A non-integer ratio variable geometry sector cascade test piece structure

Abstract

This application belongs to the technical field of aeroengine fan cascade wind tunnel tests, and particularly relates to a non-integer ratio variable geometry fan cascade test piece structure, including: an outer grid plate and an inner grid plate forming an arc-shaped channel, a left side wall and a right side wall sealed on both sides; a guide vane and a measured blade in the arc-shaped channel; wherein, the guide vane is installed between the outer grid plate and the inner grid plate through an angle adjustment mechanism, which includes a tenon shaft fixed at both ends of the guide vane, the tenon shafts respectively pass through through holes of the outer grid plate and the inner grid plate, and a corner positioning block is also sleeved outside the outer grid plate on the tenon shaft, and the corner positioning block is connected with the tenon shaft in a shape-matching manner to limit the rotation of the guide vane along the tenon shaft. The corner positioning block has a plurality of circumferentially distributed positioning holes, and the outer grid plate has a plurality of pin holes at the positions of the positioning holes. A pin shaft passes through the positioning holes and is connected with the pin holes; the deflection angle of the guide vane can be adjusted by adjusting the angular position relationship between the positioning holes and the pin holes.

Description

Technical Field

[0001] This application belongs to the technical field of aeroengine sector cascade wind tunnel tests, and particularly relates to a non-integer ratio variable geometry sector cascade test piece structure. Background Art

[0002] In the basic research on the performance of compressor and turbine blades, a large number of cascade wind tunnel blowing tests are required to verify theoretical research such as airfoil design.

[0003] Compared with a flat cascade, an annular cascade can reflect the complex three-dimensional flow structure in the cascade passage and is closer to the aerodynamic environment of the whole machine. To save the cost of test pieces and gas sources, a certain central angle range of the annular cascade is generally intercepted to form a sector cascade. As Figure 1 shown, the sector cascade test piece consists of inner and outer grid plates, two side walls, guide vanes, and the measured blades. The components of the existing sector cascade test pieces are all connected by welding, without the function of disassembling and replacing blades, without the function of adjusting the attack angle of the guide vanes, and without considering the circumferential non-uniformity of the flow field.

[0004] When the number of blades of the measured blades and the guide vanes is a non-integer ratio (excluding 0.5 times), the wake of the guide vanes will be at different circumferential positions in the passage of the measured blades, resulting in different circumferential flow fields within the entire circumference. Therefore, selecting sector cascades at different circumferential positions will result in different test results; the circumferential distribution of the periodic gradient of the aerodynamic parameters at the outlet of the sector cascade is uneven, so it is particularly important to reduce the circumferential non-uniformity degree and determine the circumferential position of the measurement section behind the grid; for the research on the variable attack angle characteristics, a reliable angle adjustment method should also be determined. Summary of the Invention

[0005] To solve the above problems, this application provides a non-integer ratio variable geometry sector cascade test piece structure, including:

[0006] An outer grid plate and an inner grid plate forming an arc-shaped passage, both the outer grid plate and the inner grid plate are arc-shaped, and gas passes through the arc-shaped passage;

[0007] A left side wall and a right side wall sealed on both circumferential sides of the outer grid plate and the inner grid plate;

[0008] A plurality of guide vanes circumferentially installed at the front end of the arc-shaped passage in the oncoming flow direction;

[0009] A plurality of measured blades circumferentially installed at the rear end of the guide vanes in the arc-shaped passage;

[0010] Among them, the guide vane is installed between the outer grid plate and the inner grid plate through an angle adjustment mechanism. The angle adjustment mechanism includes: tenon shafts fixed at both ends of the guide vane. The tenon shafts respectively pass through through holes of the outer grid plate and the inner grid plate. A corner positioning block is sleeved outside the outer grid plate on the tenon shaft. The corner positioning block is connected with the tenon shaft in a shape-matching manner to limit the rotation of the guide vane along the tenon shaft. The corner positioning block has a plurality of positioning holes distributed circumferentially. The outer grid plate has a plurality of pin holes at the positions of the positioning holes. A pin shaft passes through the positioning hole and is connected with the pin hole; the deflection angle of the guide vane can be adjusted by adjusting the angular position relationship between the positioning hole and the pin hole.

[0011] Preferably, the tenon shaft includes:

[0012] The outer grid plate positioning tenon shaft connected to the outer grid plate

[0013] And the inner grid plate positioning tenon shaft connected to the inner grid plate;

[0014] A disc-shaped outer grid plate positioning tenon is fixed on the outer grid plate positioning tenon shaft. The outer grid plate positioning tenon is installed in an outer circular groove on the inner wall surface of the outer grid plate;

[0015] A disc-shaped inner grid plate positioning tenon is fixed on the inner grid plate positioning tenon shaft. The inner grid plate positioning tenon is installed in an inner circular groove on the inner wall surface of the inner grid plate.

[0016] Preferably, the outer grid plate has a measured blade measurement structure for observing the measured blade. The measured blade measurement structure has a visualization window made of plexiglass.

[0017] Preferably, the surface covered by the measured blade measurement structure is a measurement section; the measurement section covers 1 to 3 cascade channels. The midpoint of the measurement section is located at the position of 1 / 4 circumferential angle from the left side wall. The left side wall is the wall surface corresponding to the suction surface of the measured blade; among them, the cascade channel is the channel formed between adjacent measured blades.

[0018] Preferably, at least two complete cascade channels are reserved on the left side edge of the measurement section.

[0019] Preferably, the end of the wake of the guide vane is at the middle position of the cascade channel. The wake is the extension line of the tail of the guide vane.

[0020] Preferably, the sectional line of the profile surfaces of the left side wall and the right side wall is the trajectory line of the air flow passing through the arc-shaped channel.

[0021] Preferably, under the integral ring condition, the number of measured blades is a non-integer multiple and a non-0.5 multiple of the number of guide vanes; the number of measured blades n≥7; the measured blades and the guide vanes are evenly distributed in the arc-shaped channel. The circumferential angle α of the fan-shaped cascade test piece structure satisfies: Among them, N is the number of measured blades in a full circle, and the integral ring condition is when the circumferential direction of the sector cascade test piece structure forms a complete ring.

[0022] Preferably, the number of the positioning holes of the corner positioning block is: n1 + 1; the circumferential angle interval between adjacent positioning holes is 360° / (n1 + 1);

[0023] where d is the angle adjustment interval of the guide vane; n1 is the number of angles of attack of the guide vane.

[0024] Preferably, the number of pin holes opened on the outer grid plate is n1 + 1;

[0025] The circumferential angle interval between adjacent pin holes is 360° / (n1 + 1) - d.

[0026] The advantages of this application include: 1. The ratio of the number of blades of the measured blade to the guide vane is a non-integer, resulting in different circumferential flow fields within the full circle. Therefore, selecting sector cascades at different circumferential positions will produce different test results. The present invention proposes a method for determining the circumferential position, which can ensure that the measured results meet the design requirements and ensure the accuracy of the test results;

[0027] 2. The periodic circumferential distribution gradient of the aerodynamic parameters at the outlet of the sector cascade is uneven, and different measurement results will be caused by the measurement section being at different circumferential positions. The present invention proposes a method for determining the circumferential position of the measurement section, which can ensure that the measured results meet the design requirements and ensure the test accuracy;

[0028] 3. A guide vane angle adjustment mechanism and its adjustment method are proposed to solve the problem of adjustable angle of attack of the guide vane. It can effectively avoid the inaccuracy of test measurement caused by the uneven circumferential flow field in the full circle and the different circumferential gradients of the flow field of the sector cascade. It can ensure that the measured results meet the design requirements and ensure the correctness of the test measurement parameters. Description of the Drawings

[0029] Figure 1 is a schematic diagram of the traditional sector cascade structure;

[0030] Figure 2 is a schematic diagram of the test piece structure of a preferred embodiment of this application;

[0031] Figure 3 is a schematic diagram of the axial section of the test piece of a preferred embodiment of this application;

[0032] Figure 4 is a schematic diagram of the non-integer ratio structure and flow field characteristics of a preferred embodiment of this application;

[0033] Figure 5 is a schematic diagram of the guide vane angle adjustment mechanism of a preferred embodiment of this application. Detailed Embodiments

[0034] To make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation manners of this application will be described in more detail below with reference to the accompanying drawings in the implementation manners of this application. In the drawings, the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The described implementation manners are part of the implementation manners of this application, rather than all of the implementation manners. The implementation manners described below by referring to the accompanying drawings are exemplary and are intended to explain this application, and should not be construed as a limitation of this application. All other implementation manners obtained by those of ordinary skill in the art based on the implementation manners in this application without creative efforts belong to the scope of protection of this application. The implementation manners of this application will be described in detail below with reference to the accompanying drawings.

[0035] This application provides a non-integer ratio variable geometry sector cascade test piece structure, as Figure 2 , Figure 3 and Figure 5 shown, including: composed of an outer grid plate 1, an inner grid plate 2, a left side wall 3, a right side wall 4, a guide vane 5, a measured blade 6, and an angle adjustment mechanism 7. This application provides a non-integer ratio variable geometry sector cascade test piece structure, including:

[0036] The outer grid plate 1 and the inner grid plate 2 that form an arc-shaped channel, both the outer grid plate 1 and the inner grid plate 2 are arc-shaped, and gas passes through the arc-shaped channel;

[0037] The left side wall 3 and the right side wall 4 sealed on the circumferential two sides of the outer grid plate 1 and the inner grid plate 2. The outer grid plate and the inner grid plate are connected to the left side wall and the right side wall by bolts; the left side wall and the right side wall are provided with a left side wall groove 31 and a right side wall groove 41 for placing rubber sealing rings in the thickness direction to achieve sealing.

[0038] A plurality of guide vanes 5 circumferentially installed at the front end of the oncoming flow direction of the arc-shaped channel;

[0039] A plurality of measured blades 6 circumferentially installed at the rear end of the guide vanes 5 in the arc-shaped channel. The measured blades are connected to the outer tenon groove 14 of the outer grid plate and the inner tenon groove 23 on the inner grid plate through the blade root tenon and the blade tip tenon; the guide vanes and the measured blades are detachable and replaceable.

[0040] Among them, the guide vane 5 is installed between the outer grid plate 1 and the inner grid plate 2 through the angle adjustment mechanism 7 to achieve the angle of attack adjustment; the angle adjustment mechanism 7 includes: tenon shafts fixed at both ends of the guide vane 5, the tenon shafts respectively pass through the through holes of the outer grid plate 1 and the inner grid plate 2, and a corner positioning block 72 is sleeved outside the outer grid plate 1 on the tenon shaft. The corner positioning block 72 is connected with the tenon shaft in a shape-matching manner to limit the rotation of the guide vane 5 along the tenon shaft. The corner positioning block 72 has a plurality of positioning holes distributed circumferentially, and the outer grid plate 1 has a plurality of pin holes 11 at the positions of the positioning holes. The pin shaft passes through the positioning holes and is connected with the pin holes 11; the deflection angle of the guide vane 5 can be adjusted by adjusting the angular position relationship between the positioning holes and the pin holes 11.

[0041] In some alternative embodiments, the tenon shaft includes:

[0042] The outer grid plate positioning tenon shaft connected to the outer grid plate 1;

[0043] And the inner grid plate positioning tenon shaft connected to the inner grid plate 2;

[0044] A disc-shaped outer grid plate positioning tenon 71 is fixed on the outer grid plate positioning tenon shaft, and the outer grid plate positioning tenon 71 is installed in the outer circular groove 13 on the inner wall surface of the outer grid plate 1;

[0045] A disc-shaped inner grid plate positioning tenon 73 is fixed on the inner grid plate positioning tenon shaft, and the inner grid plate positioning tenon 73 is installed in the inner circular groove 22 on the inner wall surface of the inner grid plate 2. The outer grid plate positioning tenon and the inner grid plate positioning tenon are welded or integrally processed with the guide vane; the size of the outer grid plate positioning tenon shaft is slightly smaller than the diameter of the outer grid plate through hole 12, and the diameter of the inner grid plate positioning tenon shaft is 0.5 times the diameter of the inner grid plate through hole 21. An inner grid plate collar 74 is sleeved on the inner grid plate positioning tenon shaft to realize the fitting installation of the inner grid plate positioning tenon shaft and the inner grid plate through hole 21.

[0046] In some alternative embodiments, the outer grid plate 1 has a measured blade measurement structure 8 for observing the measured blade. The measured blade measurement structure 8 has a visualization window made of plexiglass. During the test, the measuring instrument can measure the arc-shaped channel through the measured blade measurement structure 8. The center of the measured blade measurement structure 8 is at the position of the left 1 / 4 circumferential angle. This structure can be an observation window or a mounting seat for a displacement mechanism.

[0047] In some alternative embodiments, the surface covered by the measured blade measurement structure 8 is the measurement cross-section, which is a cross-section that can be observed and measured through the measured blade measurement structure 8. The measurement cross-section is the cross-section formed by the intersection of the arc-shaped channel and the sector surface with the axis of the arc-shaped channel as the center and perpendicular to the axis of the arc-shaped channel. The measurement cross-section covers 1 to 3 cascade channels, and the midpoint of the measurement cross-section is located at the position of 3 / 4 circumferential angle from the left side wall 3. The left side wall 3 is the wall surface corresponding to the suction surface of the measured blade 6. Here, the cascade channel is the channel formed between adjacent measured blades 6. For better understanding, the blade includes a suction surface and a pressure surface. Among them, the suction surface is the convex side of the blade, and the pressure surface is the concave side of the blade. In this embodiment, the suction surface of the measured blade 6 is the convex side of the measured blade.

[0048] In some alternative embodiments, at least two complete cascade channels are reserved on the left side edge of the measurement cross-section.

[0049] In some alternative embodiments, the end of the wake of the guide vane is at the middle position of the cascade channel, and the wake is the extension line of the tail of the guide vane.

[0050] In some alternative embodiments, the cross-sectional line of the profile surfaces of the left side wall 3 and the right side wall 4 is the trajectory line of the airflow passing through the arc-shaped channel.

[0051] In some alternative embodiments, under the condition of a complete ring, the number of measured blades is a non-integer multiple and non-0.5 multiple of the number of guide vanes 5; the number n of measured blades 6 ≥ 7; the measured blades 6 and the guide vanes 5 are evenly distributed in the arc-shaped channel, and the circumferential angle α of the sector cascade test piece structure satisfies: Where N is the number of measured blades in a full circle, and the complete ring condition is when the sector cascade test piece structure forms a complete ring circumferentially.

[0052] In some alternative embodiments, the number of the positioning holes of the corner positioning block 72 is: n1 + 1; the interval between adjacent positioning holes is 360° / (n1 + 1);

[0053] Where d is the angle adjustment interval of the guide vane 5; n1 is the number of attack angles of the guide vane 5.

[0054] In some alternative embodiments, the number of the pin holes 11 on the outer grid plate 1 is n1 + 1;

[0055] The interval of the pin holes 11 is 360° / (n1 + 1) - d.

[0056] The design method of the non-integer ratio (excluding 0.5 times) variable geometry sector cascade test piece of the present application includes the following steps:

[0057] Step 1. Determine the number n of measured blades and the circumferential angle α of the sector cascade:

[0058] To meet the periodicity of the fan-shaped cascade, the number of measured blades should satisfy n≥7. Determine the number of measured blades n, and then determine the circumferential angle as where N is the number of blades in a full circle, and at the same time ensure that the maximum flow rate under the test condition is not greater than the maximum gas source flow rate of the tester.

[0059] Step 2: Determine the circumferential position of the measurement section of the measured blade:

[0060] As Figure 2 shown, the left side of the test piece is the pressure surface side of the measured blade, and the right side is the suction surface side of the measured blade. As Figure 4 shown, for the fan-shaped cascade of double-row cascades, the aerodynamic periodicity on the pressure surface side of the measured blade is significantly stronger than that on the suction surface side of the measured blade. The measurement section of the measured blade generally covers 1 - 3 cascade channels. The circumferential position of the measurement section of the measured blade should be close to the pressure surface side of the measured blade, and its midpoint is located at the 1 / 4 circumferential angle position starting from the left side, as Figure 2 shown in Figure 8. At least two complete cascade channels should be reserved on the left side of the measurement section, where the cascade channel is the channel formed between adjacent measured blades (6).

[0061] Step 3: Determine the circumferential position of the fan-shaped cascade in the annular cascade:

[0062] As Figure 4 shown, for cascades with non-integer ratios (excluding 0.5 times), the wakes of the guide vanes are at different circumferential positions in the channels of the measured blades. Ensure that the wake of the guide vane is at the middle position of the channel of the measured blade in the measurement section of Step 2. Combine with the circumferential angle determined in Step 1 to determine the circumferential position of the fan-shaped cascade in the annular cascade.

[0063] Step 4: Determine the sidewall structure:

[0064] Determine the profiles of the two sidewalls according to the streamline of the airflow at the design point.

[0065] Step 5: Determine the positioning dimensions of the guide vane angle adjustment mechanism:

[0066] According to the guide vane angle adjustment interval d and the number of attack angles n1, determine the number of opening holes n1 + 1 and the opening interval 360° / (n1 + 1) of the positioning holes on the angle adjustment block 7-2 of the angle adjustment mechanism, and determine the number of opening holes n1 + 1 and the interval 360° / (n1 + 1) - d of the pin holes on the outer grid plate. And ensure that one of the positioning pin holes is on the axis of the test piece to achieve 0° attack angle positioning;

[0067] Step 6: Determine other structures:

[0068] Determine other measurement positions and structures according to the test plan;

[0069] Step 7: Assemble the test piece.

[0070] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A non-integer ratio variable geometry sector cascade test piece structure, characterized in that, Comprising: An outer grid plate (1) and an inner grid plate (2) that form an arc-shaped channel. Both the outer grid plate (1) and the inner grid plate (2) are arc-shaped, and gas passes through the arc-shaped channel; A left side wall (3) and a right side wall (4) that seal the circumferential two sides of the outer grid plate (1) and the inner grid plate (2); A plurality of guide vanes (5) circumferentially installed at the front end of the incoming flow direction of the arc-shaped channel; A plurality of measured vanes (6) circumferentially installed at the rear end of the guide vanes (5) in the arc-shaped channel; Among them, the guide vane (5) is installed between the outer grid plate (1) and the inner grid plate (2) through an angle adjustment mechanism (7). The angle adjustment mechanism (7) includes: tenon shafts fixed at both ends of the guide vane (5). The tenon shafts respectively pass through through holes of the outer grid plate (1) and the inner grid plate (2). A corner positioning block (72) is also sleeved outside the outer grid plate (1) on the tenon shaft. The corner positioning block (72) is connected with the tenon shaft in a shape-fitting manner to limit the rotation of the guide vane (5) along the tenon shaft. The corner positioning block (72) has a plurality of circumferentially distributed positioning holes. The outer grid plate (1) has a plurality of pin holes (11) at the positions of the positioning holes. A pin shaft passes through the positioning hole and is connected with the pin hole (11); by adjusting the angular position relationship between the positioning hole and the pin hole (11), the deflection angle of the guide vane (5) can be adjusted.

2. The non-integer ratio variable geometry sector cascade test piece structure according to claim 1, characterized in that, The tenon shaft includes: An outer grid plate positioning tenon shaft connected to the outer grid plate (1) And an inner grid plate positioning tenon shaft connected to the inner grid plate (2); A disc-shaped outer grid plate positioning tenon (71) is fixed on the outer grid plate positioning tenon shaft. The outer grid plate positioning tenon (71) is installed in an outer circular groove (13) on the inner wall surface of the outer grid plate (1); A disc-shaped inner grid plate positioning tenon (73) is fixed on the inner grid plate positioning tenon shaft. The inner grid plate positioning tenon (73) is installed in an inner circular groove (22) on the inner wall surface of the inner grid plate (2).

3. The non-integer ratio variable geometry sector cascade test piece structure according to claim 1, characterized in that, The outer grid plate (1) has a measured vane measurement structure (8) for observing the measured vanes. The measured vane measurement structure (8) has a visualization window made of plexiglass.

4. The non-integer ratio variable geometry sector cascade test piece structure according to claim 1, characterized in that, The arc-shaped channel is provided with a measurement cross-section covering the surface; the measurement cross-section covers 1 to 3 cascade channels. The midpoint of the measurement cross-section is located at a position of 1 / 4 circumferential angle from the left side wall (3). The left side wall (3) is the wall surface corresponding to the suction surface of the measured vane (6); among them, the cascade channel is the channel formed between adjacent measured vanes (6).

5. The non-integer ratio variable geometry sector cascade test piece structure according to claim 4, characterized in that, At least two complete cascade channels are reserved on the left side of the measurement cross-section.

6. The non-integer ratio variable geometry sector cascade test piece structure according to claim 1, characterized in that, The end of the wake of the guide vane is at the middle position of the cascade channel. The wake is the extension line of the tail of the guide vane.

7. The non-integer ratio variable geometry sector cascade test piece structure according to claim 1, characterized in that, The cross-sectional line of the profile surfaces of the left side wall (3) and the right side wall (4) is the trajectory line of the gas flowing through the arc-shaped channel.

8. The non-integer ratio variable geometry sector cascade test piece structure according to claim 1, characterized in that, Under the condition of an integral domain, the number of the measured blades is a non-integer multiple and a non-0.5 multiple of the number of the guide vanes (5); the number n of the measured blades (6) is n≥7; the measured blades (6) and the guide vanes (5) are evenly distributed in the arc-shaped channel; the circumferential angle α of the fan-shaped cascade test piece structure satisfies: Among them, N is the number of measured vanes in the whole circumference.

9. The non-integer ratio variable geometry sector cascade test piece structure according to claim 1, characterized in that, The number of the positioning holes of the corner positioning block (72) is: n1 + 1; the circumferential angle interval of adjacent positioning holes is 360° / (n1 + 1); Among them, d is the angle adjustment interval of the guide vane (5); n1 is the number of attack angles of the guide vane (5).

10. The non-integer ratio variable geometry sector cascade test piece structure according to claim 9, characterized in that, The number of drilled holes of the pin holes (11) on the outer grid plate (1) is n1 + 1; The circumferential angle interval of the pin holes (11) is 360° / (n1 + 1) - d.

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