Turbine

Abstract

A turbine housing is provided that includes a housing partition wall extending circumferentially about a central axis of the turbine housing. A housing partition wall axially separates the first inlet volute and the second inlet volute. The housing partition wall includes a circumferentially extending tip configured to receive a nozzle ring. The tip is shaped to impart a tortuous geometry on a leakage passage defined between the first inlet volute and the second inlet volute.

Description

[0001] The present invention relates to a turbine housing and assembly for a dual inlet turbine, and in particular to such a turbine housing and assembly in which leakage between corresponding inlet volutes is reduced.

[0002] A turbocharger is a well-known device for supplying air to the intake of an internal combustion engine at a pressure above atmospheric pressure (boost pressure). A conventional turbocharger comprises an exhaust-driven turbine wheel mounted on a rotatable shaft within a turbine housing. The rotation of the turbine wheel rotates a compressor wheel at the other end of the shaft, mounted within a compressor housing. The compressor wheel delivers compressed air to the engine's intake manifold, thereby increasing engine power. The turbocharger shaft is typically supported by journal and thrust bearings (including an appropriate lubrication system) located within a center bearing housing connected between the turbine and compressor wheel housings.

[0003] In known turbochargers, the turbine stage includes a turbine chamber in which a turbine wheel is mounted; an inlet passage extending circumferentially defined between opposing walls disposed around the turbine chamber; an inlet volute disposed around the inlet passage; and an outlet passage extending from the turbine chamber. The passage and chamber communicate so that pressurized exhaust gas entering the inlet volute flows through the inlet passage to the outlet passage via the turbine, thereby rotating the turbine wheel. It is also known to improve turbine performance by providing vanes (referred to as nozzle vanes) in the inlet passage to deflect the gas flowing through the inlet passage toward the direction of rotation of the turbine wheel.

[0004] Turbines can be of fixed geometry or variable geometry. Variable geometry turbines include a mechanism that allows the geometry of the inlet passage to be changed during use. Fixed geometry turbines do not include such a mechanism, and therefore the geometry of the inlet passage of a fixed geometry turbine cannot be adjusted during use.

[0005] Turbines can be of either single-inlet or multi-inlet type. Single-inlet turbines include a single inlet volute that typically receives all exhaust gas from the internal combustion engine. Multi-inlet turbines include more than one volute that typically receives separate exhaust gas streams from different cylinder banks of the internal combustion engine. One form of multi-inlet turbine is a "dual-inlet" turbine, in which two volutes extend circumferentially around the turbine axis, aligned at an angle to each other. In such "dual-inlet" turbines, a dividing wall is used to separate the volutes from each other.

[0006] In a multi-inlet turbine, the exhaust flows in the different inlet volutes will exhibit transient pressure pulses caused by the separate cylinder groups. Typically this means that when the first volute exhibits high pressure, the adjacent second volute exhibits low pressure. If the pressure difference between the two volutes is high enough, this will cause the exhaust from the first (higher pressure) volute to overflow the dividing wall and enter the second (lower pressure) volute. The presence of high pressure gas in the second volute creates a fluid blockage that can hinder the exhaust flow through the second volute during the next exhaust cycle, thereby increasing the pumping work required by the engine and resulting in engine energy loss. During the next exhaust cycle, the high pressure gas in the second volute can overflow the dividing wall into the first volute to form a fluid blockage in the first volute. This fluid interaction between the different volutes is known as "crosstalk".

[0007] It is beneficial to keep the inlet flow streams separated from each other until as close to the turbine wheel as possible. By keeping the two flows separated until just before the turbine wheel, energy losses are minimized. Therefore, in fixed-geometry turbines that include nozzle vanes, the dividing wall typically extends through the nozzle vanes, for example in a plane generally orthogonal to the turbine axis. This ensures that the inlet flows remain separated until just downstream of the trailing edge of the nozzle vanes, which is located immediately adjacent to the turbine wheel's inducer.

[0008] Due to the complex geometry of the divider wall and nozzle ring, it is often impossible to manufacture the nozzle vanes integrally with the turbine housing. Consequently, such turbines typically include a separate nozzle ring and turbine housing. In such configurations, the nozzle ring defines the nozzle vanes and the portion of the divider wall that passes through them, while the turbine defines the inlet volute and the portion of the divider wall positioned between the inlet volutes. Because the nozzle ring and turbine housing are separate, an interface is defined between the portion of the divider wall defined by the nozzle ring and the portion of the divider wall defined by the turbine housing.

[0009] It's impossible for the nozzle ring to contact the turbine housing's partition wall at this interface. Typically, the turbine housing and nozzle ring must be made of different materials. During use, when heated by the hot exhaust gas, the nozzle ring and turbine housing will expand at different rates. Without a gap, this results in the nozzle ring exerting high stress on the partition wall, which can lead to material failure in the turbine housing. Therefore, the nozzle ring and partition wall are sized so that a narrow gap, or leakage path, exists at the interface, allowing some exhaust gas to pass through. However, the presence of the gap allows crosstalk to occur before the nozzle ring, thereby reducing turbine efficiency.

[0010] It is an object of the present invention to mitigate or prevent leakage across the nozzle ring of a turbine.It is another object of the present invention to obviate or mitigate one or more disadvantages of the prior art, whether described herein or elsewhere.

[0011] According to a first aspect of the present invention, there is provided a turbine housing comprising:

[0012] a casing divider wall extending circumferentially about a central axis of the turbine casing, the casing divider wall axially separating a first inlet volute and a second inlet volute;

[0013] wherein the housing divider wall includes a circumferentially extending tip configured to receive a nozzle ring, the tip being shaped to impart a tortuous geometry on a leakage path defined between the first inlet volute and the second inlet volute.

[0014] During use, when a pressure pulse occurs in one of the inlet volutes, the fluid in that volute tends to pass through the leakage channel and into the other volute. When the leakage channel is not tortuous, the path defined by the leakage channel is short, straight, and direct. However, because the tip of the housing dividing wall is shaped to impart a tortuous shape to the leakage channel, the path defined by the leakage channel of the present invention is longer and more complex. This has two effects. First, increasing the length of the leakage channel increases the surface area of ​​the leakage channel in contact with the fluid passing through it. As a result, the fluid is exposed to increased frictional shear forces exerted on it by the surfaces of the leakage channel, resulting in energy losses within the fluid. Second, increasing the complexity of the leakage channel causes the fluid passing through it to undergo one or more significant changes in direction. When the fluid changes direction, internal friction between particles within the fluid (i.e., viscous friction) causes further energy losses. Therefore, compared to a straight leakage channel, a leakage channel with a tortuous geometry will result in greater energy losses within the fluid passing through it. The lower-energy fluid effectively "throttles" the leakage channel, restricting flow through it, thereby reducing the total amount of leakage from one volute to the other. Thus, the problems associated with crosstalk discussed above are alleviated.

[0015] The term "tortuous" generally encompasses any geometry that causes a fluid passing through a leakage path to undergo one or more changes in flow direction, particularly significant changes in flow direction. This may include, for example, geometries configured to impart one or more bends, twists, turns, doglegs, boustrophedonic paths, zigzags, etc., to the leakage path.

[0016] The term "leakage channel" includes a channel defined between the first inlet volute and the second inlet volute through which fluid can be transferred between the volutes. In particular, such a leakage channel can be free of, and preferably is substantially free of, mechanical sealing elements. Such mechanical sealing elements can include, for example, o-rings, sealing rings, compression joints, interference fits, or any other mechanical structure configured to block or otherwise prevent flow through the leakage channel. Thus, in such embodiments, the only means of mitigating and / or preventing leakage along the leakage channel between the first and second volutes is provided by frictional forces exerted on the fluid in the leakage channel due to the tortuous geometry of the leakage channel itself.

[0017] The tip may include a feature configured to impart a tortuous geometry to the leakage path. The term "feature" generally encompasses any mechanical structure capable of deflecting or directing a fluid, such as exhaust gas, etc. Such features may include, among other things, edges, protrusions, recesses, labyrinth seals, steps, etc. The term "leakage path" encompasses the spatial region at least partially defined between the tip of the housing partition wall and the nozzle ring, which allows fluid communication between the first inlet volute and the second inlet volute.

[0018] This configuration can include a stepped portion extending circumferentially around the central axis, which defines at least a portion of the leakage path. The term "stepped portion" encompasses a sharp discontinuity in the tip or an abrupt change in radius between two surfaces of the tip. The stepped portion can be embodied, for example, by an annular surface extending between two cylindrical surfaces of the tip. Such a step can form a portion of the leakage path and thus define the tortuous geometry described above.

[0019] The step portion may define an inner edge, and the inner edge may be curved. The term "inner edge" encompasses an edge defined between two surfaces that form a portion of a concave structure. For example, the inner edge may be an edge defined by the inside of an elbow that defines a portion of the step portion. The two surfaces that define the inner edge may be oriented at approximately 90° relative to each other. The term "curved" encompasses a circular geometry that is configured to provide a smooth transition between the two surfaces that define the inner edge. Such a curved edge helps to deflect the incident flow along the tortuous geometry of the leakage channel and thereby reduce the internal energy of the leaking fluid, thereby enhancing the "throttling" effect. In addition, the curved edge can reduce the internal stress within the material of the shell partition wall. That is, the curved edge reduces the incidence of stress concentration within the tip of the shell partition wall.

[0020] The step portion may define an outer edge, and the outer edge may be sharp. The term "outer edge" encompasses an edge defined between two surfaces forming part of a convex structure. For example, the outer edge may be an edge defined by the outside of an elbow that defines part of the step portion. The two surfaces defining the outer edge may be oriented at approximately 90° relative to each other. The term "sharp" encompasses a substantially discontinuous change in the angle between the two surfaces defining the outer edge. Because the outer edge is sharp, the boundary layer of fluid flowing over the outer edge can separate from the pointed step portion. This flow separation can be used to effectively "narrow" the available flow area of ​​the leakage path, thereby enhancing the "throttling" effect. Additionally, the sharp edge can allow or even encourage fluid passing over it to continue flowing in a direction parallel to the central axis, thereby preventing the fluid from colliding with another object (e.g., the nozzle divider wall of the nozzle ring).

[0021] The configuration may be a first configuration; and the tip further includes a second configuration defining at least a portion of the leakage path, the second configuration being configured to combine with the first configuration to impart a tortuous geometry to the leakage path. Because the second configuration, combined with the first configuration, imparts a tortuous geometry to the leakage path, the second configuration also contributes to the "throttling" effect of the leakage path. In other words, the second configuration defines an increased degree of tortuosity in the tortuous path between the first inlet volute and the second inlet volute, thereby further restricting flow therebetween.

[0022] The second configuration may be a second stepped portion extending circumferentially around the central axis, and the stepped portion may define at least a portion of the leakage path. The second stepped portion may have a structure substantially corresponding to the first stepped portion described above.

[0023] The second step portion may define an inner edge, and the inner edge may be arcuate. The inner edge of the second step portion may have a structure substantially corresponding to the inner edge of the first step portion described above. In particular, the two surfaces defining the inner edge may be oriented at approximately 90° relative to each other.

[0024] The second step portion may define an outer edge, and the outer edge may be sharp. The outer edge of the second step portion may have a structure substantially corresponding to the outer edge of the first step portion described above. In particular, the two surfaces defining the outer edge may be oriented at approximately 90° relative to each other.

[0025] The second configuration can be positioned opposite the first configuration about a plane perpendicular to the central axis to define a recess therebetween. The term "recess" encompasses a groove or channel extending circumferentially about the central axis. This geometry is easy to manufacture and provides a configuration suitable for defining the necessary tortuous path to reduce leakage between the inlet volutes.

[0026] The tip of the divider wall can include a tab extending in a radial direction toward the central axis. The tip of the divider wall can include a plurality of tabs, which can be equally spaced about the central axis. The one or more tabs can be configured to be received by a correspondingly shaped receptacle of the nozzle ring divider wall (described below).

[0027] According to a second aspect of the present invention, there is provided a turbine housing assembly comprising:

[0028] The turbine housing of the first aspect of the present invention; and

[0029] a nozzle ring comprising a nozzle ring divider wall and at least one nozzle vane extending from the nozzle ring divider wall;

[0030] wherein the nozzle ring divider wall is aligned with the tip of the housing divider wall such that the nozzle ring divider wall and the tip of the housing divider wall define a leakage passage therebetween.

[0031] The term "nozzle ring divider wall" encompasses a generally annular flange-like structure extending in a generally radial direction relative to the central axis.

[0032] The configuration can define the outer radius R o and inner radius R i The nozzle ring partition wall may define the nozzle ring radius R n . Outer radius R o Can be larger than the nozzle ring radius R n The outer radius R of the configuration o Can be compared with the nozzle ring radius R n大 About 0.5% to about 1.5%, and preferably about 0.9% or about 1%.

[0033] Inner radius R i Can be equal to or greater than the nozzle ring radius R n Because the inner radius R i Equal to or greater than the nozzle radius R n , which ensures that the nozzle partition wall can be received within the inner radius R of the turbine housing partition wall during assembly. i However, even if no overlap is created between the configuration and the nozzle ring dividing wall, the configuration can still create a tortuous path that serves to reduce leakage through the leakage channel. i Can be compared with the nozzle ring radius R n About 0.1% to about 0.5%, and preferably about 0.2% or 0.3%.

[0034] The turbine may be a turbine including the first configuration and the second configuration as described above. Inner radius Ri may be an inner radius of the first configuration and may define a first inner radius R 1，i The second configuration may define a second inner radius R 2，i . Outer radius R o It can be a common outer radius of the first configuration and the second configuration. The first inner radius R 1，i and the second inner radius R 2，i Can be equal to or greater than the nozzle ring radius R n The first inner radius R 1，i and the second inner radius R 2，i Can be compared with the nozzle ring radius R n About 0.1% to about 0.5%, and preferably about 0.2% or 0.18%.

[0035] Inner radius R i Can be smaller than the nozzle ring radius R n Because the inner radius R i Smaller than the nozzle ring radius R n , so this creates a radial overlap between the housing partition wall and the nozzle ring partition wall. This overlap further increases the curvature of the leakage path and thus improves the sealing effect.

[0036] The inner radius R of the configuration i Can be the radius of the nozzle ring R n As little as about 0.3% to about 1.5%, and preferably about 0.4%, about 0.7% or about 1.1%.

[0037] The turbine may be a turbine comprising a first configuration and a second configuration as described above. The first configuration may define a first inner radius R 1，i . Inner radius R i The inner radius of the second configuration may be defined and a second inner radius R may be defined. 2，i . Outer radius R o It can be a common outer radius of the first configuration and the second configuration. The first inner radius R 1，i Can be equal to or greater than the nozzle ring radius R n The second inner radius R 2，i Can be smaller than the nozzle ring radius R n Because the first inner radius R 1，i Equal to or greater than the nozzle ring radius R n , and the second inner radius R 2，i Smaller than the nozzle ring radius R n , so this ensures that the nozzle ring partition wall can be received within the first inner radius R of the housing partition wall during assembly 1，i The second inner radius R 2，i Forming radial overlap.

[0038] First inner radius R 1，i Can be compared with the nozzle ring radius R n About 0.1% to about 0.5%, and preferably about 0.2% or 0.18%. The second inner radius R 2，i Can be compared with the nozzle ring radius R n As little as about 0.3% to about 1.5%, and preferably about 0.4%, about 0.7% or about 1.1%.

[0039] The turbine may be a turbine including the first configuration and the second configuration as described above. Inner radius R i can be an inner radius of the first configuration and defines a first inner radius R 1，i The second configuration may define a second inner radius R 2，i . Outer radius R o It can be a common outer radius of the first configuration and the second configuration. The first inner radius R 1，i Can be equal to or smaller than the nozzle ring radius R n The second inner radius R 2，i Can be equal to or smaller than the nozzle ring radius R n Because the first inner radius R 1，i Equal to or less than the nozzle ring radius R n ; and the second inner radius R 2，i Equal to or less than the nozzle ring radius R n , so that a radial overlap is created between the two configurations of the casing partition wall and the nozzle ring partition wall. Such an embodiment may be manufacturable, for example, by additive manufacturing or by thermally shrinking the nozzle ring and / or thermally expanding the turbine casing to allow the nozzle ring to pass through the first configuration and / or the second configuration.

[0040] First inner radius R 1，i and the second inner radius R 2，i Can be compared with the nozzle ring radius R n As little as about 0.3% to about 1.5%, and preferably about 0.4%, about 0.7% or about 1.1%.

[0041] The turbine may be a turbine comprising the first and second configurations as described above.The nozzle ring dividing wall may be axially aligned with a midpoint between the first and second configurations.

[0042] According to a third aspect of the present invention, there is provided a nozzle ring for a twin-inlet turbine, the twin-inlet turbine comprising a first inlet volute and a second inlet volute separated by a casing partition wall, the nozzle ring comprising:

[0043] a nozzle ring divider wall extending circumferentially about a central axis of the nozzle ring;

[0044] at least one nozzle vane extending from the nozzle ring divider wall;

[0045] wherein the nozzle ring divider wall includes a circumferentially extending tip configured to be received by the casing divider wall, the tip being shaped to impart a tortuous geometry on a leakage path defined between the first inlet volute and the second inlet volute.

[0046] The advantages of this arrangement and the definitions of "tortuous" and "leakage path" may be the same as set out above in relation to the first aspect of the invention.

[0047] The tip may include a configuration configured to impart a tortuous geometry to the leakage path. The configuration may include a stepped portion extending circumferentially about the central axis, the stepped portion defining at least a portion of the leakage path. The stepped portion may define an inner edge, which may be curved. The stepped portion may define an outer edge, which may be sharp.

[0048] The configuration may be a first configuration; and the tip may further include a second configuration defining at least a portion of the leakage path, the second configuration being configured to impart a tortuous geometry to the leakage path in combination with the first configuration. The second configuration may be a second stepped portion extending circumferentially about the central axis, the stepped portion defining at least a portion of the leakage path. The second stepped portion may define an inner edge, which may be curved. The second stepped portion may define an outer edge, which may be sharp.

[0049] The second configuration may be positioned opposite the first configuration about a plane perpendicular to the central axis so as to define a recess therebetween.

[0050] The nozzle ring divider wall may include a socket configured to receive a corresponding tab of the housing divider wall.The nozzle ring divider wall may include a plurality of sockets, which may be arranged equidistantly around the central axis.

[0051] According to a fourth aspect of the present invention, there is provided a turbine housing assembly comprising:

[0052] The nozzle ring of the third aspect of the present invention; and

[0053] a turbine housing including a housing divider wall extending circumferentially about a central axis of the turbine housing, the housing divider wall axially dividing a turbine inlet into a first inlet volute and a second inlet volute, wherein the housing divider wall includes a circumferentially extending tip;

[0054] wherein the tip of the nozzle ring partition wall is aligned with the tip of the housing partition wall such that the tip of the nozzle ring partition wall and the tip of the housing partition wall define the leakage passage therebetween.

[0055] According to a fifth aspect of the present invention, there is provided a turbine housing assembly comprising:

[0056] The turbine housing according to the first aspect of the present invention; and

[0057] A nozzle ring according to a third aspect of the present invention;

[0058] wherein the tip of the nozzle ring partition wall is aligned with the tip of the housing partition wall such that the tip of the nozzle ring partition wall and the tip of the housing partition wall define the leakage passage therebetween.

[0059] The following describes in detail several embodiments of the present invention with reference to the accompanying drawings, in which:

[0060] Figure 1 is a schematic cross-sectional view of a turbine including a turbine housing assembly having a turbine housing according to an embodiment of the present invention;

[0061] Figure 2 yes Figure 1 A schematic cross-sectional view of a portion of a turbine;

[0062] Figure 3 yes Figure 1 a schematic cross-sectional view of another portion of the turbine;

[0063] Figure 4 is a schematic cross-sectional view of a portion of an alternative embodiment of a turbine housing assembly including a turbine housing according to the present invention;

[0064] Figure 5 is a schematic cross-sectional view of a portion of another alternative embodiment of a turbine housing assembly including a turbine housing according to the present invention;

[0065] Figure 6 is a graph of normalized turbine efficiency at different pressure ratios between a first inlet volute and a second inlet volute for various comparative examples of turbine inlet arrangements;

[0066] Figure 7 is a schematic cross-sectional view of another alternative embodiment of a turbine housing assembly including a nozzle ring according to the present invention; and

[0067] Figure 8 is a schematic cross-sectional view of another alternative embodiment of a turbine housing assembly including a turbine housing and a nozzle ring according to the present invention.

[0068] Figure 1 A turbine 2 is shown, including a turbine wheel 4 mounted to a turbine shaft 6 supported by bearings 8 positioned within a bearing housing 10 and configured to rotate about a central axis A. The turbine 2 also includes a turbine housing assembly 12, which includes a turbine housing 14 and a nozzle ring 15. The turbine housing 14 includes a housing divider wall 16 that axially separates a first inlet volute 18 from a second inlet volute 20. The housing divider wall 16 includes a tip 22 that extends circumferentially about the central axis A. The nozzle ring 15 includes a nozzle ring divider wall 24, a pair of end walls 26, and a plurality of nozzle vanes 28. The end walls 26 are received within corresponding recesses in the turbine housing 14 and corresponding recesses in the bearing housing 10. The end walls 26 are spaced approximately equidistantly from the nozzle ring divider wall 24 to define a first nozzle passage 30 and a second nozzle passage 32 therebetween. However, in alternative embodiments, the end wall 26 may be located at different distances from the nozzle ring divider wall 24 such that the first nozzle passage 30 and the second nozzle passage 32 define different axial widths. Furthermore, in other embodiments, the nozzle ring 15 may not include the end wall 26. In such embodiments, the end wall 26 may form part of the turbine housing 14, the bearing housing, or another component. Nozzle vanes 28 extend axially parallel to the central axis A from the nozzle ring divider wall 24 through the nozzle passages 30, 32 to a corresponding one of the end walls 26. The nozzle ring divider wall 24 is axially aligned with the tip 22 of the casing divider wall 16. A leakage channel 34 is defined between the tip 22 of the casing divider wall and an outer portion of the nozzle ring divider wall 24.

[0069] During use, exhaust gas received from separate cylinder banks of an internal combustion engine (not shown) is delivered to the first and second inlet volutes 18, 20. From the inlet volutes 18, 20, the exhaust gas passes through nozzle passages 30, 32 to the turbine wheel 4, thereby rotating the turbine wheel 4 and generating mechanical power utilized by the turbine shaft 6. Because the first and second inlet volutes 18, 20 are fed by different cylinder banks of the engine, the transient pressure profile of the exhaust gas in the first inlet volute 18 will differ from the transient pressure profile of the exhaust gas in the second inlet volute 20. Consequently, during a large portion of the operating cycle of the turbine 2, a pressure differential exists between the first and second inlet volutes 18, 20, causing exhaust gas to pass between the first and second inlet volutes 18, 20 along a leakage path 34. This flow between the first and second inlet volutes 18, 20 along the leakage path 34 is referred to as "crosstalk." This crosstalk may act to reduce the pressure of the exhaust gases in the high pressure inlet volute and increase the pressure in the low pressure inlet volute through pressure pulse superposition, and may therefore reduce the amount of power produced by the turbine wheel 4 .

[0070] Figure 2 A schematic, enlarged, cross-sectional view of leakage path 34 is shown. As shown, tip 22 of housing divider wall 16 is shaped to impart a tortuous geometry to leakage path 34. Specifically, tip 22 of housing divider wall 16 includes a first feature 36 on the side of first inlet volute 18 and a second feature 38 on the side of second inlet volute 20. First feature 36 and second feature 38 are radially extending circumferential flanges that define a circumferentially extending recess 40 between first feature 36 and second feature 38. First feature 36 includes a first stepped portion 42, and second feature 38 includes a second stepped portion 44. Both first and second stepped portions 42 and 44 extend radially inward from the base of recess 40. Nozzle ring divider wall 24 is axially aligned with the midpoint between first feature 36 and second feature 38.

[0071] The radially innermost point of the first formation 36 defines a first inner radius R relative to the axis A. 1，i The radially innermost point of the second configuration 36 defines a second inner radius R relative to the axis A. 2，i , and the radially outermost portion of the recess 40 defines an outer radius R relative to the axis A o The first configuration 36 can be considered to be from the first inner radius R 1，i extends to the recess 40, and the second configuration 38 can be considered to be extending from the second inner radius R 2，i 4. The outermost portion of the nozzle ring divider wall 24 extends to the recess 40. Thus, the recess 40 can be considered to define the outer radius of the first configuration 36 and the outer radius of the second configuration 38. The radially outermost portion of the nozzle ring divider wall 24 defines the nozzle ring radius R n .

[0072] As can be seen from the figure, the first inner radius R 1，i Larger than the nozzle ring radius R n , and the second inner radius R 2，i Smaller than the nozzle ring radius R n. Thus, the leakage path 34 includes a plurality of bends, causing any fluid passing therethrough to change direction multiple times, a geometry considered to be a tortuous geometry. This provides two key advantages. First, the length of the leakage path 34 between the first inlet volute 18 and the second inlet volute 20 is increased compared to conventional arrangements in which the tip 22 defines a flat, axially straight leakage path 34 (i.e., a non-tortuous geometry in which the housing dividing wall 16 does not include the first configuration 36 and the second configuration 38). Consequently, the contact area between the surfaces defining the leakage path 34 and the fluid passing therethrough is increased, and as a result, the fluid loses a greater amount of internal energy due to frictional losses. Second, the leakage path 34 includes a plurality of bends, which cause any fluid passing therethrough to change direction multiple times. As the fluid changes direction, further frictional energy losses occur due to viscous effects, so these two factors work in combination to ensure a greater amount of internal energy loss of the fluid between the first inlet volute 18 and the second inlet volute 20. Because the fluid passing through the leakage passage 34 loses a greater amount of energy, the flow resistance through the leakage passage 34 is increased, and thus the tendency of the fluid to leak between the first inlet volute 18 and the second inlet volute 20 is reduced.

[0073] Due to the above-described configuration of the leakage passage 34, it will be appreciated that sealing between the first volute 18 and the second volute 20 is provided solely by way of fluid friction within the exhaust gas passing through the leakage passage 34. Not only has this fluid seal been found to provide sufficient mitigation of crosstalk to improve turbine efficiency, but it also eliminates the need to provide any form of mechanical sealing elements, such as O-rings, seals, interference fits, etc. Consequently, the leakage passage 34 is substantially free of any mechanical sealing elements, thereby reducing manufacturing and assembly costs.

[0074] Figure 3 A further enlarged view of the leakage channel 34 is shown. The first step portion 42 defines a circumferentially extending first inner edge 46 at the point where it engages the base of the recess 40. Similarly, the second step portion 44 defines a circumferentially extending second inner edge 48 at the point where it engages the base of the recess 40. The cross-section of the circumferentially extending first inner edge 46 and second inner edge 48 is generally arc-shaped. This arc shape forces any fluid passing through the leakage channel 34 to change between flowing in a radial or axial direction relative to the axis A and flowing in the other direction relative to the axis A. By forcing the fluid to change direction in this way, it helps to ensure that internal energy is lost due to viscous forces within the fluid. Essentially any suitable arc geometry can be used for this purpose, including, for example, a rounded (i.e., filleted) geometry or a variable radius arc geometry.

[0075] The first step portion 42 defines a circumferentially extending first outer edge 50 at its radially innermost point, and the second step portion 44 defines a circumferentially extending first outer edge 52 at its radially innermost point. The first outer edge 50 and the second outer edge 52 are sharp edges compared to the first inner edge 46 and the second inner edge 48. Because the outer edges 50, 52 are sharp, this promotes boundary layer separation as the fluid passes over the outer edges 50, 52. This boundary layer separation can have the effect of narrowing the available flow area of ​​the leakage path 34, thereby increasing energy losses and resistance to flow therethrough, and thus further reducing the tendency of fluid to leak between the first inlet volute 18 and the second inlet volute 20.

[0076] return Figure 2 It can be seen that the outer radius R of the recess 40 o Larger than the nozzle ring radius R n This is necessary to provide clearance (i.e., leakage path 34) between the nozzle ring divider wall 24 and the casing divider wall 16. If no clearance existed, the nozzle ring divider wall 24 and the casing divider wall 16 would be in mechanical contact with each other. However, during use, the nozzle ring 15 and the turbine casing 14 will heat up and thermally expand at different rates, thereby placing significant stresses on the nozzle ring divider wall 24 and the casing divider wall 16, potentially leading to mechanical failure (i.e., cracking, etc.). In order to provide sufficient clearance between the nozzle ring divider wall 24 and the casing divider wall 16, the outer radius R o Ratio of nozzle ring radius to n However, in alternative embodiments, the outer radius R of the notch 40 is o Can be compared with the nozzle ring radius R n About 0.5% to about 1.5%, or about 1%.

[0077] Continue to refer Figure 2 , it can be seen that the first inner radius R 1，i Larger than the nozzle ring radius R n Because the first inner radius R 1，i Larger than the nozzle ring radius R n , which enables the nozzle ring divider wall 24 to pass under the first formation 36 so that it can be aligned with the housing divider wall 16. In particular, the first inner radius R 1，i Ratio of nozzle ring radius to n However, it will be appreciated that in alternative embodiments, the first inner radius R 1，i Can be equal to the nozzle ring radius R n Or the nozzle ring radius R n Up to about 0.5% larger than the nozzle ring radius R n In the range of about 0.1% to about 0.5%, or more than the nozzle ring radius R nAbout 0.2%.

[0078] Furthermore, although the second configuration 38 Figure 1 10 as being positioned on the same side of the housing divider wall 16 as the bearing housing 10, and the first formation 36 is positioned on the side of the housing divider wall 16 opposite the bearing housing 10, but it should be understood that in alternative embodiments, the first formation 36 may be positioned on the same side of the housing divider wall 16 as the bearing housing 10, and the second formation 38 may be positioned on the side of the housing divider wall 16 opposite the bearing housing 10. This arrangement may facilitate assembly of the nozzle ring 15, which is typically received within the turbine housing 14 from the same side as the bearing housing 10.

[0079] from Figure 2 It can be further seen that the second inner radius R 2，i Smaller than the nozzle ring radius R n Because the second inner radius R 2，i Smaller than the nozzle ring radius R n , which creates a radial overlap region between the nozzle partition wall 24 and the stepped portion 44 of the second configuration 38. Consequently, this increases the length of the leakage channel 34 and increases the tortuosity of the leakage channel 34, both of which contribute to increasing energy losses through the leakage channel 34 and thus reducing flow therethrough. In particular, the second inner radius R 2，i Ratio of nozzle ring radius to n However, it should be understood that in alternative embodiments, the second inner radius R 2，i Can be compared with the nozzle ring radius R n As little as about 0.3% to about 1.5%, and preferably about 0.4%, about 0.7% or about 1.1%.

[0080] return Figure 3 , it can be seen that the leakage channel 34 defines a width W in the axial direction between the side of the nozzle ring partition wall 24 and the second formation 38. Preferably, the width W should have approximately the same size as the distance between the radially outermost portion of the nozzle ring partition wall 24 and the recess 40. That is, the width W should be approximately equal to the width given by the equation W=R o -R nA defined distance. Preferably, the width W of the leakage passage 34 should be substantially constant over the length of the leakage passage 34 from the first volute 18 to the second volute 20. Therefore, the axial distance between the first formation 36 and the nozzle ring divider wall 24 is also preferably approximately equal to the aforementioned width W. Because the width W of the leakage passage 34 is substantially constant over the length of the leakage passage 34 from the first volute 18 to the second volute 20, this provides sufficient clearance between the housing divider wall 16 and the nozzle ring divider wall 24 to prevent mechanical contact therebetween. This avoids the formation of contact stresses that could lead to component failure. However, it should be understood that in alternative embodiments, the width W may have any suitable value and may vary over the length of the leakage passage 34.

[0081] Figure 4 Another embodiment of the present invention is shown wherein the first configuration 36 defines a first inner radius R 1，i , the first inner radius R 1，i The second inner radius R defined by the second configuration 38 2，i In particular, the first inner radius R 1，i and the second inner radius R 2，i Ratio of nozzle ring radius to n However, in an alternative embodiment, the first inner radius R 1，i and the second inner radius R 2，i Can be equal to the nozzle ring radius R n Or the nozzle ring radius R n Up to about 0.5% larger than the nozzle ring radius R n In the range of about 0.1% to about 0.5%, or more than the nozzle ring radius R n In yet another alternative embodiment, the first inner radius R 1，i and the second inner radius R 2，i Different radii may be defined relative to the axis A, wherein a first inner radius R 1，i and the second inner radius R 2，i are equal to or greater than the nozzle ring radius R n .

[0082] Figure 5 Yet another embodiment of the present invention is shown wherein the first configuration 36 defines a first inner radius R 1，i , the first inner radius R 1，i The second inner radius R defined by the second configuration 38 2，i aligned (i.e., the same size). However, in Figure 5 In the embodiment, the first inner radius R 1，i and the second inner radius R 2，i are smaller than the nozzle ring radius R n In particular, the first inner radius R1，i and the second inner radius R 2，i Ratio of nozzle ring radius to n However, it should be understood that in alternative embodiments, the first inner radius R 1，i and the second inner radius R 2，i Can be compared with the nozzle ring radius R n Less than about 0.3% to about 1.5%, and preferably about 0.4%, about 0.7% or about 1.1%. In yet another alternative embodiment, the first inner radius R 1，i and the second inner radius R 2，i Different radii may be defined relative to the axis A, wherein a first inner radius R 1，i and the second inner radius R 2，i are smaller than the nozzle ring radius R n .

[0083] Figure 6 Graphs of normalized turbine efficiency at different pressure ratios between the first inlet volute 18 and the second inlet volute 20 are shown for various comparative examples A to F of turbine inlet arrangements. Figure 6 The data depicted in were analyzed using computational fluid dynamics modeling. Figure 6 The dimensions of the exemplary turbine inlet arrangements A to F compared in FIG. 1 are shown below in Table 1. In particular, Table 1 shows the first inner radius R 1，i , second inner radius R 2，I and outer radius R o With the nozzle ring radius R n Compared to the relative size difference expressed in percentage. That is, Table 1 is based on the nozzle ring radius R n The first inner radius R is shown in the form of a ratio 1，i , second inner radius R 2，I and outer radius R o and nozzle ring radius R n How much bigger or smaller than.

[0084] Table 1: R n % Difference in Size

[0085]

[0086] Example A is a comparative example of a conventional arrangement, in which the first inner radius R 1，i , second inner radius R 2，I and outer radius R o are all equal. This therefore corresponds to an arrangement in which the tip 22 of the housing partition wall 16 is completely flat, so that the leakage path 34 is completely axially straight (and does not include bends, etc.). Example B corresponds to the arrangement discussed above. Figure 4 Examples C to E correspond to the above Figure 2 and Figure 3 An arrangement in which the amount of radial overlap between the second configuration 38 and the nozzle divider wall 24 is increased. Example F corresponds to a theoretical "perfect" arrangement that completely eliminates the leakage path 34. Thus, while Examples A and F do not include a tortuous geometry, Examples B through E all include a tortuous geometry.

[0087] from Figure 6 As can be seen, the most efficient arrangement for the above examples at all pressure ratios is the theoretical "perfect" arrangement of Example F. Likewise, the worst performing arrangement is Example A, which corresponds to a conventional arrangement having a straight (i.e., flat, non-tortuous) leakage path 34. However, all of the examples that include a tortuous geometry, i.e., Examples B through E, provide improved performance over the conventional arrangement of Example A. As expected, these examples fail to meet the performance provided by the theoretical "perfect" arrangement of Example F. Therefore, it can be determined that the use of a leakage path 34 having a tortuous geometry provides improved turbine efficiency. It is believed that this improved turbine efficiency is due to the tortuous nature of the leakage path 34, which serves to reduce fluid flow through the leakage path 34, thereby reducing the tendency for crosstalk to occur between the first inlet volute 18 and the second inlet volute 20.

[0088] from Figure 6 It can be further determined that the performance of each exemplary sealing arrangement increases with increasing amounts of radial overlap between the second configuration 38 and the nozzle ring divider wall 24. In particular, it is noteworthy that, of the four examples that include zigzag geometries, Example B (which does not include any radial overlap between the second configuration 38 and the nozzle ring 24) exhibits the smallest improvement over the conventional arrangement of Example A, while Example E (which includes the largest radial overlap between the second configuration 38 and the nozzle ring 24) exhibits the greatest performance improvement over the conventional arrangement of Example A. However, the change in performance between Example B and Example E is small compared to the improvements provided by both arrangements over the conventional arrangement of Example A.

[0089] While the present invention has been described with respect to a tortuous geometry imparted to the leakage passage 34 by the tip 22 of the housing divider wall 16, it should be understood that in alternative embodiments, the nozzle ring divider wall 24 may be configured to impart a tortuous geometry instead of or in combination with the tip 22 of the housing divider wall 16. Such embodiments may be described in detail in the following manner: Figure 7 As shown in Figure 7A turbine casing assembly 12' is depicted, including a nozzle ring 15' and a casing divider wall 16', which define a leakage passage 34' therebetween. The nozzle ring 15' includes a nozzle ring divider wall 24' having a circumferentially extending tip 54. The tip 54 of the nozzle ring 24' includes a first configuration 56 and a second configuration 58, which define a recess 60 therebetween. Thus, the tip 54 of the nozzle ring 24' is configured to impart a tortuous geometry to the leakage passage 34' in a manner corresponding to the tip 22 of the casing divider wall 16 discussed above with respect to the previous embodiment. Thus, the nozzle ring 24' of this embodiment is configured to provide improved leakage performance in substantially the same manner as the above-described embodiments (particularly, this is a corollary of Example B described above). For the sake of completeness, it should also be understood that the configurations 56, 58 of the nozzle ring divider wall 24' may have a corresponding axial overlap with the casing divider wall 16'. In particular, one or both of the formations 56 , 58 may radially overlap the housing partition wall 16 ′.

[0090] Figure 8 Another embodiment of a turbine housing assembly 12" according to the present invention is shown. The turbine housing assembly 12" includes a nozzle ring 15" and a housing divider wall 16", which define a leakage passage 34" therebetween. The housing divider wall 16" includes a circumferentially extending tip 22", which includes a formation 36". The nozzle ring 15" includes a nozzle ring divider wall 24" having a circumferentially extending tip 54". The tip 54" of the nozzle ring 24" includes a first formation 56" and a second formation 58", which define a recess 60" therebetween. The nozzle ring divider wall 24" and the housing divider wall 16" are aligned such that the formation 36" of the housing divider wall 16" is aligned with the midpoint of the recess 60" of the tip 54" of the nozzle ring divider wall 24". Thus, the configurations 56 ″, 58 ″ of the tip 54 ″ of the nozzle ring partition wall 24 ″ and the configuration 36 ″ of the tip 22 ″ of the housing partition wall 16 ″ are jointly designed to impart a meandering geometry to the leakage channel 34 ″. Figure 8 The nozzle ring 24 ″ of the embodiment provides improved leakage performance in substantially the same manner as the above-described embodiments.

[0091] Figure 9 A cross-sectional view of another embodiment of a turbine 2 according to the invention is shown. In addition to the addition of radially extending tabs 62 formed by the tips 22 of the housing partition walls 16, Figure 9The embodiment is substantially the same as the previously described embodiments. Radially extending tabs 62 are received within correspondingly shaped receptacles 64 formed by the nozzle ring divider wall 24. Receiving the tabs 62 within the receptacles 64 prevents the nozzle ring 15 from rotating relative to the turbine axis A, thereby ensuring that the nozzle ring 15 remains in a specific rotational orientation and does not move during use (e.g., due to the force of the exhaust gas on the nozzle vanes 28).

[0092] In the illustrated embodiment, the tab 62 is approximately half the thickness of the tip 22 of the turbine housing divider wall 16. Similarly, the socket 64 is approximately half the thickness of the nozzle ring divider wall 24. The tab 62 and the socket 64 are relatively small in angular extent about the turbine axis and, in particular, may define only a small portion of the circumference of the tip 22 of the housing divider wall 16 and the outer circumference of the nozzle ring divider wall 24. Preferably, each of the tab 62 and the socket 64 extends in a circumferential direction relative to the turbine axis A by no more than about 10% of the circumference of the tip 22 and / or the nozzle ring divider wall 24, and in particular, no more than about 5%.

[0093] Any number of tabs 62 and corresponding sockets 64 may be provided. In principle, the anti-rotational advantages provided by the tabs 62 and sockets 64 can be achieved with only a single tab 62 and corresponding socket 64. However, preferably, at least three sets of tabs 62 and corresponding sockets 64 are provided. When multiple tabs 62 and corresponding sockets 64 are provided, these may be equally spaced about the turbine axis A. It will be appreciated that positioning the tabs 62 and corresponding sockets 64 so that they are unequally spaced (i.e., introducing a degree of rotational asymmetry) may be beneficial. This ensures that the nozzle ring 15 can only be assembled to the turbine housing 14 in a single angular position.

[0094] It should be understood that, outside of the circumferential extent of the tabs 62 and receptacles 64, the geometries of the tips 22 of the nozzle ring divider wall 24 and the housing divider wall 16 may otherwise be unaffected and unchanged from the various embodiments described above. Furthermore, in other embodiments, the tabs 62 may be formed as radial extensions of, for example, the first configuration 36 or the second configuration 38. In such embodiments, the nozzle ring divider wall 24 may be sized so that it is the same width as the housing divider wall 16 so that a corresponding receptacle 64 may be formed in the nozzle ring divider wall 24 to receive the tabs 62.

[0095] although Figure 9The embodiments have been described as having tabs 62 formed by the housing divider wall 16 and receptacles 64 formed by the nozzle ring divider wall 24, but it should be understood that in other embodiments, the opposite arrangement is possible, such as having tabs 62 formed by the nozzle ring divider wall 24 and receptacles 64 formed by the housing divider wall 16. In still other embodiments, each of the housing divider wall 16 and the nozzle ring divider wall 24 may define a mixing assembly of tabs 62 and receptacles 64.

[0096] With respect to all of the embodiments discussed above, although the configuration has been described as being in the form of a radially extending flange of the housing divider wall 16 or the nozzle ring divider wall 24, it should be understood that essentially any mechanical structure may be used to impart a tortuous geometry to the leakage path 34. Such configurations may include, among others, edges, protrusions, recesses, labyrinth seals, steps, etc. Such configurations may be integrally formed with the housing divider wall 16 or the nozzle ring divider wall 24, or may be provided as a separate component.

[0097] While the above embodiments contemplate the use of a pair of configurations to define a tortuous geometry, it will be appreciated that the principles of the present invention will work equally well using only a single configuration, provided such configuration is capable of imparting a tortuous geometry to the leakage path 34 .

[0098] While the nozzle ring 15 described above has been shown as a single, unitary component, it will be appreciated that, in practice, the nozzle ring 15 may be constructed from a plurality of separate components that are assembled together to define separate nozzle rings.

Claims

1. A turbine housing, comprising: a casing divider wall extending circumferentially about a central axis of the turbine casing, the casing divider wall axially separating a first inlet volute and a second inlet volute; wherein the housing divider wall includes a circumferentially extending tip configured to receive a nozzle ring, the tip being shaped to impart a tortuous geometry on a leakage path defined between the first inlet volute and the second inlet volute.

2. The turbine housing according to claim 1, wherein: The tip includes a configuration configured to impart a tortuous geometry on the leakage path.

3. The turbine housing according to claim 1 or 2, wherein: The configuration includes a stepped portion extending circumferentially about the central axis, the stepped portion defining at least a portion of the leakage path.

4. The turbine housing according to claim 3, wherein: The stepped portion defines an inner edge, and wherein the inner edge is arcuate.

5. The turbine housing according to claim 3 or 4, wherein: The step portion defines an outer edge, and wherein the outer edge is sharp.

6. The turbine housing according to any one of claims 2 to 5, wherein: The configuration is a first configuration; and The tip also includes a second formation defining at least a portion of the leakage path, the second formation being configured to combine with the first formation to impart a tortuous geometry on the leakage path.

7. The turbine housing according to claim 6, wherein: The second configuration is a second stepped portion extending circumferentially about the central axis, the second stepped portion defining at least a portion of the leakage path.

8. The turbine housing according to claim 7, wherein: The second step portion defines an inner edge, and wherein the inner edge is arcuate.

9. The turbine housing according to claim 7 or 8, wherein: The second step portion defines an outer edge, and wherein the outer edge is sharp.

10. The turbine housing according to any one of claims 6 to 9, wherein The second configuration is positioned opposite the first configuration about a plane perpendicular to the central axis so as to define a recess between the first configuration and the second configuration.

11. A turbine housing according to any preceding claim, wherein The tip of the partition wall includes a tab extending in a radial direction toward the central axis.

12. A turbine housing assembly comprising: A turbine housing according to any preceding claim; as well as a nozzle ring comprising a nozzle ring divider wall and at least one nozzle vane extending from the nozzle ring divider wall; The nozzle ring divider wall is aligned with the tip of the housing divider wall such that the tips of the nozzle ring divider wall and the housing divider wall define the leakage path therebetween.

13. The turbine housing assembly of claim 12, wherein: The configuration defines an outer radius (R o ) and inner radius (R i ); The nozzle ring divider wall defines the nozzle ring radius (R n );and The outer radius (R o ) is larger than the nozzle ring radius (R n ).

14. The turbine housing assembly according to claim 13, wherein: The outer radius (R o ) than the nozzle ring radius (R n ) is about 0.5% to about 1.5% and is preferably greater than the nozzle ring radius (R n ) approximately 0.9% or approximately 1%.

15. A turbine housing assembly according to claim 13 or 14, wherein: The inner radius (R i ) is equal to or greater than the nozzle ring radius (R n ).

16. The turbine housing assembly of claim 15, wherein: The inner radius (R i ) than the nozzle ring radius (R n ) is about 0.1% to about 0.5%, and is preferably greater than the nozzle ring radius (R n ) about 0.2% or 0.3%.

17. A turbine housing assembly according to claim 15 or 16, wherein: The turbine is a turbine according to any one of claims 6 to 10; The inner radius (R i ) is the inner radius of the first configuration and defines a first inner radius (R 1，i ); The second configuration defines a second inner radius (R 2，i ); The outer radius (R o ) is the common outer radius of the first configuration and the second configuration; The first inner radius (R 1，i ) and the second inner radius (R 2，i ) is equal to or greater than the nozzle ring radius (R n ).

18. The turbine housing assembly of claim 17, wherein: The first inner radius (R 1，i ) and the second inner radius (R 2，i ) than the nozzle ring radius (R n ) is about 0.1% to about 0.5%, and is preferably greater than the nozzle ring radius (R n ) is approximately 0.2% or 0.18%.

19. The turbine housing assembly according to claim 13 or 14, wherein: The inner radius (R i ) is smaller than the nozzle ring radius (R n ).

20. The turbine housing assembly of claim 19, wherein: The inner radius (R i ) than the nozzle ring radius (R n ) is about 0.3% to about 1.5% smaller and is preferably smaller than the nozzle ring radius (R n ) is less than approximately 0.4%, less than approximately 0.7% or less than approximately 1.1%.

21. A turbine housing assembly according to claim 19 or 20, wherein: The turbine is a turbine according to any one of claims 6 to 11; The first configuration defines a first inner radius (R 1，i ); The inner radius (R i ) is the inner radius of the second configuration and defines a second inner radius (R 2，i ); The outer radius (R o ) is the common outer radius of the first configuration and the second configuration; The first inner radius (R 1，i ) is equal to or greater than the nozzle ring radius (R n );and The second inner radius (R 2，i ) is smaller than the nozzle ring radius (R n ).

22. The turbine housing assembly of claim 21, wherein: The first inner radius (R 1，i ) than the nozzle ring radius (R n ) is about 0.1% to about 0.5%, and is preferably greater than the nozzle ring radius (R n ) is approximately 0.2% or 0.18%.

23. A turbine housing assembly according to claim 21 or 22, wherein: The second inner radius (R 2，i ) than the nozzle ring radius (R n ) is about 0.3% to about 1.5% smaller and is preferably smaller than the nozzle ring radius (R n ) is less than approximately 0.4%, less than approximately 0.7% or less than approximately 1.1%.

24. The turbine housing assembly of claim 13 or 14, wherein: The turbine is a turbine according to any one of claims 6 to 11; The inner radius (R i ) is the inner radius of the first configuration and defines a first inner radius (R 1，i ); The second configuration defines a second inner radius (R 2，i ); The outer radius (R o ) is a common outer radius of the first configuration and the second configuration; The first inner radius (R 1，i ) is equal to or less than the nozzle ring radius (R n );and The second inner radius (R 2，i ) is equal to or less than the nozzle ring radius (R n ).

25. The turbine housing assembly of claim 24, wherein: The first inner radius (R 1，i ) and the second inner radius (R 2，i ) than the nozzle ring radius (R n ) is about 0.3% to about 1.5% smaller and is preferably smaller than the nozzle ring radius (R n ) is less than approximately 0.4%, less than approximately 0.7% or less than approximately 1.1%.

26. A turbine housing assembly according to any one of claims 12 to 25, wherein: The turbine is a turbine according to any one of claims 6 to 11; and wherein the nozzle ring divider wall is axially aligned with a midpoint between the first configuration and the second configuration.

27. A nozzle ring for a dual inlet turbine, the dual inlet turbine comprising a first inlet volute and a second inlet volute separated by a casing partition wall, the nozzle ring comprising: a nozzle ring divider wall extending circumferentially about a central axis of the nozzle ring; at least one nozzle vane extending from the nozzle ring divider wall; wherein the nozzle ring divider wall includes a circumferentially extending tip configured to be received by the casing divider wall, the tip being shaped to impart a tortuous geometry on a leakage path defined between the first inlet volute and the second inlet volute.

28. The nozzle ring of claim 27, wherein: The tip includes a configuration configured to impart a tortuous geometry on the leakage path.

29. The nozzle ring of claim 28, wherein The configuration includes a stepped portion extending circumferentially about the central axis, the stepped portion defining at least a portion of the leakage path.

30. The nozzle ring of claim 29, wherein: The stepped portion defines an inner edge, and wherein the inner edge is arcuate.

31. A nozzle ring according to claim 29 or 30, wherein The step portion defines an outer edge, and the outer edge is sharp.

32. The nozzle ring according to any one of claims 27 to 31 , wherein: The configuration is a first configuration; and The tip also includes a second configuration defining at least a portion of the leakage path, the second configuration being configured to, in combination with the first configuration, impart a tortuous geometry on the leakage path.

33. The nozzle ring of claim 32, wherein: The second configuration is a second stepped portion extending circumferentially about the central axis, the second stepped portion defining at least a portion of the leakage path.

34. The nozzle ring of claim 33, wherein: The second step portion defines an inner edge, and wherein the inner edge is arcuate.

35. A nozzle ring according to claim 33 or 34, wherein The second step portion defines an outer edge, and wherein the outer edge is sharp.

36. A nozzle ring according to any one of claims 32 to 35, wherein The second configuration is positioned opposite the first configuration about a plane perpendicular to the central axis so as to define a recess between the first configuration and the second configuration.

37. A nozzle ring according to any one of claims 27 to 36, wherein The nozzle ring divider wall includes a socket configured to receive a corresponding tab of the housing divider wall.

38. A turbine housing assembly comprising: A nozzle ring according to any one of claims 27 to 37; as well as a turbine housing including a housing divider wall extending circumferentially about a central axis of the turbine housing, the housing divider wall axially dividing a turbine inlet into a first inlet volute and a second inlet volute, wherein the housing divider wall includes a circumferentially extending tip; wherein the tip of the nozzle ring partition wall is aligned with the tip of the housing partition wall such that the tip of the nozzle ring partition wall and the tip of the housing partition wall define the leakage channel therebetween.

39. A turbine housing assembly comprising: A turbine housing according to any one of claims 1 to 11; as well as A nozzle ring according to any one of claims 27 to 37; wherein the tip of the nozzle ring partition wall is aligned with the tip of the housing partition wall such that the tip of the nozzle ring partition wall and the tip of the housing partition wall define the leakage channel therebetween.

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