A ground test apparatus for supersonic boundary layer suction

Abstract

The application relates to the field of aerodynamics, and particularly discloses a ground test device for supersonic boundary layer suction, which comprises a Y-shaped stabilizing pipe, a vacuum tank, a first pipe group, a second pipe group and a suction pipeline; the first pipe group comprises a variable Mach number nozzle section, a low pressure section and a first diffuser section, the variable Mach number nozzle section is connected with one of the outlets of the Y-shaped stabilizing pipe, and the first diffuser section is connected with the vacuum tank; the second pipe group comprises a test nozzle section, a suction section and a second diffuser section, the test nozzle section is connected with the other outlet of the Y-shaped stabilizing pipe, and the second diffuser section is connected with the vacuum tank; one end of the suction pipeline is communicated with the suction section, and the other end of the suction pipeline is communicated with the low pressure section; the ground test device for supersonic boundary layer suction can realize supersonic boundary layer suction experiment without introducing a suction pump, and can solve the problems of "suction failure" and inaccurate suction flow.

Description

Technical Field

[0001] This invention relates to the field of aerodynamics, and more specifically to a ground-based test apparatus for supersonic boundary layer extraction. Background Technology

[0002] To accurately model the boundary layer suction process and establish a suction flow rate model, wind tunnel experiments are indispensable. Although the Mach number of hypersonic vehicles is generally greater than 5, after compression by the shock train, the Mach number of the airflow in the inlet is between 2 and 4. To simulate the supersonic boundary layer suction process within this Mach number range, experiments need to be conducted in a supersonic wind tunnel. Most supersonic wind tunnels are air-breathing wind tunnels, meaning the diffuser section is connected to a vacuum tank, and therefore the total pressure of the wind tunnel is atmospheric pressure. Calculations based on the isentropic relationship show that the static pressure in the wind tunnel experimental section is relatively low. Therefore, to meet the suction requirements, an external suction pump or connection of the suction port to a vacuum tank is necessary.

[0003] For a wind tunnel with a total pressure of atmospheric pressure (101325 Pa), the static pressures of the experimental sections at Mach numbers 2, 3, and 4, calculated using the isentropic relationship, are 13000 Pa, 2750 Pa, and 665 Pa, respectively. Even with shock wave pressurization generated by a shock wave generator, the pressure on the walls is very low. Therefore, the suction pump can easily become unable to pump, and the suction experiment may even turn into a jet experiment. In addition, the suction pump method does not accurately control the suction flow rate, which leads to errors in the establishment of the suction model and makes it unsuitable for application in real flight environments. The method of using a vacuum tank for suction also has similar drawbacks. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a ground test device for supersonic boundary layer suction, which can realize supersonic boundary layer suction experiments without introducing a suction pump, and solves the problems of "not being able to pump" and inaccurate suction flow.

[0005] To solve the above problems, the present invention adopts the following technical solution:

[0006] A ground test apparatus for supersonic boundary layer suction includes: a Y-shaped stabilizing tube, a vacuum tank, a first tube assembly, a second tube assembly, and suction lines.

[0007] The first and second pipe groups have the same total length.

[0008] The first tube assembly includes a variable Mach number nozzle section, a low-pressure section, and a first diffuser section connected sequentially along the airflow direction. The variable Mach number nozzle section is connected to one of the outlets of the Y-shaped stabilizing tube, and the first diffuser section is connected to the vacuum tank.

[0009] The second pipe group comprises a test nozzle section, a suction section and a second diffuser section connected in sequence along the airflow direction, the test nozzle section is connected with the other outlet of the Y-shaped stabilizing pipe, and the second diffuser section is connected with the vacuum tank.

[0010] One end of the suction pipeline is communicated with the suction section, and the other end of the suction pipeline is communicated with the low-pressure section, and the Mach number of the low-pressure section is configured to be greater than the Mach number of the experimental section to realize the suction effect.

[0011] The first diffuser section and the second diffuser section are both provided with pneumatic valves between the vacuum tank.

[0012] In the ground test device for supersonic boundary layer suction provided by at least one embodiment of the present disclosure, the test nozzle section is a solid wall nozzle.

[0013] In the ground test device for supersonic boundary layer suction provided by at least one embodiment of the present disclosure, the variable Mach number nozzle section comprises a driving rod, a nozzle wall, a fulcrum and a driving mechanism.

[0014] In the ground test device for supersonic boundary layer suction provided by at least one embodiment of the present disclosure, the driving mechanism is an electric hydraulic jack.

[0015] In the ground test device for supersonic boundary layer suction provided by at least one embodiment of the present disclosure, at least two optical windows are arranged on the suction section.

[0016] In the ground test device for supersonic boundary layer suction provided by at least one embodiment of the present disclosure, connection holes are arranged on the suction section and the low-pressure section, and the suction section and the low-pressure section are communicated with the suction pipeline through the connection holes thereon.

[0017] In the ground test device for supersonic boundary layer suction provided by at least one embodiment of the present disclosure, an adjusting valve is arranged on the Y-shaped stabilizing pipe for controlling the airflow inflow.

[0018] In the ground test device for supersonic boundary layer suction provided by at least one embodiment of the present disclosure, the central axis of the first pipe group is parallel to the central axis of the second pipe group.

[0019] In the ground test device for supersonic boundary layer suction provided by at least one embodiment of the present disclosure, the suction section and the low-pressure section are both perpendicular to the suction pipeline.

[0020] In the ground test device for supersonic boundary layer suction provided by at least one embodiment of the present disclosure, the optical window has three.

[0021] Two of the optical windows are located on the side wall of the suction section.

[0022] The remaining optical window is located on the upper wall of the suction section.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. No external suction pump is needed to achieve the suction effect, and the low-pressure section pressure is generated by a well-designed nozzle, ensuring stable suction back pressure and preventing situations where suction cannot be achieved.

[0025] 2. The suction flow rate is controllable. By changing the throat area of ​​the variable Mach number nozzle, the static pressure in the low-pressure section can be controlled, thereby changing the suction flow rate.

[0026] 3. The Y-shaped stabilization section ensures that the airflow in both channels can be connected through a single valve. The low-pressure section can also be used as the test section for wind tunnel experiments, demonstrating good versatility. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the component layout of a ground test device for supersonic boundary layer suction according to the present invention.

[0029] Figure 2 This is a schematic diagram of the component layout for the second pipe assembly.

[0030] Figure 3 This is a schematic diagram of the component layout for the first tube assembly.

[0031] Figure 4 This is a schematic diagram of the distribution of the fulcrum.

[0032] Figure 5 Flowchart for solving the relationship between the suction flow coefficient Q and the rotation angle.

[0033] In the picture:

[0034] 10. Y-shaped stabilizer tube;

[0035] 20. Vacuum container;

[0036] 30. First nozzle assembly; 31. Variable Mach number nozzle section; 32. Low-pressure section; 33. First diffuser section; 311. Drive rod; 312. Nozzle wall; 313. Fulcrum;

[0037] 40. Second tube assembly; 41. Test nozzle section; 42. Suction section; 43. Second diffuser section;

[0038] 50. Suction tubing;

[0039] 60. Connecting hole. Detailed Implementation

[0040] The technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments, not all embodiments.

[0041] Example

[0042] like Figures 1 to 4 As shown, a ground test device for supersonic boundary layer suction includes: a Y-shaped stabilizing tube 10, a vacuum tank 20, a first tube assembly 30, a second tube assembly 40, and a suction pipeline 50.

[0043] In this embodiment, the Y-shaped stabilizing tube 10 is a three-way tube with two outlets and one inlet.

[0044] In this embodiment, the first tube assembly 30 and the second tube assembly 40 have the same total length. The first tube assembly 30 includes a variable Mach number nozzle section 31, a low-pressure section 32, and a first diffuser section 33 connected sequentially along the airflow direction. The variable Mach number nozzle section 31 is connected to one outlet of the Y-shaped stabilizing tube 10, and the first diffuser section 33 is connected to the vacuum tank 20. The second tube assembly 40 includes a test nozzle section 41, a suction section 42, and a second diffuser section 43 connected sequentially along the airflow direction. The test nozzle section 41 is connected to the other outlet of the Y-shaped stabilizing tube 10, and the second diffuser section 43 is connected to the vacuum tank 20.

[0045] The low-pressure section 32 is located downstream of the variable Mach number nozzle section 31 and is used to provide adjustable back pressure for the experimental section. The suction section 42 is located downstream of the experimental nozzle section 41 and is mainly used for boundary layer suction experiments.

[0046] In this embodiment, pneumatic valves (not shown) are provided on both the first and second diffuser sections. The pneumatic valves are located upstream of the vacuum tank 20 and can be used to achieve a vacuum environment inside the wind tunnel flow channel.

[0047] In this embodiment, one end of the suction line 50 is connected to the suction section 42, and the other end of the suction line 50 is connected to the low-pressure section 32. The Mach number of the low-pressure section 32 is configured to be greater than that of the experimental section in order to achieve the suction effect and provide back pressure for the suction section 42.

[0048] Specifically, both the suction section 42 and the low-pressure section 32 are provided with connection holes 60, and both the suction section 42 and the low-pressure section 32 are connected to the suction pipeline 50 through their respective connection holes.

[0049] In the embodiment, the test nozzle section 41 is a solid wall nozzle, which specifically includes a convergent section, a throat and a divergent section, and is designed by using the method of characteristics.

[0050] In the embodiment, the variable Mach number nozzle section 31 is designed by using the scheme of profile rotation nozzle, which specifically includes a driving rod 311, a nozzle wall 312, a fulcrum 313 and a driving mechanism (not shown). The nozzle exit area of the variable Mach number nozzle section 31 is constant, and the throat area can be freely adjusted according to the rotation angle, so as to change the exit Mach number.

[0051] Specifically, the driving mechanism is an electric hydraulic jack.

[0052] In the embodiment, an adjusting valve (not shown) is arranged at the inlet of the Y-shaped stable tube 10, and the adjusting valve is used to control the airflow inflow.

[0053] Exemplarily, the adjusting valve is a butterfly valve.

[0054] In the embodiment, the central axis of the first tube group 30 is parallel to the central axis of the second tube group 40. The suction section 42 and the low pressure section 32 are both perpendicular to the suction pipeline 50.

[0055] In the embodiment, the first diffuser section 33 and the second diffuser section 43 are used to connect the vacuum tank and receive the upstream airflow, so as to prevent blockage. The vacuum tank 20 is located at the most downstream, and is used to provide the back pressure condition of the entire wind tunnel test. The pressure in the vacuum tank 20 should meet the requirement of the start-up pressure corresponding to the nozzle Mach number.

[0056] In some embodiments, one optical window (not shown) is arranged on the suction section 42, and the optical window is located on the upper wall of the suction section 42.

[0057] In some embodiments, two optical windows (not shown) are arranged on the suction section 42, and the two optical windows are located on the side wall of the suction section 42.

[0058] In some embodiments, three optical windows (not shown) are arranged on the suction section 42, two of which are located on the side wall of the suction section 42, and the remaining one is located on the upper wall of the suction section 42. By being equipped with the optical windows, the optical measurement means such as the schlieren and the particle image velocimetry can be met.

[0059] The working principle of the ground test device for supersonic boundary layer suction in the embodiment will be further disclosed below:

[0060] The Mach number of the test nozzle section for supersonic boundary layer suction experiment is M1, and the static pressure of the suction section is P1; the variable Mach number nozzle section is used to generate a low pressure environment, and the Mach number is M2, and the static pressure of the low pressure section is P2. According to the isentropic formula, the relationship between the wind tunnel Mach number and the static pressure of the experimental section (referring to the low pressure section and the suction section) can be obtained:

[0061]

[0062] where P0 is the total pressure of the wind tunnel, i.e. the ambient atmospheric pressure, γ is the specific heat ratio of the gas, generally taken as 1.4, P is the static pressure of the test section, M a is the Mach number of the wind tunnel, i.e. the design Mach number of the nozzle. It can also be seen from the formula that the larger the Mach number, the smaller the corresponding static pressure of the test section. In order to meet the pumping requirements, P2 should be less than P1, so M2 needs to be greater than M1. In the non-choking case, the supersonic pumping flow coefficient Q is expressed as follows:

[0063]

[0064] where M1 is the Mach number of the pumping section, P1 and P2 are the static pressures of the pumping section and the low-pressure section respectively, and θ is the flow deflection angle, which is given by the Prandtl-Meyer relationship: θ = v(M3) - v(M1). Therefore, in the non-choking case, after the Mach number of the pumping section and the back pressure of the pumping, i.e. P2, are determined, the pumping flow coefficient can be determined.

[0065] It can be seen from formula 4 that in order to adjust the pumping flow, only the value of P1 / P2 needs to be changed, so only the Mach number ratio of the pumping section and the low-pressure section, i.e. M1 / M2, needs to be changed. However, considering the characteristics of the uniform zone of the variable-Mach-number nozzle, setting the pumping section as a variable-Mach-number nozzle is likely to lead to a decline in flow field quality and failure of the boundary layer pumping experiment. Therefore, the nozzle for generating a low-pressure environment is designed as a variable-Mach-number nozzle with a Mach number range of 2-4, which ensures that P1 / P2 is adjustable. For a Laval nozzle, the relationship between the nozzle area ratio and the Mach number is as follows:

[0066]

[0067] where A * is the throat area, A is the nozzle exit area, M a is the exit Mach number, and γ is the specific heat ratio of the gas. For a two-dimensional nozzle, it can also be written as:

[0068]

[0069] where H * is the throat height, and H is the nozzle exit height.

[0070] The variable-Mach-number nozzle adopts a simple structure of a profile rotating nozzle, and the entire nozzle profile can be rotated around a fulcrum to change the throat height and thus the exit Mach number, as shown in Figure 3 When the nozzle is rotated, the relationship between the angle change and the throat height change is as follows:

[0071] ΔH = L * sin Δβ; (7)

[0072] where L is the distance from the pivot point to the throat, AH is the change in throat height, and Δβ is the change in the angle of the nozzle contour about the pivot point. Thus, a relationship between the angle of rotation and the Mach number is established: assuming the minimum throat height allowed by the contoured rotating nozzle is h, and defining the position at which this occurs as the baseline, the relationship between the angle of rotation and the Mach number is:

[0073]

[0074] Thus, a relationship between the suction flow coefficient Q and the angle of rotation is obtained, and the solution procedure is as shown in Figure 5

[0075] Although embodiments of the present application have been shown and described above, the scope of the present application is not limited to the above examples, and any changes or substitutions not requiring inventive labor are encompassed within the scope of the present application; unless explicitly stated, any elements, actions, or instructions used herein should not be interpreted as critical or essential.​

Claims

1. A ground test apparatus for supersonic boundary layer suction, characterized by, The utility model relates to a test device for hypersonic nozzle, comprising: a Y-shaped stabilizing pipe, a vacuum tank, a first pipe group, a second pipe group and a suction pipeline; the total length of the first pipe group and the second pipe group is same; the first pipe group contains the low pressure section and the first diffusion section which are connected in sequence along the airflow direction, and the variable mach number nozzle section is connected with one of the outlets of the Y-shaped stabilizing pipe, and the first diffusion section is connected with the vacuum tank; the second pipe group contains the suction section and the second diffusion section which are connected in sequence along the airflow direction, and the test nozzle section is connected with the other outlet of the Y-shaped stabilizing pipe, and the second diffusion section is connected with the vacuum tank; one end of the suction pipeline is communicated with the suction section, and the other end of the suction pipeline is communicated with the low pressure section; the first diffusion section and the second diffusion section are both provided with pneumatic valves between the vacuum tank.

2. A ground test apparatus for supersonic boundary layer suction according to claim 1, characterized in that the test nozzle section is a solid wall nozzle.

3. A ground test apparatus for supersonic boundary layer suction as recited in claim 1, wherein the variable mach number nozzle section contains a driving rod, a nozzle wall, a fulcrum and a driving mechanism.

4. A ground test apparatus for supersonic boundary layer suction according to claim 3, wherein the driving mechanism is an electric hydraulic jack.

5. A ground test apparatus for supersonic boundary layer suction as recited in claim 1, wherein at least two optical windows are arranged on the suction section.

6. A ground test apparatus for supersonic boundary layer suction as recited in claim 1, wherein the suction section and the low pressure section are both provided with connecting holes, and the suction section and the low pressure section are both communicated with the suction pipeline through the connecting holes on them.

7. A ground test apparatus for supersonic boundary layer suction as recited in claim 1, wherein the Y-shaped stabilizing pipe is provided with an adjusting valve for controlling the airflow inflow.

8. A ground test apparatus for supersonic boundary layer suction as recited in claim 1, wherein the central axis of the first pipe group is parallel to the central axis of the second pipe group.

9. A ground test apparatus for supersonic boundary layer suction as recited in claim 1, wherein, the suction section and the low pressure section are both perpendicular to the suction pipeline.

10. A ground test apparatus for supersonic boundary layer suction as recited in claim 5, wherein, the optical window has three; two of the optical windows are located on the side wall of the suction section; the remaining optical window is located on the upper wall of the suction section.

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