A CMC turbine outer ring assembly having a cold gas enclosed cavity and method of manufacture

Abstract

The present application relates to the technical field of ceramic matrix composite turbine components, and discloses a CMC turbine outer ring assembly with a cold gas closed cavity and a preparation method, wherein the closed outer ring cold gas cavity is arranged on the CMC turbine outer ring, so that the cold gas leakage rate can be reduced, and the overall structure design is simplified. The elastic structure of the present application can adaptively match the thermal expansion deformation difference between the CMC turbine outer ring and the metal casing caused by different materials, the elastic sealing element can seal the gap, further avoid additional leakage of cold gas, improve the utilization rate of cold gas, and ensure the cooling effect. The present application adopts the weight reduction hole arranged on the front middle layer casing, which can reduce the weight of the CMC turbine outer ring assembly. Meanwhile, the closed cold gas cavity cooperates with the cooling channel to form the air film cooling layer on the concave side wall surface of the CMC turbine outer ring, which can simultaneously realize the cooling of the CMC turbine outer ring body and surface, improve the cooling efficiency of the CMC turbine outer ring, and prolong the service life of the component.

Description

Technical Field

[0001] This invention relates to the field of ceramic matrix composite turbine components, and discloses a CMC turbine outer ring assembly with a cold gas sealed cavity and its preparation method. Background Technology

[0002] In the field of gas turbine engines, the turbine outer ring, as a core stationary component that isolates high-temperature combustion gases and ensures stable operation of the turbine system, directly determines the engine's performance ceiling and service life through its cooling effect and lightweight design. Current technologies generally rely on a gap-like cooling space formed by the "middle casing-outer ring" fit, meaning that cooling gas can only flow within the contact gap between the middle casing and the outer ring, achieving cooling of the outer ring through indirect heat exchange. However, existing technologies have the following drawbacks:

[0003] (1) The constraint of the cooling gas depends on the connection and sealing between the middle casing and the outer ring. When the two are assembled, multiple sealing structures (such as sealing strips, metal gaskets, etc.) need to be set around the gap accuracy. However, due to the influence of processing errors and thermal deformation, micro gaps are prone to appear on the sealing surface, resulting in a high cooling gas leakage rate. This not only reduces the cooling efficiency, but also interferes with the gas flow channel due to the leaked gas, indirectly affecting the turbine's working efficiency. At the same time, in order to ensure the stability of the cooling gap, the middle casing needs to be designed as a continuous solid load-bearing structure. It is impossible to reduce the weight by hollowing out or other means, resulting in the casing weight accounting for more than 60% of the total weight of the outer ring connection components, which is contrary to the "lightweight" development requirements of aero-engines.

[0004] (2) The existing intermittent cooling space has a dispersed airflow path, making it difficult for the cooling air to evenly cover the outer ring arc body. This easily leads to the formation of "hot spots" in local areas of the ring (such as the middle of the flow channel surface or the joint of the mounting edge), resulting in a temperature difference of 150~200℃ in the outer ring. This accelerates the aging and cracking of outer ring materials such as ceramic matrix composites (CMC), shortening the service life of the components. In addition, the rigid connection structure between the middle casing and the outer ring is prone to thermal mismatch stress under high-temperature conditions due to the difference in their thermal expansion coefficients (such as the thermal expansion coefficients of the high-temperature alloy casing and the CMC outer ring differing by 3~5 times). This further damages the sealing performance and structural stability of the cooling gap, forming a vicious cycle of "sealing failure - decreased cooling efficiency - increased thermal stress". Summary of the Invention

[0005] The purpose of this invention is to provide a CMC turbine outer ring assembly with a cold air sealed cavity and a manufacturing method thereof, which can solve the technical problems of high cooling gas leakage rate, large component weight, and poor thermal deformation compatibility of existing turbine outer ring connection structures.

[0006] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows: A CMC turbine outer ring assembly with a cold gas sealed cavity includes: The CMC turbine outer ring is a hollow annular structure with a closed outer ring cold air chamber, and the closed outer ring cold air chamber is provided with a first air inlet; the CMC turbine outer ring is provided with several cooling channels for guiding the cold air in the closed outer ring cold air chamber to the concave side wall of the CMC turbine outer ring to cool the CMC turbine outer ring and form an air film cooling layer on the concave side wall. The front middle layer casing is connected to the front mounting edge, and the front middle layer casing is provided with a second air inlet; the second air inlet is connected to the first air inlet and is used to guide cold air into the closed outer ring cold air chamber. The rear middle casing is connected to the rear mounting edge on one side and to the front middle casing on the other side. A design gap is reserved between the rear middle casing and the outer ring of the CMC turbine. An elastic structure and an elastic sealing element are provided in the design gap. The elastic structure is used to adapt to the deformation difference between the rear middle casing and the outer ring of the CMC turbine under hot conditions. The elastic sealing element is used to seal the design gap.

[0007] Furthermore, the CMC turbine outer ring is composed of several arc-shaped segments spliced ​​together, and sealing plates are provided at both ends of the arc-shaped segments to seal the splice seam between two adjacent arc-shaped segments.

[0008] Furthermore, the arc-shaped segment includes an arc-shaped plate, a front mounting edge, a rear mounting edge, and a cover plate; the front mounting edge, the rear mounting edge, and the cover plate are all disposed on the outer convex side wall of the arc-shaped plate, and together with the arc-shaped plate, form the closed outer ring cold air cavity; the first air inlet is disposed on the front mounting edge.

[0009] Furthermore, the front middle layer casing includes a first mounting edge, a second mounting edge, and an arc-shaped connecting plate; the arc-shaped connecting plate is disposed in close contact with the outer convex wall surface of the arc-shaped plate, the arc-shaped connecting plate is provided with a weight reduction hole, and a boss positioning surface that abuts against the outer convex wall surface of the arc-shaped plate is provided on the concave side wall surface of the arc-shaped connecting plate; the first mounting edge and the second mounting edge are respectively disposed on both sides of the arc-shaped connecting plate, and the first mounting edge is connected to the front mounting edge through a first connector; the second air inlet is disposed on the first mounting edge; the first connector is provided with a third air inlet for guiding cold air into the closed outer ring cold air chamber.

[0010] Furthermore, the diameter of the first air inlet is determined by the following formula: ; in: The diameter of the first air inlet; The preset total coolant mass flow rate required for the CMC turbine outer ring; The density of the cold air; It is the pressure difference across the first air intake port; This is the cold air flow distribution coefficient; This is a preset CMC material process correction factor; This refers to the number of the first air intake holes; The given flow rate coefficient for the first air inlet; This refers to the number of third air intakes; The given flow coefficient for the third air inlet; This represents the physical flow area of ​​the third air inlet.

[0011] Furthermore, the rear middle layer casing includes a third mounting edge, a fourth mounting edge, and a fifth mounting edge; the third mounting edge and the fifth mounting edge are respectively disposed on both sides of the fourth mounting edge, the third mounting edge is connected to the rear mounting edge by a second connecting pin, the fifth mounting edge is connected to the second mounting edge by a third connecting bolt, and the design gap is reserved between the third mounting edge and the rear mounting edge, and between the fifth mounting edge and the second mounting edge.

[0012] Furthermore, the elastic structure is a spring coil, which is sleeved on the second connecting pin, and the two ends of the spring coil abut against the third mounting edge and the rear mounting edge, respectively.

[0013] A method for fabricating a CMC turbine outer ring assembly with high air-cooling efficiency, comprising the following steps: A CMC turbine outer ring preform was prepared and densified to obtain the CMC turbine outer ring; The CMC turbine outer ring is assembled with the front middle casing, the rear middle casing, the elastic structure, and the elastic seal to obtain the CMC turbine outer ring assembly.

[0014] Furthermore, the steps for preparing the CMC turbine outer ring preform include: Several layers of fiber cloth or fiber strips are laid on the lower mold to form an arc-shaped preform; Several layers of fiber cloth or fiber strips are laid on the upper mold to form an upper preform, which includes a Z-shaped sub-preform, a U-shaped sub-preform, and a C-shaped sub-preform. Install the cooling channel forming embedded part on the lower mold, and make the lower end of the cooling channel forming embedded part penetrate the arc plate preform; The lower mold and the upper mold are closed together, and the upper end of the cooling channel forming pre-embedded part penetrates the U-shaped sub-preform. Then the arc plate preform is sewn to the upper preform to form a CMC turbine outer ring preform containing the cooling channel forming pre-embedded part.

[0015] Furthermore, after obtaining the CMC turbine outer ring preform, the CMC turbine outer ring preform is densified, and then the cooling channel forming embedded part is removed in a directional manner to obtain the CMC turbine outer ring.

[0016] Compared with the prior art, the beneficial effects of this invention are: This invention utilizes a closed-loop cooling chamber on the outer ring of the CMC turbine. This allows for efficient cooling of the outer ring using cold air without requiring additional external cooling air channels, reducing leakage and simplifying the overall structural design. The invention employs an elastic structure that adaptively accommodates the thermal expansion differences between the CMC turbine outer ring and the metal casing, while elastic sealing components further prevent additional cold air leakage, improving cooling efficiency and ensuring effective cooling. The invention also incorporates weight-reduction holes on the front and middle casing to reduce the weight of the CMC turbine outer ring assembly. Simultaneously, the closed-loop cooling chamber, in conjunction with cooling channels, forms a film cooling layer on the concave sidewall of the CMC turbine outer ring, achieving simultaneous cooling of both the outer ring body and its surface, improving cooling efficiency and extending component lifespan. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the CMC turbine outer ring assembly with a cold air sealed cavity in the embodiment; Figure 2 This is a first cross-sectional view of the CMC turbine outer ring assembly with a cold air sealed cavity in the embodiment; Figure 3 This is a second cross-sectional view of the CMC turbine outer ring assembly with a cold air sealed cavity in the embodiment; Figure 4 This is a first-view schematic diagram of the CMC turbine outer ring in the embodiment; Figure 5 This is a second-view schematic diagram of the CMC turbine outer ring in the embodiment; Figure 6 This is a cross-sectional view of the outer ring of the CMC turbine in the embodiment; Figure 7 This is a schematic diagram of the structure of the first connecting pin in the embodiment; Figure 8 This is a schematic diagram of the front middle casing in the embodiment; Figure 9 This is a cross-sectional view of the front middle casing in the embodiment; Figure 10 This is a schematic diagram of the rear middle casing in the embodiment; Figure 11 This is a schematic diagram of the sealing sheet and the outer ring of the CMC turbine in the embodiment; Figure 12 This is a schematic diagram of the CMC turbine outer ring preform without the pre-embedded cooling channel forming parts in the embodiment; Figure 13 This is a schematic diagram of the upper and lower molds being closed in the embodiment; Figure 14 This is a schematic diagram of the upper mold in the embodiment; Figure 15 This is a schematic diagram of the lower mold in the embodiment; Figure 16 This is a schematic diagram of the structure of the pre-embedded part for forming the cooling channel in the embodiment; Figure 17 This is a schematic diagram of the cooling channel positioning plate in the embodiment; Figure 18 This is a cross-sectional view of the cooling channel positioning plate in the embodiment; Figure 19 This is a schematic diagram of the cooling channel positioning plate assembly in the embodiment; Figure 20 This is a cross-sectional view of the cooling channel positioning plate assembly in the embodiment; Figure 21 This is a flowchart illustrating the method for fabricating the CMC turbine outer ring assembly with a cold gas sealed cavity in the embodiment; Among them, 1-front middle casing, 11-first mounting edge, 12-second air intake, 13-arc connecting plate, 14-second mounting edge, 16-weight reduction hole, 17-boob positioning surface, 2-CMC turbine outer ring, 21-front mounting edge, 22-rear mounting edge, 23-cover plate, 24-arc plate, 25-first air intake, 26-first pin hole, 27-second pin hole, 28-U-shaped sealing groove, 29-I-shaped sealing groove, 211-closed outer ring cold air chamber, 212-cooling channel, 3-rear middle casing, 31-third mounting edge, 32-fourth mounting edge, 33-fifth mounting edge, 4-first connecting pin, 41-third air intake, 5-second connecting pin, 6-third connecting bolt, 8-W sealing ring, 9 - Spring ring, 10-U-shaped sealing plate, 20-Straight sealing plate, 501-Z-type sub-preform, 502-U-type sub-preform, 503-C-type sub-preform, 504-Arc-shaped plate preform, 601-Upper mold, 6011-Left sub-mold, 6012-Middle sub-mold, 6013-Right sub-mold, 6014-Preform radial upper stitching hole, 6015-Preform axial upper stitching hole, 901-Cooling channel forming embedded part, 902-Lower mold, 9021-Preform radial lower stitching hole, 9022-Embedded part lower positioning hole, 9020-Mold positioning groove, 904-Cooling channel positioning plate, 9041-Positioning block, 9042-Fixing hole, 9043-Fixing groove, 909-Cooling channel positioning plate assembly. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0019] See Figures 1 to 20 The present invention provides a CMC turbine outer ring assembly with a cold air sealed cavity, comprising: The CMC turbine outer ring 2 is a hollow annular structure with a closed outer ring cooling chamber 211, and the closed outer ring cooling chamber 211 is provided with a first air inlet 25; the CMC turbine outer ring 2 is provided with a plurality of cooling channels 212 for guiding the cold air in the closed outer ring cooling chamber 211 to the concave side wall of the CMC turbine outer ring 2 to cool the CMC turbine outer ring 2 and form an air film cooling layer on the concave side wall; The front middle layer casing 1 is connected to the front mounting edge 21, and the front middle layer casing 1 is provided with a second air inlet 12; the second air inlet 12 is connected to the first air inlet 25 and is used to guide cold air into the closed outer ring cold air chamber 211. The rear middle casing 3 is connected to the rear mounting edge 22 on one side and to the front middle casing 1 on the other side. A design gap is reserved between the rear middle casing 3 and the CMC turbine outer ring 2. An elastic structure and an elastic sealing element are provided within this design gap. The elastic structure adapts to the deformation difference between the rear middle casing 3 and the CMC turbine outer ring 2 under hot conditions. The elastic sealing element is used to seal the design gap. The elastic sealing element is a W-shaped sealing ring 8.

[0020] Based on the same inventive concept, see Figure 21 The present invention also provides a method for fabricating a CMC turbine outer ring assembly with high air-cooling efficiency, for fabricating the aforementioned CMC turbine outer ring assembly, comprising the following steps: A CMC turbine outer ring preform was prepared and densified to obtain CMC turbine outer ring 2; The CMC turbine outer ring 2 is assembled with the front middle casing 1, the rear middle casing 3, the elastic structure, and the elastic sealing component to obtain the CMC turbine outer ring assembly.

[0021] This invention utilizes a closed outer ring cooling chamber on the CMC turbine outer ring 2, achieving efficient cooling of the CMC turbine outer ring 2 with cool air without requiring additional external cooling air channels, thus reducing the cool air leakage rate and simplifying the overall structural design. The invention employs an elastic structure that adaptively matches the thermal expansion difference between the CMC turbine outer ring 2 and the metal casing, while the elastic sealing component seals the gap, further preventing additional cool air leakage, improving cool air utilization, and ensuring cooling effect. The invention incorporates weight-reduction holes 16 on the front middle casing 1, reducing the weight of the CMC turbine outer ring assembly. Simultaneously, the closed cooling chamber, in conjunction with the cooling channels, forms a film cooling layer on the concave sidewall of the CMC turbine outer ring 2, achieving simultaneous cooling of both the body and surface of the CMC turbine outer ring 2, significantly improving its cooling efficiency and extending component lifespan.

[0022] Example This embodiment further elaborates on the CMC turbine outer ring assembly with high air-cooling efficiency and its preparation method, as detailed below.

[0023] See Figures 1 to 20 A CMC turbine outer ring assembly with a cold air sealed cavity includes a front middle casing 1, a CMC turbine outer ring 2, a rear middle casing 3, a first connector, a second connecting pin 5, a third connecting bolt 6, a W sealing ring 8, and a spring ring 9; the components work together to form an integrated structure that combines cooling, connection, sealing, and weight reduction functions.

[0024] See Figures 4 to 6 The CMC turbine outer ring 2 adopts a closed outer ring design, which is a hollow annular structure with a closed outer ring cooling chamber 211, and is composed of several arc-shaped segments. Each arc-shaped segment includes an arc plate 24, a front mounting edge 21, a rear mounting edge 22, and a cover plate 23. The arc plate 24 forms a ring to create an engine combustion gas flow channel. The front mounting edge 21, the rear mounting edge 22, and the cover plate 23 are all located on the convex side wall of the arc plate 24, and together with the arc plate 24, they form the closed outer ring cooling chamber 211. Furthermore, a first air inlet 25 is provided on the front mounting edge 21, which is used to guide external cold air into the closed outer ring cooling chamber 211. The arc-shaped plate 24 is provided with a plurality of cooling channels 212, which are used to guide the cold air in the closed outer ring cold air cavity 211 to the concave side of the arc-shaped plate 24 to cool the arc-shaped plate 24 and form an air film cooling layer on the concave side wall of the arc-shaped plate 24.

[0025] Further, see Figures 4 to 6 , Figure 11Both ends of the arc segment are provided with sealing grooves, including a U-shaped sealing groove 28 and a straight sealing groove 29. A U-shaped sealing plate 10 and a straight sealing plate 20 are respectively installed in the U-shaped sealing groove 28 and the straight sealing groove 29 to seal the splice between two adjacent arc segments and reduce the leakage of cold air between two adjacent arc segments.

[0026] Further, see Figures 4 to 6 The front mounting edge 21 is provided with a first pin hole 26, and the rear mounting edge 22 is provided with a second pin hole 27. When connected with the front middle casing 1 and the rear middle casing 3, the first pin hole 26 and the second pin hole 27 are respectively used to assemble pins to realize the positioning connection between the CMC turbine outer ring 2 and the middle casing.

[0027] See Figures 8 to 9 The front middle casing 1 includes a first mounting edge 11, a second mounting edge 14, and an arc-shaped connecting plate 13. The arc-shaped connecting plate 13 is attached to the outer convex wall surface of the arc-shaped plate 24, and the axis of the arc-shaped connecting plate 13 is coaxial with the axis of the arc-shaped plate 24. The first mounting edge 11 and the second mounting edge 14 are respectively located on both sides of the arc-shaped connecting plate 13, and the first mounting edge 11 is connected to the front mounting edge 21 by a first connecting pin 4, and the second mounting edge 14 is connected to the rear middle casing 3 by a third connecting bolt 6. Moreover, a second air inlet 12 is provided on the first mounting edge 11, which is aligned and connected with the first air inlet 25 to guide external cold air into the closed outer ring cold air chamber 211. The arc-shaped connecting plate 13 adopts a hollow structure, and multiple weight-reduction holes 16 are evenly opened along the circumference of the arc-shaped connecting plate 13 to achieve lightweighting of the front middle casing 1 and reduce the overall weight of the CMC turbine outer ring 2 structural assembly. Meanwhile, a boss positioning surface 17 is provided on the concave side wall of the arc-shaped connecting plate 13 to abut against the convex side wall of the arc-shaped plate 24, so as to ensure the coaxiality of the assembly of the front middle layer casing 1 and the outer ring.

[0028] It should be noted that, see Figure 7 The first connecting pin 4 is provided with a third air inlet 41, through which some external cold air enters the closed outer ring cold air chamber 211. Moreover, the cold air can enhance the cooling of the first connecting pin 4, reduce its operating temperature, and minimize its deformation during operation. This matches the deformation of the first pin hole 26 on the CMC turbine outer ring 2, preventing the first connecting pin 4 from deforming too much relative to the first pin hole 26 during operation, which could lead to the failure of the first pin hole 26.

[0029] See Figure 10The rear middle casing 3 includes a third mounting edge 31, a fourth mounting edge 32, and a fifth mounting edge 33. The third mounting edge 31 and the fifth mounting edge 33 are respectively located on both sides of the fourth mounting edge 32, forming a Z-shape. The third mounting edge 31 is positioned and connected to the rear mounting edge 22 by a second connecting pin 5, and the fifth mounting edge 33 is fixed to the second mounting edge 14 by a third connecting bolt 6. Design gaps are reserved between the third mounting edge 31 and the rear mounting edge 22, and between the fifth mounting edge 33 and the second mounting edge 14, so they do not directly contact each other. A spring ring 9 is fitted onto the second connecting pin 5. The spring ring 9 is located within the design gap, and its two ends abut against the third mounting edge 31 and the rear mounting edge 22, respectively. The compression of the spring ring 9 can be adaptively adjusted according to the thermal deformation of the CMC turbine outer ring 2 and the rear middle casing 3, maintaining the pressure of the spring ring 9 on the CMC turbine outer ring 2 and the rear middle casing 3, and preventing the structural components of the CMC turbine outer ring 2 from loosening under hot conditions. At the same time, a W sealing ring 8 is also provided within the design gap. Its cross-section is "W" shaped, and the material is selected from high-temperature resistant elastic materials such as nickel-based high-temperature alloys or ceramic matrix composites to seal the design gap. It can effectively block the leakage of gas from the design gap, and can also adapt to the thermal deformation between the CMC turbine outer ring 2 and the rear middle casing 3.

[0030] The CMC turbine outer ring assembly of this invention has two different cold air introduction paths: Path 1: Cold air is directly introduced from the second air inlet 12 of the front middle casing 1, and enters the closed outer ring cold air chamber 211 through the aligned first air inlet 25; Path 2: Cold air enters the closed outer ring cold air chamber 211 of the CMC turbine outer ring 2 through the third air inlet 41 of the first connecting pin 4. The inlets of these two paths share the air source in front of the front middle casing, and the outlets of both paths are connected to the closed outer ring cold air chamber 211, which is a typical parallel flow relationship.

[0031] After the cold air diffuses within the closed outer ring cooling chamber 211, it enters the pre-set cooling channel 212 inside the arc plate 24. As the cold air flows along the cooling channel 212, it carries away the heat from the outer ring 2 of the CMC turbine through heat conduction. At the same time, the cold air is ejected from the outlet of the cooling channel 212, forming a continuous air film cooling layer on the concave side wall of the arc plate 24. This prevents the high-temperature combustion gas from the engine combustion passage from directly scouring the arc plate 24, significantly improving the cooling efficiency.

[0032] It should be noted that the diameter of the first air inlet 25 is determined by the following formula: ; in: The diameter of the first air inlet 25; The preset total cooling gas mass flow rate is required for the outer ring 2 of the CMC turbine. This preset total cooling gas mass flow rate must meet the design film cooling efficiency and the convective heat transfer requirements in the cooling channel. The specific value of the preset total cooling gas mass flow rate is determined by thermal analysis. The density of the cold air; It is the pressure difference before and after the first air intake port 25; This is the cold air flow distribution coefficient. Its physical meaning is: under the condition of parallel dual-path air supply, the uniformity coefficient of the cold air distribution to the most unfavorable cooling channel unit in the closed outer ring cold air chamber 211 represents the ratio of the actual flow rate to the ideal average flow rate of the most unfavorable cooling channel unit that plays a key role in the air film cooling efficiency. The specific value of the cold air flow distribution coefficient needs to be determined by combining the CDF analysis data of the CMC turbine outer ring assembly under the design conditions of this invention. To preset the CMC material process correction factor, Its physical meaning is: after the ceramic matrix composite preform is formed by the densification process, the surface roughness of the inner wall of the cooling channel 212 is significantly higher than that of the machined metal hole wall. The CMC material process correction coefficient is used to correct the reduction of the effective flow area and the additional friction loss caused by the inherent roughness of CMC. The specific value is determined and adjusted by those skilled in the art based on experience. The number of the first air intake 25; The given flow coefficient for the first air inlet 25 is determined manually or adjusted based on experience. The number of third air intakes 41; The given flow coefficient for the third air inlet 41 is determined manually or adjusted based on experience. The physical flow area of ​​the third air inlet 41.

[0033] When determining the diameter of the first air inlet 25, this invention takes into account the preset total cold air mass flow rate required by the CMC turbine outer ring 2. Pressure difference before and after the first air inlet 25 Cooling air flow distribution coefficient Preset CMC material process correction coefficient The number of first air inlets 25 The given flow coefficient of the first air inlet 25 The number of third air intake holes 41 The given flow coefficient of the third air inlet 41 The calculated diameter of the first inlet hole 25 is matched to the cooling air flow requirements under the design conditions of the turbine outer ring. This avoids the problems of local overheating and reduced structural reliability caused by insufficient cooling air supply, while also preventing the loss of overall cycle efficiency of the gas turbine due to excessive cooling air supply. This ensures that the CMC turbine outer ring assembly meets the cooling requirements while taking into account the overall working performance of the gas turbine.

[0034] It should be noted that the preset CMC material process correction coefficient... The value range can be determined based on the conventional CMC process, combined with the measured flow resistance data of the outer ring of the ceramic matrix composite turbine, for high-quality molded parts (fully densified, with smooth inner walls of the channels and few pores). The value range can be 1.05~1.1 for conventional mass-produced parts (standard densification process, medium roughness, stable batch). The value range can be 1.1~1.2, which is suitable for ordinary molded parts (with large channel roughness, local micropores, and general molding accuracy). The value range can be 1.2 to 1.4.

[0035] Based on the same inventive concept, this embodiment provides a method for manufacturing a CMC turbine outer ring assembly with a cold air sealed cavity. Traditional machining methods cannot process the internally curved cooling channel 212 and will damage the internal fibers. This method can directly form the internally curved cooling channel 212 without damaging the fibers, reducing machining processes and lowering costs.

[0036] See Figures 13 to 20 When preparing the CMC turbine outer ring 2, a preform forming mold is required. The preform forming mold is divided into an upper mold 601, a lower mold 902, a cooling channel forming embedded part 901, and a cooling channel positioning plate 904.

[0037] See Figure 15 The lower mold 902 is an arc plate structure with mold positioning grooves 9020 on both sides. Several radially downward stitching holes 9021 of the preform and several lower positioning holes 9022 of the embedded parts are opened through the arc plate structure, and the radially downward stitching holes 9021 of the preform and the lower positioning holes 9022 of the embedded parts do not coincide.

[0038] See Figure 14The upper mold 601 is composed of three parts: a left sub-mold 6011, a middle sub-mold 6012, and a right sub-mold 6013. Each of the left sub-mold 6011, middle sub-mold 6012, and right sub-mold 6013 has a plurality of radially upward stitching holes 6014 and axially upward stitching holes 6015 for the preform, as well as a plurality of positioning holes on the pre-embedded parts for the cooling channels. The radially upward stitching holes 6014 of the preform in the upper mold 601 and the radially downward stitching holes 9021 of the preform in the lower mold 902 correspond one-to-one.

[0039] See Figure 16 The cooling channel forming embedded part 901 is used to form a cooling channel 212 during the preparation of the CMC turbine outer ring 2. The cooling channel forming embedded part 901 has the same shape, size, and arrangement as the cooling channel 212. Specifically, the cooling channel forming embedded part 901 includes several sub-embedded parts, the shape and size of which are made according to the shape and size of the cooling channel 212. In this embodiment, the cooling channel forming embedded part 901 includes several straight cylindrical sub-embedded parts and curved sub-embedded parts. The cooling channel forming embedded part 901 is made of a material capable of directional ablation. In this embodiment, the cooling channel forming embedded part 901 is made of Al2O3, which has a melting point of 2050℃ and will not react during the CVI-PIP densification process.

[0040] See Figure 17 and Figure 18 The cooling channel positioning plate 904 is used to accurately position the cooling channel forming pre-embedded part 901 on the lower mold 902. The cooling channel positioning plate 904 is provided with fixing holes 9042 and fixing grooves 9043 for positioning the cooling channel forming pre-embedded part 901. The cooling channel forming pre-embedded part 901 is inserted into the fixing holes 9042 and fixing grooves 9043 without loosening or falling out, forming the cooling channel positioning plate assembly 909. See [link to documentation]. Figure 19 and Figure 20 Furthermore, the cooling channel positioning plate 904 is equipped with a positioning block 9041, which cooperates with the mold positioning groove 9020 of the lower mold 902 to achieve positioning and ensure that the cooling channel forming embedded part 901 can be accurately inserted into the embedded part lower positioning hole 9022 of the lower mold 902.

[0041] In this embodiment, the steps of the CMC turbine outer ring assembly fabrication method include: Step 1: Lay several layers of fiber cloth or fiber strips on the lower mold 902 to form the arc-shaped preform 504.

[0042] Step 2: Assemble the cooling channel forming embedded part 901 and the cooling channel positioning plate 904 into a cooling channel positioning plate assembly 909. Then, assemble the cooling channel positioning plate assembly 909 with the lower mold 902 containing the arc-shaped plate preform 504. The positioning block 9041 of the cooling channel positioning plate is inserted into the mold positioning groove 9020 of the lower mold 902. After the lower end of the cooling channel forming embedded part 901 pierces through the arc-shaped plate preform 504, it is inserted into the lower positioning hole 9022 of the embedded part in the lower mold 902 and fixed on the lower mold 902. During the process of the cooling channel forming embedded part 901 piercing through the arc-shaped plate preform 504, the fibers at local positions of the arc-shaped plate preform 504 undergo slight movement, providing space for the cooling channel forming embedded part 901 without disrupting the fiber continuity.

[0043] Step 3: Place the prepared Z-shaped sub-preform 501 into the left sub-mold 6011 and conform it to the surface of the left sub-mold 6011. Place the middle sub-mold 6012 into the preset position. Finally, place the C-shaped sub-preform 503 and the right sub-mold 6013 into the preset position. The Z-shaped sub-preform 501, U-shaped sub-preform 502, and C-shaped sub-preform 503 together constitute the upper preform.

[0044] Step 4: Remove the cooling channel positioning plate 904, close the upper mold 601 and the lower mold 902, and at the same time, make the upper end of the cooling channel forming embedded part 901 penetrate the upper preform and pass out through the positioning hole on the cooling channel forming embedded part of the upper mold 601. When closing the mold, the upper mold 601 and the lower mold 902 are positioned and fixed by matching the positioning pin and the mold positioning groove 9020 of the lower mold 902.

[0045] Step 5: Radially stitch the combination of the arc plate preform 504 and the upper preform along the radial stitching hole 6014 of the preform in the upper mold 601 and the radial stitching hole 9021 of the preform in the lower mold 902. Axially stitch the combination along the axial stitching hole 6015 of the preform in the upper mold 601 to finally form the CMC turbine outer ring preform, which contains the cooling channel forming embedded part 901 inside.

[0046] Step Six: The turbine outer ring preform is densified using the CVI-PIP process to obtain the CMC turbine outer ring 2. Then, the CMC turbine outer ring 2 is immersed in a directional removal liquid, causing the pre-embedded cooling channel forming part 901 within the CMC turbine outer ring 2 to react and dissolve with the directional removal liquid. After all the pre-embedded cooling channel forming part 901 is dissolved and removed, the required cooling channel 212 is formed within the CMC turbine outer ring 2. Finally, the CMC turbine outer ring 2 with the internal cooling channel 212 is removed. The directional removal liquid is molten NaOH at a temperature not exceeding 800℃. It should be noted that those skilled in the art can use other processes to densify the turbine outer ring preform.

[0047] Step 7: Assemble the CMC turbine outer ring 2 with the front middle casing 1, the rear middle casing 3, the W sealing ring 8, and the spring ring 9 to obtain the CMC turbine outer ring assembly.

[0048] Compared with the prior art, the present invention has the following significant advantages: This invention adopts a closed outer ring design, in which cold air is directly introduced into the closed outer ring cold air chamber from the front middle casing. Combined with the cooling channel inside the CMC turbine outer ring 2 and the outer surface air film cooling layer, it has the advantages of short cooling path and high cooling efficiency, which can effectively reduce the operating temperature of the CMC turbine outer ring 2 and extend the service life of CMC material.

[0049] The present invention provides a spring ring between the rear middle casing 3 and the CMC turbine outer ring 2, which can adaptively adjust the difference in thermal deformation between the two under hot conditions, avoid loosening or stress concentration of the CMC turbine outer ring 2, and improve the stability and thermal deformation compatibility of the structure.

[0050] The present invention opens weight reduction holes on the front middle layer casing. Under the premise of sealing the cold air in the CMC turbine outer ring 2, the weight of the casing can be reduced, which meets the lightweight requirements of aero engines. This invention effectively blocks gas leakage, improves sealing reliability, enhances turbine efficiency, and reduces corrosion of the casing by setting a square-shaped sealing plate 10 and a straight sealing plate 20 between the arc segments, and setting a W sealing ring 8 between the outer ring 2 of the CMC turbine and the rear middle casing 3.

[0051] The components of this invention are positioned by pins and connected by bolts, which makes assembly convenient, ensures assembly accuracy, facilitates later maintenance and component replacement, and reduces maintenance costs.

[0052] This invention overcomes the bottleneck of forming complex cooling channels inside CMC by pre-embedding cooling channels into embedded parts 901 within the pre-fabricated body of the CMC turbine outer ring and employing a physical / chemical dissolution process. This eliminates the need for subsequent machining of the CMC turbine outer ring 2, thereby reducing overall manufacturing costs. Furthermore, it avoids damaging the fiber continuity of the CMC turbine outer ring 2, facilitating its manufacturing.

[0053] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A CMC turbine outer ring assembly with a cold air sealed cavity, characterized in that, include: The CMC turbine outer ring (2) is a hollow annular structure with a closed outer ring cold air chamber (211), and the closed outer ring cold air chamber (211) is provided with a first air inlet (25); the CMC turbine outer ring (2) is provided with a plurality of cooling channels (212) for guiding the cold air in the closed outer ring cold air chamber (211) to the concave side wall of the CMC turbine outer ring (2) to cool the CMC turbine outer ring (2) and form a film cooling layer on the concave side wall; The front middle layer casing (1) is connected to the front mounting edge (21), and the front middle layer casing (1) is provided with a second air inlet (12); the second air inlet (12) is connected to the first air inlet (25) and is used to guide cold air into the closed outer ring cold air chamber (211). The rear middle casing (3) is connected to the rear mounting edge (22) on one side and to the front middle casing (1) on the other side. A design gap is reserved between the rear middle casing (3) and the CMC turbine outer ring (2). An elastic structure and an elastic sealing element are provided in the design gap. The elastic structure is used to adapt to the deformation difference between the rear middle casing (3) and the CMC turbine outer ring (2) under hot conditions. The elastic sealing element is used to seal the design gap.

2. The CMC turbine outer ring assembly according to claim 1, characterized in that, The CMC turbine outer ring (2) is composed of several arc segments spliced ​​together. The two ends of the arc segments are provided with sealing plates to seal the splice seam between two adjacent arc segments.

3. The CMC turbine outer ring assembly according to claim 2, characterized in that, The arc segment includes an arc plate (24), a front mounting edge (21), a rear mounting edge (22), and a cover plate (23); the front mounting edge (21), the rear mounting edge (22), and the cover plate (23) are all located on the outer convex side wall of the arc plate (24), and together with the arc plate (24) form the closed outer ring cold air cavity (211); the first air inlet (25) is located on the front mounting edge (21).

4. The CMC turbine outer ring assembly according to claim 3, characterized in that, The front middle layer casing (1) includes a first mounting edge (11), a second mounting edge (14), and an arc-shaped connecting plate (13); the arc-shaped connecting plate (13) is fitted to the outer convex wall surface of the arc-shaped plate (24), the arc-shaped connecting plate (13) is provided with a weight reduction hole (16), and a boss positioning surface (17) that abuts against the outer convex wall surface of the arc-shaped plate (24) is provided on the inner concave side wall surface of the arc-shaped connecting plate (13); the first mounting edge (11) and the second mounting edge (14) are respectively provided on both sides of the arc-shaped connecting plate (13), and the first mounting edge (11) is connected to the front mounting edge (21) through a first connector; the second air inlet (12) is provided on the first mounting edge (11); the first connector is provided with a third air inlet (41) for guiding cold air into the closed outer ring cold air chamber (211).

5. The CMC turbine outer ring assembly according to claim 4, characterized in that, The diameter of the first air inlet (25) is determined by the following formula: ； in: The diameter of the first air inlet (25); The preset total cold air mass flow rate required for the CMC turbine outer ring (2); The density of the cold air; It is the pressure difference before and after the first air inlet (25); This is the cold air flow distribution coefficient; This is a preset CMC material process correction factor; The number of the first air inlet (25); The given flow coefficient for the first air inlet (25); The number of the third air inlet (41); The given flow coefficient for the third air inlet (41); The physical flow area of ​​the third air inlet (41).

6. The CMC turbine outer ring assembly according to claim 5, characterized in that, The rear middle layer casing (3) includes a third mounting edge (31), a fourth mounting edge (32), and a fifth mounting edge (33); the third mounting edge (31) and the fifth mounting edge (33) are respectively disposed on both sides of the fourth mounting edge (32). The third mounting edge (31) is connected to the rear mounting edge (22) by a second connecting pin (5), and the fifth mounting edge (33) is connected to the second mounting edge (14) by a third connecting bolt (6). The design gap is reserved between the third mounting edge (31) and the rear mounting edge (22) and between the fifth mounting edge (33) and the second mounting edge (14).

7. The CMC turbine outer ring assembly according to claim 6, characterized in that, The elastic structure is a spring coil (9), which is sleeved on the second connecting pin (5), and the two ends of the spring coil (9) abut against the third mounting edge (31) and the rear mounting edge (22) respectively.

8. A method for fabricating a CMC turbine outer ring assembly with high air-cooling efficiency, used to fabricate the CMC turbine outer ring assembly as described in any one of claims 1-7, characterized in that, Includes the following steps: A CMC turbine outer ring preform was prepared and densified to obtain a CMC turbine outer ring (2); The CMC turbine outer ring (2) is assembled with the front middle casing (1), the rear middle casing (3), the elastic structure, and the elastic seal to obtain the CMC turbine outer ring assembly.

9. The method for manufacturing the CMC turbine outer ring assembly according to claim 8, characterized in that, The steps for preparing the CMC turbine outer ring preform include: Several layers of fiber cloth or fiber strips are laid on the lower mold (902) to form an arc-shaped preform (504); Several layers of fiber cloth or fiber strips are laid on the upper mold (601) to form an upper preform, the upper preform including a Z-shaped sub-preform (501), a U-shaped sub-preform (502) and a C-shaped sub-preform (503); Install the cooling channel forming embedded part (901) on the lower mold (902) and make the lower end of the cooling channel forming embedded part (901) penetrate the arc plate preform (504); The lower mold (902) and the upper mold (601) are closed, and the upper end of the cooling channel forming pre-embedded part (901) penetrates the U-shaped sub-preform (502). Then the arc plate preform (504) is sewn to the upper preform to form a CMC turbine outer ring preform containing the cooling channel forming pre-embedded part (901).

10. The method for manufacturing the CMC turbine outer ring assembly according to claim 9, characterized in that, After the CMC turbine outer ring preform is made, the CMC turbine outer ring preform is densified, and then the cooling channel forming embedded part (901) is removed in a directional manner to obtain the CMC turbine outer ring (2).

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