downstream direction relative to the main turbine flow, and wherein the auxiliary flow direction is angularly inclined at an angle between about 30° and about 90° relative to an opposite direction of the spray direction.

85. The method of claim 80, wherein: The auxiliary passage is configured to direct the auxiliary flow into the turbine outlet passage in an auxiliary flow direction facing downstream relative to the turbine main body flow, and The auxiliary flow direction is inclined at an angle of at least about 45° relative to a centerline of the turbine outlet passage.

86. The method of claim 80, wherein: The auxiliary passage is configured to direct the auxiliary flow into the turbine outlet passage in an auxiliary flow direction facing upstream relative to the turbine main body flow, and The auxiliary flow direction is inclined at an angle of at least about 45° relative to a centerline of the turbine outlet passage.

87. The method of any one of claims 80 to 86, wherein: The nozzle of the dosing module is positioned within the auxiliary passage such that the dosing module is configured to deliver aftertreatment fluid to the turbine outlet passage via the auxiliary passage.

88. The method of claim 87, wherein: The auxiliary passage includes an outlet portion extending from the nozzle to the auxiliary passage outlet, the outlet portion defining an outlet axis, and wherein the outlet axis is inclined at an angle of up to about 70° relative to a centerline of the turbine outlet passage.

89. The method of claim 87 or 88, wherein: The auxiliary passage includes an inlet portion extending from an auxiliary passage inlet to the nozzle, the inlet portion defining an inlet axis, and wherein the inlet axis is inclined at an angle between about 20° and about 70° relative to a centerline of the turbine outlet passage.

90. A turbine for a turbocharger, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine body flow; a turbine wheel chamber configured to receive the turbine body flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the turbine body flow from the turbine wheel chamber; a distribution module configured to deliver a spray of aftertreatment fluid into a spray region of the turbine outlet passage through which the turbine body flow travels; and an auxiliary passage configured to receive a portion of the main turbine flow from a first location of the turbine upstream of the turbine outlet passage, the portion of the main turbine flow received by the auxiliary passage defining an auxiliary flow, the auxiliary passage further configured to deliver the auxiliary flow to the main turbine flow at a second location of the turbine downstream of the turbine wheel chamber; wherein the turbine is configured such that the auxiliary flow is always allowed to flow from the first position of the turbine to the second position of the turbine, and Wherein, in the second position, the auxiliary passage is configured to direct the auxiliary flow into the spray region of the turbine outlet passage.

91. A turbine according to claim 90, wherein: The dosing module comprises a nozzle, and the auxiliary channel is configured to direct the auxiliary flow through the nozzle in a direction substantially normal to the spraying direction.

92. The turbine according to claim 90, wherein: The dosing module is configured to deliver the post-treatment fluid in a spray direction, and the auxiliary channel is configured to guide the auxiliary flow into the spray region in an auxiliary flow direction opposite to the spray direction.

93. A turbine according to claim 92, wherein: The auxiliary flow is oriented in an upstream direction relative to the main turbine flow, and wherein the auxiliary flow direction is angularly inclined at an angle between about 50° and about 90° relative to an opposite direction of the spray direction.

94. A turbine according to claim 93, wherein: The auxiliary flow is directed in a downstream direction relative to the main turbine flow, and wherein the auxiliary flow direction is angularly inclined at an angle between about 30° and about 90° relative to an opposite direction of the spray direction.

95. The turbine according to claim 90, wherein: The auxiliary passage is configured to direct the auxiliary flow into the turbine outlet passage in an auxiliary flow direction facing downstream relative to the turbine main body flow, and The auxiliary flow direction is inclined at an angle of at least about 45° relative to a centerline of the turbine outlet passage.

96. The turbine according to claim 90, wherein: The auxiliary passage is configured to direct the auxiliary flow into the turbine outlet passage in an auxiliary flow direction facing upstream relative to the turbine main body flow, and The auxiliary flow direction is inclined at an angle of at least about 45° relative to a centerline of the turbine outlet passage.

97. A turbine according to any one of claims 90 to 96, wherein The auxiliary passage includes a valve configured to control flow through the auxiliary passage, and Therein, the valve is configured such that the auxiliary flow is allowed to pass through the valve during all operating conditions of the turbine.

98. A turbine according to claim 97, wherein: The valve is configured such that the auxiliary flow through the valve always accounts for at least about 0.1% of the mass flow of exhaust gas delivered from the engine to the turbine inlet passage.

99. A turbine according to claim 97 or 98, wherein: The dosing module is configured to deliver aftertreatment fluid to the turbine outlet passage via the auxiliary passage.

100. A method of operating a turbine for a turbocharger, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet passage, the exhaust gas received by the turbine inlet passage defining a turbine bulk flow; receiving the turbine body flow from the turbine inlet passage into a turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; receiving the turbine body flow from the turbine wheel chamber into a turbine outlet passage; delivering an aftertreatment fluid using a dosing module into a spray region of the turbine outlet passage through which the turbine body flow travels; receiving a portion of the turbine main flow from the turbine at a first location upstream of the turbine outlet passage into an auxiliary passage, the portion of the turbine main flow received by the auxiliary passage defining an auxiliary flow; delivering the auxiliary flow to a second location of the turbine downstream of the turbine wheel chamber; allowing the auxiliary flow to flow from the first position of the turbine to the second position of the turbine under all operating conditions of the turbine; as well as The secondary flow is directed into the spray region of the turbine outlet passage.

101. The method according to claim 100, wherein: The dosing module comprises a nozzle, and the auxiliary channel is configured to direct the auxiliary flow through the nozzle in a direction substantially normal to the spraying direction.

102. The method of claim 100, wherein: The dosing module is configured to deliver the post-treatment fluid in a spray direction, and the auxiliary channel is configured to guide the auxiliary flow into the spray region in an auxiliary flow direction opposite to the spray direction.

103. The method of claim 102, wherein: The auxiliary flow is oriented in an upstream direction relative to the main turbine flow, and wherein the auxiliary flow direction is angularly inclined at an angle between about 50° and about 90° relative to an opposite direction of the spray direction.

104. The method of claim 102, wherein: The auxiliary flow is directed in a downstream direction relative to the main turbine flow, and wherein the auxiliary flow direction is angularly inclined at an angle between about 30° and about 90° relative to an opposite direction of the spray direction.

105. The method of claim 101, wherein: The auxiliary passage is configured to direct the auxiliary flow into the turbine outlet passage in an auxiliary flow direction facing downstream relative to the turbine main body flow, and The auxiliary flow direction is inclined at an angle of at least about 45° relative to a centerline of the turbine outlet passage.

106. The method of claim 101, wherein: The auxiliary passage is configured to direct the auxiliary flow into the turbine outlet passage in an auxiliary flow direction facing upstream relative to the turbine main body flow, and The auxiliary flow direction is inclined at an angle of at least about 45° relative to a centerline of the turbine outlet passage.

107. The method according to any one of claims 101 to 105, wherein: The auxiliary passage includes a valve configured to control flow through the auxiliary passage, and Therein, the valve is configured such that the auxiliary flow is allowed to pass through the valve during all operating conditions of the turbine.

108. The method of claim 107, wherein: The valve is configured such that the auxiliary flow through the valve always accounts for at least about 0.1% of the mass flow of exhaust gas delivered from the engine to the turbine inlet passage.

109. The method according to claim 107 or 108, wherein: The dosing module is configured to deliver aftertreatment fluid to the turbine outlet passage via the auxiliary passage.

110. A turbine for a turbocharger, comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine body flow; a turbine wheel chamber configured to receive the turbine body flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation; a turbine outlet passage configured to receive the turbine body flow from the turbine wheel chamber, the turbine outlet passage being at least partially defined by a turbine outlet passage surface, and the turbine outlet passage defining a centerline; a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; and An auxiliary channel, the auxiliary channel comprising: - an auxiliary passage inlet configured to receive a portion of the turbine main body flow from the turbine outlet passage, the portion of the turbine main body flow received by the auxiliary passage defining an auxiliary flow; and an auxiliary channel outlet configured to convey the auxiliary flow from the auxiliary channel to the turbine outlet channel, Wherein, the auxiliary passage outlet is configured to direct the auxiliary flow along the turbine outlet passage surface in an auxiliary flow layer.

111. The turbine according to claim 110, wherein: The dosing module includes a nozzle in fluid communication with the turbine outlet passage, the nozzle being configured to produce a spray of aftertreatment fluid; and wherein the nozzle is positioned on a side of the turbine outlet passage opposite the auxiliary flow layer such that, during use, the auxiliary flow layer inhibits aftertreatment fluid from reaching a portion of the turbine outlet passage surface opposite the nozzle.

112. A turbine according to any one of claims 110 or 111, wherein The turbine wheel imparts a swirl momentum to the turbine body flow, the swirl momentum of the turbine body flow defining a positive angular direction, and wherein the auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage in a direction that induces a swirl of the auxiliary flow layer about the centerline along the positive angular direction.

113. A turbine according to any one of claims 110 to 112, wherein: The auxiliary passage is at least partially defined by an auxiliary passage surface, wherein the auxiliary passage surface and the turbine outlet passage surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the turbine outlet channel surface.

114. A turbine according to any one of claims 110 to 113, wherein: The turbomachine further includes a sensor arrangement including a sensor passage having a sensor passage inlet and a sensor passage outlet; wherein the sensor passage inlet is configured to receive a portion of the turbine body flow from the turbine outlet passage to define a sensor flow, and the sensor passage outlet is configured to deliver the sensor flow to the turbine outlet passage; and The auxiliary passage is configured to guide the auxiliary flow into the turbine outlet passage so that the auxiliary flow layer passes downstream of the sensor passage outlet.

115. A turbine according to any one of claims 110 to 115, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that the thickness of the auxiliary flow layer is between at least about 5% and at most about 25% of a distance defined between the turbine outlet channel surface and the centerline.

116. A turbine according to any one of claims 110 to 115, wherein The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that a width of the auxiliary flow layer is between about 50% and about 100% of a diameter of the turbine outlet channel defined by the turbine outlet channel surface.

117. A turbine according to any one of claims 110 to 116, wherein The secondary channel outlet defines a width and a depth, and wherein the depth is about 15% to about 50% of the width, and preferably about 25% of the width.

118. A turbine according to any one of claims 110 to 117, wherein: The auxiliary passage includes a wastegate valve configured to selectively allow or prevent the auxiliary flow from traveling through the auxiliary passage; The wastegate valve includes a valve opening defining a valve flow area; The auxiliary passage outlet defines an auxiliary flow area in a plane normal to the direction of the auxiliary flow; and The auxiliary flow area is approximately 1.2 times the valve flow area.

119. A turbine according to any one of claims 110 to 118, wherein The secondary passage is configured to direct the secondary flow layer in a generally axial direction downstream relative to the centerline.

120. A method of operating a turbine for a turbocharger, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet passage, the exhaust gas received by the turbine inlet passage defining a turbine body flow; receiving the turbine body flow from the turbine inlet passage into a turbine wheel chamber configured to house a turbine wheel supported for rotation; receiving the turbine body flow from the turbine wheel chamber into a turbine outlet passage, the turbine outlet passage being at least partially defined by a turbine outlet passage surface, the turbine outlet passage defining a centerline; receiving a portion of the turbine main flow from the turbine outlet passage into an auxiliary passage through an auxiliary passage inlet, the portion of the turbine main flow received by the auxiliary passage defining an auxiliary flow; delivering the auxiliary flow to a second location of the turbine downstream of the turbine wheel chamber; allowing the auxiliary flow to flow from a first position of the turbine to the second position of the turbine under all operating conditions of the turbine; as well as The secondary flow is directed along the turbine outlet passage surface in a secondary flow layer through the secondary passage outlet.

121. The method of claim 120, wherein: The dosing module includes a nozzle in fluid communication with the turbine outlet passage, the nozzle being configured to produce a spray of aftertreatment fluid; and wherein the nozzle is positioned on a side of the turbine outlet passage opposite the auxiliary flow layer such that, during use, the auxiliary flow layer inhibits aftertreatment fluid from reaching a portion of the turbine outlet passage surface opposite the nozzle.

122. The method of any one of claims 120 or 121, wherein: The turbine wheel imparts a swirl momentum to the turbine body flow, the swirl momentum of the turbine body flow defining a positive angular direction, and wherein the auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage in a direction that induces a swirl of the auxiliary flow layer about the centerline along the positive angular direction.

123. The method according to any one of claims 120 to 122, wherein: The auxiliary passage is at least partially defined by an auxiliary passage surface, wherein the auxiliary passage surface and the turbine outlet passage surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the turbine outlet channel surface.

124. The method of any one of claims 120 to 123, wherein: The turbomachine further includes a sensor arrangement including a sensor passage having a sensor passage inlet and a sensor passage outlet; wherein the sensor passage inlet is configured to receive a portion of the turbine body flow from the turbine outlet passage to define a sensor flow, and the sensor passage outlet is configured to deliver the sensor flow to the turbine outlet passage; and The auxiliary passage is configured to guide the auxiliary flow into the turbine outlet passage so that the auxiliary flow layer passes downstream of the sensor passage outlet.

125. The method of any one of claims 120 to 124, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that the thickness of the auxiliary flow layer is between at least about 5% and at most about 25% of a distance defined between the turbine outlet channel surface and the centerline.

126. The method of any one of claims 120 to 125, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that a width of the auxiliary flow layer is between about 50% and about 100% of a diameter of the turbine outlet channel defined by the turbine outlet channel surface.

127. The method of any one of claims 120 to 126, wherein: The secondary channel outlet defines a width and a depth, and wherein the depth is about 15% to about 50% of the width, and preferably about 25% of the width.

128. The method of any one of claims 120 to 127, wherein: The auxiliary passage includes a wastegate valve configured to selectively allow or prevent the auxiliary flow from traveling through the auxiliary passage; The wastegate valve includes a valve opening defining a valve flow area; The auxiliary passage outlet defines an auxiliary flow area in a plane normal to the direction of the auxiliary flow; and The auxiliary flow area is approximately 1.2 times the valve flow area.

129. The method of any one of claims 120 to 128, wherein: The secondary passage is configured to direct the secondary flow layer in a generally axial direction downstream relative to the centerline.

130. A turbine for a turbocharger, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine body flow; a turbine wheel chamber configured to receive the turbine body flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the turbine body flow from the turbine wheel chamber, the turbine outlet passage being at least partially defined by a turbine outlet passage surface, and the turbine outlet passage defining a centerline; a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; and an auxiliary passage configured to receive a portion of the main turbine flow from a first location of the turbine upstream of the turbine outlet passage, the portion of the main turbine flow received by the auxiliary passage defining an auxiliary flow, the auxiliary passage further configured to deliver the auxiliary flow to the main turbine flow at a second location of the turbine downstream of the turbine wheel chamber; wherein the turbine is configured such that the auxiliary flow is always allowed to flow from the first position of the turbine to the second position of the turbine, and Wherein, in the second position, the auxiliary passage is configured to direct the auxiliary flow along the turbine outlet passage surface in an auxiliary flow layer.

131. The turbine according to claim 130, wherein: The dosing module includes a nozzle in fluid communication with the turbine outlet passage, the nozzle being configured to produce a spray of aftertreatment fluid; and wherein the nozzle is positioned on a side of the turbine outlet passage opposite the auxiliary flow layer such that, during use, the auxiliary flow layer inhibits aftertreatment fluid from reaching a portion of the turbine outlet passage surface opposite the nozzle.

132. A turbine according to any one of claims 130 or 131, wherein The turbine wheel imparts a swirl momentum to the turbine body flow, the swirl momentum of the turbine body flow defining a positive angular direction, and wherein the auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage in a direction that induces a swirl of the auxiliary flow layer about the centerline along the positive angular direction.

133. A turbine according to any one of claims 130 to 132, wherein: The auxiliary passage is at least partially defined by an auxiliary passage surface, wherein the auxiliary passage surface and the turbine outlet passage surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the turbine outlet channel surface.

134. A turbine according to any one of claims 130 to 133, wherein: The turbomachine further includes a sensor arrangement including a sensor passage having a sensor passage inlet and a sensor passage outlet; wherein the sensor passage inlet is configured to receive a portion of the turbine body flow from the turbine outlet passage to define a sensor flow, and the sensor passage outlet is configured to deliver the sensor flow to the turbine outlet passage; and The auxiliary passage is configured to guide the auxiliary flow into the turbine outlet passage so that the auxiliary flow layer passes downstream of the sensor passage outlet.

135. A turbine according to any one of claims 130 to 134, wherein The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that the thickness of the auxiliary flow layer is between at least about 5% and at most about 25% of a distance defined between the turbine outlet channel surface and the centerline.

136. A turbine according to any one of claims 130 to 135, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that a width of the auxiliary flow layer is between about 50% and about 100% of a diameter of the turbine outlet channel defined by the turbine outlet channel surface.

137. A turbine according to any one of claims 130 to 136, wherein: The secondary channel outlet defines a width and a depth, and wherein the depth is about 15% to about 50% of the width, and preferably about 25% of the width.

138. A turbine according to any one of claims 130 to 137, wherein: The auxiliary passage includes a wastegate valve configured to selectively allow or prevent the auxiliary flow from traveling through the auxiliary passage; The wastegate valve includes a valve opening defining a valve flow area; The auxiliary passage outlet defines an auxiliary flow area in a plane normal to the direction of the auxiliary flow; and The auxiliary flow area is approximately 1.2 times the valve flow area.

139. A turbine according to any one of claims 130 to 138, wherein The secondary passage is configured to direct the secondary flow layer in a generally axial direction downstream relative to the centerline.

140. A method of operating a turbine for a turbocharger, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet passage, the exhaust gas received by the turbine inlet passage defining a turbine body flow; receiving the turbine body flow from the turbine inlet passage into a turbine wheel chamber configured to house a turbine wheel supported for rotation; receiving the turbine body flow from the turbine wheel chamber into a turbine outlet passage, the turbine outlet passage being at least partially defined by a turbine outlet passage surface, the turbine outlet passage defining a centerline; receiving a portion of the turbine main flow from a first location of the turbine upstream of the turbine outlet passage into an auxiliary passage, the portion of the turbine main flow received by the auxiliary passage defining an auxiliary flow; delivering a spray of aftertreatment fluid into the turbine outlet passage using a dosing module; delivering to the turbine body flow at a second location of the turbine downstream of the turbine wheel chamber; as well as The secondary flow is directed along the turbine outlet passage surface in a secondary flow layer.

141. The method of claim 140, wherein: The dosing module includes a nozzle in fluid communication with the turbine outlet passage, the nozzle being configured to produce a spray of aftertreatment fluid; and wherein the nozzle is positioned on a side of the turbine outlet passage opposite the auxiliary flow layer such that, during use, the auxiliary flow layer inhibits aftertreatment fluid from reaching a portion of the turbine outlet passage surface opposite the nozzle.

142. The method of any one of claims 140 or 141, wherein: The turbine wheel imparts a swirl momentum to the turbine body flow, the swirl momentum of the turbine body flow defining a positive angular direction, and wherein the auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage in a direction that induces a swirl of the auxiliary flow layer about the centerline along the positive angular direction.

143. The method of any one of claims 140 to 142, wherein: The auxiliary passage is at least partially defined by an auxiliary passage surface, wherein the auxiliary passage surface and the turbine outlet passage surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the turbine outlet channel surface.

144. The method of any one of claims 140 to 143, wherein: The turbomachine further includes a sensor arrangement including a sensor passage having a sensor passage inlet and a sensor passage outlet; wherein the sensor passage inlet is configured to receive a portion of the turbine body flow from the turbine outlet passage to define a sensor flow, and the sensor passage outlet is configured to deliver the sensor flow to the turbine outlet passage; and The auxiliary passage is configured to guide the auxiliary flow into the turbine outlet passage so that the auxiliary flow layer passes downstream of the sensor passage outlet.

145. The method of any one of claims 140 to 144, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that the thickness of the auxiliary flow layer is between at least about 5% and at most about 25% of a distance defined between the turbine outlet channel surface and the centerline.

146. The method of any one of claims 140 to 145, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the turbine outlet channel such that a width of the auxiliary flow layer is between about 50% and about 100% of a diameter of the turbine outlet channel defined by the turbine outlet channel surface.

147. The method of any one of claims 140 to 146, wherein: The secondary channel outlet defines a width and a depth, and wherein the depth is about 15% to about 50% of the width, and preferably about 25% of the width.

148. The method of any one of claims 140 to 147, wherein: The auxiliary passage includes a wastegate valve configured to selectively allow or prevent the auxiliary flow from traveling through the auxiliary passage; The wastegate valve includes a valve opening defining a valve flow area; The auxiliary passage outlet defines an auxiliary flow area in a plane normal to the direction of the auxiliary flow; and The auxiliary flow area is approximately 1.2 times the valve flow area.

149. The method of any one of claims 140 to 148, wherein: The secondary passage is configured to direct the secondary flow layer in a generally axial direction downstream relative to the centerline.

150. An aftertreatment system for an internal combustion engine system, comprising: a decomposition chamber configured to receive a bulk flow from the internal combustion engine, the decomposition chamber being at least partially defined by a decomposition chamber surface, and the decomposition chamber defining a centerline; a dispensing module configured to deliver a spray of post-treatment fluid into the decomposition chamber; a turbine, the turbine comprising a turbine inlet passage, a turbine wheel chamber, and a turbine outlet passage; and An auxiliary channel, the auxiliary channel comprising: - an auxiliary passage inlet configured to receive a portion of the main flow from the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; and - an auxiliary channel outlet configured to convey the auxiliary flow from the auxiliary channel to the decomposition chamber; Wherein, the auxiliary channel outlet is configured to guide the auxiliary flow along the decomposition chamber surface in an auxiliary flow layer.

151. The aftertreatment system of claim 150, wherein: The dispensing module includes a nozzle in fluid communication with the decomposition chamber, the nozzle being configured to produce the spray of post-treatment fluid; and Wherein, the nozzle is positioned on a side of the decomposition chamber opposite to the auxiliary flow layer, so that during use, the auxiliary flow layer inhibits post-treatment fluid from reaching a portion of the decomposition chamber surface opposite to the nozzle.

152. The aftertreatment system of any one of claims 150 to 151, wherein: The secondary passage is configured to direct the secondary flow layer in a generally axial direction downstream relative to the centerline.

153. The aftertreatment system of any one of claims 150 to 152, wherein: The auxiliary channel is configured to deliver the auxiliary flow to the decomposition chamber in a direction that induces a vortex of the auxiliary flow layer about the centerline.

154. The aftertreatment system of claim 153, wherein: The auxiliary channel is configured to deliver the auxiliary flow to the decomposition chamber in a tangential direction relative to the decomposition chamber surface in a plane normal to the centerline.

155. The aftertreatment system of claim 150, wherein: The internal combustion engine system includes a turbine having a turbine wheel, and the auxiliary passage receives the auxiliary flow from a location upstream of the turbine wheel, wherein the turbine imparts a swirl momentum to the bulk flow, the swirl momentum of the bulk flow defining a positive angular direction, and The auxiliary channel is configured to deliver the auxiliary flow to the decomposition chamber in a direction that induces the auxiliary flow layer to swirl around the center line along the positive angle direction.

156. The aftertreatment system of any one of claims 150 to 155, wherein: The auxiliary channel is at least partially defined by an auxiliary channel surface, wherein the auxiliary channel surface and the decomposition chamber surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the decomposition chamber surface.

157. The aftertreatment system of any one of claims 150 to 156, wherein: The auxiliary channel includes an auxiliary channel outlet, which is configured to deliver the auxiliary flow into the decomposition chamber so that the thickness of the auxiliary flow layer is between at least about 5% and at most about 25% of the distance defined between the decomposition chamber surface and the centerline.

158. The aftertreatment system of any one of claims 150 to 157, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the decomposition chamber such that a width of the auxiliary flow layer is between about 50% and about 100% of a diameter of the turbine outlet channel defined by the decomposition chamber surface.

159. The aftertreatment system of any one of claims 158, wherein: The secondary channel outlet defines a width and a depth, and wherein the depth is about 15% to about 50% of the width, and preferably about 25% of the width.

160. An aftertreatment system for an internal combustion engine system, comprising: a decomposition chamber configured to receive a bulk flow from the internal combustion engine, the decomposition chamber being at least partially defined by a decomposition chamber surface, and the decomposition chamber defining a centerline; a dispensing module configured to deliver a spray of post-treatment fluid into the decomposition chamber; a turbine, the turbine comprising a turbine inlet passage, a turbine wheel chamber, and a turbine outlet passage; and an auxiliary passage configured to receive a portion of the main flow from a first location upstream of the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow, the auxiliary passage further configured to deliver the auxiliary flow to the main flow at a second location downstream of the turbine wheel chamber; wherein the aftertreatment system is configured such that the auxiliary flow is always allowed to flow from the first position to the second position; and Wherein, the auxiliary channel is configured to guide the auxiliary flow along the decomposition chamber surface in an auxiliary flow layer.

161. The aftertreatment system of claim 160, wherein: The dispensing module includes a nozzle in fluid communication with the decomposition chamber, the nozzle being configured to produce the spray of post-treatment fluid; and Wherein, the nozzle is positioned on a side of the decomposition chamber opposite to the auxiliary flow layer, so that during use, the auxiliary flow layer inhibits post-treatment fluid from reaching a portion of the decomposition chamber surface opposite to the nozzle.

162. The aftertreatment system of any one of claims 160 to 161, wherein: The secondary passage is configured to direct the secondary flow layer in a generally axial direction downstream relative to the centerline.

163. The aftertreatment system of any one of claims 160 to 162, wherein: The auxiliary channel is configured to deliver the auxiliary flow to the decomposition chamber in a direction that induces a vortex of the auxiliary flow layer about the centerline.

164. The aftertreatment system of claim 163, wherein: The auxiliary channel is configured to deliver the auxiliary flow to the decomposition chamber in a tangential direction relative to the decomposition chamber surface in a plane normal to the centerline.

165. The aftertreatment system of claim 160, wherein: The internal combustion engine system includes a turbine having a turbine wheel, and the auxiliary passage receives the auxiliary flow from a location upstream of the turbine wheel, wherein the turbine imparts a swirl momentum to the bulk flow, the swirl momentum of the bulk flow defining a positive angular direction, and The auxiliary channel is configured to deliver the auxiliary flow to the decomposition chamber in a direction that induces the auxiliary flow layer to swirl around the center line along the positive angle direction.

166. The aftertreatment system of any one of claims 160 to 165, wherein: The auxiliary channel is at least partially defined by an auxiliary channel surface, wherein the auxiliary channel surface and the decomposition chamber surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the decomposition chamber surface.

167. The aftertreatment system of any one of claims 160 to 166, wherein: The auxiliary channel includes an auxiliary channel outlet, which is configured to deliver the auxiliary flow into the decomposition chamber so that the thickness of the auxiliary flow layer is between at least about 5% and at most about 25% of the distance defined between the decomposition chamber surface and the centerline.

168. The aftertreatment system of any one of claims 160 to 167, wherein: The auxiliary channel includes an auxiliary channel outlet configured to deliver the auxiliary flow into the decomposition chamber such that a width of the auxiliary flow layer is between about 50% and about 100% of a diameter of the turbine outlet channel defined by the decomposition chamber surface.

169. The aftertreatment system of any one of claims 160 to 168, wherein: The secondary channel outlet defines a width and a depth, and wherein the depth is about 15% to about 50% of the width, and preferably about 25% of the width.

170. A turbine for a turbocharger, comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine body flow; a turbine wheel chamber configured to receive the turbine body flow from the turbine inlet passage, the turbine wheel chamber housing a turbine wheel supported for rotation; a turbine outlet passage configured to receive the turbine body flow from the turbine wheel chamber, the turbine outlet passage defining a centerline; and An auxiliary channel, the auxiliary channel comprising: - an auxiliary passage inlet configured to receive a portion of the turbine main body flow, the portion of the turbine main body flow received by the auxiliary passage defining an auxiliary flow; and - an auxiliary channel outlet configured to convey the auxiliary flow from the auxiliary channel to the turbine outlet channel; wherein the turbine wheel is configured to discharge the turbine body flow into the turbine outlet passage so that the turbine body flow swirls about the centerline in a positive angular direction; and The auxiliary passage is configured to guide the auxiliary flow into the turbine outlet passage at a negative angle direction opposite to the positive angle direction.

171. The turbine of claim 170, further comprising a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage.

172. A turbine according to claim 170 or 171, wherein The auxiliary flow collides with the turbine main flow within the turbine outlet passage to produce a turbulent region, and wherein the dosing module includes a nozzle configured to produce the spray of after-treatment fluid, wherein the nozzle is oriented to direct the after-treatment fluid into the turbulent region.

173. A turbine according to any one of claims 170 to 172, wherein: The swirl momentum imparted to the turbine body flow by the turbine impeller defines a first swirl angle, and wherein the auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage at a second swirl angle that is equal to or steeper in magnitude than the first swirl angle.

174. The turbine according to claim 173, wherein: The auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage in a direction between 0° and about 60° relative to a direction normal to the centerline.

175. A turbine according to any one of claims 170 to 174, wherein The auxiliary passage is at least partially defined by an auxiliary passage surface, wherein the auxiliary passage surface and the turbine outlet passage surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the turbine outlet channel surface.

176. A turbine according to any one of claims 170 to 175, wherein The auxiliary channel is configured such that an auxiliary flow is always allowed to pass through the auxiliary channel.

177. The turbine according to claim 176, wherein The auxiliary passage is sized such that, during use, the flow rate of the auxiliary flow is between about 0.1% and about 2% of the flow rate of the main turbine flow received by the turbine inlet passage.

178. A turbine according to any one of claims 170 to 177, wherein The turbine outlet passage defines a diffuser portion.

179. The turbine according to claim 178, wherein: The secondary passage outlet is defined by a surface of the diffuser portion.

180. A method of operating a turbine for a turbocharger, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet passage, the exhaust gas received by the turbine inlet passage defining a turbine body flow; receiving the turbine body flow from the turbine inlet passage into a turbine wheel chamber, the turbine wheel chamber housing a turbine wheel, the turbine wheel supported for rotation; receiving the turbine body flow from the turbine wheel chamber into a turbine outlet passage, the turbine outlet passage defining a centerline; receiving a portion of the turbine main flow from the turbine outlet passage into an auxiliary passage through an auxiliary passage inlet, the portion of the turbine main flow received by the auxiliary passage defining an auxiliary flow; discharging the turbine body flow through an auxiliary passage outlet into the turbine outlet passage using the turbine impeller so that the turbine body flow swirls about the centerline in a positive angular direction; as well as The secondary flow is directed into the turbine outlet passage at a negative angular direction opposite to the positive angular direction.

181. The method of claim 180, further comprising a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage.

182. The method of claim 180 or 181, wherein: The auxiliary flow collides with the turbine main flow within the turbine outlet passage to produce a turbulent region, and wherein the dosing module includes a nozzle configured to produce the spray of after-treatment fluid, wherein the nozzle is oriented to direct the after-treatment fluid into the turbulent region.

183. The method of any one of claims 180 to 182, wherein: The swirl momentum imparted to the turbine body flow by the turbine impeller defines a first swirl angle, and wherein the auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage at a second swirl angle that is equal to or steeper in magnitude than the first swirl angle.

184. The method of claim 183, wherein: The auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage in a direction between 0° and about 60° relative to a direction normal to the centerline.

185. The method of any one of claims 180 to 184, wherein: The auxiliary passage is at least partially defined by an auxiliary passage surface, wherein the auxiliary passage surface and the turbine outlet passage surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the turbine outlet channel surface.

186. The method of any one of claims 180 to 185, wherein: The auxiliary channel is configured such that an auxiliary flow is always allowed to pass through the auxiliary channel.

187. The method of claim 186, wherein: The auxiliary passage is sized such that, during use, the flow rate of the auxiliary flow is between about 0.1% and about 2% of the flow rate of the main turbine flow received by the turbine inlet passage.

188. The method of any one of claims 180 to 187, wherein: The turbine outlet passage defines a diffuser portion.

189. The method of claim 118, wherein: The secondary passage outlet is defined by a surface of the diffuser portion.

190. A turbine for a turbocharger, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine body flow; a turbine wheel chamber configured to receive the turbine body flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation; a turbine outlet passage configured to receive the turbine body flow from the turbine wheel chamber, the turbine outlet passage defining a centerline; and an auxiliary passage configured to receive a portion of the main turbine flow from a first location of the turbine upstream of the turbine outlet passage, the portion of the main turbine flow received by the auxiliary passage defining an auxiliary flow, the auxiliary passage further configured to deliver the auxiliary flow to the main turbine flow at a second location of the turbine downstream of the turbine wheel chamber; wherein the turbine is configured such that the auxiliary flow is always allowed to flow from the first position of the turbine to the second position of the turbine; wherein the turbine wheel is configured to discharge the turbine body flow into the turbine outlet passage so that the turbine body flow swirls about the centerline in a positive angular direction; and Wherein, at the second position, the auxiliary passage is configured to direct the auxiliary flow into the turbine outlet passage at a negative angle direction opposite to the positive angle direction.

191. The turbine of claim 190, further comprising a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage.

192. A turbine according to claim 190 or 191, wherein The auxiliary flow collides with the turbine main flow within the turbine outlet passage to produce a turbulent region, and wherein the dosing module includes a nozzle configured to produce the spray of after-treatment fluid, wherein the nozzle is oriented to direct the after-treatment fluid into the turbulent region.

193. A turbine according to any one of claims 190 to 192, wherein: The swirl momentum imparted to the turbine body flow by the turbine impeller defines a first swirl angle, and wherein the auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage at a second swirl angle that is equal to or steeper in magnitude than the first swirl angle.

194. The turbine according to claim 193, wherein: The auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage in a direction between 0° and about 60° relative to a direction normal to the centerline.

195. A turbine according to any one of claims 190 to 194, wherein The auxiliary passage is at least partially defined by an auxiliary passage surface, wherein the auxiliary passage surface and the turbine outlet passage surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the turbine outlet channel surface.

196. The turbine according to claim 190, wherein: The auxiliary passage includes a valve configured to control a flow rate of an auxiliary stream through the auxiliary passage.

197. The turbine according to claim 196, wherein: The auxiliary passage is sized such that when the valve is open, a flow rate of auxiliary flow through the auxiliary passage is between at least about 25% and about 50% of a flow rate of main turbine flow received by the turbine inlet passage.

198. The turbine according to claim 196, wherein: The auxiliary passage is sized such that, during use, the flow rate of the auxiliary flow is between about 0.1% and about 2% of the flow rate of the main turbine flow received by the turbine inlet passage.

199. A turbine according to any one of claims 190 to 197, wherein The turbine outlet passage defines a diffuser portion.

200. A method of operating a turbine for a turbocharger, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet passage, the exhaust gas received by the turbine inlet passage defining a turbine body flow; receiving the turbine body flow from the turbine inlet passage into a turbine wheel chamber, the turbine wheel chamber housing a turbine wheel, the turbine wheel supported for rotation; receiving the turbine body flow from the turbine wheel chamber into a turbine outlet passage, the turbine outlet passage defining a centerline; receiving a portion of the turbine main flow into an auxiliary passage at a first location of the turbine upstream of the turbine outlet passage, the portion of the turbine main flow received by the auxiliary passage defining an auxiliary flow; discharging the turbine body flow into the turbine outlet passage using the turbine wheel so that the turbine body flow swirls about the centerline in a positive angular direction; delivering the auxiliary flow to the main turbine flow at a second location of the turbine downstream of the turbine wheel chamber; as well as The secondary flow is directed into the turbine outlet passage at a negative angular direction opposite to the positive angular direction.

201. The turbine of claim 200, further comprising a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage.

202. A turbine according to claim 200 or 201, wherein: The auxiliary flow collides with the turbine main flow within the turbine outlet passage to produce a turbulent region, and wherein the dosing module includes a nozzle configured to produce the spray of after-treatment fluid, wherein the nozzle is oriented to direct the after-treatment fluid into the turbulent region.

203. A turbine according to any one of claims 200 to 202, wherein The swirl momentum imparted to the turbine body flow by the turbine impeller defines a first swirl angle, and wherein the auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage at a second swirl angle that is equal to or steeper in magnitude than the first swirl angle.

204. The turbine according to claim 203, wherein: The auxiliary passage is configured to deliver the auxiliary flow to the turbine outlet passage in a direction between 0° and about 60° relative to a direction normal to the centerline.

205. A turbine according to any one of claims 200 to 204, wherein The auxiliary passage is at least partially defined by an auxiliary passage surface, wherein the auxiliary passage surface and the turbine outlet passage surface define an interface therebetween, and Wherein, at the interface, the auxiliary channel surface is substantially tangent to the turbine outlet channel surface.

206. The turbine according to claim 200, wherein: The auxiliary passage includes a valve configured to control a flow rate of an auxiliary stream through the auxiliary passage.

207. The turbine according to claim 206, wherein: The auxiliary passage is sized such that when the valve is open, a flow rate of auxiliary flow through the auxiliary passage is between at least about 25% and about 50% of a flow rate of main turbine flow received by the turbine inlet passage.

208. The turbine according to claim 206, wherein: The auxiliary passage is sized such that, during use, the flow rate of the auxiliary flow is between about 0.1% and about 2% of the flow rate of the main turbine flow received by the turbine inlet passage.

209. A turbine according to any one of claims 200 to 207, wherein The turbine outlet passage defines a diffuser portion.

210. A turbine for a turbocharger, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine body flow; a turbine wheel chamber configured to receive the turbine body flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the turbine body flow from the turbine wheel chamber, the turbine outlet passage extending along a centerline, and the turbine outlet passage being at least partially defined by a first surface of a dividing wall; a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; and An auxiliary channel, the auxiliary channel comprising: an auxiliary passage inlet configured to receive a portion of the turbine main flow from the turbine outlet passage, the portion of the turbine main flow received by the auxiliary passage defining an auxiliary flow, the auxiliary passage being at least partially defined by the second surface of the dividing wall; and - an auxiliary channel outlet configured to convey the auxiliary flow from the auxiliary channel to the turbine outlet channel; Wherein the partition wall is configured to provide thermal communication from the auxiliary channel to the first surface via the second surface.

211. The turbine according to claim 210, wherein: The turbine includes a turbine wheel having an inducer defining an inducer diameter, and The dosing module includes a nozzle configured to inject the spray of aftertreatment fluid into the turbine outlet passage, and Wherein the nozzle of the dosing module is spaced apart from the outlet inducer of the turbine impeller along the centerline of the turbine outlet passage by a distance of at most about 10 times the outlet inducer diameter.

212. A turbine according to any one of claims 210 to 211, wherein The distribution module is configured to deliver an atomized spray of after-treatment fluid into the turbine outlet passage in a direction facing the first surface.

213. A turbine according to any one of claims 210 to 212, wherein The auxiliary passage defines an auxiliary passage outlet configured to deliver the auxiliary flow into the turbine outlet passage, and wherein the auxiliary passage outlet is located at least about 0.5 outlet inducer diameters downstream of the nozzle along the centerline.

214. A turbine according to any one of claims 210 to 213, wherein The turbine outlet passage includes a diffuser portion that is at least partially defined by the dividing wall.

215. The turbine according to claim 214, wherein: The distribution module is configured to deliver an aftertreatment fluid into the diffuser portion.

216. A turbine according to any one of claims 210 to 215, wherein The turbine outlet passage comprises a curved portion defining a top end, and wherein the dosing module comprises a nozzle configured to deliver aftertreatment fluid into the turbine outlet passage, the nozzle being positioned at the top end of the curved portion or upstream of the top end of the curved portion.

217. A turbine according to any one of claims 210 to 216, wherein The first surface defines a surface of the curved portion, and the nozzle faces the first surface.

218. The turbine of any one of claims 210 to 217, further comprising a turbine housing assembly, the turbine housing assembly comprising: a turbine housing defining the turbine inlet passage, the turbine wheel chamber, and at least a portion of the turbine outlet passage; and a connection adapter defining at least a portion of the turbine outlet passage and at least a portion of the auxiliary passage, the connection adapter coupled to the turbine housing at a first interface; wherein the connection adapter is configured to support the partition wall to extend along the centerline; and Wherein, the partition wall extends axially along the center line through the first interface.

219. A turbine according to claim 218, wherein: The turbine housing assembly also includes a downtube adapter configured to be connected to the downtube, wherein the down tube adapter defines at least a portion of the auxiliary passage and / or the turbine outlet passage, and the down tube adapter is coupled to the connection adapter at a second interface; and Wherein, the partition wall extends axially along the center line through the second interface.

220. A method of operating a turbine for a turbocharger, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet passage, the exhaust gas received by the turbine inlet passage defining a turbine body flow; receiving the turbine body flow from the turbine inlet passage into a turbine wheel chamber configured to house a turbine wheel supported for rotation; receiving the turbine body flow from the turbine wheel chamber into a turbine outlet passage, the turbine outlet passage extending along a centerline and the turbine outlet passage being at least partially defined by a first surface of a dividing wall; delivering an atomized spray of aftertreatment fluid into the turbine outlet passage using a dosing module including a nozzle; receiving a portion of the turbine main body flow from the turbine outlet passage into an auxiliary passage through an auxiliary passage inlet, the portion of the turbine main body flow received by the auxiliary passage defining an auxiliary flow, the auxiliary passage being at least partially defined by a second surface of the dividing wall; as well as directing the auxiliary flow into the turbine outlet passage through an auxiliary passage outlet; Wherein the partition wall is configured to provide thermal communication from the auxiliary channel to the first surface via the second surface.

221. The method of claim 220, wherein: The turbine includes a turbine wheel having an inducer defining an inducer diameter, and The dosing module includes a nozzle configured to inject the spray of aftertreatment fluid into the turbine outlet passage, and Wherein the nozzle of the dosing module is spaced apart from the outlet inducer of the turbine impeller along the centerline of the turbine outlet passage by a distance of at most about 10 times the outlet inducer diameter.

222. The method according to any one of claims 220 to 221, wherein: The dosing module is configured to deliver the atomized spray of after-treatment fluid into the turbine outlet passage in a direction facing the first surface.

223. The method according to any one of claims 220 to 222, wherein: The auxiliary passage defines an auxiliary passage outlet configured to deliver the auxiliary flow into the turbine outlet passage, and wherein the auxiliary passage outlet is located at least about 0.5 outlet inducer diameters downstream of the nozzle along the centerline.

224. The method according to any one of claims 220 to 223, wherein: The turbine outlet passage includes a diffuser portion that is at least partially defined by the dividing wall.

225. The method of claim 224, wherein: The distribution module is configured to deliver an aftertreatment fluid into the diffuser portion.

226. The method of any one of claims 220 to 225, wherein: The turbine outlet passage comprises a curved portion defining a top end, and wherein the dosing module comprises a nozzle configured to deliver aftertreatment fluid into the turbine outlet passage, the nozzle being positioned at the top end of the curved portion or upstream of the top end of the curved portion.

227. The method of any one of claims 220 to 226, wherein: The first surface defines a surface of the curved portion, and the nozzle faces the first surface.

228. The method of any one of claims 220 to 227, further comprising a turbine housing assembly, the turbine housing assembly comprising: a turbine housing defining the turbine inlet passage, the turbine wheel chamber, and at least a portion of the turbine outlet passage; and a connection adapter defining at least a portion of the turbine outlet passage and at least a portion of the auxiliary passage, the connection adapter coupled to the turbine housing at a first interface; wherein the connection adapter is configured to support the partition wall to extend along the centerline; and Wherein, the partition wall extends axially along the center line through the first interface.

229. The method of claim 228, wherein: The turbine housing assembly also includes a downtube adapter configured to be connected to the downtube, wherein the down tube adapter defines at least a portion of the auxiliary passage and / or the turbine outlet passage, and the down tube adapter is coupled to the connection adapter at a second interface; and Wherein, the partition wall extends axially along the center line through the second interface.

230. A turbine for a turbocharger, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a turbine body flow; a turbine wheel chamber configured to receive the turbine body flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the turbine body flow from the turbine wheel chamber, the turbine outlet passage extending along a centerline, and the turbine outlet passage being at least partially defined by a first surface of a dividing wall; a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; and an auxiliary passage configured to receive a portion of the main turbine flow from a first location of the turbine upstream of the turbine outlet passage, the portion of the main turbine flow received by the auxiliary passage defining an auxiliary flow, the auxiliary passage being at least partially defined by a second surface of the dividing wall, and the auxiliary passage being further configured to deliver the auxiliary flow to the main turbine flow at a second location of the turbine downstream of the turbine wheel chamber; wherein the turbine is configured such that the auxiliary flow is always allowed to flow from the first position of the turbine to the second position of the turbine; and Wherein the partition wall is configured to provide thermal communication from the auxiliary channel to the first surface via the second surface.

231. The turbine according to claim 230, wherein: The auxiliary passage includes a valve device configured to selectively allow, prevent and / or regulate flow of the auxiliary fluid through the auxiliary passage.

232. A turbine according to any one of claims 230 to 231, wherein: The turbine includes a turbine wheel having an inducer defining an inducer diameter, and The dosing module includes a nozzle configured to inject the spray of aftertreatment fluid into the turbine outlet passage, and Wherein the nozzle of the dosing module is spaced apart from the outlet inducer of the turbine impeller along the centerline of the turbine outlet passage by a distance of at most about 10 times the outlet inducer diameter.

233. A turbine according to any one of claims 230 to 232, wherein: The dosing module is configured to deliver the atomized spray of after-treatment fluid into the turbine outlet passage in a direction facing the first surface.

234. A turbine according to any one of claims 230 to 233, wherein The auxiliary passage defines an auxiliary passage outlet configured to deliver the auxiliary flow into the turbine outlet passage, and wherein the auxiliary passage outlet is located at least about 0.5 outlet inducer diameters downstream of the nozzle along the centerline.

235. A turbine according to any one of claims 230 to 234, wherein The turbine outlet passage includes a diffuser portion that is at least partially defined by the dividing wall.

236. The turbine according to claim 235, wherein: The distribution module is configured to deliver an aftertreatment fluid into the diffuser portion.

237. A turbine according to any one of claims 230 to 236, wherein The auxiliary channel includes an auxiliary channel outlet, which is configured to deliver a portion of the auxiliary flow to the turbine outlet channel at a position downstream of the nozzle of the distribution module, and wherein the partition wall includes an auxiliary orifice, which is configured to deliver a portion of the auxiliary flow to the turbine outlet channel at a position aligned with the nozzle or at a position upstream of the nozzle.

238. The turbine of any one of claims 230 to 237, further comprising a turbine housing assembly, the turbine housing assembly comprising: a turbine housing defining the turbine inlet passage, the turbine wheel chamber, and at least a portion of the turbine outlet passage; and a connection adapter defining at least a portion of the turbine outlet passage and at least a portion of the auxiliary passage, the connection adapter coupled to the turbine housing at a first interface; wherein the connection adapter is configured to support the partition wall to extend along the centerline; and Wherein, the partition wall extends axially along the center line through the first interface.

239. A turbine according to claim 238, wherein: The turbine housing assembly also includes a downtube adapter configured to be connected to the downtube, wherein the down tube adapter defines at least a portion of the auxiliary passage and / or the turbine outlet passage, and the down tube adapter is coupled to the connection adapter at a second interface; and Wherein, the partition wall extends axially along the center line through the second interface.

240. A method of operating a turbine for a turbocharger, comprising: receiving exhaust gas from an internal combustion engine into a turbine inlet passage, the exhaust gas received by the turbine inlet passage defining a turbine body flow; receiving the turbine body flow from the turbine inlet passage into a turbine wheel chamber configured to house a turbine wheel supported for rotation; receiving the turbine body flow from the turbine wheel chamber into a turbine outlet passage, the turbine outlet passage extending along a centerline and the turbine outlet passage being at least partially defined by a first surface of a dividing wall; delivering an atomized spray of aftertreatment fluid into the turbine outlet passage using a dosing module including a nozzle; receiving a portion of the turbine main flow from a first location of the turbine upstream of the turbine outlet passage into an auxiliary passage, the portion of the turbine main flow received by the auxiliary passage defining an auxiliary flow, the auxiliary passage being at least partially defined by a second surface of the dividing wall; delivering the auxiliary flow to the main turbine flow at a second location of the turbine downstream of the turbine wheel chamber; Wherein the partition wall is configured to provide thermal communication from the auxiliary channel to the first surface via the second surface.

241. The method of claim 240, wherein: The auxiliary passage includes a valve device configured to selectively allow, prevent and / or regulate flow of the auxiliary fluid through the auxiliary passage.

242. The method of any one of claims 240 to 241, wherein: The turbine includes a turbine wheel having an inducer defining an inducer diameter, and The dosing module includes a nozzle configured to inject the spray of aftertreatment fluid into the turbine outlet passage, and Wherein the nozzle of the dosing module is spaced apart from the outlet inducer of the turbine impeller along the centerline of the turbine outlet passage by a distance of at most about 10 times the outlet inducer diameter.

243. The method of any one of claims 240 to 242, wherein: The dosing module is configured to deliver the atomized spray of after-treatment fluid into the turbine outlet passage in a direction facing the first surface.

244. The method of any one of claims 240 to 243, wherein: The auxiliary passage defines an auxiliary passage outlet configured to deliver the auxiliary flow into the turbine outlet passage, and wherein the auxiliary passage outlet is located at least about 0.5 outlet inducer diameters downstream of the nozzle along the centerline.

245. The method of any one of claims 240 to 244, wherein: The turbine outlet passage includes a diffuser portion that is at least partially defined by the dividing wall.

246. The method of claim 176, wherein: The distribution module is configured to deliver an aftertreatment fluid into the diffuser portion.

247. The method of any one of claims 240 to 246, wherein: The auxiliary channel includes an auxiliary channel outlet, which is configured to deliver a portion of the auxiliary flow to the turbine outlet channel at a position downstream of the nozzle of the distribution module, and wherein the partition wall includes an auxiliary orifice, which is configured to deliver a portion of the auxiliary flow to the turbine outlet channel at a position aligned with the nozzle or at a position upstream of the nozzle.

248. The method of any one of claims 240 to 247, further comprising a turbine housing assembly, the turbine housing assembly comprising: a turbine housing defining the turbine inlet passage, the turbine wheel chamber, and at least a portion of the turbine outlet passage; and a connection adapter defining at least a portion of the turbine outlet passage and at least a portion of the auxiliary passage, the connection adapter coupled to the turbine housing at a first interface; wherein the connection adapter is configured to support the partition wall to extend along the centerline; and Wherein, the partition wall extends axially along the center line through the first interface.

249. The method of claim 278, wherein: The turbine housing assembly also includes a downtube adapter configured to be connected to the downtube, wherein the down tube adapter defines at least a portion of the auxiliary passage and / or the turbine outlet passage, and the down tube adapter is coupled to the connection adapter at a second interface; and Wherein, the partition wall extends axially along the center line through the second interface.

250. An exhaust aftertreatment system comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage; and An auxiliary channel, the auxiliary channel comprising: an auxiliary passage inlet configured to receive a portion of the main flow from the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; and an auxiliary passage outlet configured to deliver the auxiliary flow from the auxiliary passage to the exhaust passage; wherein the exhaust passage includes a predicted aftertreatment fluid concentration region, and Wherein the auxiliary passage is configured to deliver the auxiliary flow to the exhaust passage to the predicted aftertreatment fluid concentration area.

251. The exhaust aftertreatment system of claim 250, wherein: The exhaust passage defines a centerline and includes a non-linear portion that causes a change in the bulk flow volume, The turbine includes a turbine wheel having an inducer defining an inducer diameter; and The auxiliary passage is configured to deliver the auxiliary flow into the predicted aftertreatment fluid concentration area at a location within about 5 outlet inducer diameters from the non-linear portion along the centerline.

252. An exhaust aftertreatment system according to any one of claims 250 to 251, wherein: The exhaust passage includes a curved portion having an inner curved surface and an outer curved surface, the inner curved surface defining an inner curved radius, the outer curved surface defining an outer curved radius, the outer curved radius being greater than the inner curved radius, A portion of the predicted post-treatment fluid concentration area covers at least a portion of the outer curved surface; and The auxiliary channel is configured to deliver the auxiliary flow into the portion of the predicted after-treatment fluid concentration area covering the outer curved surface.

253. An exhaust aftertreatment system according to any one of claims 250 to 252, wherein: The predicted after-treatment fluid concentration region includes a spatial region in which a concentration of the after-treatment fluid is at least about 50% greater than an expected concentration of the after-treatment fluid in the exhaust passage when the after-treatment fluid is uniformly distributed.

254. The exhaust aftertreatment system of claim 253, wherein: The predicted post-treatment fluid concentration region includes a spatial region in which a concentration of post-treatment fluid is at least about 2.25% by volume of the bulk flow. 255.An exhaust aftertreatment system comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage; and An auxiliary channel, the auxiliary channel being configured as follows: receiving a portion of the main flow from a first location of the exhaust aftertreatment system upstream of the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; and delivering the auxiliary flow to the main turbine flow at a second location of the exhaust aftertreatment system downstream of the turbine wheel chamber; wherein the exhaust aftertreatment system is configured such that the auxiliary flow is always allowed to flow from the first position of the exhaust aftertreatment system to the second position of the exhaust aftertreatment system; wherein the exhaust passage includes a predicted aftertreatment fluid concentration region, and Wherein the auxiliary passage is configured to deliver the auxiliary flow to the exhaust passage to the predicted aftertreatment fluid concentration area.

256. The exhaust aftertreatment system of claim 255, wherein: The exhaust passage defines a centerline and includes a non-linear portion that causes a change in the bulk flow volume, The turbine includes a turbine wheel having an inducer defining an inducer diameter; and The auxiliary passage is configured to deliver the auxiliary flow into the predicted aftertreatment fluid concentration area at a location within about 5 outlet inducer diameters from the non-linear portion along the centerline.

257. An exhaust aftertreatment system according to any one of claims 255 to 256, wherein: The exhaust passage includes a curved portion having an inner curved surface and an outer curved surface, the inner curved surface defining an inner curved radius, the outer curved surface defining an outer curved radius, the outer curved radius being greater than the inner curved radius, A portion of the predicted post-treatment fluid concentration area covers at least a portion of the outer curved surface; and The auxiliary channel is configured to deliver the auxiliary flow into the portion of the predicted after-treatment fluid concentration area covering the outer curved surface.

258. An exhaust aftertreatment system according to any one of claims 255 to 257, wherein: The predicted after-treatment fluid concentration region includes a spatial region in which a concentration of the after-treatment fluid is at least about 50% greater than an expected concentration of the after-treatment fluid in the exhaust passage when the after-treatment fluid is uniformly distributed.

259. The exhaust aftertreatment system of claim 258, wherein: The predicted post-treatment fluid concentration region includes a spatial region in which a concentration of post-treatment fluid is at least about 2.25% by volume of the bulk flow. 260.An exhaust aftertreatment system comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis, the turbine having an inducer defining an inducer diameter; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage, the exhaust passage defining a centerline and including a non-linear portion; and An auxiliary channel, the auxiliary channel comprising: an auxiliary passage inlet configured to receive a portion of the main flow from the turbine outlet, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; and an auxiliary passage outlet configured to deliver the auxiliary flow from the auxiliary passage to the exhaust passage; The auxiliary passage is configured to deliver the auxiliary flow into the exhaust passage at a position within about 5 times the outlet guide diameter from the non-linear portion along the center line.

261. The exhaust aftertreatment system of claim 260, wherein: The non-linear portion includes a curved portion.

262. An exhaust aftertreatment system according to claim 260 or 261, wherein: The curved portion includes an inner curved surface and an outer curved surface, the inner curved surface defines an inner curved radius, the outer curved surface defines an outer curved radius, the outer curved radius is greater than the inner curved radius; and The auxiliary passage outlet is defined by an opening formed in the outer curved surface.

263. The exhaust aftertreatment system of claim 262, wherein: The outer curved surface defines a proximal end and a distal end relative to the direction of the bulk flow, and The auxiliary channel outlet is positioned at the distal end of the outer curved surface.

264. An exhaust aftertreatment system according to any one of claims 260 to 263, wherein: The bend defines a centerline having an inlet vector and an outlet vector, and The exit vector is inclined at an angle of at least about 30° relative to the entry vector. 265.An exhaust aftertreatment system comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber housing a turbine wheel supported for rotation about a turbine axis, the turbine having an inducer defining an inducer diameter; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage, the exhaust passage defining a centerline and including a non-linear portion; and An auxiliary channel, the auxiliary channel being configured as follows: receiving a portion of the main flow from a first location of the exhaust aftertreatment system upstream of the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; and delivering the auxiliary flow to the main turbine flow at a second location of the exhaust aftertreatment system downstream of the turbine wheel chamber; wherein the exhaust aftertreatment system is configured such that the auxiliary flow is always allowed to flow from the first position of the exhaust aftertreatment system to the second position of the exhaust aftertreatment system; Wherein, the second position is located within about 5 times the outlet guide diameter of the non-linear portion along the center line.

266. The exhaust aftertreatment system of claim 265, wherein: The non-linear portion includes a curved portion.

267. An exhaust aftertreatment system according to claim 265 or 266, wherein: The curved portion comprises an inner curved surface and an outer curved surface, the inner curved surface defines an inner curved radius, the outer curved surface defines an outer curved radius, and the outer curved radius is greater than the inner curved radius; the auxiliary passage comprising an auxiliary passage outlet configured to deliver the auxiliary flow to the exhaust passage; and The auxiliary passage outlet is defined by an opening formed in the outer curved surface.

268. The exhaust aftertreatment system of claim 267, wherein: The outer curved surface defines a proximal end and a distal end relative to the direction of the bulk flow, and The auxiliary channel outlet is positioned at the distal end of the outer curved surface.

269. An exhaust aftertreatment system according to any one of claims 265 to 268, wherein: The bend defines a centerline having an inlet vector and an outlet vector, and The exit vector is inclined at an angle of at least about 30° relative to the entry vector. 270.An exhaust aftertreatment system comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage; and an auxiliary passage including an auxiliary passage inlet configured to receive a portion of the main flow from the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; wherein the inner surface of the exhaust passage includes a predicted aftertreatment fluid impact risk area, and Wherein, the auxiliary channel is configured to direct the auxiliary flow in an auxiliary flow layer along a portion of the inner surface defining the predicted post-treatment fluid impact risk zone.

271. The exhaust aftertreatment system of claim 270, wherein: The exhaust passage defines a centerline and includes a non-linear portion that causes a change in bulk flow mass, the non-linear portion being defined at least in part by a portion of the interior surface that includes the aftertreatment fluid impingement risk zone.

272. An exhaust aftertreatment system according to claim 270 or 271, wherein: The non-linear portion includes a curved portion of the exhaust passage.

273. The exhaust aftertreatment system of claim 272, wherein: The curved portion includes an inner curved surface and an outer curved surface, the inner curved surface defines an inner curved radius, the outer curved surface defines an outer curved radius, the outer curved radius is greater than the inner curved radius, and The outer curved surface includes a portion of the inner surface that defines the predicted after-treatment fluid impact risk zone.

274. The exhaust aftertreatment system of claim 273, wherein: The auxiliary passage outlet is defined by an opening formed in the outer curved surface.

275. An exhaust aftertreatment system comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage; and An auxiliary channel, the auxiliary channel being configured as follows: receiving a portion of the main flow from a first location of the exhaust aftertreatment system upstream of the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; and delivering the auxiliary flow to the main turbine flow at a second location of the exhaust aftertreatment system downstream of the turbine wheel chamber; wherein the exhaust aftertreatment system is configured such that the auxiliary flow is always allowed to flow from the first position of the exhaust aftertreatment system to the second position of the exhaust aftertreatment system; wherein the inner surface of the exhaust passage includes a predicted aftertreatment fluid impact risk area, and Wherein, the auxiliary channel is configured to direct the auxiliary flow in an auxiliary flow layer along a portion of the inner surface defining the predicted post-treatment fluid impact risk zone.

276. The exhaust aftertreatment system of claim 275, wherein: The exhaust passage defines a centerline and includes a non-linear portion that causes a change in bulk flow mass, the non-linear portion being defined at least in part by a portion of the interior surface that includes the aftertreatment fluid impingement risk zone.

277. An exhaust aftertreatment system according to claim 275 or 276, wherein: The non-linear portion includes a curved portion of the exhaust passage.

278. The exhaust aftertreatment system of claim 277, wherein: The curved portion includes an inner curved surface and an outer curved surface, the inner curved surface defines an inner curved radius, the outer curved surface defines an outer curved radius, the outer curved radius is greater than the inner curved radius, and The outer curved surface includes a portion of the inner surface that defines the predicted after-treatment fluid impact risk zone.

279. The exhaust aftertreatment system of claim 278, wherein: The auxiliary passage includes an auxiliary passage outlet configured to deliver the auxiliary flow to the exhaust passage, and The auxiliary passage outlet is defined by an opening formed in the outer curved surface. 280.An exhaust aftertreatment system comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage, the exhaust passage including a non-linear portion defined by an inner surface of the exhaust passage; and an auxiliary passage including an auxiliary passage inlet configured to receive a portion of the main flow from the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; The auxiliary channel is configured to guide the auxiliary flow along the inner surface of the non-linear portion in an auxiliary flow layer through an auxiliary channel outlet.

281. The exhaust aftertreatment system of claim 280, wherein: The non-linear portion includes a curved portion of the exhaust passage.

282. An exhaust aftertreatment system according to claim 280 or 281, wherein: The curved portion includes an inner curved surface and an outer curved surface, the inner curved surface defines an inner curved radius, the outer curved surface defines an outer curved radius, the outer curved radius is greater than the inner curved radius, and the outer curved surface includes the inner surface; and The auxiliary channel is configured to direct the auxiliary flow layer along the outer curved surface.

283. An exhaust aftertreatment system according to any one of claims 280 to 282, wherein: The auxiliary passage outlet is defined by an opening formed in the outer curved surface.

284. The exhaust aftertreatment system of claim 283, wherein: The outer curved surface defines a proximal end and a distal end relative to the direction of the bulk flow, and The auxiliary channel outlet is positioned at the distal end of the outer curved surface. 285.An exhaust aftertreatment system comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage, the exhaust passage including a non-linear portion defined by an inner surface of the exhaust passage; and An auxiliary channel, the auxiliary channel being configured as follows: receiving a portion of the main flow from a first location of the exhaust aftertreatment system upstream of the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; and delivering the auxiliary flow to the main turbine flow at a second location of the exhaust aftertreatment system downstream of the turbine wheel chamber; wherein the exhaust aftertreatment system is configured such that the auxiliary flow is always allowed to flow from the first position of the exhaust aftertreatment system to the second position of the exhaust aftertreatment system; The auxiliary channel is configured to guide the auxiliary flow along the inner surface of the non-linear portion in an auxiliary flow layer.

286. The exhaust aftertreatment system of claim 285, wherein: The non-linear portion includes a curved portion of the exhaust passage.

287. An exhaust aftertreatment system according to claim 285 or 286, wherein: The curved portion includes an inner curved surface and an outer curved surface, the inner curved surface defines an inner curved radius, the outer curved surface defines an outer curved radius, the outer curved radius is greater than the inner curved radius, and the outer curved surface includes the inner surface; and The auxiliary channel is configured to direct the auxiliary flow layer along the outer curved surface.

288. An exhaust aftertreatment system according to any one of claims 285 to 287, wherein: The auxiliary passage includes an auxiliary passage outlet configured to deliver the auxiliary flow to the exhaust passage, and The auxiliary passage outlet is defined by an opening formed in the outer curved surface.

289. The exhaust aftertreatment system of claim 288, wherein: The outer curved surface defines a proximal end and a distal end relative to the direction of the bulk flow, and The auxiliary channel outlet is positioned at the distal end of the outer curved surface.

290. An exhaust aftertreatment system comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage; and An auxiliary channel, the auxiliary channel comprising: an auxiliary channel inlet configured to receive a portion of the main flow, the portion of the main flow received by the auxiliary channel defining an auxiliary flow; and an auxiliary passage outlet configured to direct the auxiliary flow into the exhaust passage; wherein the exhaust passage is at least partially defined by a first surface of a partition wall, and the auxiliary passage is at least partially defined by a second surface of the partition wall, the partition wall being configured to provide thermal communication from the auxiliary passage to the first surface via the second surface; and Wherein, at least a portion of the first surface of the partition wall includes a post-treatment fluid impact risk area.

291. The exhaust aftertreatment system of claim 290, wherein: The exhaust passage includes a non-linear portion defined at least in part by a portion of the first surface including the after-treatment fluid impingement risk zone.

292. An exhaust aftertreatment system according to any one of claims 290 to 291, wherein: The non-linear portion includes a curved portion.

293. The exhaust aftertreatment system of claim 292, wherein: The curved portion includes an inner curved surface and an outer curved surface, the inner curved surface defines an inner curved radius, the outer curved surface defines an outer curved radius, the outer curved radius is greater than the inner curved radius, and The outer curved surface includes a portion of the first surface that defines the post-treatment fluid impact risk zone.

294. The exhaust aftertreatment system of claim 293, wherein: The auxiliary passage outlet is defined by an opening formed in the outer curved surface. 295.An exhaust aftertreatment system, comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage; and An auxiliary channel, the auxiliary channel being configured as follows: receiving a portion of the main flow from a first location of the exhaust aftertreatment system upstream of the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; and delivering the auxiliary flow to the main turbine flow at a second location of the exhaust aftertreatment system downstream of the turbine wheel chamber; wherein the exhaust aftertreatment system is configured such that the auxiliary flow is always allowed to flow from the first position of the exhaust aftertreatment system to the second position of the exhaust aftertreatment system; wherein the exhaust passage is at least partially defined by a first surface of a partition wall, and the auxiliary passage is at least partially defined by a second surface of the partition wall, the partition wall being configured to provide thermal communication from the auxiliary passage to the first surface via the second surface; and Wherein, at least a portion of the first surface of the partition wall includes a post-treatment fluid impact risk area.

296. The exhaust aftertreatment system of claim 295, wherein: The exhaust passage includes a non-linear portion defined at least in part by a portion of the first surface including the after-treatment fluid impingement risk zone.

297. An exhaust aftertreatment system according to any one of claims 295 to 296, wherein: The non-linear portion includes a curved portion.

298. The exhaust aftertreatment system of claim 297, wherein: The curved portion includes an inner curved surface and an outer curved surface, the inner curved surface defines an inner curved radius, the outer curved surface defines an outer curved radius, the outer curved radius is greater than the inner curved radius, and The outer curved surface includes a portion of the first surface that defines the post-treatment fluid impact risk zone.

299. The exhaust aftertreatment system of claim 298, wherein: The auxiliary passage includes an auxiliary passage outlet configured to deliver the auxiliary flow to the exhaust passage, and The auxiliary passage outlet is defined by an opening formed in the outer curved surface.

300. An exhaust aftertreatment system comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage, the exhaust passage defining a bend; and An auxiliary channel, the auxiliary channel comprising: an auxiliary passage inlet configured to receive a portion of the main flow from the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; and an auxiliary passage outlet configured to direct the auxiliary flow into the exhaust passage; The bend of the exhaust passage is at least partially defined by a first surface of a partition wall, and the auxiliary passage is at least partially defined by a second surface of the partition wall, and the partition wall is configured to provide thermal connectivity from the auxiliary passage to the first surface via the second surface.

301. The exhaust aftertreatment system of claim 300, wherein: The first surface is provided on a side of the partition wall opposite to the second surface.

302. An exhaust aftertreatment system according to claim 300 or 301, wherein: The dividing wall defines a thickness between the first surface and the second surface, wherein the turbine includes a turbine wheel having an outlet inducer portion, the outlet inducer portion defining an outlet inducer diameter, and wherein the thickness of the dividing wall is about 1% to about 10% of the outlet inducer diameter.

303. An exhaust aftertreatment system according to any one of claims 300 to 302, wherein: The curved portion includes an inner curved surface and an outer curved surface, the inner curved surface defines an inner curved radius, the outer curved surface defines an outer curved radius, the outer curved radius is greater than the inner curved radius, and The outer curved surface includes the first surface of the partition wall.

304. The exhaust aftertreatment system of claim 303, wherein: The auxiliary passage outlet is defined by an opening formed in the outer curved surface.

305. An exhaust aftertreatment system comprising: A turbine configured to receive an exhaust gas flow from an internal combustion engine, the turbine comprising: a turbine inlet passage configured to receive exhaust gas from an internal combustion engine, the exhaust gas received by the turbine inlet passage defining a bulk flow; a turbine wheel chamber configured to receive the bulk flow from the turbine inlet passage, the turbine wheel chamber configured to house a turbine wheel supported for rotation about a turbine axis; a turbine outlet passage configured to receive the bulk flow from the turbine wheel chamber; and a distribution module configured to deliver a spray of aftertreatment fluid into the turbine outlet passage; an exhaust passage configured to receive the bulk flow from the turbine outlet passage, the exhaust passage defining a bend; and An auxiliary channel, the auxiliary channel comprising: an auxiliary passage inlet configured to receive a portion of the main flow from the turbine outlet passage, the portion of the main flow received by the auxiliary passage defining an auxiliary flow; and an auxiliary passage outlet configured to direct the auxiliary flow into the exhaust passage; The bend of the exhaust passage is at least partially defined by a first surface of a partition wall, and the auxiliary passage is at least partially defined by a second surface of the partition wall, and the partition wall is configured to provide thermal connectivity from the auxiliary passage to the first surface via the second surface.

306. The exhaust aftertreatment system of claim 305, wherein: The first surface is disposed on a side of the partition wall opposite to the second surface.

307. An exhaust aftertreatment system according to claim 305 or 306, wherein: The dividing wall defines a thickness between the first surface and the second surface, wherein the turbine includes a turbine wheel having an outlet inducer portion, the outlet inducer portion defining an outlet inducer diameter, and wherein the thickness of the dividing wall is about 1% to about 10% of the outlet inducer diameter.

308. An exhaust aftertreatment system according to any one of claims 305 to 307, wherein: The curved portion includes an inner curved surface and an outer curved surface, the inner curved surface defines an inner curved radius, the outer curved surface defines an outer curved radius, the outer curved radius is greater than the inner curved radius, and The outer curved surface includes the first surface of the partition wall.

309. The exhaust aftertreatment system of claim 308, wherein: The auxiliary passage includes an auxiliary passage outlet configured to deliver the auxiliary flow to the exhaust passage, and The auxiliary passage outlet is defined by an opening formed in the outer curved surface.

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