A suction structure for improving the flow field quality of a plane cascade wind tunnel and a design method thereof

Abstract

The application belongs to the technical field of subsonic plane cascade wind tunnel test, and particularly relates to a suction structure for improving the flow field quality of a plane cascade wind tunnel and a design method thereof. The structure comprises: an inlet flow channel formed between the movable lower guide wall and the movable upper guide wall; a plurality of blades are installed on the plane cascade test piece at equal cascade pitch; the upper end wall is the suction surface of the uppermost blade of the plane cascade test piece, the leading edge of the upper end wall is connected with the end of the movable upper guide wall, and a through suction slit is formed along the normal direction of the surface of the upper end wall; and the lower end wall is the suction surface of the lowermost blade of the plane cascade test piece, and the leading edge of the lower end wall is connected with the end of the movable lower guide wall. The suction structure for improving the flow field quality of the plane cascade wind tunnel can partially or completely weaken the adverse effects of the flow field quality, thereby improving the flow field quality of the plane cascade wind tunnel and ensuring the effectiveness of the test data.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of subsonic plane cascade wind tunnel test, and particularly relates to a suction structure for improving the flow field quality of a plane cascade wind tunnel and a design method thereof. BACKGROUND

[0002] The plane cascade wind tunnel is a basic test device widely used in the design and research of axial flow turbomachinery. The design of the core components of an aero-engine, such as compressor and turbine blades, cannot be separated from the support of a large number of plane cascade wind tunnel tests. The plane cascade wind tunnel test technology is widely used in blade performance verification, blade design method verification, CFD design program verification, and new test measurement technology verification. The cascade blowing test database established based on the plane cascade wind tunnel test technology has always been the technical core of major aero-engine companies.

[0003] In the plane cascade test, the flow before the cascade first contacts the upper end wall of the plane cascade. When the flow passes through the upper end wall with large curvature, it is bent obviously, and flow separation is easily generated, which leads to the blockage of the upper end wall passage, the increase of the static pressure before the cascade, and the decrease of the Mach number. Under the action of the circumferential pressure difference, the flow deviates to the lower end wall side, resulting in the difference in the flow of each passage of the plane cascade, the decrease of the uniformity of the inlet Mach number and flow angle, and the decrease of the periodicity of the flow field after the cascade, which cannot meet the requirements of the plane cascade test.

[0004] The inherent influence of the flow field quality of the plane cascade wind tunnel described above will be particularly prominent for modern high-load compressor blades with high subsonic speed and airflow deflection angle as typical characteristics. Therefore, it is hoped that a regulation and control technical solution can partially or completely weaken the adverse effects of the flow field quality described above, and then improve the flow field quality of the plane cascade wind tunnel and ensure the effectiveness of the test data.

[0005] Therefore, it is hoped that a technical solution can overcome or at least alleviate at least one of the above-mentioned defects of the prior art. SUMMARY

[0006] The purpose of the present application is to provide a suction structure for improving the flow field quality of a plane cascade wind tunnel and a design method thereof, so as to solve at least one problem existing in the prior art.

[0007] The technical solution of the present application is:

[0008] The first aspect of the present application provides a suction structure for improving the flow field quality of a plane cascade wind tunnel, comprising:

[0009] a movable upper guide wall;

[0010] a movable lower guide wall, wherein the movable lower guide wall and the movable upper guide wall form an inlet flow passage therebetween;

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

[0012] An upper end wall, which is a suction surface of an uppermost blade of the planar cascade test piece, wherein a leading edge of the upper end wall is connected to a terminal end of the movable upper guide wall, and a through suction slit is formed along a normal direction of a surface of the upper end wall;

[0013] A lower end wall, which is a suction surface of a lowermost blade of the planar cascade test piece, wherein a leading edge of the lower end wall is connected to a terminal end of the movable lower guide wall.

[0014] In at least one embodiment of the present application, the planar cascade test piece is installed on a test section through a rotatable disc.

[0015] In at least one embodiment of the present application,

[0016] Leading edges of the plurality of blades jointly form a leading edge line of the planar cascade test piece.

[0017] Trailing edges of the plurality of blades jointly form a trailing edge line of the planar cascade test piece.

[0018] In at least one embodiment of the present application, the suction slit is parallel to the leading edge line and the trailing edge line of the plurality of blades on the planar cascade test piece.

[0019] A second aspect of the present application provides a suction structure design method for improving flow field quality of a planar cascade wind tunnel, which is used for designing the suction structure for improving flow field quality of the planar cascade wind tunnel as described above, and comprises the following steps:

[0020] Step one, determining a chordwise position of the suction slit;

[0021] Step two, determining a height B of the suction slit;

[0022] Step three, determining a width W of the suction slit;

[0023] Step four, realizing design of the suction structure for improving flow field quality of the planar cascade wind tunnel according to the parameters.

[0024] In at least one embodiment of the present application, in step one, determining the chordwise position of the suction slit, comprises:

[0025] S11, determining a leading edge point and a trailing edge point position of an uppermost blade on the planar cascade test piece according to a size of the planar cascade test piece and an inlet angle;

[0026] S12, obtaining a blade chord length C;

[0027] S13, determine the chordwise position of the suction slot according to the leading edge point and the trailing edge point of the uppermost blade on the planar cascade test piece, and the chord length C.

[0028] In at least one embodiment of the present application, in S13, the distance between the center of the suction slot and the leading edge point of the uppermost blade is L=0.4-0.8C, and the center of the suction slot is located on the inner wall surface of the upper end wall.

[0029] In at least one embodiment of the present application, in step two, the height B of the suction slot is determined, comprising:

[0030] Obtaining the height H of the blade on the planar cascade test piece;

[0031] Determining the height B of the suction slot according to the height H of the blade, comprising:

[0032] The distance d between the two ends of the suction slot and the spanwise boundary of the blade is in the range of 0.1-0.15H, that is, the height B of the suction slot is in the range of 0.7-0.8H.

[0033] In at least one embodiment of the present application, in step three, the width W of the suction slot is determined, comprising:

[0034] The width W of the suction slot is in the range of 0.1-0.3C.

[0035] In at least one embodiment of the present application,

[0036] When the planar cascade test piece is in a negative angle of attack state, the distance L between the center of the suction slot and the leading edge point of the uppermost blade is in the range of 0.4-0.6C, and the width W of the suction slot is in the range of 0.1-0.2C;

[0037] When the planar cascade test piece is in a positive angle of attack state, the distance L between the center of the suction slot and the leading edge point of the uppermost blade is in the range of 0.6-0.8C, and the width W of the suction slot is in the range of 0.2-0.3C.

[0038] The present application has at least the following beneficial technical effects:

[0039] The suction structure for improving the flow field quality of the planar cascade wind tunnel of the present application can partially or completely weaken the adverse effects of the above-mentioned flow field quality, thereby improving the flow field quality of the planar cascade wind tunnel and ensuring the effectiveness of the test data. BRIEF DESCRIPTION OF DRAWINGS

[0040] Fig. 1 is a schematic diagram of the suction structure for improving the flow field quality of the planar cascade wind tunnel according to an embodiment of the present application;

[0041] Fig. 2is a schematic diagram of an upper end wall of a suction structure for improving flow field quality of a plane cascade wind tunnel according to an embodiment of the present application;

[0042] Fig. 3 is a schematic diagram of a suction slot of a suction structure for improving flow field quality of a plane cascade wind tunnel according to an embodiment of the present application.

[0043] wherein:

[0044] 11 - movable upper flow guide wall; 12 - movable lower flow guide wall; 21 - plane cascade test piece; 22 - upper end wall; 23 - lower end wall; 24 - suction slot; 31 - rotatable disc. DETAILED DESCRIPTION

[0045] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings. In the drawings, identical or similar reference numerals represent identical or similar elements or elements having identical or similar functions throughout. The described embodiments are some embodiments of the present application, rather than all embodiments of the present application. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application. The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0046] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application.

[0047] The accompanying drawings will be described below in conjunction with the Figs. 1-3 The present application will be described in further detail.

[0048] A first aspect of the present application provides a suction structure for improving flow field quality of a plane cascade wind tunnel, comprising: a movable upper flow guide wall 11, a movable lower flow guide wall 12, a plane cascade test piece 21, an upper end wall 22, a suction slot 24 and a lower end wall 23.

[0049] Specifically, Fig. 1As shown, the movable lower flow guide wall 12 and the movable upper flow guide wall 11 form an inlet flow passage; the planar cascade test piece 21 is installed on the test section through the rotatable disc 31, a plurality of blades are installed on the planar cascade test piece 21 at equal cascade intervals, the leading edges of the plurality of blades jointly form a leading edge line of the planar cascade test piece 21, and the trailing edges of the plurality of blades jointly form a trailing edge line of the planar cascade test piece 21.

[0050] The upper end wall 22 is a suction surface of the uppermost blade of the planar cascade test piece 21, the leading edge of the upper end wall 22 is connected with the end of the movable upper flow guide wall 11, a through suction slit 24 is formed along the normal direction of the surface of the upper end wall 22, and the suction slit 24 is parallel to the leading edge line and the trailing edge line of the plurality of blades of the planar cascade test piece 21; the lower end wall 23 is a suction surface of the lowermost blade of the planar cascade test piece 21, and the leading edge of the lower end wall 23 is connected with the end of the movable lower flow guide wall 12.

[0051] The suction structure for improving the flow field quality of the planar cascade wind tunnel of the present application is provided by arranging a limited number of same blades on the planar cascade test piece 21 and linearly arranging the blades according to a certain distance to form a planar cascade model, so as to simulate the periodic flow possessed by the annular elementary cascade of the compressor or turbine blade. In order to obtain blowing test data reflecting the real performance of the blade profile, the planar cascade test piece 21 has good flow field periodicity and can meet the flow field quality requirements.

[0052] The suction structure for improving the flow field quality of the planar cascade wind tunnel of the present application is provided by arranging a limited number of same blades on the planar cascade test piece 21 and linearly arranging the blades according to a certain distance to form a planar cascade model, so as to simulate the periodic flow possessed by the annular elementary cascade of the compressor or turbine blade. In order to obtain blowing test data reflecting the real performance of the blade profile, the planar cascade test piece 21 has good flow field periodicity and can meet the flow field quality requirements.

[0053] The second aspect of the present application provides a design method of a suction structure for improving the flow field quality of a planar cascade wind tunnel, which is used for designing the above-mentioned suction structure for improving the flow field quality of the planar cascade wind tunnel, and the design method comprises the following steps:

[0054] Step one, determining the chordwise position of the suction slit 24;

[0055] Step two, determining the height B of the suction slit 24;

[0056] Step three, determining the width W of the suction slit 24;

[0057] Step four, according to various parameters to realize the suction structure design of improving the flow field quality of the plane cascade wind tunnel.

[0058] The suction structure design method for improving the flow field quality of the plane cascade wind tunnel provided by the present application, in step one, the chordwise position of the suction slot 24 is determined, which comprises:

[0059] S11, according to the size and inlet angle of the plane cascade test piece 21, the leading edge point and the trailing edge point of the uppermost blade on the plane cascade test piece 21 are determined;

[0060] S12, the blade chord length C is obtained;

[0061] S13, according to the leading edge point and the trailing edge point of the uppermost blade on the plane cascade test piece 21, and the blade chord length C, the chordwise position of the suction slot 24 is determined.

[0062] In the preferred embodiment of the present application, in S13, the distance between the center of the suction slot 24 and the leading edge point of the uppermost blade is L=0.4-0.8C, and the center of the suction slot 24 is located on the inner wall surface of the upper wall.

[0063] The suction structure design method for improving the flow field quality of the plane cascade wind tunnel provided by the present application, in step two, the height B of the suction slot 24 is determined, which comprises:

[0064] The height H of the blade on the plane cascade test piece 21 is obtained;

[0065] According to the height H of the blade, the height B of the suction slot 24 is determined, which comprises:

[0066] The distance d between the two ends of the suction slot 24 and the blade span boundary is in the range of 0.1-0.15H, that is, the height B of the suction slot 24 is in the range of 0.7-0.8H.

[0067] The suction structure design method for improving the flow field quality of the plane cascade wind tunnel provided by the present application, in step three, the width W of the suction slot 24 is determined, which comprises:

[0068] The width W of the suction slot 24 is in the range of 0.1-0.3C.

[0069] In the embodiment, when determining the width W of the suction slot 24: when the planar cascade test piece 21 is in a negative attack angle state, the distance L between the center of the suction slot 24 and the leading edge point of the uppermost blade is in the range of 0.4-0.6C, and the width W of the suction slot 24 is in the range of 0.1-0.2C; when the planar cascade test piece 21 is in a positive attack angle state, the distance L between the center of the suction slot 24 and the leading edge point of the uppermost blade is in the range of 0.6-0.8C, and the width W of the suction slot 24 is in the range of 0.2-0.3C.

[0070] The suction structure design method for improving the flow field quality of a planar cascade wind tunnel of the application can more directly or more closely act on the core area of the flow field deterioration of the upper end wall 22 by arranging the suction slot 24 on the surface of the upper end wall 22 as a suction structure, and thus the improvement effect on the flow separation and blockage in the passage of the upper end wall 22 is more prominent. The low-energy fluid in the passage of the upper end wall 22 can be sucked away under the consumption of smaller suction flow, thereby relieving the blockage degree of the passage of the upper end wall 22 and effectively improving the uniformity of the inlet flow field and the periodicity of the outlet flow field of the planar cascade. Compared with the suction mode at the tail of the movable upper guide wall 11, the suction on the surface of the upper end wall 22 has less interference on the inlet flow field of the planar cascade, and can obtain better inlet flow field uniformity under the consumption of smaller suction flow. In addition, the suction at the tail of the movable upper guide wall 11 has less improvement effect on the outlet flow field of the planar cascade, and mainly indirectly improves the outlet flow field quality by improving the inlet flow field quality. The suction on the surface of the upper end wall 22 is very close to the cascade outlet, and can directly weaken the scattering of the airflow to the surrounding atmosphere after the airflow separates from the cascade by suction, and has a very obvious inhibitory effect on the interference of the outlet atmospheric boundary, and thus directly improves the periodicity of the cascade outlet Mach number and the airflow angle.

[0071] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto. Any changes or replacements within the technical range disclosed in the application can be easily thought by those skilled in the art, and should be covered within the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A suction structure for improving the quality of the flow field in a plane cascade wind tunnel, characterized in that, The improved suction structure for improving the flow field quality of a plane cascade wind tunnel comprises: a movable upper guide wall (11); a movable lower guide wall (12) forming an inlet flow channel with the movable upper guide wall (11); a plane cascade test piece (21) having a plurality of blades installed at a cascade pitch; an upper end wall (22) being a suction surface of the uppermost blade of the plane cascade test piece (21), a leading edge of the upper end wall (22) being connected with an end of the movable upper guide wall (11), and a suction slit (24) being formed through the upper end wall (22) along a normal direction of a surface of the upper end wall (22); a lower end wall (23) being a suction surface of the lowermost blade of the plane cascade test piece (21), a leading edge of the lower end wall (23) being connected with an end of the movable lower guide wall (12); the plane cascade test piece (21) being installed on a test section through a rotatable disc (31); and the suction slit (24) being parallel to leading edge lines and trailing edge lines of the plurality of blades of the plane cascade test piece (21).

2. The improved suction structure for improving the flow field quality of a plane cascade wind tunnel according to claim 1, wherein: the leading edges of the plurality of blades jointly form the leading edge lines of the plane cascade test piece (21); and the trailing edges of the plurality of blades jointly form the trailing edge lines of the plane cascade test piece (21).

3. A method for designing a suction structure for improving the flow field quality in a plane cascade wind tunnel, according to any one of claims 1 to 2, characterized in that, The improved suction structure for improving the flow field quality of a plane cascade wind tunnel comprises: Step 1: determining a chordwise position of the suction slit (24); Step 2: determining a height B of the suction slit (24); Step 3: determining a width W of the suction slit (24); Step 4: designing the improved suction structure for improving the flow field quality of a plane cascade wind tunnel according to the parameters.

4. The method of claim 3, wherein the method is characterized by: In Step 1, the chordwise position of the suction slit (24) is determined, comprising: S11: determining a leading edge point and a trailing edge point of the uppermost blade of the plane cascade test piece (21) according to the size of the plane cascade test piece (21) and an inlet angle; S12: obtaining a blade chord length C; S13: determining the chordwise position of the suction slit (24) according to the leading edge point and the trailing edge point of the uppermost blade of the plane cascade test piece (21) and the blade chord length C.

5. The method of claim 4, wherein, In S13, the distance between the center of the suction slit (24) and the leading edge point of the uppermost blade is L=0.4~0.8C, and the center of the suction slit (24) is located on the inner wall surface of the upper end wall.

6. The method of suction-structure design for improving the flow-field quality in a two-dimensional cascade wind tunnel according to claim 5, wherein, In Step 2, the height B of the suction slit (24) is determined, comprising: obtaining a height H of the blade of the plane cascade test piece (21); determining the height B of the suction slit (24) according to the height H of the blade, comprising: the distance d between the two ends of the suction slit (24) and the blade span boundary is 0.1~0.15H, that is, the height B of the suction slit (24) is 0.7~0.8H.

7. The method of suction-structure design for improving the flow-field quality in a two-dimensional cascade wind tunnel according to claim 6, wherein, In Step 3, the width W of the suction slit (24) is determined, comprising: the width W of the suction slit (24) is 0.1~0.3C.

8. The improved suction structure design method for improving the flow field quality of a plane cascade wind tunnel according to claim 7, wherein: When the planar cascade test piece (21) is in a negative attack angle state, the distance L between the center of the suction slot (24) and the leading edge point of the uppermost blade is in the range of 0.4-0.6C, and the width W of the suction slot (24) is in the range of 0.1-0.2C; When the planar cascade test piece (21) is in a positive attack angle state, the distance L between the center of the suction slot (24) and the leading edge point of the uppermost blade is in the range of 0.6-0.8C, and the width W of the suction slot (24) is in the range of 0.2-0.3C.

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