A supersonic inlet wind tunnel test model and a method for calculating related parameters thereof

Abstract

The application belongs to the technical field of inlet wind tunnel test, and particularly relates to a supersonic inlet wind tunnel test model and a related parameter calculation method, simulates a fuselage and an inlet installed on the fuselage; a central cone is installed at an inlet of the inlet, the central cone comprises a cone body at a front end and a straight pipe at a rear section, the straight pipe has a hollow channel inside, the straight pipe and the cone body are connected at a position provided with a flow leakage groove for guiding airflow into the hollow channel, an airflow channel tail is connected with a flow leakage pipeline, a flow leakage flow measurement rake and a flow leakage flow control valve are installed in the flow leakage pipeline; an inlet outlet total pressure measurement rake and a suction pipeline are installed at an outlet of the inlet, a suction flow control valve is installed in the suction pipeline, and the inlet flow is controlled through the suction flow control valve in the suction pipeline; in a supersonic airflow state, the application obtains inlet aerodynamic performance such as an inlet total pressure recovery coefficient and a distortion index under matching of different inlet flows and various flow leakage flows.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inlet wind tunnel test, and particularly relates to a supersonic inlet wind tunnel test model and a related parameter calculation method thereof. BACKGROUND

[0002] The aerodynamic performance of a supersonic inlet needs to meet the flow field quality requirements of inlet airflow in the full speed range including low speed, subsonic speed, transonic speed and supersonic speed. In the supersonic flight state, considering the rapid development of the boundary layer, the bleed technology is usually considered to be used, and a bleed slot is arranged near the throat. The bleed can enhance the stability margin of the terminal shock wave in the critical state and improve the flow field quality of the inlet airflow. The inlet wind tunnel test is an important technical means to obtain the aerodynamic performance of the inlet and is also an important basis for judging the aerodynamic performance of the inlet. For the supersonic inlet wind tunnel test considering the influence of the bleed, there are many technical difficulties, including test model design, bleed discharge and flow control, test data analysis and the like. In the test model design, due to the large difference between the size of the bleed slot and the size of the supersonic body, in order to meet the size requirements of the test model for the wind tunnel, the scale ratio is usually small. If the size of the bleed slot is scaled according to the same scale ratio as the body, the width size of the bleed slot is extremely small, which may cause a large difference between the bleed effect and the real flow condition, directly affecting the reliability of the test results. In the bleed discharge and flow control, due to the small size of the model, there are difficulties in the design of the bleed discharge channel, the measurement and control of the flow and the like. In the test data analysis, due to the equivalent design of the model, a special test data analysis method of pre-branch matching must be used. Therefore, it is of great practical significance to develop a supersonic inlet wind tunnel test method considering the influence of the bleed. SUMMARY

[0003] In order to solve the above problems, the application provides a supersonic inlet wind tunnel test model considering the influence of the bleed, which comprises:

[0004] A simulation body (8) and an inlet (3) installed on the simulation body (8);

[0005] A center cone (1) is installed at the inlet of the inlet (3), the center cone (1) comprises a cone at the front end and a straight pipe at the rear section, the straight pipe has a hollow channel inside, the connection part of the straight pipe and the cone has a bleed slot (2) for guiding the airflow into the hollow channel, the tail part of the airflow channel is connected with a bleed pipeline (5), the bleed pipeline (5) is provided with a bleed flow measurement rake (6) and a bleed flow control valve (7) inside;

[0006] The inlet passage (3) is provided with an inlet passage outlet total pressure measuring rake (4) and a suction pipeline (10) with a suction flow control valve (11) installed therein. The inlet passage flow is controlled by the suction flow control valve (11) in the suction pipeline (10) to simulate the inlet passage air flow of the aircraft in different flight states. The steady-state total pressure, dynamic total pressure and static pressure of the air flow at the inlet passage outlet section are measured by the inlet passage outlet total pressure measuring rake (4), and the inlet passage flow, total pressure recovery coefficient and distortion index are calculated accordingly.

[0007] Preferably, the calculation method of the inlet passage flow is as follows:

[0008]

[0009] wherein k is the specific heat ratio of air, G is the flow at the inlet passage outlet position, T0 is the total temperature at the inlet passage outlet position, P0 is the total pressure at the inlet passage outlet position, and P is the static pressure at the inlet passage outlet position.

[0010] Preferably, the bleed pipeline is provided with a total pressure measuring rake and a wall static pressure measuring point for calculating the bleed pipeline flow.

[0011] A calculation method of related parameters of a supersonic inlet passage wind tunnel test model, the supersonic inlet passage wind tunnel test model considering the bleed effect, a steady-state circumferential distortion index calculation method, comprising:

[0012] The average total pressure of the inlet passage outlet section is obtained by the arithmetic average or flow average of the steady-state total pressure measured by the steady-state total pressure measuring pipe of the inlet passage outlet total pressure measuring rake (4)

[0013] The total pressure P of the incoming flow is obtained 0∞ ;

[0014] The average total pressure of the inlet passage outlet section is obtained by the arithmetic average or flow average of the steady-state total pressure measured by the steady-state total pressure measuring pipe of the inlet passage outlet total pressure measuring rake (4) and the total pressure P 0∞ of the incoming flow, and the total pressure recovery coefficient σ of the inlet passage outlet section is calculated;

[0015] The inlet passage outlet section is divided into J sectors, and the average total pressure recovery coefficient σ of each sector is solved one by one

[0016] The angle ζ j corresponding to the jth measuring rake is taken as the abscissa, the sector average total pressure recovery coefficient σ j is taken as the ordinate, and a function is constructed

[0017] Based on the function the average total pressure recovery coefficient of each low pressure zone of the inlet passage outlet section is solved one by one, and the minimum average total pressure recovery coefficient σ0 is obtained.

[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 at the inlet outlet section.

[0019] Preferably, the average total pressure at the intake duct outlet section is calculated using an arithmetic mean. The formula is:

[0020]

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

[0022] Preferably, the average total pressure at the intake duct outlet section is calculated by averaging the flow rate. The formula is:

[0023]

[0024]

[0025] q(λ ij Let ΔA be the flow function. ij To measure the area of ​​a single surface element in a cross-section.

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

[0027]

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

[0029] Preferably, the formula for calculating the minimum average total pressure recovery coefficient σ0 is as follows:

[0030]

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

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

[0033]

[0034] Preferably, the formula for calculating the turbulence intensity τ is:

[0035]

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

[0037]

[0038] wherein, is the dynamic total pressure average; P 0t-j is the dynamic total pressure at the jth dynamic measuring point of the inlet passage 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: the present application obtains the inlet passage aerodynamic performance such as the total pressure recovery coefficient and the distortion index of the inlet passage under the condition of different inlet flow rates and various bleed flow rates matching the supersonic incoming flow state. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a schematic diagram of a supersonic inlet wind tunnel test model of a preferred embodiment of the present application considering the influence of the bleed flow. DETAILED DESCRIPTION

[0043] In order to make the technical solutions of the present application and its advantages clearer, the technical solutions of the present application will be further clearly and completely described in detail below in combination with the drawings. It can be understood that the specific embodiments described herein are only part of the embodiments of the present application, and are only used to explain the present application, but not to limit the present application. It should be noted that, for the purpose of description, only parts related to the present application are shown in the drawings, and other related parts can be referred to the general design. In the case of no conflict, the embodiments in the present application and the technical features in the embodiments can be combined to obtain new embodiments.

[0044] In addition, it should be noted that, unless otherwise explicitly specified and limited, the terms such as "mounting", "connecting", "connecting" and the like used in the description of the present application should be understood in a broad sense, for example, the connection can be fixed connection, or detachable connection, or integral connection; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through intermediate medium, or the internal communication of two elements, and those skilled in the art can understand the specific meaning of the present application according to the specific circumstances.

[0045] a) as shown in a supersonic inlet wind tunnel test model considering the influence of the bleed flow, Figure 1

[0046] The present application provides a supersonic inlet wind tunnel test model considering the influence of the bleed flow, comprising: ​

[0047] a) Test model

[0048] A center cone (1) is installed at the inlet of the inlet duct (3), which includes a tapered body at the front end and a straight pipe at the rear section. The straight pipe has a hollow passage inside, and the connection between the straight pipe and the tapered body has a leakage groove (2) to guide the airflow into the hollow passage. The tail of the airflow passage is connected to a leakage pipeline (5), which is installed with a leakage flow measurement rake (6) and a leakage flow control valve (7).

[0049] An inlet duct outlet total pressure measurement rake (4) and a suction pipeline (10) are installed at the outlet of the inlet duct (3). The suction pipeline (10) is installed with a suction flow control valve (11), which controls the inlet duct flow through the suction flow control valve (11) in the suction pipeline (10) to simulate the inlet duct inlet flow under different flight conditions. The inlet duct outlet cross-section steady-state total pressure, dynamic total pressure, and static pressure are measured by the inlet duct outlet total pressure measurement rake (4), and the inlet duct flow, total pressure recovery coefficient, and distortion index are calculated accordingly.

[0050] The inlet duct model is connected to the aircraft body through a rack, and the entire test model is fixed at the test section of the wind tunnel. The different angle of attack and side slip angle states of the test model can be adjusted by using the angle of attack / side slip angle adjustment structure of the wind tunnel.

[0051] b) Test model

[0052] The test model scale is determined according to the test section size of the test wind tunnel and the inlet suction capacity, and needs to meet the requirements of blockage, model length and span, inlet duct flow demand, etc. The test model needs to include the fuselage, wings, etc. before the inlet of the inlet duct, and the inlet lip, internal pipeline, etc. need to be strictly simulated.

[0053] c) Inlet duct flow control and measurement

[0054] By adjusting the position of the inlet duct flow control valve, the cross-sectional area of the airflow passage in the suction pipeline is changed, and the air flow into the inlet duct is controlled. The total pressure measurement rake and wall static pressure measurement points are set at the outlet of the inlet duct, and the inlet duct inlet 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, total temperature, total pressure, and static pressure at the outlet of the inlet duct, respectively.

[0057] d) Leakage flow control and measurement

[0058] By adjusting the position of the flow control valve in the venting pipeline, the cross-sectional area of ​​the airflow channel in the venting pipeline is changed, thereby controlling the flow rate entering the venting pipeline. A total pressure measuring rake and a static pressure measuring point on the wall are set in the venting pipeline, and the venting flow rate is calculated using formula (1). In the calculation, T0, P0, and P are taken as the total temperature, total pressure, and static pressure at the measuring section position in the venting pipeline, respectively.

[0059] e) Experimental data processing methods

[0060] The total pressure recovery coefficient σ at the intake duct outlet section is defined as the sum of the average total pressure P0 at the intake duct outlet section and the free flow total pressure P. 0∞ The ratio, i.e.

[0061]

[0062] In the formula, It is obtained by arithmetic average or flow rate average of the steady-state total pressure measured by the measuring rake at the intake outlet.

[0063] Suppose that the total pressure measuring rake (4) at the intake outlet contains I rake walls, and J steady-state total pressure measuring tubes are arranged on each rake wall, then The formula for calculating the arithmetic mean is:

[0064]

[0065] The formula for calculating average flow rate is:

[0066]

[0067] In the formula, q(λ) ij Let ΔA be the flow function. ij To measure the area of ​​a single surface element in a cross-section. q(λ) ij The formula for calculating ) is:

[0068]

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

[0070]

[0071] The angle ζ corresponding to the measuring rake j The x-axis represents the average total pressure recovery coefficient of the sector region. Use the ordinate as the constructor. Solve for the average total pressure recovery coefficient of each low-pressure zone at the intake duct outlet section and take the minimum value:

[0072]

[0073] where ζ Start and ζ End correspond to the start and end angles of the low pressure region with the minimum average total pressure recovery coefficient. Then, the steady state circumferential distortion index is calculated as:

[0074]

[0075] The calculation of the turbulence intensity τ is based on the dynamic total pressure data at the exit section of the inlet duct. The number of dynamic total pressure measuring points is generally the same as the number of the pressure rake. Similarly, the exit section of the inlet duct is divided into J sectors, and the turbulence intensity τ j of each sector is solved one by one. Finally, the arithmetic mean of the turbulence intensity τ j of all sectors is calculated.

[0076]

[0077] where:

[0078]

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

[0080]

[0081] The above merely provides a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which shall be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A supersonic inlet wind tunnel test model that accounts for bleed effects, characterized in that, The test model comprises: a simulation body (8) and an inlet duct (3) installed on the simulation body (8); a center cone (1) is installed at the inlet of the inlet duct (3), the center cone (1) comprises a cone at the front end and a straight pipe at the rear section, the straight pipe has a hollow passage inside, and the straight pipe has a flow leakage groove (2) at the joint with the cone, the flow leakage groove (2) is used to guide the airflow into the hollow passage, the airflow passage is connected with a flow leakage pipeline (5) at the tail, the flow leakage pipeline (5) is installed with a flow leakage flow measurement rake (6) and a flow leakage flow control valve (7); an inlet duct outlet total pressure measurement rake (4) and a suction pipeline (10) are installed at the outlet of the inlet duct (3), the suction pipeline (10) is installed with a suction flow control valve (11), the flow of the inlet duct is controlled through the suction flow control valve (11) in the suction pipeline (10), so as to simulate the inlet flow of the inlet duct under different flight states, the steady-state total pressure, dynamic total pressure and static pressure of the airflow at the outlet cross section of the inlet duct are measured by using the inlet duct outlet total pressure measurement rake (4), and the inlet duct flow, total pressure recovery coefficient and distortion index are calculated according to the measured values. The calculation method of the inlet duct flow is as follows: wherein k is the specific heat ratio of air, G is the flow at the outlet position of the inlet duct, T0 is the total temperature at the outlet position of the inlet duct, P0 is the total pressure at the outlet position of the inlet duct, and P is the static pressure at the outlet position of the inlet duct.

2. The supersonic inlet wind tunnel test model considering bleed effects of claim 1, wherein, The flow leakage pipeline is provided with a total pressure measurement rake and a wall static pressure measurement point, which are used to calculate the flow of the flow leakage pipeline.

3. A method for calculating steady-state circumferential distortion index of a supersonic inlet wind tunnel model, characterized in that, The steady-state circumferential distortion index calculation method of the supersonic inlet duct wind tunnel test model considering the flow leakage effect comprises: The average total pressure of the intake port exit section is obtained by arithmetic mean or flow mean of the measured values of the steady-state total pressure measuring tubes of the rake (4) by intake port exit total pressure measurement acquiring total pressure P of incoming flow 0∞ ; By the average total pressure of the inlet duct outlet section With the incoming flow total pressure P 0∞ The total pressure recovery coefficient σ of the inlet duct outlet section is calculated; The inlet channel outlet section is divided into multiple sector zones, and the average total pressure recovery coefficient of each sector zone is solved one by one with the angle ζ corresponding to the jth measuring rake j with the average total pressure recovery coefficient of the sector as abscissa with the constructor as ordinate Based on functions Solving the average total pressure recovery coefficient of each low pressure area of the inlet passage outlet section one by one, the minimum average total pressure recovery coefficient σ0 is obtained; 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 at the inlet duct outlet section 4. The method for calculating the steady-state circumferential distortion index of the supersonic inlet wind tunnel test model as described in claim 3, characterized in that, The average total pressure of the inlet passage outlet section is calculated by arithmetic mean The formula is: I is the number of rake walls of the inlet duct outlet total pressure measurement rake (4), and J is the number of steady-state total pressure measurement tubes of each rake wall.

5. The method for calculating the steady-state circumferential distortion index of the supersonic inlet wind tunnel test model as described in claim 4, characterized in that, The average total pressure of the inlet duct outlet section is calculated by flow averaging The formula is: q(λ ij ) is the flow function, ΔA ij is the area of a single panel of the measurement section.

6. The method for calculating the steady-state circumferential distortion index of the supersonic inlet wind tunnel test model as described in claim 5, characterized in that, The average total pressure recovery coefficient The calculation formula is: σ ij The total pressure recovery coefficient for the i-th measurement point of the j-th sector.

7. The method for calculating the steady-state circumferential distortion index of the supersonic inlet wind tunnel test model as described in claim 6, characterized in that, The calculation formula of the minimum average total pressure recovery coefficient σ0 is as follows: where ζ Start and ζ End correspond to the start and end angles of the low pressure region with the smallest average total pressure recovery coefficient.

8. The method for calculating the steady-state circumferential distortion index of the supersonic inlet wind tunnel test model as described in claim 7, characterized in that, Steady state circumferential distortion index The formula for calculating the steady state circumferential distortion index is:

9. The method for calculating the steady-state circumferential distortion index of the supersonic inlet wind tunnel test model as described in claim 8, characterized in that, The calculation formula of the turbulent degree τ is as follows: where: τ j is the turbulent intensity of the jth sector; wherein Pdynj is the dynamic total pressure at the jth dynamic measuring point at the exit section of the inlet channel; and 0t-j Pdynj is the dynamic total pressure at the jth dynamic measuring point at the exit section of the inlet channel.

10. The method for calculating the steady-state circumferential distortion index of the supersonic inlet wind tunnel test model as described in claim 9, characterized in that, The calculation formula of the total pressure comprehensive distortion index W is as follows:

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