Ground test device for supersonic boundary layer suction

Abstract

The invention relates to the technical 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 spray pipe section, a low-pressure section and a first diffusion section, the variable Mach number spray pipe section is connected with one outlet of the Y-shaped stabilizing pipe, and the first diffusion section is connected with the vacuum tank; the second pipe group comprises a test spray pipe section, a suction section and a second diffusion section, the test spray pipe 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; according to the ground test device for suction of the supersonic boundary layer, a suction experiment of the supersonic boundary layer can be realized under the condition that a suction pump is not introduced, and the problems that suction cannot be carried out and the suction flow is not accurate are solved.

Description

Technical Field

[0001] The invention relates to the technical field of aerodynamics, and in particular to a ground test device for supersonic boundary layer suction. Background Art

[0002] In order to simulate the boundary layer suction process and accurately establish the suction flow model, wind tunnel experiments are indispensable. Although the flight Mach number of hypersonic aircraft is generally greater than 5, after the compression of the shock wave train, the Mach number of the airflow in the inlet is between 2-4. In order to simulate the supersonic boundary layer suction process in this Mach number range, it is necessary to conduct experiments in a supersonic wind tunnel. Most supersonic wind tunnels are air-suction wind tunnels, that is, the diffuser section is connected to the vacuum tank, so the total pressure of the wind tunnel is the atmospheric pressure. According to the isentropic relationship, it is calculated that the static pressure of the wind tunnel test section is relatively low. Therefore, in order to meet the suction requirements, an external suction pump is required or the suction hole is connected to the vacuum tank.

[0003] For a wind tunnel with a total pressure of atmospheric pressure (101325Pa), the static pressure of the test section at Mach numbers 2, 3, and 4 is calculated to be 13000Pa, 2750Pa, and 665Pa respectively through the isentropic relationship. Even if the shock wave generator is used to generate shock wave pressurization, the pressure on the wall is very low, so it is easy for the suction pump to "not be able to pump", and even the suction experiment will be transformed into a jet experiment. In addition, the suction pump suction scheme does not accurately control the suction flow, which leads to errors in the establishment of the suction model and cannot be applied in a real flight environment. The method of using a vacuum tank to achieve suction also has such shortcomings. Summary of the invention

[0004] In order 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 experiment without introducing a suction pump and solve the problems of "inability to pump" and inaccurate suction flow.

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

[0006] A ground test device for supersonic boundary layer suction comprises: a Y-shaped stabilizing tube, a vacuum tank, a first tube group, a second tube group and a suction pipeline.

[0007] The first tube group and the second tube group have the same total length.

[0008] The first tube group includes a variable Mach number nozzle section, a low pressure section and a first diffuser section which are sequentially connected 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 tube group includes a test nozzle section, a suction section and a second diffuser section which are sequentially connected along the airflow direction; the test nozzle section is connected to another outlet of the Y-shaped stabilizing tube; and the second diffuser section is connected to the vacuum tank.

[0010] One end of the suction pipeline is connected to the suction section, and the other end of the suction pipeline is connected to the low-pressure section. The Mach number of the low-pressure section is configured to be greater than the Mach number of the experimental section to achieve a suction effect.

[0011] Pneumatic valves are arranged between the first diffuser section, the second diffuser section and 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 includes a drive rod, a nozzle wall, a fulcrum and a drive 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 provided 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, 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 connected to the suction pipeline through their respective connecting holes.

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

[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 tube group is parallel to the central axis of the second tube 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 extraction provided by at least one embodiment of the present disclosure, there are three optical windows.

[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 the present invention are:

[0024] 1. No external suction pump is required to achieve the suction effect, and the low-pressure section pressure is generated by a well-designed nozzle. The suction back pressure is stable and there will be no "unable to pump" situation.

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

[0026] 3. The Y-shaped stable section can ensure that the dual-channel airflow can be connected through only a single valve. The low-pressure section can also become the experimental section of the wind tunnel experiment, which has good versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

[0029] Figure 2 Schematic diagram of the component layout of the second pipe group.

[0030] Figure 3 Schematic diagram of the component layout of the first tube group.

[0031] Figure 4 Schematic diagram of the distribution of fulcrums.

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

[0033] In the figure:

[0034] 10. Y-shaped stabilizer tube;

[0035] 20. Vacuum tank;

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

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

[0038] 50. Suction pipeline;

[0039] 60. Connecting hole. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments will be described clearly and completely below in conjunction with the drawings in the embodiments. Obviously, the described embodiments are only a part of the embodiments, rather than all the 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 group 30, a second tube group 40 and a suction pipeline 50.

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

[0044] In this embodiment, the total length of the first tube group 30 and the second tube group 40 is the same. The first tube group 30 includes a variable Mach number nozzle section 31, a low pressure section 32 and a first diffuser section 33 connected in sequence along the airflow direction. The variable Mach number nozzle section 31 is connected to one of the outlets of the Y-shaped stabilizing tube 10, and the first diffuser section 33 is connected to the vacuum tank 20. The second tube group 40 includes a test nozzle section 41, a suction section 42 and a second diffuser section 43 connected in sequence 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 an adjustable back pressure for the test section. The suction section 42 is located downstream of the test nozzle section 41 and is mainly used to perform boundary layer suction experiments.

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

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

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

[0049] In this embodiment, the test nozzle section 41 is a solid wall nozzle, specifically including a contraction section, a throat and an expansion section, and is designed using the characteristic line method.

[0050] In this embodiment, the variable Mach number nozzle section 31 adopts a profile rotating nozzle design, specifically including a driving rod 311, a nozzle wall 312, a fulcrum 313 and a driving mechanism (not shown). The nozzle outlet area of ​​the variable Mach number nozzle section 31 is constant, and the throat area can be freely adjusted according to the rotation angle, thereby changing its outlet Mach number.

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

[0052] In this embodiment, a regulating valve (not shown) is provided at the inlet of the Y-shaped stabilizing tube 10, and the regulating valve is used to control the inflow of airflow.

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

[0054] In this 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 this embodiment, the first diffuser section 33 and the second diffuser section 43 are used to connect the vacuum tank and receive the upstream flow 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 starting pressure requirement corresponding to the nozzle Mach number.

[0056] In some embodiments, an optical window (not shown) is provided 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 provided 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 provided on the suction section 42, two of which are located on the side walls of the suction section 42, and the remaining optical window is located on the upper wall of the suction section 42. By equipping with optical windows, optical measurement methods such as schlieren and particle image velocimetry can be met.

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

[0060] The Mach number of the test nozzle section used 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, 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 test 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 capacity of the gas, which is generally taken as 1.4, P is the static pressure of the experimental section, M a is the wind tunnel Mach number, that is, 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 suction requirements, P2 should be less than P1, so M2 needs to be greater than M1. In the case of non-congestion, the supersonic suction flow coefficient Q is expressed as follows:

[0063]

[0064] Where M1 is the Mach number of the suction section, P1 and P2 are the static pressures of the suction section and the low-pressure section respectively, and θ is the streamline deflection angle, which is given by the Prandtl-Meyer relationship: θ = v(M3)-v(M1). Therefore, under non-congested conditions, after determining the Mach number of the suction section and the suction back pressure, that is, P2, the suction flow coefficient can be determined.

[0065] It can be seen from formula 4 that in order to adjust the suction flow, it is only necessary to change the value of P1 / P2, so it is only necessary to change the Mach number ratio of the suction section and the low-pressure section, that is, M1 / M2. However, considering the characteristics of the uniform area of ​​the variable Mach number nozzle, setting the suction section to a variable Mach number is likely to cause a decrease in the flow field quality and failure of the boundary layer suction experiment. Therefore, the nozzle used to generate a low-pressure environment is designed as a variable Mach number nozzle, and its Mach number range is 2-4, which ensures that P1 / P2 is adjustable. For the Laval nozzle, the relationship between the nozzle area ratio and the Mach number is as follows:

[0066]

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

[0068]

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

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

[0071] ΔH=L*sinΔβ;(7)

[0072] Among them, L is the distance from the fulcrum to the throat, ΔH is the change in throat height, and Δβ is the angular change of the nozzle profile around the fulcrum. Therefore, the relationship between the rotation angle and the Mach number is established: Assuming that the minimum throat height allowed by the profile rotating nozzle is h, and the position here is defined as the baseline, then the relationship between the rotation angle and the Mach number is:

[0073]

[0074] Therefore, the relationship between the suction flow coefficient Q and the rotation angle is obtained, and the solution process is as follows: Figure 5 shown.

[0075] Although the embodiments of the present application have been shown and described above, the scope of protection of the present invention is not limited thereto, and any changes or substitutions that are not conceivable through creative work should be included in the scope of protection of the present invention; unless explicitly stated, any elements, actions or instructions used in this document should not be interpreted as critical or necessary.

Claims

1. A ground test device for supersonic boundary layer extraction, characterized in that: include: Y-shaped stabilizing tube, vacuum tank, first tube group, second tube group and suction pipeline; The first tube group and the second tube group have the same total length; The first tube group includes a variable Mach number nozzle section, a low pressure section and a first diffuser section which are sequentially connected 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; The second tube group includes 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 to the other outlet of the Y-shaped stabilizing tube, and the second diffuser section is connected to the vacuum tank; One end of the suction pipeline is connected to the suction section, and the other end of the suction pipeline is connected to the low-pressure section; Pneumatic valves are arranged between the first diffuser section, the second diffuser section and the vacuum tank.

2. A ground test device for supersonic boundary layer extraction according to claim 1, characterized in that: The test nozzle section is a solid-wall nozzle.

3. A ground test device for supersonic boundary layer extraction according to claim 1, characterized in that: The variable Mach number nozzle section includes a driving rod, a nozzle wall, a fulcrum and a driving mechanism.

4. A ground test device for supersonic boundary layer extraction according to claim 1, characterized in that: The driving mechanism is an electric hydraulic jack.

5. A ground test device for supersonic boundary layer extraction according to claim 1, characterized in that: At least two optical windows are arranged on the suction section.

6. A ground test device for supersonic boundary layer extraction according to claim 1, characterized in that: 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 connected with the suction pipeline through the connecting holes respectively provided thereon.

7. A ground test device for supersonic boundary layer extraction according to claim 1, characterized in that: The Y-shaped stabilizing tube is provided with a regulating valve for controlling the inflow of airflow.

8. A ground test device for supersonic boundary layer extraction according to claim 1, characterized in that: The central axis of the first tube group is parallel to the central axis of the second tube group.

9. A ground test device for supersonic boundary layer extraction according to claim 1, characterized in that: The suction section and the low-pressure section are both perpendicular to the suction pipeline.

10. A ground test device for supersonic boundary layer extraction according to claim 5, characterized in that: The optical windows have 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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