Supersonic air inlet channel wind tunnel test model and related parameter calculation method thereof

Abstract

The invention belongs to the technical field of air inlet channel wind tunnel tests, and particularly relates to a supersonic air inlet channel wind tunnel test model and a related parameter calculation method thereof, a simulation machine body and an air inlet channel installed on the simulation machine body. A center cone is installed at an inlet of the air inlet channel and comprises a cone body at the front end and a straight pipe at the rear section, a hollow channel is formed in the straight pipe, a drainage groove for guiding airflow into the hollow channel is formed in the connecting position of the straight pipe and the cone body, the tail of the airflow channel is connected with a drainage pipeline, and a drainage flow measuring rake and a drainage flow control valve are installed in the drainage pipeline. An air inlet channel outlet total pressure measuring rake and a suction pipeline are installed at an air inlet channel outlet, a suction flow control valve is installed in the suction pipeline, and the flow of the air inlet channel is controlled through the suction flow control valve in the suction pipeline. And the air inlet channel aerodynamic performance such as the total pressure recovery coefficient and the distortion index of the air inlet channel under the matching of different air inlet flow rates and various discharge flow rates is obtained.

Description

Technical Field

[0001] The present application belongs to the technical field of inlet wind tunnel tests, and in particular relates to a supersonic inlet wind tunnel test model and a method for calculating related parameters thereof. Background Art

[0002] The aerodynamic performance of a supersonic inlet needs to meet the quality requirements of the inlet airflow field in the full speed range, including low speed, subsonic, transonic and supersonic. Under supersonic flight conditions, considering the rapid development of the boundary layer, it is usually considered to adopt the leakage technology and open a leakage groove near the throat. The leakage can enhance the stability margin of the tail shock wave under the critical state and improve the quality of the inlet airflow field. The inlet wind tunnel test is an important technical means to obtain the aerodynamic performance of the inlet, and it is also an important basis for judging the aerodynamic performance of the inlet. For the supersonic inlet wind tunnel test considering the influence of leakage, there are many technical difficulties, including test model design, leakage discharge and flow control, test data analysis, etc. In the design of the test model, due to the large difference between the size of the venting slot and the size of the supersonic fuselage, in order to meet the wind tunnel's requirements for the test model size, the scale ratio is usually small. If the venting slot size is scaled down according to the same scale ratio as the fuselage, the width of the venting slot will be extremely small, which may lead to a large difference between the venting effect and the actual flow situation, directly affecting the reliability of the test results; in terms of venting discharge and flow control, due to the small size of the model, there are difficulties in designing the venting discharge channel, measuring and controlling the flow, etc.; in the test data analysis, due to the model equivalent design, a special test data analysis method of advance matching must be used. Therefore, it is of great practical significance to develop a supersonic inlet wind tunnel test method that considers the effect of venting. Summary of the invention

[0003] In order to solve the above problems, the present application provides a supersonic inlet wind tunnel test model considering the influence of leakage flow, including:

[0004] A simulated body (8) and an air inlet (3) mounted on the simulated body (8);

[0005] A central cone (1) is installed at the inlet of the air inlet duct (3). The central cone (1) includes a cone at the front end and a straight pipe at the rear end. The straight pipe has a hollow passage inside. A discharge groove (2) is provided at the connection between the straight pipe and the cone to guide the airflow into the hollow passage. The tail of the airflow passage is connected to a discharge pipeline (5). A discharge flow measurement rake (6) and a discharge flow control valve (7) are installed in the discharge pipeline (5).

[0006] An inlet duct outlet total pressure measuring rake (4) and a suction pipeline (10) are installed at the outlet of the inlet duct (3), and a suction flow control valve (11) is installed in the suction pipeline (10). The inlet duct flow rate is controlled by the suction flow control valve (11) in the suction pipeline (10) to simulate the inlet duct air flow rate of the aircraft under different flight conditions. The inlet duct outlet total pressure measuring rake (4) is used to measure the steady-state total pressure, dynamic total pressure and static pressure of the airflow at the inlet duct outlet cross section, and the inlet duct flow rate, total pressure recovery coefficient and distortion index are calculated based on the measured values.

[0007] Preferably, the calculation method of the intake duct flow is:

[0008]

[0009] Wherein, k is the specific heat ratio of air; G is the flow rate at the inlet duct outlet, T0 is the total temperature at the inlet duct outlet, P0 is the total pressure at the inlet duct outlet, and P is the static pressure at the inlet duct outlet.

[0010] Preferably, a total pressure measuring rake and a wall static pressure measuring point are provided in the leakage pipeline for calculating the flow rate of the leakage pipeline.

[0011] A method for calculating relevant parameters of a supersonic inlet wind tunnel test model, a method for calculating a steady-state circumferential distortion index of a supersonic inlet wind tunnel test model taking leakage flow influence into consideration, comprising:

[0012] The average total pressure of the intake duct outlet section is obtained by arithmetic averaging or flow averaging of the steady-state total pressure measuring tube measurement values ​​of the intake duct outlet total pressure measuring rake (4).

[0013] Get the total pressure P of the incoming flow 0∞ ;

[0014] Average total pressure across the inlet duct outlet section Total pressure of incoming flow P 0∞ Calculate the total pressure recovery coefficient σ of the inlet duct outlet section;

[0015] Divide the inlet outlet section into J sectors, and solve the average total pressure recovery coefficient of each sector one by one

[0016] The angle ζ corresponding to the jth measuring rake j is the horizontal axis, and the average total pressure recovery coefficient σ in the fan-shaped area j For the vertical coordinate, the constructor

[0017] Function-based Solve the average total pressure recovery coefficient of each low-pressure area in the inlet outlet section one by one to obtain the minimum average total pressure recovery coefficient σ0;

[0018] The steady-state circumferential distortion index is calculated based on the minimum average total pressure recovery coefficient σ0 and the total pressure recovery coefficient σ of the inlet outlet section.

[0019] Preferably, the average total pressure of the inlet duct outlet cross section is calculated by arithmetic averaging The formula is:

[0020]

[0021] I is the number of rake walls of the intake duct outlet total pressure measurement rake (4), and J is the number of steady-state total pressure measurement tubes of each rake wall.

[0022] Preferably, the average total pressure of the inlet duct outlet cross section is calculated by flow averaging The formula is:

[0023]

[0024]

[0025] q(λ ij ) is the flow function, ΔA ij To measure the area of ​​a single element of a cross section.

[0026] Preferably, the average total pressure recovery coefficient The calculation formula is:

[0027]

[0028] σ ij is the total pressure recovery coefficient of the i-th measurement point in the j-th sector.

[0029] Preferably, the minimum average total pressure recovery coefficient σ0 is calculated as:

[0030]

[0031] In the formula, ζ Start and End The starting and ending angles of the low pressure area corresponding to the minimum average total pressure recovery coefficient.

[0032] Preferably, the steady-state circumferential distortion index The calculation formula is:

[0033]

[0034] Preferably, the calculation formula of turbulence τ is:

[0035]

[0036] Where: τ j is the turbulence intensity of the jth sector

[0037]

[0038] in, is the average value of dynamic total pressure; P 0t-j is the dynamic total pressure at the jth dynamic measurement point on the inlet outlet section.

[0039] Preferably, the calculation formula of the total pressure comprehensive distortion index W is:

[0040]

[0041] The advantages of the present application include: under a supersonic incoming flow state, the present application obtains the inlet aerodynamic performance such as the inlet total pressure recovery coefficient and the distortion index when different intake flow rates are matched with various leakage flow rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of a supersonic inlet wind tunnel test model taking into account the influence of leakage flow in a preferred embodiment of the present application. DETAILED DESCRIPTION

[0043] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be further described in detail in detail and in detail in conjunction with the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design. In the absence of conflict, the embodiments in the present application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0044] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installed", "connected", "connected" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal connection of two components. Technical personnel in the field can understand their specific meanings in this application according to the specific circumstances.

[0045] a) If Figure 1 As shown in Figure 1, a wind tunnel test model of a supersonic inlet affected by leakage flow is shown.

[0046] The present application provides a supersonic inlet wind tunnel test model considering the effect of leakage flow, including:

[0047] A simulated body (8) and an air inlet (3) mounted on the simulated body (8);

[0048] A central cone (1) is installed at the inlet of the air inlet duct (3). The central cone (1) includes a cone at the front end and a straight pipe at the rear end. The straight pipe has a hollow passage inside. A discharge groove (2) is provided at the connection between the straight pipe and the cone to guide the airflow into the hollow passage. The tail of the airflow passage is connected to a discharge pipeline (5). A discharge flow measurement rake (6) and a discharge flow control valve (7) are installed in the discharge pipeline (5).

[0049] An inlet duct outlet total pressure measuring rake (4) and a suction pipeline (10) are installed at the outlet of the inlet duct (3), and a suction flow control valve (11) is installed in the suction pipeline (10). The inlet duct flow rate is controlled by the suction flow control valve (11) in the suction pipeline (10) to simulate the inlet duct air flow rate of the aircraft under different flight conditions. The inlet duct outlet total pressure measuring rake (4) is used to measure the steady-state total pressure, dynamic total pressure and static pressure of the airflow at the inlet duct outlet cross section, and the inlet duct flow rate, total pressure recovery coefficient and distortion index are calculated based on the measured values.

[0050] The air inlet model is connected to the aircraft body through a bracket, and the entire test model is fixed in the wind tunnel test section. The wind tunnel angle of attack / sideslip angle adjustment structure can be used to adjust the test model to different angles of attack and sideslip angles.

[0051] b) Test model

[0052] The proportion of the test model is determined according to the size of the test section of the test wind tunnel and the intake suction capacity, and needs to meet the requirements of blockage, model length and span, intake flow requirements, etc. The test model needs to include the fuselage and wings before the intake, and the intake lip and inner pipe need to be strictly simulated.

[0053] c) Inlet flow control and measurement

[0054] By adjusting the position of the intake duct flow control valve, the cross-sectional area of ​​the airflow channel in the suction pipeline is changed to control the air flow entering the intake duct; a total pressure measurement rake and a wall static pressure measurement point are set at the intake duct outlet, and the intake duct intake flow is calculated using the following formula

[0055]

[0056] Where k is the specific heat ratio of air; G, T0, P0, and P are the flow rate, total temperature, total pressure, and static pressure at the inlet outlet, respectively.

[0057] d) Discharge flow control and measurement

[0058] By adjusting the position of the flow control valve in the leakage pipeline, the cross-sectional area of ​​the airflow channel in the leakage pipeline is changed to control the flow rate of the leakage flow entering; a total pressure measurement rake and a wall static pressure measurement point are set in the leakage pipeline, and the leakage flow rate is calculated using formula (1). When calculating, T0, P0, and P are the total temperature, total pressure, and static pressure at the measurement section position in the leakage pipeline, respectively.

[0059] e) Test data processing method

[0060] The total pressure recovery coefficient σ of the inlet duct outlet section is defined as the average total pressure P0 of the inlet duct outlet section and the total pressure of the free flow P 0∞ The ratio of

[0061]

[0062] In the formula, It is obtained by taking the arithmetic average or flow average of the steady-state total pressure pipe measurement values ​​at the inlet outlet.

[0063] Assume that the intake duct outlet total pressure measuring rake (4) comprises I rake walls, and J steady-state total pressure measuring tubes are arranged on each rake wall, then The arithmetic mean calculation formula is:

[0064]

[0065] The flow average calculation formula is:

[0066]

[0067] In the formula, q(λ ij ) is the flow function, ΔA ij is the area of ​​a single element of the measured cross section. ij ) is calculated as:

[0068]

[0069] Steady-state circumferential distortion index The calculation is based on the steady-state total pressure data of the inlet duct outlet section. The inlet duct outlet section is divided into J sectors, and the average total pressure recovery coefficient of each sector is solved one by one. The calculation formula is as follows:

[0070]

[0071] The angle ζ corresponding to the measuring rake j is the horizontal axis, and the average total pressure recovery coefficient of the fan-shaped area is For the vertical coordinate, the constructor Solve the average total pressure recovery coefficient of each low-pressure area in the inlet outlet section one by one and take the minimum value:

[0072]

[0073] In the formula, ζ Start and End The starting and ending angles of the low pressure zone corresponding to the minimum average total pressure recovery coefficient. Then, the steady-state circumferential distortion index The calculation formula is:

[0074]

[0075] The calculation of turbulence intensity τ is based on the dynamic total pressure data of the inlet outlet section. The number of dynamic total pressure measurement points is generally the same as the number of pressure rakes. Similarly, the inlet outlet section is divided into J sectors, and the turbulence intensity τ of each sector is solved one by one. j , and finally for all sectors turbulence τ j Find the arithmetic mean.

[0076]

[0077] in:

[0078]

[0079] The total pressure integrated distortion index W is defined as the turbulence intensity τ and the steady-state circumferential distortion index The sum of

[0080]

[0081] The above is only a specific implementation 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 a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A supersonic inlet wind tunnel test model considering the effect of leakage flow, characterized in that: include: A simulated body (8) and an air inlet (3) mounted on the simulated body (8); A central cone (1) is installed at the inlet of the air inlet duct (3). The central cone (1) includes a cone at the front end and a straight pipe at the rear end. The straight pipe has a hollow passage inside. A discharge groove (2) for introducing airflow into the hollow passage is provided at the connection between the straight pipe and the cone. The tail of the airflow passage is connected to a discharge pipeline (5). A discharge flow measurement rake (6) and a discharge flow control valve (7) are installed in the discharge pipeline (5). An inlet duct outlet total pressure measuring rake (4) and a suction pipeline (10) are installed at the outlet of the inlet duct (3), and a suction flow control valve (11) is installed in the suction pipeline (10). The inlet duct flow rate is controlled by the suction flow control valve (11) in the suction pipeline (10) to simulate the inlet duct air flow rate of the aircraft under different flight conditions. The inlet duct outlet total pressure measuring rake (4) is used to measure the steady-state total pressure, dynamic total pressure and static pressure of the airflow at the inlet duct outlet cross section, and the inlet duct flow rate, total pressure recovery coefficient and distortion index are calculated based on the measured values.

2. The supersonic inlet wind tunnel test model considering leakage flow effect as claimed in claim 1, characterized in that: The calculation method of the intake flow is: Wherein, k is the specific heat ratio of air; G is the flow rate at the inlet duct outlet, T0 is the total temperature at the inlet duct outlet, P0 is the total pressure at the inlet duct outlet, and P is the static pressure at the inlet duct outlet.

3. The supersonic inlet wind tunnel test model considering leakage flow effect as claimed in claim 1, characterized in that: A total pressure measuring rake and a wall static pressure measuring point are arranged in the leakage pipeline for calculating the flow rate of the leakage pipeline.

4. A method for calculating relevant parameters of a supersonic inlet wind tunnel test model, characterized in that: Using the supersonic inlet wind tunnel test model considering the leakage flow effect as described in any one of claims 1 to 3, a method for calculating the steady-state circumferential distortion index comprises: The average total pressure of the intake duct outlet section is obtained by arithmetic averaging or flow averaging of the steady-state total pressure measuring tube measurement values ​​of the intake duct outlet total pressure measuring rake (4). Get the total pressure P of the incoming flow 0∞ ; Average total pressure across the inlet duct outlet section Total pressure of incoming flow P 0∞ Calculate the total pressure recovery coefficient σ of the inlet duct outlet section; Divide the inlet outlet section into multiple sectors and solve the average total pressure recovery coefficient of each sector one by one The angle ζ corresponding to the jth measuring rake j is the horizontal axis, and the average total pressure recovery coefficient of the fan-shaped area is For the vertical coordinate, the constructor Function-based Solve the average total pressure recovery coefficient of each low-pressure area in the inlet outlet section one by one to obtain the minimum average total pressure recovery coefficient σ0; The steady-state circumferential distortion index is calculated based on the minimum average total pressure recovery coefficient σ0 and the total pressure recovery coefficient σ of the inlet outlet section.

5. The method for calculating the steady-state circumferential distortion index of a supersonic inlet wind tunnel test model according to claim 4, characterized in that: Calculate the average total pressure at the inlet duct outlet cross section by arithmetic averaging The formula is: I is the number of rake walls of the intake duct outlet total pressure measurement rake (4), and J is the number of steady-state total pressure measurement tubes of each rake wall.

6. The method for calculating the steady-state circumferential distortion index of a supersonic inlet wind tunnel test model according to claim 5, characterized in that: Calculate the average total pressure at the inlet duct outlet section by flow averaging The formula is: q(λ ij ) is the flow function, ΔA ij To measure the area of ​​a single element of a cross section.

7. The method for calculating the steady-state circumferential distortion index of a supersonic inlet wind tunnel test model according to claim 6, characterized in that: Average total pressure recovery coefficient The calculation formula is: σ ij is the total pressure recovery coefficient of the i-th measurement point in the j-th sector.

8. The method for calculating the steady-state circumferential distortion index of a supersonic inlet wind tunnel test model according to claim 7, characterized in that: The calculation formula for the minimum average total pressure recovery coefficient σ0 is: In the formula, ζ Start and End The starting and ending angles of the low pressure area corresponding to the minimum average total pressure recovery coefficient.

9. The method for calculating the steady-state circumferential distortion index of a supersonic inlet wind tunnel test model according to claim 8, characterized in that: Steady-state circumferential distortion index The calculation formula is:

10. The method for calculating the steady-state circumferential distortion index of a supersonic inlet wind tunnel test model according to claim 9, characterized in that: The calculation formula of turbulence τ is: Where: τ j is the turbulence intensity of the jth sector; in, is the average value of dynamic total pressure; P 0t-j is the dynamic total pressure at the jth dynamic measurement point on the inlet outlet section.

11. The method for calculating the steady-state circumferential distortion index of a supersonic inlet wind tunnel test model according to claim 10, characterized in that: The calculation formula of total pressure comprehensive distortion index W is:

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