Outlet guide vane cooler

Abstract

An outlet guide vane (OGV) structure for a gas turbine engine includes a plurality of radially extending guide vanes (30), at least one guide vane including at least one inlet (35) and at least one outlet (36), wherein the at least one inlet allows air to pass into at least one internal cavity (37) within the guide vane, and the at least one outlet allows air to exit the at least one internal cavity, wherein the inlet is disposed upstream of the outlet in a direction of airflow over the guide vane in use.

Description

Technical Field

[0001] This invention relates to an improved cooling arrangement for a gas turbine engine, and more particularly, but not exclusively, to an improved cooling arrangement for a geared turbofan engine. More specifically, the invention relates to a cooling arrangement that creates new surfaces available for heat transfer while resisting damage during flight. Background Technology

[0002] Geared turbofan engines offer higher propulsive efficiency compared to conventional gas turbine engines. This is achieved by providing a gearbox located between the fan (at the front of the engine) and the engine's drive shaft (which itself is driven by a turbine at the rear of the engine). Rotation of the drive shaft causes the gearbox to rotate, which in turn causes the fan to rotate.

[0003] Depending on the gearbox used, the gear ratio can be selected to match the engine's optimal speed and / or maximize the fan's speed. For example, rotary gearboxes offer extremely high gear ratios within a compact housing and are commonly used in geared turbofan designs.

[0004] Operating the gearbox connected to the drive shaft of the gas turbine engine results in extremely high speeds and corresponding heat generation. Although the efficiency of the gearbox may be very high (on the order of 99.5%), energy loss is dissipated as heat.

[0005] To cool the gearbox, conventional layouts utilize cold air in the engine's bypass passage to cool the gearbox and remove and control heat. This allows for convenient gearbox cooling using cold air in the bypass passage. An oil passage from the gearbox to the heat exchanger, located near the engine's external bypass passage, is used to exchange heat from the oil in the gearbox to the cold air passing through the bypass passage. This allows for gearbox cooling.

[0006] While this arrangement increases the weight and complexity of the bypass passage, it advantageously allows for convenient cooling of the gearbox using a large volume of cold air passing through the engine at high speed. Such a conventional arrangement has sufficient cooling capacity to cool larger and higher gear ratio gearboxes. However, positioning the cooling passages within the bypass passage exposes them to impacts from any debris or ice carried by the high-speed airflow. Therefore, the passages need to be sufficiently robust and rigid to resist any impact damage. Increasing strength requires even more robust passages, but this compromises the passage's heat transfer properties.

[0007] The inventors have designed an alternative cooling arrangement for bypass channels that utilizes outlet guide vanes for heat dissipation while addressing concerns about impact damage. This arrangement allows for more compact and efficient cooling of gearboxes, such as turnaround gearboxes, with fewer components and less complexity. It also allows for weight reduction in the cooling system used for the gearbox, which advantageously reduces the overall engine weight. Summary of the Invention

[0008] Various aspects of the invention are set forth in this application.

[0009] From a first aspect, an outlet guide vane (OGV) structure for a gas turbine engine is provided, the structure comprising a plurality of radially extending guide vanes, wherein at least one guide vane includes at least one inlet and at least one outlet, wherein the at least one inlet allows air to enter into at least one cavity within the guide vane, and the at least one outlet allows air to exit from the at least one cavity, wherein the inlet is arranged upstream of the outlet in the airflow direction above the guide vane during use.

[0010] Therefore, according to the invention described herein, an arrangement is provided in which an inner cavity leading to an outlet guide vane is provided to contain one or more cooling channels or conduits. Air passing through the guide vane structure can advantageously be allowed to pass through the cavity of one or more vanes, resulting in heat transfer from the conduits contained within the respective vanes. As air passes through the outlet guide vane structure, air flows into and out of the cavity or each cavity.

[0011] Each guide vane of this structure may include a pressure surface defining one side of the vane and opposing suction surfaces defining the opposite side of the vane. The cavity can then be conveniently located between these two opposing sides of the vane. In effect, these two surfaces provide a protective housing for the cavity and also provide a heat transfer surface that air can flow over as it passes through the engine.

[0012] Advantageously, the inlet for each blade can be arranged to extend through the pressure surface of that blade. Specifically, the inlet is located on a portion of the pressure surface that is not aligned with the airflow axis passing through the engine during engine operation. By positioning the inlet behind the leading edge of the blade and on the pressure surface, the inlet is shielded or protected from foreign debris that may travel along the engine axis. Any such object would therefore need to significantly change direction to enter the inlet, and due to its velocity and orientation along the engine axis (being entrained in the airflow), such an object is unlikely to enter the inlet.

[0013] There may be a single inlet or multiple separate inlets, which extend along the blade, for example, in a radial direction away from the hub of the OGV structure. The one or more inlets may be arranged in the first 50% of the blade chord length measured from the leading edge to the trailing edge. Similarly, the at least one outlet may be arranged in the last 50% of the blade chord length measured from the leading edge to the trailing edge. This configuration provides a flow path from the upstream inlet to the downstream outlet when measured along the blade chord length. Air can then flow into the one or more blade cavities through the inlets and out of the one or more cavities through the one or more outlets to provide a heat transfer path.

[0014] Advantageously, the at least one inlet can be arranged within the first 25% of the blade chord length measured from the leading edge to the trailing edge. This allows air to enter one or more blade cavities towards the leading edge (within the first 25% of the chord length), maximizing the volume of inlet air received within the cavity and, additionally, minimizing the risk of foreign objects entering the inlet. This is due to the airfoil shape of the blade, where the leading edge includes a curved surface for deflecting the impinging air. This curved surface minimizes the risk of objects traveling along the engine axis entering the inlet.

[0015] More specifically, the structure may advantageously include a main axis corresponding to the axis of the air entering the engine during operation (this is the direction in which the air travels into the engine and is likely to carry foreign objects or debris). A portion of the leading edge of the suction surface of at least one guide vane extends in a direction substantially perpendicular to this main axis to overlap with the pressure surface of the vane, such that the pressure surface of the vane is not visible when viewed along the main axis of the structure. In operation, the airflow entering the engine is not perfectly straight or linear. More specifically, the airflow entering the engine is not perfectly still. Crosswinds, takeoff rotation, etc., are events during operation where there may be slight differences between the main rotor axis and the airflow entering the engine. However, they are generally or substantially the same. The relationship between the cavity inlet and the engine main rotor axis is somewhat fixed. The intended meaning of the arrangement described herein is that, due to the aforementioned spacing, the air entering the engine during operation generally cannot directly enter the guide vane cavity.

[0016] In practice, the suction surface of the blade bends around its leading edge and then intersects with the pressure surface of the blade, which defines the side of the blade opposite the suction side. This suction surface defines the leading edge of the blade, which conceals or covers the pressure surface when the blade is viewed along the engine's main axis. Therefore, the first portion of the pressure surface, measured along its chord, is not visible because it is concealed behind the suction surface. More specifically, the inlet must be offset relative to a line extending parallel to the axis of the airflow entering the engine, and this line contacts the leading edge of the blade at its outermost point (where the suction and pressure surfaces converge or merge).

[0017] Another way to describe this arrangement is that, due to the blade curvature, the pressure side of the fan outlet guide vanes is usually not visible when the engine inlet is viewed from a distance.

[0018] The location of the inlet can be selected based on the engine's expected airflow characteristics to prevent objects or debris from being drawn into the inlet leading to one or more blade chambers. Therefore, the leading edge of at least one inlet can be spaced a predetermined distance from the farthest edge of the suction surface leading edge, wherein this distance is measured in a direction perpendicular to the main axis of the structure.

[0019] The internal space of each blade can be arranged as a single volume or cavity, or it can be subdivided into one or more cavities, thereby containing, for example, internal structural components or parts.

[0020] To achieve heat transfer within the cavity, the cooling medium flows through one or more separate ducts passing through the blade cavity. Therefore, the cavity may include at least one duct arranged in use to allow fluid to flow through it. This fluid can be any suitable fluid that allows heat to be transferred from the fluid through the duct to the airflow passing through the blade cavity. This thus allows heat transfer from the fluid to the air. In practice, the pipes / ducts within the blade are used to allow coolant (in the form of a fluid, etc.) to flow through the blade's cavity to induce cooling.

[0021] These conduits can be arranged within the blade in any suitable path or configuration. For example, the cavity may include:

[0022] (a) A plurality of conduits, each extending radially through the blade, and each conduit being spaced apart along a length measured along the chord of the guide blade; and / or

[0023] (b) A plurality of ducts, each extending along a portion of the guide vane measured along the chord of the vane, and each duct being radially separated by the vane.

[0024] In arrangement (a), each duct extends away from the hub of the OGV structure and dissipates heat as air impacts the side surface of each duct. In arrangement (b), each duct extends along a portion of the chord length of the blade (i.e., typically along the airflow direction within the cavity) and dissipates heat as air travels along the side surface of the duct.

[0025] To provide a flow path for coolant to the aircraft's gearbox or motor within the ducts, these ducts can be arranged to exit from and extend toward a portion of the blade, which is close to the central hub portion of the OGV structure to which each blade is attached. Coolant can then flow into the hub portion of the OGV structure and radially outward into each blade. The coolant can then return, providing a corresponding flow path through the engine to the components to be cooled by the arrangement described herein.

[0026] In another arrangement, these ducts can be arranged to extend radially inward from the outer periphery of the OGV structure toward the engine's central axis; that is, these ducts can be arranged to extend from and return to the outer periphery of the OGV within the blades. This provides the advantage that an OGV can be replaced during maintenance without disassembling most of the engine.

[0027] In this arrangement, to allow coolant to flow from the blades into the gearbox (or heat exchanger), the ducts can be arranged as part of a pylon that physically connects the engine to the aircraft wing. This pylon contains internal space that allows the ducts to flow from the outer periphery of the blades to and from the gearbox. Therefore, the gearbox can be cooled by the outlet guide vanes, and each guide vane cooling arrangement can be easily accessed from outside the engine.

[0028] The ducts within each blade can be arranged in various locations within the blade cavity. In one arrangement, these ducts can contact the inner surfaces of the pressure and / or suction surfaces of the guide vanes within the cavity. Advantageously, by positioning some or all of the ducts in direct contact with the pressure and / or suction surfaces, wall conduction can allow for highly efficient heat transfer. As high-speed air passes over the externally facing surfaces of the pressure and suction surfaces, these surfaces are cooled to or near ambient air temperature, which is significantly lower than the typical oil circuit temperature of a gas turbine at higher altitudes. Arranging these ducts along the inner surfaces of the blades allows these outer surfaces to function as effective radiators to remove heat from the coolant or fluid within the ducts.

[0029] In an alternative arrangement, these conduits can be positioned to extend through and pass through each cavity, such that the outer surface of each conduit is exposed to the airflow within the cavity. Here, heat is dissipated into the airflow within the cavity.

[0030] Each duct can be arranged within each blade in any suitable path. For example, the duct can have a fluid inlet and a fluid outlet, and the duct can alternate radially along the chord direction of the guide blade, i.e., the duct can flow backward from the hub and forward toward the hub while extending along the chord length of the blade (effectively a serpentine structure within the blade). Heat can then be dissipated throughout the entire volume within the blade (or against the pressure and suction surfaces).

[0031] In an arrangement where the blades include multiple conduits, a manifold can be provided to allow fluid or coolant to flow efficiently from a central conduit connected to a gearbox (e.g.) to the multiple conduits within the blade. For example, the blade, or each blade, may include multiple conduits and a manifold, wherein the multiple conduits extend radially within the blade, and the manifold is located at each radial end of the multiple conduits to allow fluid communication between adjacent conduits. In such an arrangement, the manifold can be positioned at any radial end of the blade to distribute coolant to the individual conduits, and then the flow is combined such that the cooled fluid returns to the gearbox.

[0032] The cross-sectional area of ​​these inlets can be smaller than the cross-sectional area of ​​the cavity located between the inlet and outlet, measured along the chord length of the guide vane. The natural shape of the guide vane allows for a thinner profile near the leading and trailing edges.

[0033] The location, size, and profile of these inlets can be adjusted according to the operating conditions and airflow within the engine. For example, multiple inlets can be positioned close to the leading edge of the pressure surface of the guide vane. These inlets can also be radially spaced along the length of the guide vane. Thus, multiple discrete inlets can be arranged to extend radially along each vane. This advantageously allows for improved structural integrity of the vane and, if multiple cavities are included, additionally allows airflow into different cavities within the vane.

[0034] Similarly, multiple outlets can be positioned close to the trailing edge of the guide vane and radially spaced along the length of the guide vane. The inlet can then be in fluid communication with the corresponding outlet (for airflow). A combination of several chambers can be used within the vane, each chamber having an independent inlet and outlet.

[0035] Advantageously, and with reference to Figure 15A and Figure 15B The size of the inlet measured along the chord direction can be smaller than the size of the inlet measured along the radial direction, i.e., L 径向 >L 弦In fact, these inlets are longer when measured radially than when measured chordally. This improves airflow efficiency and minimizes turbulence. By comparison, Figure 15B The opposite configuration with a less optimized arrangement is shown.

[0036] It will be appreciated that the invention described herein is particularly relevant to the cooling of geared turbofan engines, and one aspect of the invention extends to such engines. However, additionally and / or alternatively, this arrangement can be used to cool other components of the engine, such as electric motors, oil bearings, etc. Such electric motors can be used for propulsion.

[0037] From another aspect of the invention described herein, a method for cooling a reduction gearbox of a geared turbofan engine is provided, wherein coolant is circulated to a cooling arrangement structure including the outlet guide vane structure described herein.

[0038] From another aspect of the invention described herein, a method is provided for a cooling fan propulsion arrangement of one or more electric motors, wherein coolant is caused to flow into the cooling arrangement including the outlet guide vane structure described herein.

[0039] The coolant flow to individual blades can be selectively controlled through a suitable valve arrangement. Therefore, these blades and the amount of cooling can be selectively activated to achieve cooling. For example, during engine startup, it may be desirable to deactivate all or part of the cooling to allow oil temperatures, etc., to reach operating temperatures. The cooling arrangement described herein can then be activated and controlled to regulate temperature levels according to operational performance requirements.

[0040] The cooling arrangement described in this article offers numerous advantages, including:

[0041] 1. Reduced number of parts. This reduces the number of components typically required to cool the gearbox in a geared turbofan engine, including the piping system needed to direct fluid flow to bypass channels and back.

[0042] 2. Compact solution. This arrangement makes full use of the wetted surface area of ​​the OGV (the surface over which air flows) to achieve effective heat exchange.

[0043] 3. Enhanced functionality. OGV features integrated heat exchange functionality.

[0044] 4. Reduce oil foaming. The compact layout reduces the likelihood of air and oil mixing together and forming "foam" inside the gearbox.

[0045] 5. Reduce oil volume. Reducing the layout dimensions allows for a reduction in the amount of oil required to cool the gearbox.

[0046] The cooling arrangement described herein can be additionally adapted to be in fluid communication with a heat exchanger in or around a bypass passage of the engine. A fluid-carrying passage near the airflow within the bypass passage can conveniently radiate heat from the cooling fluid to the high-speed airflow within the bypass passage. By fluidly connecting the forward center body heat exchanger described herein to this bypass passage arrangement, additional cooling can be selectively operated at extreme temperatures. This enhances the arrangement described herein to provide a high-capacity cooling configuration.

[0047] The invention described herein can be extended to gearbox control arrangements in which a fluid control valve can be operated to achieve cooling in response to a temperature sensor within the gearbox or within the gearbox fluid. Attached Figure Description

[0048] One or more embodiments of the invention will now be described by way of example only and with reference to the following drawings, in which:

[0049] Figure 1 A cross-section of a geared turbofan engine is shown;

[0050] Figure 2A and Figure 2B An end view of the outlet guide vane structure, viewed along the main axis, corresponds to the air axis entering the engine during operation;

[0051] Figure 3 It shows Figure 2A and Figure 2B Another view of the outlet guide vane structure;

[0052] Figure 4 Showing from Figure 2A , Figure 2B and Figure 3 A single guide vane of the structure shown;

[0053] Figure 5 It shows crossing Figure 4 The cross-section of the guide vane;

[0054] Figure 6 It shows Figure 5 A series of adjacent guide vanes;

[0055] Figure 7 Further details of the modified guide vane structure of the invention described herein are shown;

[0056] Figure 8 A cross-section of the modified guide vane, including internal cooling channels, is shown.

[0057] Figure 9 An embodiment of a cooling channel within a modified guide vane is shown;

[0058] Figure 10 The manifold and cooling channel arrangement of one embodiment of the modified guide vanes is shown;

[0059] Figure 11A , Figure 11B and Figure 11C An alternative embodiment of a cooling channel with modified guide vanes is shown;

[0060] Figure 12A and Figure 12B The inlet and outlet arrangement of the guide vanes for the modified version described herein is shown, wherein Figure 12B It is a cross-section showing the outlines of the inlet and outlet ports;

[0061] Figure 13 This is an end view showing the OGV structure with adjacent modified guide vane cooling connected in series; and

[0062] Figure 14 This is a cross-section through the guide vanes, showing the cross-sectional areas of the cavity's inlet, outlet, and central region; and

[0063] Figure 15A and Figure 15B The optimal and suboptimal configurations of the guide vane inlet profile are shown (respectively).

[0064] Any references to prior art documents in this specification should not be construed as an admission that such prior art is widely known or forms part of common general knowledge in the art. As used herein, the words “comprising,” “including,” and similar terms should not be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean “including, but not limited to,” the specific examples provided herein. The invention is further described with reference to the examples described herein. It should be understood that the claimed invention is not intended to be limited in any way to these examples. It will also be appreciated that the invention covers not only the individual embodiments but also combinations of the embodiments described herein. Detailed Implementation

[0065] Figure 1 A cross-section through a geared turbofan engine 2 is shown. The operation of a geared turbofan engine will be understood by those skilled in the art of engine design. However, for clarity, in this application, engine 2 includes a central core 15 centered on a central axis 13 of engine 2. This engine core includes a forward-facing portion that rotates and supports radially extending fan blades 3. These fan blades extend from the core into a bypass passage 8 surrounding the core 15.

[0066] These fan blades are rotatably mounted relative to the core via a planetary gearbox 14 (also called a planetary gearbox). The planetary gearbox receives rotational input from the engine's central shaft and has a predetermined gear ratio to control the rotational speed of the fan blades 3. The engine includes an intake duct 16 through which air flows via guide vanes 17 to the compressor 5 and a combustion chamber (not shown) downstream of the intake duct 16.

[0067] The combustion process drives a turbine (not shown), which in turn drives a central shaft (arranged along axis 13), which in turn drives the input to the planetary gearbox 14. Due to the high rotational speed of the central shaft, heat is generated in the planetary gearbox. This heat is typically dissipated through an oil cooling system that circulates oil from the gearbox to a heat exchanger located in the engine compartment. Thus, the circulating oil cools the gearbox, allowing continued operation.

[0068] The invention described herein relates to a modified arrangement of an outlet guide vane 18.

[0069] The outlet guide vane 18 enters from the outer surface of the core 15 and passes through the bypass channel 8 to reach the bypass channel wall 19. The channel wall 19 is typically divided into several sections and is sometimes referred to as the fan housing, rear fan housing, and similar terms in the art. Figure 2A and Figure 2B As shown, the outlet guide vanes extend around the periphery of the core.

[0070] Figure 2A This is a front-view rear view of the entire Outlet Guide Vane (OGV) assembly 20. Assembly 20 includes an outer ring 21, which is typically... Figure 1 The bypass channel wall 19 shown is a sub-section, and this sub-section is connected to... Figure 1 The external body of the bypass passage 8 is shown. Component 20 also includes an inner frame structure (or hub) 22, which is connected to bearings and supports within the core and defines a central portion through which the central shaft can pass. This component forms a structural part of the engine.

[0071] Between the outer ring 21 and the inner frame structure 22, the OGV assembly 20 includes a plurality of individual guide vanes 23 that structurally connect the outer ring 21 and the inner frame structure 22. Each vane is arranged to control the direction of airflow within the bypass channel. More specifically, these vanes are configured with a specific profile that allows airflow away from the fan blades 3 (e.g., ...). Figure 1The air is redirected (as shown) to exit the engine in a direction generally parallel to the engine axis 13. This maximizes the thrust generated by the engine by ensuring that the air leaving the bypass duct is in a rearward or rearward direction. Some variations of the blade profile can be used around the periphery to improve airflow around the structure allowing the engine core ducts and the underwing mounting structures located in the bypass duct. Therefore, the blade profile does not necessarily have to be the same for all exit guide vanes 23.

[0072] Figure 3 It shows that it does not have Figure 2A and Figure 2B The outer ring of the OGV assembly is shown. Individual OGV23s are shown. In this arrangement, the blades are equidistantly spaced to individually split and deflect the airflow through the assembly. The accompanying figure illustrates... Figure 2A and Figure 2B Some of the 48 guide vanes shown in the assembly may be used, but different numbers of vanes may be used depending on the engine size and architecture. Another option is a configuration with some OGVs with a first chord length and at least one additional vane configuration with a second chord length positioned between the two vanes with the first chord length. The arrangement of these vanes depends on the specific engine design.

[0073] Figure 4 Showing from Figure 3 A single outlet guide vane 23 is shown, but attachment features are not shown.

[0074] The blade 23 has a proximal end or root 24 for connection to the inner ring or hub of the assembly 20. The blade 23 has a corresponding and opposite outer end 25 for connection to the outer ring of the assembly 20. Each blade 23 also has a forward-facing leading (or upstream / front) edge 26 and a rearward-facing trailing (or downstream / rear) edge 27, wherein the forward-facing leading edge faces forward in the direction of flight of the aircraft, and the rearward-facing trailing edge faces the exhaust of the engine.

[0075] like Figure 4 As shown, the blade has a profile that curves from the leading edge 26 to the trailing edge 27. The curvature (as shown) is more pronounced at the leading edge to influence the deflection of air as it impacts the sides of the blade. The sides of the blade are in the form of a pressure side 29 and a suction side 28.

[0076] As the aircraft moves through the air, the air approaches the engine, is pressurized by the fan, and enters a vortex or cyclic motion. The vortex and pressurized air then impact the leading edge of blade 23. The air then travels along the pressure side 29 of the blade and along the opposing suction side 28, exiting the blade from the trailing edge 23 in a direction different from the impact direction on the blade. This is indicated by arrows A and A'.

[0077] Figure 4 This illustrates a conventional configuration for outlet guide vanes in a gas turbine engine, including a geared gas turbine engine. In such a conventional arrangement, the aerodynamic and thermal functions of the guide vanes are solely used to control the direction of airflow through the bypass channel to increase thrust.

[0078] The invention described herein relates to an enhanced outlet guide vane assembly that not only provides conventional air direction control functions, but also additionally provides a cooling arrangement structure for an engine gearbox as described above.

[0079] Furthermore, the enhanced OGV arrangement described herein provides a highly efficient heat transfer arrangement that conveniently prevents foreign objects in the bypass airflow from damaging the cooling arrangement.

[0080] Reference Figures 5 to 12B Describe the enhanced OGV layout structure.

[0081] Figure 5 A cross-section through the enhanced exit guide vane according to the invention described herein is shown.

[0082] The modified guide vane 30 includes a leading edge 31 and a trailing edge 32. In use, air travels from the leading edge along the side surface of the vane to the trailing edge. The modified vane 30 includes a pressure surface or pressure side 33 and an opposing suction side or suction surface 34. The pressure side of the vane is the side on which air impacts when it flows through the engine and contacts the vane.

[0083] However, with, for example Figure 4 Unlike conventional blades, the modified blade 30 includes an inlet orifice 35 near the leading edge 31 and an opposing outlet orifice 36 near the trailing edge 32. The inlet 35 and outlet 36 provide a flow path 37 within the blade 30. In effect, air can flow not only along the outer surface of the blade 30, but also additionally within the blade and along the cavity 37 defined between the pressure surface and the suction surface of the blade.

[0084] In use, air approaches the modified blade 30, causing the air to change direction from the leading edge to the trailing edge. Additionally, air can enter the blade and pass through one or more cavities within the blade (defined between the pressure surface and the suction surface) and reach an outlet at the trailing edge of the blade.

[0085] Figure 6Multiple adjacent modified blades 30a, 30b, 30c, and 30d are shown. Each adjacent blade defines spaces 30a', 30b', 30c', and 30d' between them, through which air in a bypass channel can flow. Additionally, each blade provides internal channels 31a, 31b, 31c, and 31d through which air can flow.

[0086] The internal channels 31a, 31b, 31c and 31d of the modified blades 30a-30d allow for the formation of a highly efficient and effective cooling zone within each blade.

[0087] Figure 7 A cross-section through the modified blade 30 is shown. As shown, the modified blade 30 includes a leading edge LE and a trailing edge TE. Arrow FD indicates the aircraft's flight axis and the direction in which a foreign object travels with the airflow without fan interference. Arrow SD indicates the flow axis of the vortex air leaving the fan blades and traveling along the bypass channel. The vortex is caused by the interaction between the incoming airflow and the high-speed rotating fan blades, driving the airflow along the bypass channel and out of the engine.

[0088] Foreign objects traveling into the engine may collide with guide vanes or other support vanes extending across the bypass passage. This type of damage is referred to in the art as FOD or foreign object damage.

[0089] FOD can be caused by a series of debris or objects in the air, including runway debris, sand, ice, or even birds.

[0090] According to the invention described herein, these blades are additionally used to provide a cooling function. Specifically, the inner cavity 37 is used to accommodate a plurality of cooling channels. These cooling channels are arranged to carry coolant that can transfer heat from the gearbox (or the like) along conduits to the blade cavity 37 or the channels within each blade cavity 37.

[0091] Because the invention provides air passages through the blades, high-speed air travels through the blade cavities when the engine is running. This high-speed air provides a convenient radiator to remove heat from the outer surfaces of the passages located within cavity 37. Cool airflow surrounding the outer surfaces of these passages absorbs heat from the outer surfaces of the passages. This thereby provides cooling for the cooling medium contained within each passage.

[0092] Figure 7 Multiple coolant channels 38 are shown. Figure 7 In the illustrated embodiment, a series of channels 38 are shown extending along the inner cavity 37 of the blade. The open LE of the blade allows air to enter the cavity and flow above and around the channels before exiting the TE of the blade.

[0093] Severe (i.e., relatively large) foreign objects are more likely to travel in the direction of arrow FD; that is, the foreign object is sucked into the engine and travels at high speed along the bypass channel in a direction roughly parallel to the direction of flight (i.e., parallel to the engine axis). Conversely, airflow in the vortex direction is less likely to carry severe foreign objects. The inlet 35 of the blade cavity is configured to capture a portion of the vortex air and avoid FOD in the direction of flight. Therefore, this minimizes the risk of the blade cavity receiving foreign objects that could damage the internal passage 38. In the case of hail as a foreign object, if the hail interacts with the fan, it will be dispersed into smaller and less severe fragments, resulting in particles with vortex motion. A similar situation applies to the case of birds as foreign objects, where the mass entering the vortex motion will cause a lower degree of harmful effect because the impact is less concentrated.

[0094] Advantageously, since the internal channels 38 are protected from FOD by selectively entering the blade cavity, these internal channels 38 can have thinner walls, which enhances the heat transfer properties of each channel and reduces weight.

[0095] Refer again Figure 7 It can be observed that the inlet 35 leading to the blade cavity 37 is located downstream of the leading edge end 39 on the suction side of the blade and upstream of the leading edge end 40 on the pressure side of the blade. More specifically, the distance d indicates the distance d between the suction side end 39 and the pressure side end 40. This spacing or distance means that the suction side end overlaps with the pressure side end to ensure that foreign objects cannot enter the blade cavity 37; such foreign objects cannot bypass the sharp corner at the leading edge to enter the inner cavity of the blade.

[0096] By providing a concealed or hidden inlet 37 (viewed from the leading edge of the blade toward the trailing edge) behind a portion of the leading edge on the suction side of the blade, any debris traveling along the airflow axis FD will not easily enter the blade cavity. Thus, the internal coolant passages located within the blade cavity are protected from collisions with FOD or debris traveling along the engine axis FD.

[0097] Conversely, swirling air (as indicated by arrow SD) is less likely to carry debris or foreign objects. This air has a greater chance of entering cavity 37 of blade 30.

[0098] Figure 8 An example embodiment of the coolant passage within the modified guide vane described herein is shown. Figure 8 The examples shown include alternating or serpentine paths in the direction of cooling channel 41.

[0099] Cooling path 41 extends from and returns to hub 42, which forms the central portion of the outlet guide vane assembly structure, with each of the plurality of blades attached to hub 42. Blade 30 extends from hub 42 to outer ring 43, which defines the outer ring of the outlet guide vane structure. In use, a coolant, such as oil, flows through cooling circuit inlet 44, through a duct to outlet 45, and thus into cooling passage 42. Inlet 44 and outlet 45 are in fluid communication with the gearbox of a geared turbofan engine (in one example).

[0100] In an alternative arrangement, the duct within the blade can extend radially inward, i.e., to interact with... Figure 8 The opposite construction extension is shown. By extending the cooling ducts back and forth from the outer perimeter of the OGV structure, it is possible to make maintenance of the cooling arrangement easier, as it is more accessible from outside the engine. The coolant can be collected, for example, using peripheral manifolds and circulated to the gearbox (or the heat exchanger associated with the gearbox) via engine pylons that connect the engine to the wing.

[0101] This alternative arrangement can be used in engine designs where space towards the engine core is limited and / or maintenance access is restricted. Internal locations are less accessible, and wiring oil circuits to the interior of the blades can be challenging. Furthermore, oil pumps, etc., can be conveniently located on the fan housing, allowing for easier access and connection to the radially external location of the OGV. In yet another arrangement, an inlet can be located at the first end of the OGV, and an outlet at the second end.

[0102] Heat transfer occurs as cool air flows through the guide vane structure around each vane, and importantly, through the cavities within the modified vanes (as indicated by arrows A and A'). Heat is dissipated from the gearbox to a heat transfer arrangement near the gearbox (e.g., a local heat exchanger) and then flows to the modified outlet guide vane structure. Oil flows through duct 41 within one or more modified vanes (e.g., via one or more pumps). As air passes through the guide vane cavities (and above the outer surface), it collects heat from the duct walls within the vanes, thereby lowering the temperature of the coolant contained within the duct. Thus, cooling of the coolant is achieved as heat is dissipated into the air passing through the OGV structure. The coolant can then return to the gearbox to collect further unwanted heat.

[0103] Advantageously, the wall thickness of the coolant duct 41 can be reduced due to the protection provided by the modified blades of the present invention. This not only increases the heat transfer coefficient from the duct to the air passing through it, but also additionally reduces the weight of the modified blades. Combined with the weight reduction of the blades through the holes at the leading and trailing edges of each blade, the overall weight increase of the modified OGV structure can be minimized.

[0104] Any suitable material can be used for the duct 41 within each blade. For example, aluminum or aluminum alloys can be used, which benefit from good thermal conductivity and specific strength and are relatively lightweight. In another arrangement, different materials can be used for the internal oil circuit with higher thermal conductivity, such as copper. A second material can be used for the external blade surface with higher specific stiffness or strength, such as titanium or carbon fiber reinforced plastic. It can be recognized that different combinations of materials can be used based on the locally required thermal properties and structural strength. This strength can be based entirely or partially on the probability of debris impact.

[0105] Similarly, the internal arrangement of the duct 41 within the modified blade can be selected to optimize the blade's heat dissipation and / or aerodynamic performance in terms of minimizing pressure loss through the blade (or the modified blade's impact on airflow).

[0106] For example, Figure 9 A modified blade is shown, wherein the duct 41 is in the form of a channel 46 that travels along the inner surface 47 of the blade. As indicated by arrow 48, airflow can flow through the inner cavity and dissipate heat from the channel surface facing the inner side of the blade, and the opposite side of the channel facing the outer surface of the blade can similarly dissipate heat out of the channel.

[0107] Figure 10 An alternative configuration of the cooling duct 41 within the modified blade 30 is shown. In this example, inlet 44 is in fluid communication with a first manifold 49 that allows coolant to flow along multiple ducts toward an opposite end manifold 50 for collecting coolant, and to return coolant to a second manifold 51 via a second set of ducts that allows coolant to exit from the modified blade through outlet 45. This allows coolant flow to enter and exit the blade through a single port, but is branched into multiple separate ducts, thereby increasing the contact area between the ducts and the airflow within the blade. This increases heat transfer.

[0108] Each duct can be supported by a suitable support arrangement 52 extending across the blade cavity. The support arrangement 52 can also be considered as a radiator that increases heat transfer to the cavity airflow.

[0109] Figure 11A , Figure 11B and Figure 11C An alternative arrangement of the conduit within the cavity 37 of the modified blade 30 is shown.

[0110] In Example 11A, the ducts are staggered relative to the centerline of the blade to maximize contact with the air flowing through the cavity.

[0111] In embodiment 11B, each conduit is connected to the inner wall of the pressure side of the blade via a thermal bridge 53. This thermal bridge transfers heat to the wall of the blade, and the outer surface of the conduit is positioned toward the center of the blade to maximize heat transfer from the surface of each conduit.

[0112] Figure 11C Another embodiment of a coolant conduit within the cavity 37 of the modified blade 30 is shown. In this embodiment, the channel or conduit is arranged along the inner wall of the blade in a zigzag profile 54, thereby dissipating heat to the blade wall and additionally to the airflow within the blade cavity 37.

[0113] It will be recognized that any profile of the internal cooling channels or ducts can be used to optimize the heat dissipation of a given engine design. The heat dissipation surface can be defined by calculating the required heat dissipation and the available area within the blades.

[0114] The inlet to the blade cavity described in this article can take various forms. For example, multiple holes can be provided behind the leading edge of the suction surface of the blade to maintain the blade structure while allowing air to flow into the cavity.

[0115] The various modified blades constituting the OGV structure can be fluidly connected together via a first manifold at the hub and a second manifold at the outer ring of the structure. Coolant can then easily flow through each modified blade and return to the gearbox for cooling.

[0116] Alternatively or additionally, each modified blade can be used independently to achieve cooling. For example, by using multiple control valves, coolant can be arranged to selectively flow into one or more modified blades. This thus provides controlled cooling, allowing the coolant temperature to decrease by a controlled amount. Cooling can be precisely controlled by selectively controlling the volume of coolant passing through the cooling arrangement provided by the modified blades. For example, if a small amount of cooling is required, a single blade can be activated.

[0117] Alternatively, if the gearbox (e.g.) is at extreme temperatures, more or all of the modified blades can be activated to generate maximum cooling. Cooling can be activated based on environmental conditions (e.g., taxiing or flight) in conjunction with gearbox temperature. A suitable control arrangement can detect such conditions and accordingly control the inflow and outflow of coolant into and within the modified OGV structure. For example, when starting an engine in cold weather, it may be desirable to deactivate cooling to allow the gearbox oil to reach the desired temperature. Once the target oil temperature is reached, cooling can be activated and controlled to maintain the gearbox oil within a predetermined operating range.

[0118] Figure 12A and Figure 12BThe location of the inlet and outlet of the inner cavity 37 of the modified blade described above is described.

[0119] Figure 12A An alternative arrangement of the air inlets for the cavity is shown. In one arrangement, these inlets may be in the form of multiple discrete inlets 53a arranged radially outward from the hub portion along the blade. Each inlet 53a is separated by a portion of the blade to maintain the structural integrity of the blade and to maintain its normal aerodynamic performance. In this arrangement, the inlets are arranged to be concealed or separated from the leading edge of the suction side of the blade by a distance d, such that... Figure 12A As shown and as described above, distance d prevents FOD from entering inlet 53a. In an alternative arrangement, the inlet may be positioned on the surface of the pressure surface of the blade to allow airflow into a cavity within the modified blade for cooling. This is illustrated by reference numeral 53b.

[0120] Here, these inlets are positioned along the chord of the blade, that is, towards 50% of the chord length, such as... Figure 12A The markings at the base of the modified blade are shown. As shown in the figure, these inlets are positioned towards the leading edge of the blade.

[0121] Similarly, at the trailing edge of the blade, these outlets can be arranged along the very tip of the blade (indicated by reference numeral 54a), or they can be spaced apart toward 50% of the chord length, as shown by reference numeral 54b.

[0122] Figure 12B It shows crossing Figure 12A The cross-section of the modified blade is shown. As shown, the inlet can be located at position 53a or 53b, and the outlet can be located at position 54a or 54b. The inlet and outlet 53b and 54b can be positioned at any suitable location along the chord. Alternatively, combinations of positions can be used, such as an inlet at position 53a and an outlet at position 54b, and / or an inlet at 54b and an outlet at 54a. Furthermore, the inlet and outlet can be staggered or alternated between different configurations to mix the airflow leaving the cavity, thereby preventing undesirable turbulence.

[0123] Furthermore, the inlet and / or outlet can be controllable in terms of their open areas, for example, between a fully open position and a fully closed position. This can be achieved through a simple sliding door arrangement and associated actuators, allowing independent and selective control of airflow into and out of the chamber. This advantageously allows the control arrangement to control the cooling and / or steering effects of the blades by eliminating the influence of the inlet and / or outlet ports on the airflow.

[0124] Any suitable combination of materials can be used. Example combinations include, but are not limited to:

[0125] Titanium (or titanium alloy) and internal copper channels;

[0126] Aluminum (or aluminum alloy) and internal metal conduit channels;

[0127] Carbon fiber composite blades and internal metal structures defining the channels.

[0128] Those skilled in the art who have received the teachings herein will recognize that any suitable combination of the above examples may be conveniently and advantageously used.

[0129] The inlet and outlet holes can be any suitable shape. Figure 12A and Figure 12B The holes shown are for illustrative purposes only.

[0130] like Figure 12B As shown, these inlets and outlets may additionally taper according to the direction of airflow, as indicated by reference numeral 55.

[0131] Specifically, the cavity cross-sectional region directly affects the cavity airflow velocity and mass flow rate. The cavity can be designed with a diffusion flow immediately following the inlet and an acceleration flow preceding the outlet. This can advantageously optimize the Reynolds number through the cavity. For example, refer to... Figure 14 The dimensions of A1 and A2 are approximately 0.3 to 5 times the size of A3.

[0132] Specifically, the relationship can be 1 / 3 A1 <A3<5 A1 and 1 / 3 A2 <A3<5 A2.

[0133] The pressure and / or suction surfaces can be detached from the main structure of the blade to allow access to the internal cavity. This advantageously allows for maintenance and inspection, and possibly cleaning of the surfaces of each coolant passage located along with the blade cavity. This attachment can be made by any suitable means, such as recessed aerospace-grade screw fasteners, etc.

[0134] The inventors have determined that designing an OGV with an internal heat transfer medium (e.g., oil) in which a large portion of the "wetting surface" (i.e., the surface on which the air impacts) of the cold airflow is guided through the inner cavity of the OGV, the velocity of the cooling airflow can be reduced to advantageously minimize flow losses. It has been determined that using only the amount of wetting surface outside the blade profile is a limiting factor in using an OGV as a heat exchanger. Furthermore, many blades must be used for cooling, so increasing the wetting surface for cooling (the available wetting surface area per blade for cooling) is advantageous. With this in mind, in one arrangement, fins can be used around the duct to increase the wetting surface and optimize the surface area, thereby optimizing heat transfer.

[0135] Figure 13 This invention demonstrates its ability to be used in conjunction with conventional surface cooling of fan bypass channel surfaces. This can be achieved through series and / or individual control as described above. The inner surface shown can be coupled to the cooling channels of the blades.

[0136] Figure 14 A cross-sectional view of the blade described herein is shown. Here, the cross-sectional regions at the leading edge (A1), trailing edge (A2), and central region (A3) have the general relationships described above.

Claims

1. An outlet guide vane structure for a gas turbine engine, the structure comprising a plurality of radially extending guide vanes, wherein, The at least one guide vane comprises: a pressure surface and an opposing suction surface, wherein the pressure surface defines one side of the vane and the opposing suction surface defines an opposite side of the vane; at least one inlet and at least one outlet, wherein the at least one inlet allows air to enter into at least one internal cavity within the guide vane and the at least one outlet allows air to exit the at least one internal cavity, the at least one internal cavity being defined between the pressure surface and the opposing suction surface; wherein the at least one internal cavity comprises at least one conduit arranged, in use, such that a fluid flow passes through the cavity; wherein the inlet is arranged, in use, upstream of an outlet in a direction of airflow over the guide vane, wherein the at least one inlet is arranged through the pressure surface of the vane and spaced apart from a leading edge of the suction side.

2. The structure of claim 1, wherein the at least one inlet is arranged in a front 50% of a chord length of the vane measured from a leading edge to a trailing edge of the vane; and the at least one outlet is arranged in a rear 50% of the chord length of the vane measured from the leading edge to the trailing edge of the vane.

3. The structure of claim 2, wherein, the at least one inlet is arranged in a front 25% of the chord length of the vane measured from the leading edge to the trailing edge of the vane.

4. The structure of any one of claims 1 to 3, wherein, the structure comprises a main axis corresponding to an axis of air entering the engine during use, wherein a portion of a leading edge of the suction surface of the at least one guide vane extends in a direction perpendicular to the main axis to overlap with the pressure surface of the vane, such that the pressure surface of the vane is not visible when viewed along the main axis of the structure.

5. The structure of claim 4, wherein, the at least one inlet is arranged in a portion of the pressure surface that is not visible when viewed along the main axis of the structure.

6. The structure of claim 5, wherein, a leading edge of the at least one inlet is spaced apart from a distal edge of a leading edge of the suction surface by a predetermined distance, the predetermined distance being measured in a direction perpendicular to the main axis of the structure.

7. The structure of any one of claims 1 to 3, wherein, the at least one internal cavity comprises: (a) a plurality of conduits each extending radially through the vane and each spaced apart along a length of the guide vane measured along a chord of the guide vane; and / or (b) a plurality of conduits each extending along a length measured along a portion of a chord of the vane and each spaced apart radially through the vane.

8. The structure of any one of claims 1 to 3, wherein, the conduits are arranged to extend away from and towards a portion of the vane proximate to a central hub portion of the structure to which each vane is attached.

9. The structure of any one of claims 1 to 3, wherein, the conduits are arranged to extend away from and towards a portion of the vane proximate to an outer ring portion of the structure to which each vane is attached.

10. The structure of any one of claims 1 to 3, wherein, the conduits are in contact with an inner surface of the pressure surface and / or the suction surface of the guide vane within the cavity.

11. The structure of claim 10, wherein, The conduits have fluid inlets and fluid outlets, and the conduits alternate in a radial direction along a chordal direction of the guide vanes.

12. The structure of claim 8, wherein, Each vane includes: (a) a plurality of conduits and manifolds, wherein the plurality of conduits extend radially within the vane and the manifolds are located at each radial end of the plurality of conduits, thereby allowing fluid communication between adjacent conduits; and / or (b) a plurality of conduits and manifolds, wherein the plurality of conduits extend along a chord within the vane and the manifolds are located proximate a leading edge and a trailing edge, thereby allowing fluid communication between adjacent conduits.

13. The structure of any one of claims 1-3, wherein, The cross-sectional area of the inlet is less than the cross-sectional area of the cavity at a location between the inlet and the outlet, measured along a chord length of the guide vane.

14. The structure of any one of claims 1-3, wherein, A plurality of inlets are disposed proximate a leading edge of a pressure surface of the guide vane and are radially spaced along a length of the guide vane.

15. The structure of any one of claims 1-3, wherein, A plurality of outlets are disposed proximate a trailing edge of the guide vane and are radially spaced along a length of the guide vane.

16. The structure of any one of claims 1-3, wherein, The coolant flow in the outlet guide vanes is arranged in use to receive heat from at least a second fluid circuit via at least one fluid-to-fluid heat exchanger.

17. A geared turbofan engine comprising the outlet guide vane structure of any one of claims 1 to 16.

18. A method of cooling a reduction gearbox of a geared turbofan engine, wherein, Passing a coolant flow to a cooling arrangement comprising the outlet guide vane structure of any one of claims 1 to 16.

19. The method of claim 18, wherein, Selectively activating one or more guide vanes of the outlet guide vane structure of any one of claims 1 to 16 to effect cooling of the coolant.

20. The method of claim 18, wherein, The coolant flow in the outlet guide vanes is arranged in use to receive heat from at least a second fluid circuit via at least one fluid-to-fluid heat exchanger.

21. A method of cooling one or more electric motors of a fan propulsion arrangement, wherein, Passing a coolant flow to a cooling arrangement comprising the outlet guide vane structure of any one of claims 1 to 16.

22. The method of claim 21, wherein, Selectively activating one or more guide vanes of the outlet guide vane structure of any one of claims 1 to 16 to effect cooling of the coolant.

23. The method of claim 21, wherein, The coolant flow in the outlet guide vanes is arranged in use to receive heat from at least a second fluid circuit via at least one fluid-to-fluid heat exchanger.

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