Wind tunnel turbulence generator with low blockage and high turbulence level

Abstract

The invention discloses a wind tunnel turbulence generator with low blockage and high turbulence. The wind tunnel turbulence generator comprises a low-blockage and high-turbulence grating net; the at least one grid spoiler is distributed at partial nodes of the low-blockage large-turbulence grid net; and the number of the flexible turbulent flow columns is the same as that of the grid turbulent flow devices, the flexible turbulent flow columns correspond to the grid turbulent flow devices one to one, and the flexible turbulent flow columns are connected with the grid turbulent flow devices and located on the downstream of the low-blockage large-turbulence grid net. According to the invention, a small amount of grating spoilers are used to obtain large turbulence flow behind the grating, so that the grating blockage under the large turbulence test requirement can be reduced, the on-way attenuation rate of the grating turbulence is reduced by using the flexible spoiler columns, and the test requirement of the high turbulence level of the front edge of a test piece can be met; and on the other hand, the turbulence generator is modified on the basis of an existing turbulence grid, the structure is simple, and implementation is easy.

Description

Technical Field

[0001] The invention relates to the fields of wind tunnel experiments on aircraft engine parts and other small-sized wind tunnel technologies, in particular to a turbulence generator with low blockage and high turbulence. Background Art

[0002] In wind tunnel experiments, in order to control the turbulence of the incoming flow, passively controlled turbulent grids and actively controlled dynamic grids are usually used. The dynamic grid is realized by changing the vibration frequency and vibration angle of the grid pieces. This dynamic grid with a control mechanism is easy to realize in large-scale wind tunnels, but it is difficult to realize in small-scale wind tunnels because multiple grid pieces cannot be installed due to the size limitation of the grid axis. In addition, the dynamic grid uses multiple motors to control the components, which increases the complexity and processing cost. Therefore, in small-scale wind tunnels, turbulent grids are usually used to control the flow turbulence. When high turbulence is required, the turbulence grid is realized by increasing the diameter of the grid, which causes blockage of the flow channel and increased flow losses in the wind tunnel. For the exhaust wind tunnel, the power of the exhaust equipment is increased or the maximum incoming flow velocity in the wind tunnel is reduced, which is not conducive to maximizing the effectiveness of the exhaust equipment. In addition, due to the limitations of the structural design, the turbulence grid is usually far away from the leading edge of the test piece, and the exponential decay of the turbulence intensity along the way leads to high turbulence in a short distance downstream of the turbulence generator and low turbulence at the leading edge of the test piece, which is not conducive to experimental research on the impact of high turbulence on the performance of the test piece. Summary of the invention

[0003] The purpose of the present invention is to provide a low-clogging and high-turbulence wind tunnel turbulence generator to solve the problems that the turbulence grid mesh conventionally used in high-turbulence wind tunnel tests has large blockage, resulting in the inability to fully utilize the power of the exhaust wind tunnel or the reduction of the available pressure drop of the blowing wind tunnel, and the turbulence grid is far away from the test piece, resulting in a low actual turbulence at the leading edge of the test piece.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A low-clogging and high-turbulence wind tunnel turbulence generator, comprising:

[0006] A low-clogging, high-turbulence grid;

[0007] At least one grid spoiler, distributed at some nodes of the low-blockage and high-turbulence grid network;

[0008] At least one flexible spoiler column, the number of which is the same as and corresponds to the grille spoiler, is connected to the grille spoiler and is located downstream of the low-blockage and high-turbulence grille network.

[0009] Furthermore, the low-clogging and high-turbulence grid is a single-plane grid, wherein the grid wire diameter d1 is 1 mm, and the grid wire diameter spacing H is greater than 8 times the grid wire diameter d1.

[0010] Furthermore, the low-clogging and high-turbulence grid mesh is made of stainless steel and is manufactured by 3D printing.

[0011] Furthermore, the equivalent diameter D of the grille spoiler is not less than 4 mm.

[0012] Furthermore, the grille spoilers are evenly arranged at some nodes of the low-blockage and high-turbulence grille network, and the increase in geometric blockage of the turbulence generator after the grille spoilers are installed is no more than 25%.

[0013] Furthermore, the grille spoiler is spherical or cylindrical in shape.

[0014] Furthermore, the diameter d2 of the flexible spoiler column is larger than the mesh diameter d1 of the low-blockage and high-turbulence grille, and smaller than the equivalent diameter D of the grille spoiler.

[0015] Furthermore, the flexible spoiler column is a rope made of flexible material, and the flexible material is one of cotton thread, rubber and metal.

[0016] Furthermore, the length L of the flexible spoiler column is smaller than the distance between the low-blockage and high-turbulence grid and the leading edge of the test piece.

[0017] Furthermore, the maximum achievable turbulence is adjusted by controlling the size of the grille spoiler, and the turbulence attenuation rate along the way is reduced by controlling the length of the flexible spoiler column. The combination of the two can adjust the turbulence of the incoming flow at the leading edge of the test piece.

[0018] Beneficial effects: The low-clogging and high-turbulence wind tunnel turbulence generator of the present invention utilizes a small number of grille spoilers to obtain high-turbulence flow behind the grille, which is beneficial to reducing grille blockage under high-turbulence test requirements, and utilizes flexible spoiler columns to reduce the along-the-way attenuation rate of the grille turbulence, which is beneficial to meeting the test requirements of high turbulence levels at the leading edge of the test piece; on the other hand, the turbulence generator of the present invention is a modification of the existing turbulence grille, and has a simple structure and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a plane grid diagram;

[0020] Figure 2 A diagram of a wind tunnel turbulence generator with low blockage and high turbulence;

[0021] Figure 3 The turbulence intensity at 120 mm downstream of the plane grid changes with the incoming flow velocity.

[0022] Figure 4 The turbulence attenuation along the flow direction downstream of the plane blade when the incoming flow velocity is 102m / s

[0023] Among them: 1- low-blockage high-turbulence grid mesh, 2- grid spoiler, 3- flexible spoiler column;

[0024] d1-grid wire diameter, H-grid wire diameter spacing H, D-grid spoiler equivalent diameter D, d2-flexible spoiler diameter d2, L-flexible spoiler length. DETAILED DESCRIPTION

[0025] The present invention will be further explained below in conjunction with the accompanying drawings.

[0026] like Figure 1 and Figure 2 As shown, a low-clogging and high-turbulence wind tunnel turbulence generator of the present invention comprises a low-clogging and high-turbulence grid mesh 1, a grid spoiler 2 and a flexible spoiler column 3.

[0027] The low-blockage high-turbulence grid mesh 1 is a single-plane grid, wherein the grid wire diameter d1 is 1 mm, and the grid wire diameter spacing H is greater than 8 times the grid wire diameter d1 to meet the low blockage ratio requirement. The low-blockage high-turbulence grid mesh 1 is made of stainless steel and is made by 3D printing.

[0028] The equivalent diameter D of the grid spoiler 2 is not less than 4 mm, the nodes of the low-blockage and high-turbulence grid net 1 are evenly arranged, and the increase in geometric blockage of the turbulence generator after installing the grid spoiler 2 is not more than 25%. The shape of the grid spoiler 2 is spherical or cylindrical.

[0029] The number of the flexible spoiler columns 3 is the same as that of the grille spoiler 2 and corresponds to each other. The flexible spoiler columns 3 are connected to the grille spoiler 2 and are located downstream of the low-blockage high-turbulence grille mesh 1. The diameter d2 of the flexible spoiler columns 3 is greater than the grille mesh wire diameter d1 of the low-blockage high-turbulence grille mesh 1 and is smaller than the equivalent diameter D of the grille spoiler 2. The flexible spoiler columns 3 are ropes of flexible materials, and the flexible material is one of cotton thread, rubber, and metal. The length L of the flexible spoiler columns 3 is less than the distance between the low-blockage high-turbulence grille mesh 1 and the leading edge of the test piece.

[0030] By controlling the size of the grid spoiler 2 to adjust the maximum turbulence that can be achieved, and controlling the length of the flexible spoiler column 3 to reduce the turbulence decay rate along the way, the combination of the two can adjust the turbulence of the flow at the leading edge of the test piece, and finally achieve the test requirements of small grid blockage ratio and high turbulence at the leading edge of the test piece.

[0031] The present invention will be further described below in conjunction with the following examples. The present invention can be better understood according to the following examples.

[0032] Example:

[0033] In this embodiment, the design parameters of the low-blockage and high-turbulence grid mesh include the grid wire diameter d1, the grid wire diameter spacing H and the grid spoiler equivalent diameter D, and the design parameters of the flexible spoiler include the diameter d2 and the length L.

[0034] The Mach number of the incoming flow in the wind tunnel is changed, and experimental measurements are carried out on the turbulence development generated by conventional turbulence grids, turbulence grids with added grid spoilers and flexible spoilers.

[0035] For conventional turbulent grid mesh, Figure 1 Stainless steel was used for 3D printing, with a grid wire diameter of d1 = 1 mm, a wire spacing of 9 mm, and a geometric blocking ratio of 0.173.

[0036] For low-clogging and high-turbulence turbulence generators, Figure 2 The equivalent diameter of the grille spoiler is set to D = 4 mm. Figure 1 The grid mesh is evenly spaced, and the geometric blocking ratio is 0.198; the diameter of the flexible spoiler is d2 = 4mm and the length is L = 80mm.

[0037] The turbulence intensity generated by the two turbulence generators at 120 mm downstream of the plane grid changes with the incoming flow velocity. Figure 3 The turbulence generated by the low-blockage and high-turbulence turbulence generator and the plane grid mesh decreases with the increase of the incoming flow velocity, and the reduction rate of the two is the same. This is because this is the free development stage of turbulence. However, due to the presence of large-size grid spoiler columns, the turbulence generated by the low-blockage and high-turbulence turbulence generator is higher than that of the plane blade mesh.

[0038] When the incoming flow velocity is 102 m / s, the turbulence intensity produced by the two turbulence generators varies along the flow path. Figure 4 The turbulence generated by the conventional plane turbulence grid mesh decays faster along the way than the turbulence generator with low blockage and high turbulence. At 120mm downstream of the plane grid mesh, the turbulence generated by the conventional plane turbulence grid mesh is only 4.7%, while the turbulence generated by the low blockage and high turbulence generator is 7.8%, which meets the requirement of high turbulence at the measurement section.

[0039] In summary, the low-blockage and high-turbulence turbulence generator of the present invention is suitable for small-sized wind tunnel tests. The low-blockage and high-turbulence grid is a grid spoiler added to some nodes of the low-blockage uniform grid net, and the positive correlation between the turbulence intensity and the size of the grid spoiler is used to achieve high turbulence behind the grid net. The flexible spoiler column is fixed on the grid spoiler of the grid net, and the strong unsteady flow disturbance generated by the grid spoiler is used to induce the oscillation of the flexible spoiler column to reduce the low attenuation rate of turbulence along the way, and at the same time, the length of the flexible spoiler column is controlled to achieve high turbulence at the leading edge of the test piece. According to the flow mechanism of the turbulence generator generating high turbulence, the low-blockage and high-turbulence wind tunnel turbulence generator of the present invention is suitable for wind tunnel tests of any size.

[0040] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low-clogging and high-turbulence wind tunnel turbulence generator, characterized in that: include: A low-clogging, high-turbulence grid (1); At least one grid spoiler (2) distributed at some nodes of the low-blockage and high-turbulence grid network (1); At least one flexible spoiler column (3), the number of which is the same as and corresponds to the grille spoiler (2), the flexible spoiler column (3) is connected to the grille spoiler (2) and is located downstream of the low-blockage and high-turbulence grille net (1).

2. The low-clogging and high-turbulence wind tunnel turbulence generator according to claim 1, characterized in that: The low-clogging, high-turbulence grid net (1) is a single-plane grid, wherein the grid wire diameter d1 is 1 mm, and the grid wire diameter spacing H is greater than 8 times the grid wire diameter d1.

3. The low-clogging and high-turbulence wind tunnel turbulence generator according to claim 1 or 2, characterized in that: The low-clogging and high-turbulence grid mesh (1) is made of stainless steel and is manufactured by 3D printing.

4. The low-clogging and high-turbulence wind tunnel turbulence generator according to claim 1, characterized in that: The equivalent diameter D of the grille spoiler (2) is not less than 4 mm.

5. The low-clogging and high-turbulence wind tunnel turbulence generator according to claim 1 or 4, characterized in that: The grid spoilers (2) are evenly arranged at some nodes of the low-blockage and high-turbulence grid network (1); the increase in geometric blockage of the turbulence generator after the grid spoilers (2) are installed is no more than 25%.

6. The low-clogging and high-turbulence wind tunnel turbulence generator according to claim 5, characterized in that: The grille spoiler (2) is in the shape of a sphere or a column.

7. The low-clogging and high-turbulence wind tunnel turbulence generator according to claim 1, characterized in that: The diameter d2 of the flexible spoiler column (3) is larger than the mesh diameter d1 of the low-blockage and high-turbulence grid net (1) and smaller than the equivalent diameter D of the grid spoiler (2).

8. The low-clogging and high-turbulence wind tunnel turbulence generator according to claim 1 or 7, characterized in that: The flexible spoiler column (3) is a rope made of a flexible material, and the flexible material is one of cotton thread, rubber and metal.

9. The low-clogging and high-turbulence wind tunnel turbulence generator according to claim 1 or 7, characterized in that: The length L of the flexible spoiler column (3) is smaller than the distance between the low-blockage and high-turbulence grid mesh (1) and the front edge of the test piece.

10. The low-clogging and high-turbulence wind tunnel turbulence generator according to claim 1, characterized in that: The maximum achievable turbulence is adjusted by controlling the size of the grid spoiler (2), and the turbulence attenuation rate along the way is reduced by controlling the length of the flexible spoiler column (3). The combination of the two can adjust the turbulence of the incoming flow at the leading edge of the test piece.

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