Cmc airfoils and methods of forming the same

Abstract

A CMC airfoil has both aerodynamic performance and strength performance. In the height direction of the CMC airfoil, a first section formed by laying a plurality of first fiber tapes and a second section formed by laying a plurality of second fiber tapes are alternately arranged, so that in the trailing edge region of the CMC airfoil, the projections of the fibers respectively continuously extending along the pressure surface side of the airfoil and the suction surface side of the airfoil in a projection plane perpendicular to the height direction are staggered and overlapped with each other. A forming method of a CMC airfoil is used for manufacturing the aforementioned CMC airfoil.

Description

TECHNICAL FIELD

[0001] The present application relates to a CMC airfoil and a forming method thereof, in particular to a CMC airfoil of a gas turbine or an aero-engine and a forming method thereof. BACKGROUND

[0002] Turbine blades, as important turbine high-temperature components of gas turbine engines, bear very high environmental temperature and mechanical load in service state. At present, turbine blades are mainly prepared by using high-temperature alloy materials, which significantly affects the upper limit of the service temperature of turbine blades and the improvement of the overall performance of the engine. The use of ceramic matrix composite (CMC) to replace high-temperature alloy materials to prepare turbine blades can fully exert the excellent characteristics of CMC in high-temperature mechanical properties, significantly improve the upper limit of the service temperature of turbine blades and the overall performance of the engine, and reduce pollution emissions.

[0003] At present, due to the higher modulus and poorer flexibility of SiC fibers, the CMC turbine blades prepared have a larger thickness and a tail edge radius at the tail edge of the blade body, resulting in a poor aerodynamic performance of the prepared blade profile. The patent application with the publication number CN114105663 A discloses a fiber preform laying forming method for a ceramic matrix composite turbine blade body, which divides the blade body material into an inner layer and an outer layer. The inner layer is first prepared by winding a core mold, and then the outer layer is provided with a laying surface for outer layer laying forming. The stitching strengthens the strength of the blade body material in the thickness direction, but the fracture of the circumferential fiber at the tail edge of the blade body is located on the same section, which is easy to cause the problem of weak strength. Although a blade body tail edge with smaller thickness and tail edge radius can be prepared under the premise of sacrificing the continuity of the circumferential fiber at the tail edge, the local strength performance is poor. SUMMARY

[0004] An object of the present application is to provide a CMC airfoil which takes into account the tail edge aerodynamic performance and strength performance.

[0005] Another object of the present application is to provide a forming method of a CMC airfoil for the manufacture of the aforementioned CMC airfoil.

[0006] The CMC airfoil according to an aspect of the present application comprises a fiber skeleton laid by fiber tapes, the fiber skeleton comprising a fiber skeleton outer layer, the fiber skeleton outer layer comprising a circumferential fiber tape, the circumferential fiber tape comprising a first fiber tape and a second fiber tape,

[0007] The first fiber strip includes a first closed portion and a first tail edge protruding portion. The first closed portion is formed by the first fiber strip winding along the profile of the CMC airfoil and closing at the tail edge of the profile. The first tail edge protruding portion is formed by the first fiber strip continuously extending from the suction side of the first closed portion and protruding from the tail edge of the profile.

[0008] The second fiber strip includes a second closed portion and a second trailing edge extension portion. The second closed portion is formed by the second fiber strip winding along the profile of the CMC airfoil and closing at the trailing edge of the profile. The second trailing edge extension portion is formed by the second fiber strip continuously extending from the pressure side of the second closed portion and extending from the trailing edge of the profile.

[0009] In the blade height direction of the CMC airfoil, a first segment formed by multiple layers of the first fiber tape and a second segment formed by multiple layers of the second fiber tape are alternately arranged so that the projections of the fibers extending continuously along the pressure side and suction side of the airfoil in the trailing edge region of the CMC airfoil overlap each other in a projection plane perpendicular to the blade height direction.

[0010] In one embodiment, the fiber skeleton further includes an inner fiber skeleton layer distributed around a first region, and an outer fiber skeleton layer distributed around a second region, the second region containing the location of the inner fiber skeleton layer, and the outer fiber skeleton layer providing the trailing edge region of the CMC airfoil.

[0011] In one embodiment, the inner layer of the fiber skeleton includes a leaf height-direction fiber band extending along the leaf height direction and a circumferential fiber band extending along the profile of the inner layer of the fiber skeleton.

[0012] In the inner layer of the fiber skeleton, the leaf height direction fiber bands and the circumferential direction fiber bands are alternately distributed in the thickness direction of the inner layer of the fiber skeleton.

[0013] The outer layer of the fiber skeleton also includes fiber bands extending along the leaf height direction.

[0014] In the outer layer of the fiber skeleton, the leaf height direction fiber band and the first fiber band and the second fiber band extending circumferentially are alternately distributed in the thickness direction of the outer layer of the fiber skeleton.

[0015] In one embodiment, the inner fiber skeleton defines a first cavity, and the inner fiber skeleton includes a plurality of first cooling holes distributed in the blade height direction on its trailing edge side.

[0016] A second cavity is defined between the outer layer and the inner layer of the fiber skeleton on the tail edge side.

[0017] The outer layer of the fiber skeleton includes a plurality of second cooling holes distributed in the blade height direction on the pressure surface side of the trailing edge region;

[0018] The first cooling hole connects the first cavity and the second cavity, and the second cooling hole connects the second cavity and the outer surface of the trailing edge of the CMC airfoil.

[0019] In one embodiment, the first cooling hole has a first major axis direction, which is perpendicular to the blade height direction of the CMC airfoil.

[0020] The second cooling hole has a second major axis direction, which is parallel to the blade height direction of the CMC airfoil.

[0021] In one embodiment, a plurality of the first cooling holes and a plurality of the second cooling holes are staggered in the blade height direction of the CMC airfoil.

[0022] In one embodiment, the second cooling hole is formed by processing a closed mating interface at the closed position of the first fiber strip in each layer of the first segment, and the second cooling hole is located on the pressure side of the closed mating interface.

[0023] In one embodiment, the CMC airfoil is a CMC turbine blade.

[0024] According to another aspect of the present invention, a method for forming a CMC airfoil includes forming a fiber skeleton, wherein forming the fiber skeleton includes forming an outer layer of the fiber skeleton, and forming the outer layer of the fiber skeleton includes:

[0025] The fiber tape is laid in a first manner to form a first closed portion and a first tail edge protrusion portion. The first closed portion is formed by the fiber tape winding along the profile of the CMC airfoil and the closed position is at the tail edge of the profile. The first tail edge protrusion portion is formed by the fiber tape continuously extending from the suction side of the first closed portion and protruding from the tail edge of the profile.

[0026] The fiber tape is laid in a second manner to form a second closed portion and a second tail edge extension portion. The second closed portion is formed by the fiber tape winding along the profile of the CMC airfoil and the closed position is at the tail edge of the profile. The second tail edge extension portion is formed by the fiber tape continuously extending from the pressure surface side of the second closed portion and extending from the tail edge of the profile.

[0027] Along the blade height direction of the mandrel, the fiber tape is laid using the first and second methods alternately;

[0028] During the laying process, the laid fiber strips are molded and shaped to obtain the fiber preform of the CMC airfoil;

[0029] The fiber preform after curing and demolding is subjected to subtractive processing, removing the first tail edge protrusion and a portion of the second tail edge protrusion, while retaining the overlapping portions of the projections of the first tail edge protrusion and the second tail edge protrusion in a projection plane perpendicular to the blade height direction.

[0030] In one embodiment, the molding of the fiber skeleton further includes molding an inner layer of the fiber skeleton, the molding of the inner layer of the fiber skeleton including:

[0031] Fiber tapes are laid to close the fiber tapes, and the closing positions of the fiber tapes are offset from the leading and trailing edges of the inner layer of the fiber skeleton, and the closing positions of each layer of fiber tapes are dispersed from the closing positions of the adjacent layers of fiber tapes;

[0032] After the inner layer of the fiber skeleton is formed, fiber strips are laid using the inner layer of the fiber skeleton and the filling block as a core mold to complete the formation of the outer layer of the fiber skeleton.

[0033] In one embodiment, the forming of the fiber skeleton further includes the laying of fibers in the leaf height direction, with the laying of fibers in the leaf height direction and the laying of fibers in the circumferential direction alternating.

[0034] In one embodiment, a first mold block is placed behind the trailing edge of the suction surface of the airfoil to provide a layup surface for the layup shaping of the extended portion of the second trailing edge. The layup surface receives the fiber strip on the pressure surface side of the airfoil in a smooth transition at the trailing edge position and extends backward.

[0035] A second mold block is also placed on the rear side of the pressure surface trailing edge of the airfoil to provide a laying surface for the laying and shaping of the extended portion of the first trailing edge. The laying surface smoothly transitions from the trailing edge position to the suction surface side of the airfoil and extends rearward.

[0036] After the outer layer of the fiber skeleton is laid, a wedge-shaped pressure block is inserted between the first mold block and the second mold block to compact and shape the tail edge of the airfoil and the protruding parts of the first and second tail edges.

[0037] In one embodiment, the first cooling hole is processed on the trailing edge side after the inner layer of the fiber skeleton is laid.

[0038] In one embodiment, after the outer layer of the fiber skeleton is laid, the second cooling hole is processed on the trailing edge side of the outer layer of the fiber skeleton.

[0039] In one embodiment, after the CMC airfoil is cured and demolded, a portion of the first and second trailing edge protrusions is removed by subtractive processing according to the design shape of the trailing edge of the airfoil. The cutting outline is located close to the position where the first and second trailing edge protrusions overlap.

[0040] In one embodiment, the fiber tape is a unidirectional fiber tape or a unidirectional narrow fiber tape.

[0041] According to the embodiments of the present invention, the CMC airfoil obtained by means of continuous fibers extending from the pressure and suction surfaces of the blade body interlacing and overlapping each other in the blade height direction, without concentrated splicing interfaces, can significantly improve the strength and toughness of the material in this region, and at the same time facilitate the preparation of smaller trailing edge thickness and turning radius, without being limited by the minimum radius size that the unidirectional fiber band can continuously pass around; in addition, the CMC airfoil with internal cavity can have its inner surface closer to the trailing edge position, which is beneficial to increase the cooling efficiency of the trailing edge position and prevent the occurrence of trailing edge overheating problems. Attached Figure Description

[0042] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0043] Figure 1 This is a three-dimensional view of the fiber skeleton of the CMC airfoil;

[0044] Figure 2 This is a schematic diagram of the fiber skeleton layer laying process for CMC airfoil components;

[0045] Figure 3 This is a schematic diagram showing the completed inner layer of the fiber skeleton of the CMC airfoil.

[0046] Figure 4 This is a schematic diagram of the infill block;

[0047] Figure 5 This is a schematic diagram showing the combination of the filler block and the inner layer of the CMC airfoil fiber skeleton;

[0048] Figure 6 This is a schematic diagram of the morphology during the first fiber strip laying process;

[0049] Figure 7 This is a schematic diagram of the morphology during the second fiber strip laying process;

[0050] Figure 8 This is a schematic diagram of the fiber skeleton layer laying process for CMC airfoil components;

[0051] Figure 9 This is a schematic diagram of auxiliary tooling used during the layup process of the outer layer of the fiber skeleton of the CMC airfoil;

[0052] Figure 10 This is another schematic diagram showing the auxiliary tooling used during the layup process of the outer layer of the fiber skeleton of the CMC airfoil;

[0053] Figure 11 This is a schematic diagram of a CMC airfoil preform;

[0054] Figure 12A This is a schematic diagram illustrating one step of the trailing edge cutting process of a CMC airfoil preform;

[0055] Figure 12B yes Figure 12A A magnified view of a section at point I;

[0056] Figure 13A This is a schematic diagram illustrating another step in the trailing edge cutting process of the CMC airfoil preform;

[0057] Figure 13B yes Figure 13A Enlarged view of a section at point II;

[0058] Figure 14A This is a view of the CMC airfoil projected along the blade height direction;

[0059] Figure 14B yes Figure 14A A magnified view of a section at point III;

[0060] Figure 15 This is a schematic diagram of the CMC airfoil, showing the first and second cooling holes;

[0061] Figure 16 This is the front view of the CMC airfoil rotated 90°;

[0062] Figure 17A It is along Figure 16 Sectional view of line AA in the middle;

[0063] Figure 17B yes Figure 17A A magnified view of a section at point IV in the middle;

[0064] Figure 17C yes Figure 17A A magnified view of the middle V section;

[0065] Figure 18A It is along Figure 16 Sectional view of the middle BB line;

[0066] Figure 18B yes Figure 18A A magnified view of section VI in the middle. Detailed Implementation

[0067] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided to explain the invention and not to limit it. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the invention without departing from the scope or spirit thereof. For example, a feature shown or described as part of one embodiment may be used with another embodiment to produce yet another embodiment. Therefore, the invention is intended to cover these modifications and variations that fall within the scope of the appended claims and their equivalents.

[0068] As used herein, the terms “first” and “second” are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of the individual components.

[0069] Ceramic matrix composites (CMC) are a type of composite material made of ceramic as the matrix and various fibers. They have excellent properties such as high temperature resistance, high strength and modulus, low density and strong corrosion resistance.

[0070] "Fiber tape" is a continuous fiber-reinforced material, preferably a unidirectional reinforced material, and can be either a unidirectional tape or a unidirectional narrow tape. The fiber is, but is not limited to, carbon fiber, silicon carbide fiber, boron nitride fiber, or alumina fiber.

[0071] "Upstream" and "downstream" refer to the relative directions of fluid flow within a fluid path. For example, "upstream" refers to the direction from which the fluid flows, while "downstream" refers to the direction from which the fluid flows.

[0072] "Airfoil" refers to a component whose cross-sectional outline or profile is airfoil-shaped. The leading edge is the area where the airfoil's inlet edge (upstream) connects to the blade head (pressure surface) and the blade back (suction surface); the trailing edge is the area where the airfoil's exhaust edge (downstream) connects to the blade head (pressure surface) and the blade back (suction surface).

[0073] "CMC airfoil" refers to an airfoil mainly formed from ceramic matrix composite materials.

[0074] The "leading edge side" is the part of the airfoil closest to the leading edge of the airfoil, while the "tailing edge side" is the part of the airfoil closest to the tailing edge of the airfoil.

[0075] A "fiber performer" is a fiber composite reinforcement in which reinforcing material is preformed into an airfoil. The fiber skeleton is the portion of the fiber performer retained in the ceramic matrix composite airfoil after subtractive processing.

[0076] "Turbine blades" are the main structural components of the turbine in a gas turbine engine. They can be turbine guide vanes or turbine working blades. Turbine guide vanes are placed between adjacent turbine working blades and withstand ultra-high temperature and aerodynamic pressure service environments. They are used to change the direction of gas flow so that the high-speed gas flow can impact the next stage turbine rotating blades at a suitable angle to efficiently do work. Turbine working blades are placed on the outer periphery of the turbine disk and withstand the scouring of high-temperature gas and drive to do work. During service, they are subjected to the combined effects of high temperature, high centrifugal load and high-temperature gas environment.

[0077] The CMC airfoil, described later, is suitable for turbine blades, as well as blades for other applications.

[0078] Figure 1 A fiber skeleton for a CMC airfoil is shown, comprising an inner fiber skeleton layer 11 and an outer fiber skeleton layer 12. The inner fiber skeleton layer 11 is a closed inner region distributed around a first region 13, which is a cavity. The outer surface of the outer fiber skeleton layer 12 provides the aerodynamic surface of the airfoil, with its leading edge 16 and trailing edge 15 roughly corresponding to the leading and trailing edges of the CMC airfoil. The outer fiber skeleton layer 12 is distributed around a second region, which includes the location of the inner fiber skeleton layer 11. The inner fiber skeleton layer 11 and the outer fiber skeleton layer 12 form a second cavity 14 at the trailing edge. The inner fiber skeleton layer 12 is also an airfoil, with its leading edge, pressure surface, and suction surface following or conforming to the profile of the outer fiber skeleton layer 12. Except in the region containing the second cavity 14, the outer surface of the inner fiber skeleton layer 11 is in contact with the inner surface of the outer fiber skeleton layer 12. In another embodiment, the first cavity 13 and the second cavity 14 may be partially or completely filled as required by design. In yet another embodiment, the fiber skeleton comprises only the outer layer 12 of the fiber skeleton.

[0079] Figure 6 and Figure 7 Two embodiments of the circumferential fiber bands on the outer layer of the fiber skeleton are shown, wherein Figure 6 The first fiber strip 41 is shown. The first fiber strip 41 includes a first closed portion 411 and a first trailing edge extension portion 412. The first closed portion 411 is formed by the first fiber strip 41 winding along the profile of the CMC airfoil and the closed position 413 is at the trailing edge of the profile. The first trailing edge extension portion 412 is formed by the first fiber strip 41 continuously extending from the suction side of the first closed portion 411 and extending from the trailing edge of the profile.

[0080] Figure 7The second fiber strip 42 is shown. The second fiber strip 42 includes a second closed portion 421 and a second trailing edge extension portion 422. The second closed portion 421 is formed by the second fiber strip 42 winding along the profile of the CMC airfoil and the closed position 423 is at the trailing edge of the profile. The second trailing edge extension portion 422 is formed by the second fiber strip 42 continuously extending from the pressure side of the second closed portion 421 and extending from the trailing edge of the profile.

[0081] like Figure 8 As shown, in the blade height direction of the CMC airfoil, a first section made of multiple layers of first fiber strips 41 and a second section made of multiple layers of second fiber strips 42 are alternately arranged. Figure 14A and Figure 14B The trailing edge region of the CMC airfoil is shown. Due to the aforementioned alternating arrangement, the projections of the fibers extending continuously along the pressure side and suction side of the airfoil in a projection plane perpendicular to the blade height direction overlap each other.

[0082] The continuous fibers extending from the pressure and suction sides of the airfoil overlap each other in the blade height direction, without concentrated splicing interfaces. This can significantly improve the strength and toughness of the material in this region, which is also conducive to the preparation of smaller trailing edge thickness and turning radius, without being limited by the minimum radius size that the unidirectional fiber belt can continuously pass around.

[0083] Figure 2 The process of laying the fiber preform of the inner fiber skeleton layer 11 is shown. After laying a layer of leaf height direction fiber strip 111 extending along the leaf height direction, a layer of circumferential fiber strip 112 extending along the profile of the inner fiber skeleton layer is laid. Finally, in the inner fiber skeleton layer 11, the leaf height direction fiber strip and the circumferential fiber strip are alternately distributed in the thickness direction of the inner fiber skeleton layer 11.

[0084] Figure 8 The process of laying the fiber preform of the fiber skeleton outer layer 12 is shown. The fiber skeleton outer layer 12 also includes leaf height direction fibers 43 extending along the leaf height direction. After alternately laying a first fiber band 41 and a second fiber band 42 extending in the circumferential direction, another layer of leaf height direction fiber band 43 extending along the leaf height direction of the fiber skeleton outer layer is laid. In the fiber skeleton outer layer 12, the leaf height direction fiber band 43 and the circumferential fiber bands (first fiber band 41 and second fiber band 42) are alternately distributed in the thickness direction of the fiber skeleton outer layer 12.

[0085] like Figure 15 As shown, the inner fiber skeleton layer 11 includes a plurality of first cooling holes 71 distributed in the blade height direction on its trailing edge side, and the outer fiber skeleton layer 12 includes a plurality of second cooling holes 72 distributed in the blade height direction on the pressure surface side of the trailing edge region. Wherein, as Figure 17AAs shown, the first cooling hole 71 connects the first cavity 13 and the second cavity 14, as... Figure 18B As shown, the second cooling hole 72 connects the second cavity 14 and the outer surface of the trailing edge region of the CMC airfoil. Cooling airflow flows from the first cooling hole 71 into the second cavity 14, cooling the interior of the second cavity 14, and then flows from the second cavity 14 through the second cooling hole 72 along the outer surface of the trailing edge region, providing a cooling effect. The inner surface of the second cavity 14 can be closer to the trailing edge, which helps increase the cooling efficiency at the trailing edge and prevents overheating problems at the trailing edge.

[0086] Combination Figure 15 , Figure 17A and Figure 17B The first cooling hole 71 is located in the inner layer of the airfoil near the trailing edge, has a flat cross-sectional shape, and has a first major axis direction, which is perpendicular to the blade height direction of the CMC airfoil. Figure 15 As shown, the second cooling hole 72 is located on the trailing edge of the airfoil near the pressure surface, has a flat cross-section, and has a second major axis direction, which is parallel to the blade height direction of the CMC airfoil. The major axes of the first cooling hole 71 and the second cooling hole 72 are spatially perpendicular. This facilitates greater disturbance and trajectory change of the cold airflow during its passage, improving the heat exchange efficiency with the contact wall and more efficiently removing heat from the trailing edge of the airfoil, thus improving cooling efficiency. The perpendicularity or parallelism includes approximately perpendicular or parallel cases, with an error within 30 degrees.

[0087] Multiple first cooling holes 71 and multiple second cooling holes 72 are staggered along the blade height direction of the CMC airfoil, with the first cooling holes 71 and the second cooling holes 72 not aligned in height. This staggered distribution in height further enhances the disturbance and trajectory change of the cold airflow, thereby improving the heat transfer efficiency with the contact wall and increasing the cooling effect.

[0088] like Figure 15 , Figure 18A , Figure 18B As shown, the second cooling hole 72 is processed in the first section formed by laying multiple layers of first fiber tapes, and is also processed along the closed mating interface formed by the closed positions of each layer of first fiber tapes. The closed mating interface is the mating interface 413' formed by the combination of the closed positions 413 of each layer of first fiber tapes; similarly, as Figure 17CAs shown, the closed positions 423 of the second fiber strips in each layer combine to form a closed mating interface 423'. This arrangement places the cool air outlet at the trailing edge on the pressure surface (usually the concave side) near the trailing edge, rather than on the edge itself, which helps reduce aerodynamic losses in the blades. Furthermore, the trailing edge cool air outlet is positioned precisely at the closed mating interface, avoiding disruption of the existing continuous fibers. This helps minimize the impact on trailing edge strength, as the more fibers are broken, the lower the local material and structural strength properties become.

[0089] In the embodiment shown in the figure, the CMC airfoil is a CMC turbine blade; in other embodiments, the CMC airfoil is a blade for other applications. The CMC turbine blade employing the aforementioned structure has the following advantages:

[0090] The alternating interlacing layup in the trailing edge region disperses the fiber interface positions and improves the fiber continuity and strength of the airfoil trailing edge. The resulting airfoil trailing edge can have a smaller thickness and trailing edge radius, resulting in good aerodynamic performance. In addition, the first and second cooling holes have little impact on the airfoil strength, which helps to improve the cooling efficiency of the airfoil trailing edge, reduce aerodynamic losses, and reduce the weakening effect on the airfoil strength, especially the trailing edge strength.

[0091] Figure 2 The molding steps of the inner layer of the fiber skeleton are shown. The outer surface of the mandrel 2 is used as the laying surface, which optionally includes fiber strips 111 laid in the blade height direction and fiber strips 112 laid in the circumferential direction of the airfoil. The fiber strips 112 are laid to close, with the unidirectional fiber strips 112 continuously wrapping around the laying surface near the leading and trailing edges. The closing positions of the fiber strips are offset from the leading and trailing edges of the inner layer profile, meaning the unidirectional fiber strips do not connect near the leading and trailing edges, and the closing positions of each fiber strip layer are dispersed from those of adjacent layers. In the embodiment shown, the inner layer 11 of the fiber skeleton is laid and molded using fiber strips 111 and 112 according to the designed layup sequence. The completed layup state is as follows: Figure 3 As shown.

[0092] like Figure 4 and Figure 5 As shown, the filler block 3 is generally elongated, with a cross-sectional shape approximately acute-angled triangle, including a front concave surface 31. In its placement state, it adheres to the outer surface of the inner fiber skeleton layer 11 near the tail edge. It also includes an edge 32 near the tail edge. In the completed placement state, the filler block 3 and the outer surface of the inner fiber skeleton layer 11 are continuously and smoothly joined together to form the layup surface of the outer fiber skeleton layer 12.

[0093] like Figure 6As shown, the fiber tape is laid in the first manner to form the aforementioned first fiber tape 41, which can also be called the suction surface fiber tape. It forms a first closed portion 411 and a first tail edge extension portion 412. The first closed portion 411 is formed by the fiber tape winding along the profile of the CMC airfoil and the closed position 413 is at the tail edge of the profile. The first tail edge extension portion 412 is formed by the fiber tape continuously extending from the suction surface side of the first closed portion and extending from the tail edge of the profile. That is, the closed position 413 is the end of the fiber tape that closes and joins itself near the tail edge on the pressure surface side.

[0094] like Figure 7 As shown, the fiber tape is laid in a second manner to form a second closed portion 421 and a second trailing edge extension 422. The second closed portion 421 is formed by the fiber tape winding along the profile of the CMC airfoil, with the closed position 423 located at the trailing edge of the profile. The second trailing edge extension 422 is formed by the fiber tape continuously extending from the pressure side of the second closed portion 421 and extending from the trailing edge of the profile. The closed position 423 is the end of the fiber tape that self-closes and connects near the trailing edge on the suction side.

[0095] exist Figure 8 In the illustrated embodiment, optionally, during the circumferential fiber tape application, the airfoil is divided into multiple approximately horizontal continuous ring-shaped segments in the blade height direction. Then, fiber tapes 41 and 42 are used alternately in sequence along the blade height direction to circumferentially wrap and apply the aforementioned ring-shaped areas according to the first and second application methods. After completing one layer of application of continuous unidirectional fiber tape to the entire airfoil, the entire layer of fiber tape in the blade height direction is then applied, with the application area extending to a portion of the first and second trailing edge extensions 412 and 422. Referring to the above method, the continuous unidirectional fiber tape application along the circumferential and blade height directions of the airfoil is completed inside the outer layer 12 of the fiber skeleton according to the designed layering sequence.

[0096] Figure 9 and Figure 10 A schematic diagram of the tooling used for laying and molding the outer layer 12 of the airfoil at its trailing edge is provided. The mold block 51 is placed behind the trailing edge of the airfoil's suction surface, providing a laying surface for the second trailing edge extension 422. Its laying surface smoothly transitions from the trailing edge to the fiber strip on the airfoil's pressure surface and extends backward. The mold block 52 is placed behind the trailing edge of the airfoil's pressure surface, providing a laying surface for the first trailing edge extension 412. Its laying surface smoothly transitions from the trailing edge to the fiber strip on the airfoil's suction surface and extends backward. After the fiber skeleton outer layer 12 is laid, the wedge-shaped pressing block 53 is then... Figure 9 and Figure 10The airfoil's trailing edge and protruding portion are compacted and shaped between mold blocks 51 and 52. Since the molding of the airfoil area can be handled using common molding methods, the resulting CMC airfoil after molding and low-temperature curing is shown below. Figure 11 As shown.

[0097] After low-temperature curing and demolding, the CMC airfoil is processed by removing a portion of the first and second trailing edge protrusions 412 and 422 according to the actual design shape of the trailing edge of the airfoil, thereby obtaining an accurate trailing edge shape of the airfoil. Figure 12A and Figure 12B , Figure 13A and Figure 13B The diagrams show the distribution of the cutting contour lines 61 corresponding to the first and second trailing edge extensions 412 and 422, respectively. The cutting contour lines 61 are located close to the intersection of 412 and 422, and the shape of the contour lines is preferably an arc. After the CMC airfoil is cut, it is then subjected to high-temperature carbonization and matrix densification processes to complete the fabrication.

[0098] In one embodiment, the core mold 2 and the filler block 3 are replaced with materials that can be eliminated under high temperature conditions, resulting in the obtained CMC airfoil forming a first cavity 13 and a second cavity 14.

[0099] In another embodiment, the core mold 2 and the filler block 3 are made from raw materials used in the preparation of CMC preforms, such as unidirectional fiber tape, or are prepared from pre-made CMC materials, resulting in solid blades without cavities 13 and 14; the presence or absence of cavities 13 and 14 is set independently according to design requirements.

[0100] In conjunction with the aforementioned molding method, the preparation and processing of the first cooling hole 71 is preferably carried out immediately after the inner layer 11 of the fiber skeleton is laid. The preparation and processing of the second cooling hole is preferably carried out immediately after the outer layer of the fiber skeleton is laid.

[0101] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A CMC airfoil, comprising a fiber skeleton formed by fiber tape lay-up, characterized in that, The fiber skeleton includes a fiber skeleton outer layer, the fiber skeleton outer layer includes circumferential fiber bands, and the circumferential fiber bands include a first fiber band and a second fiber band. The first fiber strip includes a first closed portion and a first tail edge protruding portion. The first closed portion is formed by the first fiber strip winding along the profile of the CMC airfoil and closing at the tail edge of the profile. The first tail edge protruding portion is formed by the first fiber strip continuously extending from the suction side of the first closed portion and protruding from the tail edge of the profile. The second fiber strip includes a second closed portion and a second trailing edge extension portion. The second closed portion is formed by the second fiber strip winding along the profile of the CMC airfoil and closing at the trailing edge of the profile. The second trailing edge extension portion is formed by the second fiber strip continuously extending from the pressure side of the second closed portion and extending from the trailing edge of the profile. In the blade height direction of the CMC airfoil, a first segment formed by multiple layers of the first fiber tape and a second segment formed by multiple layers of the second fiber tape are alternately arranged so that the projections of the fibers extending continuously along the pressure side and suction side of the airfoil in the trailing edge region of the CMC airfoil overlap each other in a projection plane perpendicular to the blade height direction.

2. The CMC airfoil as described in claim 1, characterized in that, The fiber skeleton further includes an inner fiber skeleton layer distributed around a first region, and an outer fiber skeleton layer distributed around a second region, the second region containing the location of the inner fiber skeleton layer, and the outer fiber skeleton layer providing the trailing edge region of the CMC airfoil.

3. The CMC airfoil as described in claim 2, characterized in that, The inner layer of the fiber skeleton includes a leaf height direction fiber band extending along the leaf height direction and a circumferential fiber band extending along the profile of the inner layer of the fiber skeleton. In the inner layer of the fiber skeleton, the leaf height direction fiber bands and the circumferential direction fiber bands are alternately distributed in the thickness direction of the inner layer of the fiber skeleton. The outer layer of the fiber skeleton also includes fiber bands extending along the leaf height direction. In the outer layer of the fiber skeleton, the leaf height direction fiber band and the first fiber band and the second fiber band extending circumferentially are alternately distributed in the thickness direction of the outer layer of the fiber skeleton.

4. The CMC airfoil as described in claim 2 or 3, characterized in that, The inner layer of the fiber skeleton defines a first cavity, and the inner layer of the fiber skeleton includes a plurality of first cooling holes distributed in the blade height direction on its trailing edge side. A second cavity is defined between the outer layer and the inner layer of the fiber skeleton on the tail edge side. The outer layer of the fiber skeleton includes a plurality of second cooling holes distributed in the blade height direction on the pressure surface side of the trailing edge region; The first cooling hole connects the first cavity and the second cavity, and the second cooling hole connects the second cavity and the outer surface of the trailing edge of the CMC airfoil.

5. The CMC airfoil as described in claim 4, characterized in that, The first cooling hole has a first major axis direction, which is perpendicular to the blade height direction of the CMC airfoil. The second cooling hole has a second major axis direction, which is parallel to the blade height direction of the CMC airfoil.

6. The CMC airfoil as described in claim 5, characterized in that, Multiple first cooling holes and multiple second cooling holes are staggered in the blade height direction of the CMC airfoil.

7. The CMC airfoil as described in claim 4, characterized in that, The second cooling hole is formed by processing the closed docking interface formed at the closed position of the first fiber strip in each layer in the first section, and the second cooling hole is located on the pressure side of the closed docking interface.

8. The CMC airfoil as described in claim 1, characterized in that, The CMC airfoil is a CMC turbine blade.

9. A method for forming a CMC airfoil, comprising forming a fiber skeleton, wherein forming the fiber skeleton includes forming an outer layer of the fiber skeleton, characterized in that... The forming of the outer layer of the fiber skeleton includes the laying of circumferential fibers, which includes: The fiber tape is laid in a first manner to form a first closed portion and a first tail edge protrusion portion. The first closed portion is formed by the fiber tape winding along the profile of the CMC airfoil and the closed position is at the tail edge of the profile. The first tail edge protrusion portion is formed by the fiber tape continuously extending from the suction side of the first closed portion and protruding from the tail edge of the profile. The fiber tape is laid in a second manner to form a second closed portion and a second tail edge extension portion. The second closed portion is formed by the fiber tape winding along the profile of the CMC airfoil and the closed position is at the tail edge of the profile. The second tail edge extension portion is formed by the fiber tape continuously extending from the pressure surface side of the second closed portion and extending from the tail edge of the profile. Along the blade height direction of the mandrel, the fiber tape is laid using the first and second methods alternately; During the laying process, the laid fiber strips are molded and shaped to obtain the fiber preform of the CMC airfoil; The fiber preform after curing and demolding is subjected to subtractive processing, removing the first tail edge protrusion and a portion of the second tail edge protrusion, while retaining the overlapping portions of the projections of the first tail edge protrusion and the second tail edge protrusion in a projection plane perpendicular to the blade height direction.

10. The forming method of the CMC airfoil as described in claim 9, characterized in that, The forming of the fiber skeleton also includes the forming of the inner layer of the fiber skeleton, which includes the laying of circumferential fibers, and the laying of circumferential fibers includes: Fiber tapes are laid to close the fiber tapes, and the closing positions of the fiber tapes are offset from the leading and trailing edges of the inner layer of the fiber skeleton, and the closing positions of each layer of fiber tapes are dispersed from the closing positions of the adjacent layers of fiber tapes; After the inner layer of the fiber skeleton is formed, fiber strips are laid using the inner layer of the fiber skeleton and the filling block as a core mold to complete the formation of the outer layer of the fiber skeleton.

11. The forming method of the CMC airfoil as described in claim 9 or 10, characterized in that, The forming of the fiber skeleton also includes the laying of fibers in the leaf height direction, with the laying of fibers in the leaf height direction and the laying of fibers in the circumferential direction of each layer being carried out alternately.

12. The forming method of the CMC airfoil as described in claim 9 or 10, characterized in that... A first mold block is placed on the rear side of the suction surface trailing edge of the airfoil to provide a layup surface for the layup shaping of the extended portion of the second trailing edge. The layup surface receives the fiber strip on the pressure surface side of the airfoil in a smooth transition at the trailing edge position and extends backward. A second mold block is also placed on the rear side of the pressure surface trailing edge of the airfoil to provide a laying surface for the laying and shaping of the extended portion of the first trailing edge. The laying surface smoothly transitions from the trailing edge position to the suction surface side of the airfoil and extends rearward. After the outer layer of the fiber skeleton is laid, a wedge-shaped pressure block is inserted between the first mold block and the second mold block to compact and shape the tail edge of the airfoil and the protruding parts of the first and second tail edges.

13. The forming method of the CMC airfoil as described in claim 9 or 10, characterized in that... After the inner layer of the fiber skeleton is laid, the first cooling hole is processed on its trailing edge side.

14. The forming method of the CMC airfoil as described in claim 9 or 10, characterized in that... After the outer layer of the fiber skeleton is laid, the second cooling hole is processed on the trailing edge side of the outer layer of the fiber skeleton.

15. The forming method of the CMC airfoil as described in claim 9 or 10, characterized in that... After the CMC airfoil has been cured and demolded, a portion of the first and second trailing edge protrusions is removed by subtractive processing according to the design shape of the trailing edge of the airfoil. The cutting outline is positioned close to the point where the first and second trailing edge protrusions overlap.

16. The forming method of the CMC airfoil as described in claim 9 or 10, characterized in that... The fiber tape is a unidirectional fiber tape or a unidirectional narrow fiber tape.

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