Arc-shaped end wall coupling outlet tail plate structure and design method thereof

Abstract

The application belongs to the technical field of subsonic plane cascade wind tunnel test, and particularly relates to an arc-shaped end wall coupled outlet tail plate structure and a design method thereof. The structure comprises: an inlet flow channel formed between the movable lower flow guide wall and the movable upper flow guide wall; a plurality of blades are installed on the plane cascade test piece at equal cascade pitch; the arc-shaped upper end wall is installed on the plane cascade test piece, and the leading edge of the arc-shaped upper end wall is connected with the terminal end of the movable upper flow guide wall; the arc-shaped lower end wall is installed on the plane cascade test piece, and the leading edge of the arc-shaped lower end wall is connected with the terminal end of the movable lower flow guide wall; the leading edge of the upper tail plate is connected with the terminal end of the arc-shaped upper end wall; the leading edge of the lower tail plate is connected with the terminal end of the arc-shaped lower end wall, and an outlet flow channel is formed between the lower tail plate and the upper tail plate. The application can improve the flow field quality of the plane cascade wind tunnel and ensure the effectiveness of the test data.

Description

Technical Field

[0001] The present application belongs to the technical field of subsonic plane blade wind tunnel testing, and in particular relates to a curved end wall coupled outlet tail plate structure and a design method thereof. Background Art

[0002] Plane cascade wind tunnels are a fundamental test facility widely used in the design and research of axial-flow turbomachinery. The design of compressor and turbine blades, core components of aircraft engines, relies on extensive plane cascade wind tunnel testing. These tests are widely used to verify blade profile performance, validate blade profile design methods, verify CFD design programs, and validate new test and measurement techniques. The cascade wind test database established based on plane cascade wind tunnel testing technology has long been a core technology of major aircraft engine companies.

[0003] During the plane blade test, the airflow in front of the blade first contacts the upper end wall of the plane blade. When the airflow passes through the upper end wall with a larger curvature, it makes a significant turn, which easily causes flow separation, resulting in blockage of the upper end wall channel, increased static pressure in front of the blade, and reduced Mach number. Under the action of this pressure difference in the blade pitch direction, the airflow deviates toward the lower end wall, resulting in differences in the flow of each channel of the plane blade, and the uniformity of the inlet Mach number and airflow angle, as well as the period of the flow field after the blade, which cannot meet the requirements of the plane blade test.

[0004] Modern, highly loaded compressor blades are typically characterized by high subsonic speeds and airflow deflection angles. This inherent influence on the wind tunnel flow field quality of these cascade blades is particularly pronounced. Therefore, it is hoped that a control technology solution can partially or completely mitigate these adverse effects on flow field quality, thereby improving the wind tunnel flow field quality of cascade blades and ensuring the validity of the test data.

[0005] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned deficiencies of the prior art. Summary of the Invention

[0006] The purpose of the present application is to provide a curved end wall coupled outlet tail plate structure and a design method thereof, so as to solve at least one problem existing in the prior art.

[0007] The technical solution of this application is:

[0008] A first aspect of the present application provides a curved end wall coupled outlet tail plate structure, comprising:

[0009] Movable upper guide wall;

[0010] A movable lower guide wall, wherein an inlet flow channel is formed between the movable lower guide wall and the movable upper guide wall;

[0011] A plane cascade test piece, wherein a plurality of blades are installed on the plane cascade test piece at equal pitch;

[0012] an arcuate upper end wall, the arcuate upper end wall being mounted on the planar cascade test piece, the leading edge of the arcuate upper end wall being connected to the end of the movable upper guide wall;

[0013] an arcuate lower end wall, the arcuate lower end wall being mounted on the planar cascade test piece, the leading edge of the arcuate lower end wall being connected to the end of the movable lower guide wall;

[0014] an upper tail plate, the front edge of which is connected to the end of the arc-shaped upper end wall;

[0015] A lower tail plate, wherein the front edge of the lower tail plate is connected to the end of the arc-shaped lower end wall, and an outlet flow channel is formed between the lower tail plate and the upper tail plate.

[0016] In at least one embodiment of the present application, the leading edges of the plurality of blades together form the leading edge line of the planar cascade test piece, and the leading edges of the arcuate upper end wall and the arcuate lower end wall are both located on the leading edge line of the planar cascade test piece.

[0017] In at least one embodiment of the present application, the arc-shaped upper end wall and the arc-shaped lower end wall are both arc-shaped wall panels with a certain curvature.

[0018] In at least one embodiment of the present application, the upper tail panel and the lower tail panel are both straight wall panels.

[0019] A second aspect of the present application provides a method for designing a curved end wall coupled outlet tail plate structure, which is used to design the curved end wall coupled outlet tail plate structure as described above, comprising:

[0020] Step 1: Determine the shape and thickness of the arc-shaped upper end wall and the arc-shaped lower end wall;

[0021] Step 2: Determine the chord lengths of the curved upper end wall and the curved lower end wall;

[0022] Step 3: Determine the distance in the cascade direction between the leading edge of the curved upper end wall and the leading edge of the upper end blade on the plane cascade test piece, and between the leading edge of the curved lower end wall and the leading edge of the lower end blade on the plane cascade test piece;

[0023] Step 4: Determine the installation angles of the arc-shaped upper end wall and the arc-shaped lower end wall relative to the axial direction of the plane cascade test piece;

[0024] Step 5: Determine the installation angles of the upper and lower tail panels;

[0025] Step 6: Design the curved end wall coupled outlet tail plate structure according to various parameters.

[0026] In at least one embodiment of the present application, in step 1, determining the shape and thickness of the arcuate upper end wall and the arcuate lower end wall includes:

[0027] S11. Determine the shape of the lower end surface of the arc-shaped upper end wall and the shape of the upper end surface of the arc-shaped lower end wall;

[0028] S12, determining the shape of the upper end surface of the arc-shaped upper end wall and the shape of the lower end surface of the arc-shaped lower end wall;

[0029] S13. Determine the thickness of the arc-shaped upper end wall and the arc-shaped lower end wall.

[0030] In at least one embodiment of the present application, in S11, determining the shape of the lower end surface of the arc-shaped upper end wall and the shape of the upper end surface of the arc-shaped lower end wall includes:

[0031] The shape of the lower end surface of the arc-shaped upper end wall and the shape of the upper end surface of the arc-shaped lower end wall are designed according to the blade pressure surface profile of the plane cascade test piece.

[0032] In at least one embodiment of the present application, in S11, determining the shape of the lower end surface of the arc-shaped upper end wall and the shape of the upper end surface of the arc-shaped lower end wall includes:

[0033] The shape of the lower end surface of the arc-shaped upper end wall and the shape of the upper end surface of the arc-shaped lower end wall are designed according to the middle streamline of the cascade channel of the ideal two-dimensional plane cascade flow field determined by numerical simulation.

[0034] In at least one embodiment of the present application, in S12, determining the shape of the upper end surface of the arc-shaped upper end wall and the shape of the lower end surface of the arc-shaped lower end wall includes:

[0035] The shape of the upper end surface of the arc-shaped upper end wall and the shape of the lower end surface of the arc-shaped lower end wall are selected to be the same as the shape of the flow channel surface.

[0036] In at least one embodiment of the present application, in S13, determining the thickness of the arc-shaped upper end wall and the arc-shaped lower end wall includes:

[0037] Thickness of the arc-shaped upper end wall and the arc-shaped lower end wall λ w Equal to the maximum blade thickness C on the plane cascade test piece max One half of .

[0038] In at least one embodiment of the present application, in step 2, determining the chord lengths of the curved upper end wall and the curved lower end wall includes:

[0039] The chord length C of the curved upper end wall and the curved lower end wall w Equal to the blade chord length C on the plane cascade test piece.

[0040] In at least one embodiment of the present application, in step three, determining the distance in the cascade direction between the leading edge of the curved upper end wall and the leading edge of the upper end blade on the planar cascade test piece, and between the leading edge of the curved lower end wall and the leading edge of the lower end blade on the planar cascade test piece, includes:

[0041] The distance t in the cascade direction between the leading edge of the curved upper end wall and the leading edge of the upper end blade on the plane cascade test piece, and between the leading edge of the curved lower end wall and the leading edge of the lower end blade on the plane cascade test piece w , which is equal to half of the pitch t of the plane cascade test piece.

[0042] In at least one embodiment of the present application, in step 4, determining the installation angles of the curved upper end wall and the curved lower end wall relative to the axial direction of the planar cascade test piece includes:

[0043] The installation angle β of the arc-shaped upper end wall and the arc-shaped lower end wall relative to the axial direction of the plane cascade test piece w The value range is the blade installation angle β on the plane cascade test piece y +(0°~3°).

[0044] In at least one embodiment of the present application,

[0045] When the plane cascade test piece is in the range of -8° to 4° attack angle, the installation angle β of the arc-shaped upper end wall and the arc-shaped lower end wall relative to the axial direction of the plane cascade test piece is w The value range is the blade installation angle β on the plane cascade test piece y +(0°~1.5°);

[0046] When the plane cascade test piece is in the positive attack angle range of 4° to 8°, the installation angle β of the arc-shaped upper end wall and the arc-shaped lower end wall relative to the axial direction of the plane cascade test piece is w The value range is the blade installation angle β on the plane cascade test piece y +(1.5°~3°).

[0047] In at least one embodiment of the present application, in step five, determining the installation angles of the upper tailgate and the lower tailgate includes:

[0048] The installation angle γ of the upper tail plate and the lower tail plate has a value range of the design outlet angle β2 of the plane cascade test piece + (0°~5°).

[0049] In at least one embodiment of the present application,

[0050] When the plane cascade test piece is in the attack angle range of -8° to 4°, the installation angle γ of the upper tail plate and the lower tail plate is in the range of the design outlet angle β2+(0 to 2°) of the plane cascade test piece;

[0051] When the plane cascade test piece is in the positive attack angle range of 4° to 8°, the installation angle γ of the upper tail plate and the lower tail plate has a value range of the design outlet angle β2+(2° to 5°) of the plane cascade test piece.

[0052] The invention has at least the following beneficial technical effects:

[0053] The curved end wall coupled outlet tail plate structure of the present application can improve the flow field quality of the plane cascade wind tunnel and ensure the validity of the test data. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a schematic diagram of the curved end wall coupled outlet tail plate structure of one embodiment of the present application;

[0055] Figure 2 This is a schematic diagram of the geometry and aerodynamic parameters of a compressor plane cascade according to one embodiment of the present application;

[0056] Figure 3 It is a two-dimensional numerical simulation result of a certain compressor plane blade grid under an ideal periodic boundary and the intermediate streamline of the blade grid channel in one embodiment of the present application.

[0057] in:

[0058] 11- movable upper guide wall; 12- movable lower guide wall; 21- plane cascade test piece; 22- upper end blade; 23- lower end blade; 31- arcuate upper end wall; 32- arcuate lower end wall; 41- upper tail plate; 42- lower tail plate. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be understood as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0060] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as limiting the scope of protection of this application.

[0061] The following is combined with Figures 1 to 3 This application is described in further detail.

[0062] A first aspect of the present application provides a curved end wall coupled outlet tail plate structure, comprising: a movable upper guide wall 11 , a movable lower guide wall 12 , a plane cascade test piece 21 , a curved upper end wall 31 , a curved lower end wall 32 , an upper tail plate 41 and a lower tail plate 42 .

[0063] Specifically, such as Figure 1 As shown, an inlet flow channel is formed between the movable lower guide wall 12 and the movable upper guide wall 11; the plane cascade test piece 21 is located at the ends of the movable upper guide wall 11 and the movable lower guide wall 12, and a plurality of blades are installed on the plane cascade test piece 21 at equal pitches, and the leading edges of the plurality of blades together form the leading edge line of the plane cascade test piece 21.

[0064] The curved upper end wall 31 and the curved lower end wall 32 are both curved wall panels with a certain curvature. The shape and size of the curved upper end wall 31 and the curved lower end wall 32 are identical. The difference is that the lower end surface of the curved upper end wall 31 is the flow channel wall surface that contacts the airflow inside the wind tunnel, while the upper end surface of the curved lower end wall 32 is the flow channel wall surface that contacts the airflow inside the wind tunnel. The curved upper end wall 31 is installed on the plane cascade test specimen 21, and the leading edge of the curved upper end wall 31 is connected to the end of the movable upper guide wall 11; the curved lower end wall 32 is installed on the plane cascade test specimen 21, and the leading edge of the curved lower end wall 32 is connected to the end of the movable lower guide wall 12. The leading edges of the curved upper end wall 31 and the curved lower end wall 32 are both located on the leading edge line of the plane cascade test specimen 21.

[0065] The upper tail plate 41 and the lower tail plate 42 have exactly the same shape and size. Both the upper tail plate 41 and the lower tail plate 42 are straight wall plates of a certain length. The leading edge of the upper tail plate 41 is connected to the end of the curved upper end wall 31, and the leading edge of the lower tail plate 42 is connected to the end of the curved lower end wall 32. An outlet flow channel is formed between the lower tail plate 42 and the upper tail plate 41.

[0066] The curved endwall-coupled outlet tail plate structure of this application is constructed by placing a limited number of identical blades on a planar cascade test specimen 21 and linearly arranging them at a predetermined distance, forming a planar cascade model. This model simulates the periodic flow of annular elemental cascades in compressor or turbine blades. To obtain wind test data reflecting the true performance of the blade profile, the planar cascade test specimen 21 exhibits excellent flow field periodicity, meeting flow field quality requirements.

[0067] The curved end wall of the present application is coupled with an outlet tail plate structure. The plane cascade test piece 21 is installed on a rotatable disc of the test section. The inlet angle (angle of attack) of the cascade flow is adjusted by cooperating with the movable upper and lower guide walls. In order to close the flow channel to reduce flow leakage, the movable upper and lower guide walls are connected to the leading edges of the curved upper and lower end walls installed on the plane cascade test piece 21. Since the inlet angle of the cascade is generally an acute angle, the plane cascade test piece 21 is always tilted relative to the axial inlet flow of the wind tunnel. The larger the inlet angle, the more tilted the cascade. The movable upper guide wall 11 is connected to the curved upper end wall 31, and together they form the upper boundary of the test section; the movable lower guide wall 12 is connected to the curved lower end wall 32, and together they form the lower boundary of the test section.

[0068] Based on the above-mentioned curved end wall coupled outlet tail plate structure, a second aspect of the present application provides a design method for a curved end wall coupled outlet tail plate structure, including:

[0069] Step 1: Determine the shape and thickness of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32;

[0070] Step 2: Determine the chord lengths of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32;

[0071] Step 3: Determine the distance in the cascade direction between the leading edge of the curved upper end wall 31 and the leading edge of the upper end blade 22 of the planar cascade test piece 21, and between the leading edge of the curved lower end wall 32 and the leading edge of the lower end blade 23 of the planar cascade test piece 21;

[0072] Step 4: Determine the installation angles of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32 relative to the axial direction of the planar cascade test piece 21;

[0073] Step 5: Determine the installation angles of the upper tail plate 41 and the lower tail plate 42;

[0074] Step 6: Design the curved end wall coupled outlet tail plate structure according to various parameters.

[0075] In a preferred embodiment of the present application, in step 1, determining the shape and thickness of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32 includes:

[0076] S11, determining the shape of the lower end surface of the arc-shaped upper end wall 31 and the shape of the upper end surface of the arc-shaped lower end wall 32;

[0077] S12, determining the shape of the upper end surface of the arc-shaped upper end wall 31 and the shape of the lower end surface of the arc-shaped lower end wall 32;

[0078] S13 , determining the thickness of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32 .

[0079] In one embodiment of the present application, in S11, determining the shape of the lower end surface of the arc-shaped upper end wall 31 and the shape of the upper end surface of the arc-shaped lower end wall 32 includes:

[0080] The shape of the lower end surface of the arc-shaped upper end wall 31 and the shape of the upper end surface of the arc-shaped lower end wall 32 are designed according to the blade pressure surface profile of the plane cascade test piece 21 .

[0081] In another embodiment of the present application, in S11, determining the shape of the lower end surface of the arc-shaped upper end wall 31 and the shape of the upper end surface of the arc-shaped lower end wall 32 includes:

[0082] The shape of the lower end surface of the arcuate upper end wall 31 and the shape of the upper end surface of the arcuate lower end wall 32 are designed according to the middle streamline of the cascade channel of the ideal two-dimensional plane cascade flow field determined by numerical simulation.

[0083] The design method of the curved end wall coupled outlet tail plate structure of the present application provides two schemes for determining the lower end surface shape of the curved upper end wall 31 and the upper end surface shape of the curved lower end wall 32. The purpose of both schemes is to reduce the degree of deflection of the airflow when flowing through the end wall, thereby weakening the flow separation and improving the periodicity of the flow field.

[0084] In a preferred embodiment of the present application, the upper end surface of the curved upper end wall 31 and the lower end surface of the curved lower end wall 32 are both non-flow path wall surfaces that do not contact the internal flow field, and their shapes have no effect on the flow field. Considering weight and space requirements, in S12, the upper end surface of the curved upper end wall 31 and the lower end surface of the curved lower end wall 32 are shaped identically to the flow path surfaces.

[0085] The thickness of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32 can be designed to be equal in thickness. In the preferred embodiment of the present application, in S13, the thickness λ of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32 is w Equal to the maximum blade thickness C on the plane cascade test piece 21 max One half of .

[0086] In a preferred embodiment of the present application, in step 2, determining the chord lengths of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32 includes:

[0087] The chord length C of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32w It is equal to the blade chord length C on the plane cascade test piece 21.

[0088] In a preferred embodiment of the present application, in step three, determining the distance in the cascade direction between the leading edge of the curved upper end wall 31 and the leading edge of the upper end blade 22 on the planar cascade test piece 21, and between the leading edge of the curved lower end wall 32 and the leading edge of the lower end blade 23 on the planar cascade test piece 21, includes:

[0089] The distance t in the cascade direction between the leading edge of the arc-shaped upper end wall 31 and the leading edge of the upper end blade 22 on the plane cascade test piece 21, and between the leading edge of the arc-shaped lower end wall 32 and the leading edge of the lower end blade 23 on the plane cascade test piece 21 w , which is equal to half of the pitch t of the plane cascade test piece 21.

[0090] In a preferred embodiment of the present application, in step 4, determining the installation angles of the arcuate upper end wall 31 and the arcuate lower end wall 32 relative to the axial direction of the planar cascade test piece 21 includes:

[0091] The installation angle β of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32 relative to the axial direction of the plane cascade test piece 21 is w The value range is the blade installation angle β on the plane cascade test piece 21 y +(0°~3°).

[0092] In this embodiment, when the plane cascade test piece 21 is in the range of -8° to 4° attack angle, the installation angle β of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32 relative to the axial direction of the plane cascade test piece 21 is w The value range is the blade installation angle β on the plane cascade test piece 21 y +(0°~1.5°); When the plane cascade test piece 21 is in the positive attack angle range of 4°~8°, the installation angle β of the arc-shaped upper end wall 31 and the arc-shaped lower end wall 32 relative to the axial direction of the plane cascade test piece 21 w The value range is the blade installation angle β on the plane cascade test piece 21 y +(1.5°~3°).

[0093] In a preferred embodiment of the present application, in step five, determining the installation angles of the upper tail panel 41 and the lower tail panel 42 includes:

[0094] The installation angle γ of the upper tail plate 41 and the lower tail plate 42 has a value range of the designed outlet angle β2 of the plane cascade test piece 21 + (0° to 5°).

[0095] In this embodiment, when the plane cascade test piece 21 is in the attack angle range of -8° to 4°, the installation angle γ of the upper tail panel 41 and the lower tail panel 42 takes a value range of the design outlet angle β2 of the plane cascade test piece 21 + (0° to 2°); when the plane cascade test piece 21 is in the positive attack angle range of 4° to 8°, the installation angle γ of the upper tail panel 41 and the lower tail panel 42 takes a value range of the design outlet angle β2 of the plane cascade test piece 21 + (2° to 5°).

[0096] The curved end wall coupled outlet tail plate structure and its design method of the present application can effectively improve the flow field quality of the plane cascade wind tunnel test. On the one hand, the curved upper end wall design ensures that the airflow flowing through the movable upper guide wall has a smaller degree of deflection when passing through the upper end wall, which significantly suppresses the flow separation and blockage of the upper end wall channel under the conventional upper end wall configuration (composed of the suction surface of the uppermost blade of the plane cascade), thereby improving the uniformity of the plane cascade inlet Mach number and inlet airflow angle. On the other hand, the tail plate extending behind the curved end wall isolates the interference of the ambient atmosphere on the cascade outlet flow field, directly improving the periodicity of the plane cascade outlet angle and outlet Mach number. The outlet static pressure distribution formed by the appropriate tail plate installation angle can further reduce the blockage of the upper end wall channel and further improve the plane cascade inlet flow field quality.

[0097] The two most common flow field quality control methods in plane cascade wind tunnels are the tail suction of the movable upper guide wall and the use of an adjustable tail plate at the outlet. The method of the tail suction of the movable upper guide wall is ideal for improving the uniformity of the inlet flow field, but it is not effective in improving the periodicity of the outlet flow field, especially the periodicity of the outlet angle. It also has the disadvantages of high requirements for the capacity of the suction system and large interference with the inlet flow field. The method of using an adjustable tail plate at the outlet is ideal for improving the periodicity of the outlet angle of the plane cascade, but it is not effective enough in improving the uniformity of the inlet flow field. The arc-shaped end wall coupled outlet tail plate structure and its design method of the present application can achieve a very ideal improvement effect on the uniformity of the inlet flow field and the periodicity of the outlet flow field of the plane cascade. By designing a reasonable circumferential end wall in a limited wind tunnel test section, a good plane cascade wind tunnel flow field quality is established, and the main parameters required for the design of a reasonable configuration are given. In addition, the arc-shaped end wall coupled tail plate method can reduce the minimum number of blades required for the plane cascade test piece from 7 under normal circumstances to 5, greatly reducing the cost of the cascade test and enhancing the test capability of the plane cascade wind tunnel.

[0098] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A curved end wall coupled outlet tail plate structure, characterized in that: include: A movable upper guide wall (11); A movable lower guide wall (12), wherein an inlet flow channel is formed between the movable lower guide wall (12) and the movable upper guide wall (11); A plane cascade test piece (21), wherein a plurality of blades are mounted on the plane cascade test piece (21) at equal pitches; an arc-shaped upper end wall (31), the arc-shaped upper end wall (31) being mounted on the plane cascade test piece (21), the leading edge of the arc-shaped upper end wall (31) being connected to the end of the movable upper guide wall (11); an arc-shaped lower end wall (32), the arc-shaped lower end wall (32) being mounted on the plane cascade test piece (21), the leading edge of the arc-shaped lower end wall (32) being connected to the end of the movable lower guide wall (12); an upper tail plate (41), wherein a front edge of the upper tail plate (41) is connected to the end of the arc-shaped upper end wall (31); A lower tail plate (42) has a front edge connected to the end of the arc-shaped lower end wall (32), and an outlet flow channel is formed between the lower tail plate (42) and the upper tail plate (41).

2. The arc-shaped end wall coupling outlet tail plate structure according to claim 1, characterized in that: The leading edges of the plurality of blades together form the leading edge line of the plane cascade test piece (21), and the leading edges of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) are both located on the leading edge line of the plane cascade test piece (21).

3. The arc-shaped end wall coupling outlet tail plate structure according to claim 2, characterized in that: The arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) are both arc-shaped wall panels with a certain curvature.

4. The arc-shaped end wall coupling outlet tail plate structure according to claim 3, characterized in that: The upper tail plate (41) and the lower tail plate (42) are both straight wall plates.

5. A method for designing a curved end wall coupled outlet tail plate structure, used for designing a curved end wall coupled outlet tail plate structure according to any one of claims 1 to 4, characterized in that: include: Step 1: Determine the shape and thickness of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32); Step 2: Determine the chord lengths of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32); Step 3: Determine the distance in the grating direction between the leading edge of the curved upper end wall (31) and the leading edge of the upper end blade (22) on the plane cascade test piece (21), and between the leading edge of the curved lower end wall (32) and the leading edge of the lower end blade (23) on the plane cascade test piece (21); Step 4: determining the installation angles of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) relative to the axial direction of the plane cascade test piece (21); Step 5: Determine the installation angles of the upper tail plate (41) and the lower tail plate (42); Step 6: Design the curved end wall coupled outlet tail plate structure according to various parameters.

6. The method for designing a curved end wall coupled outlet tail plate structure according to claim 5, characterized in that: In step 1, the shape and thickness of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) are determined, including: S11, determining the shape of the lower end surface of the arc-shaped upper end wall (31) and the shape of the upper end surface of the arc-shaped lower end wall (32); S12, determining the shape of the upper end surface of the arc-shaped upper end wall (31) and the shape of the lower end surface of the arc-shaped lower end wall (32); S13, determining the thickness of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32).

7. The method for designing a curved end wall coupled outlet tail plate structure according to claim 6, characterized in that: In S11, the shape of the lower end surface of the arc-shaped upper end wall (31) and the shape of the upper end surface of the arc-shaped lower end wall (32) are determined, including: The shape of the lower end surface of the arc-shaped upper end wall (31) and the shape of the upper end surface of the arc-shaped lower end wall (32) are designed according to the blade pressure surface profile of the plane blade cascade test piece (21).

8. The method for designing a curved end wall coupled outlet tail plate structure according to claim 6, characterized in that: In S11, the shape of the lower end surface of the arc-shaped upper end wall (31) and the shape of the upper end surface of the arc-shaped lower end wall (32) are determined, including: The lower end surface shape of the arc-shaped upper end wall (31) and the upper end surface shape of the arc-shaped lower end wall (32) are designed according to the middle streamline of the cascade channel of the ideal two-dimensional plane cascade flow field determined by numerical simulation.

9. The method for designing a curved end wall coupled outlet tail plate structure according to claim 7 or 8, characterized in that: In S12, the upper end surface shape of the arc-shaped upper end wall (31) and the lower end surface shape of the arc-shaped lower end wall (32) are determined, including: The shape of the upper end surface of the arc-shaped upper end wall (31) and the shape of the lower end surface of the arc-shaped lower end wall (32) are selected to be the same as the shape of the flow channel surface.

10. The method for designing a curved end wall coupled outlet tail plate structure according to claim 9, characterized in that: In S13, the thickness of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) is determined, including: The thickness λ of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) w Equal to the maximum blade thickness C on the plane cascade test piece (21) max One half of .

11. The method for designing a curved end wall coupled outlet tail plate structure according to claim 10, characterized in that: In step 2, determining the chord lengths of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) includes: The chord length C of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) w It is equal to the blade chord length C on the plane cascade test piece (21).

12. The method for designing a curved end wall coupled outlet tail plate structure according to claim 11, characterized in that: In step three, determining the distance in the grating direction between the leading edge of the curved upper end wall (31) and the leading edge of the upper end blade (22) on the plane cascade test piece (21), and between the leading edge of the curved lower end wall (32) and the leading edge of the lower end blade (23) on the plane cascade test piece (21), includes: The distance t in the grating direction between the leading edge of the arc-shaped upper end wall (31) and the leading edge of the upper end blade (22) on the plane cascade test piece (21), and between the leading edge of the arc-shaped lower end wall (32) and the leading edge of the lower end blade (23) on the plane cascade test piece (21) w , which is equal to half of the pitch t of the plane cascade test piece (21).

13. The method for designing a curved end wall coupled outlet tail plate structure according to claim 12, characterized in that: In step 4, determining the installation angles of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) relative to the axial direction of the plane cascade test piece (21) includes: The installation angle β of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) relative to the axial direction of the plane blade cascade test piece (21) w The range of values ​​is the blade installation angle β on the plane cascade test piece (21) y +(0°~3°).

14. The method for designing a curved end wall coupled outlet tail plate structure according to claim 13, characterized in that: When the plane blade cascade test piece (21) is in the range of -8° to 4° attack angle, the installation angle β of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) relative to the axial direction of the plane blade cascade test piece (21) is w The range of values ​​is the blade installation angle β on the plane cascade test piece (21) y +(0°~1.5°); When the plane blade cascade test piece (21) is in the positive attack angle range of 4° to 8°, the installation angle β of the arc-shaped upper end wall (31) and the arc-shaped lower end wall (32) relative to the axial direction of the plane blade cascade test piece (21) is w The range of values ​​is the blade installation angle β on the plane cascade test piece (21) y +(1.5°~3°).

15. The method for designing a curved end wall coupled outlet tail plate structure according to claim 14, characterized in that: In step five, the installation angles of the upper tail plate (41) and the lower tail plate (42) are determined, including: The value range of the installation angle γ of the upper tail plate (41) and the lower tail plate (42) is the designed outlet angle β2 of the plane blade test piece (21) + (0° to 5°).

16. The method for designing a curved end wall coupled outlet tail plate structure according to claim 15, characterized in that: When the plane cascade test piece (21) is in the range of -8° to 4° attack angle, the installation angle γ of the upper tail plate (41) and the lower tail plate (42) has a value range of the design outlet angle β2 of the plane cascade test piece (21) + (0 to 2°); When the plane blade cascade test piece (21) is in the positive attack angle range of 4° to 8°, the installation angle γ of the upper tail plate (41) and the lower tail plate (42) has a value range of the design outlet angle β2 of the plane blade cascade test piece (21) + (2° to 5°).

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