Method for determining operating parameters of high-speed jet wind tunnel large-scale model speed pressure simulation test

Abstract

This invention belongs to the field of high-speed wind tunnel testing technology and discloses a method for determining the operating parameters of a large-scale model velocity-pressure simulation test in a high-speed jet wind tunnel, including: determining the target Mach number M and the target velocity-pressure value Q to be simulated; calculating the static pressure value P of the jet at the nozzle exit; calculating the total wind tunnel pressure P0; determining the air-to-wind tunnel pressure ratio λ1; and calculating the total air-to-wind tunnel pressure P. 01 ; Calculate the total pressure influence coefficient λ2 of the model blockage degree; Calculate the total operating pressure P of the wind tunnel after installing the large-scale model. 02 ; Calculate the influence coefficient λ3 of the total ejector pressure; Calculate the ejector pressure P 0p The method involves starting the wind tunnel and establishing a stable flow field. Within the allowable error range of velocity and pressure, fine-tuning the static pressure matching flow field is performed to optimize the flow field homogeneity in the jet uniform region. A large-scale model velocity and pressure simulation test of the high-speed jet wind tunnel is then conducted. This method allows for the selection of the total wind tunnel pressure P0 and the ejector pressure P at a given Mach number M. 0P It achieves accurate simulation of Mach number M and velocity pressure, and has practical engineering value.

Description

Technical Field

[0001] This invention belongs to the field of high-speed wind tunnel testing technology, specifically relating to a method for determining the operating parameters of a large-scale model velocity-pressure simulation test of a high-speed jet wind tunnel. Background Technology

[0002] High-speed jet wind tunnels are a type of high-speed wind tunnel with a special structural form, and have seen significant development since the mid-20th century. Unlike closed-section wind tunnels, high-speed jet wind tunnels do not have the strict limitations imposed by wall panels, allowing for relatively high levels of model obstruction. The model support methods and test equipment layouts are flexible, making them particularly suitable for conducting specialized wind tunnel tests on aircraft structural integrity and functional feasibility. They are primarily used for functional verification and evaluation of aircraft component deformation and sealing, nose cone separation, and dynamic deployment of wings / rudders / parachutes, solving many unique aerodynamic problems encountered during aircraft development.

[0003] Establishing a stable test flow field in a high-speed wind tunnel requires satisfying two conditions: nozzle profile and pressure ratio. Once the Mach number M is determined, the nozzle profile is also determined; the pressure ratio is the ratio of the total pressure in the stable section of the wind tunnel to the pressure behind the test chamber. As a special type of DC transient wind tunnel, the high-speed jet wind tunnel has the same starting total pressure as its operating total pressure, and the pressure behind the test chamber can be referenced to the local atmospheric pressure. (The last sentence appears to be incomplete and possibly refers to a different topic.) In smaller (usually less than 5%) routine tests, the corresponding air-to-wind-tunnel pressure ratio λ1 can be determined based on the functional relationship between the test Mach number M obtained from wind tunnel commissioning and the air-to-wind-tunnel pressure ratio λ1. The total wind tunnel pressure can then be calculated by referring to the local measured atmospheric pressure value, and the test can be carried out accordingly.

[0004] However, in functional verification tests such as aircraft component deformation and sealing, cowl separation, and dynamic deployment of wings / rudders / parachutes, it is usually required to use physical prototypes of the aircraft or large-scale test models that maintain high flow similarity and mass distribution similarity. The blockage degree of large-scale test models... The blockage degree is generally much higher than that of conventional high-speed wind tunnel tests. In the subsonic range, the figure has exceeded 60%, and in the supersonic range, it has exceeded 30%. Large-scale test models have a significant impact on the start-up performance of high-speed jet wind tunnels, test airflow velocity and pressure, and test chamber static pressure, especially on the main parameter of wind tunnel test operation—the total wind tunnel pressure P0.

[0005] To achieve the functional evaluation and verification test objectives, it is necessary to accurately simulate the structural loads and response of the aircraft under flight conditions while simultaneously simulating the Mach number M. In other words, the wind tunnel test velocity-pressure must be consistent with the flight velocity-pressure. At a defined target Mach number M, the high-speed jet wind tunnel requires the selection of appropriate total wind tunnel pressure P0 and ejector pressure P. 0PThis combination enables accurate simulation of velocity and pressure in large-scale model tests. If the total wind tunnel pressure P0 and the ejector pressure P... 0P An inappropriate combination of factors may, on the one hand, make it difficult to establish the target Mach number M flow field in the high-speed jet wind tunnel, causing shock wave oscillations and affecting test safety; on the other hand, it may cause the uniform region of the jet core flow field in the high-speed jet wind tunnel to become smaller and the uniformity index to be poor, making it difficult to achieve the test objectives and also affecting test efficiency.

[0006] Currently, there is an urgent need to develop a method for determining the operating parameters of a high-speed jet wind tunnel using a large-scale model velocity-pressure simulation test at a given Mach number M. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for determining the operating parameters of a large-scale model velocity-pressure simulation test of a high-speed jet wind tunnel, so as to overcome the defects of the prior art.

[0008] The method for determining the operating parameters of a large-scale model velocity-pressure simulation test in a high-speed jet wind tunnel according to the present invention includes the following steps:

[0009] S01. Determine the target Mach number M and the target velocity-pressure value Q to be simulated;

[0010] S02. Calculate the static pressure P of the jet at the nozzle exit;

[0011] According to Q=0.7•M 2 •P, calculate the corresponding nozzle outlet jet static pressure value P;

[0012] S03. Calculate the total wind tunnel pressure P0;

[0013] According to the isentropic flow equation: P0 = P•(1 + 0.2•M) 2 ) 3.5 Calculate the corresponding total wind tunnel pressure P0;

[0014] S04. Determine the air tunnel pressure ratio λ1;

[0015] Based on the functional relationship curve λ1=f1(M) between the high-speed jet wind tunnel Mach number M and the air tunnel start-up pressure ratio λ1 obtained from wind tunnel flow field measurement, the air tunnel pressure ratio λ1 is determined.

[0016] S05. Calculate the total pressure P in the air tunnel. 01 ;

[0017] Calculate the total pressure P of the air tunnel based on the pressure ratio λ1 and the measured atmospheric pressure Pa. 01 P 01 =Pa•λ1;

[0018] S06. Calculate the total pressure influence coefficient λ2 of the model blockage degree;

[0019] Based on the high-speed jet wind tunnel Mach number M and model blockage degree obtained from wind tunnel flow field measurements The functional relationship curve between the model's blockage degree and the total pressure influence coefficient λ2 is λ2=f2(M, ), thus obtaining the total pressure influence coefficient λ2 of the model blockage degree;

[0020] S07. Calculate the total operating pressure P of the wind tunnel after installing the large-scale model. 02 ;

[0021] Based on the total pressure influence coefficient λ2 of the model blockage degree, the total pressure P of the air tunnel is... 01 Make corrections and calculate the total wind tunnel pressure P required after installing the large-scale model. 02 P 02 =P 01 •λ2;

[0022] S08. Calculate the influence coefficient λ3 of the total ejector pressure;

[0023] Calculate the required total ejection pressure influence coefficient λ3, λ3=P0 / P 02 ;

[0024] S09. Calculate the ejector pressure P 0p ;

[0025] Based on the high-speed jet wind tunnel Mach number M and ejection pressure P obtained from wind tunnel flow field measurements 0P The functional relationship curve between λ3 and the total ejection pressure influence coefficient λ3 is λ3=f3(M,P). 0P ), calculate the ejector pressure P 0p ;

[0026] S10. Start the wind tunnel and establish a stable flow field;

[0027] According to the total wind tunnel pressure P0 and ejector pressure P 0p Start the high-speed jet wind tunnel to establish a stable flow field that meets the needs of large-scale model velocity-pressure simulation tests;

[0028] S11. Within the allowable error range of velocity and pressure, fine-tune the static pressure matching flow field, optimize the flow field uniformity in the jet uniform region, and carry out a large-scale model velocity and pressure simulation test of the high-speed jet wind tunnel;

[0029] Within the allowable error range of the velocity-pressure simulation, fine-tune the total wind tunnel pressure P0 or the ejector pressure P according to the static pressure matching requirements. 0p To further improve the uniformity of the flow field, a large-scale model velocity-pressure simulation test was conducted in a high-speed jet wind tunnel to determine the Mach number M.

[0030] Furthermore, the ejection pressure P 0p The total pressure is obtained by adjusting the gas collection chamber of the multi-nozzle ejector.

[0031] The method for determining the operating parameters of a large-scale model of a high-speed jet wind tunnel for velocity-pressure simulation and testing, as described in this invention, enables the selection of appropriate total wind tunnel pressure P0 and ejector pressure P0 under a given Mach number M. 0P The combination enables accurate simulation of experimental Mach number M and velocity pressure when using large-scale models. It is simple, reliable, and has practical engineering value. Attached Figure Description

[0032] Figure 1 A flowchart of the method for determining the operating parameters of a large-scale model velocity-pressure simulation test of a high-speed jet wind tunnel according to the present invention;

[0033] Figure 2 The curve showing the functional relationship between the Mach number M of the high-speed jet wind tunnel and the starting pressure ratio λ1 of the air wind tunnel is shown.

[0034] Figure 3 Mach number M of high-speed jet wind tunnel, model blockage degree The functional relationship curve between the model's blockage degree and the total pressure influence coefficient λ2;

[0035] Figure 4 For the high-speed jet wind tunnel Mach number M and ejector pressure P 0P The curve showing the functional relationship between the total ejection pressure and the influence coefficient λ3. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] Example: The high-speed jet wind tunnel in this example consists of a gas source spherical tank, a pressure regulating valve, a stabilization section, a nozzle, a test chamber, an over-expansion section (including an inlet collector), an ejector, a sub-expansion section, a silencer tower, and connecting pipes. By controlling the opening of the main inlet pressure regulating valve, the high-pressure gas ejected from the gas source spherical tank is rectified in the stabilization section and accelerated in the nozzle section to reach the required test flow field conditions in the test chamber. By controlling the opening of the ejector inlet pressure regulating valve, the high-pressure gas ejected from the gas source spherical tank reaches a stable pressure in the ejector collection chamber and is ejected through the ejector nozzle to eject and draw in the main airflow, thereby adjusting the pressure conditions in the test chamber. Finally, the test gas is discharged from the silencer tower through the expansion section.

[0038] This embodiment presents a large-scale model velocity-pressure simulation experiment of a high-speed jet wind tunnel, focusing on the model's blockage degree. The nominal Mach number is 0.323, the experimental Mach number M is 2.0, the target experimental velocity pressure Q is 70 kPa, and the measured Mach number M at the nozzle exit is 1.988 when the nominal Mach number M of the high-speed jet wind tunnel is 2.0; the ejector pressure P 0P The adjustment range is: 420kPa≤P 0P ≤1100kPa.

[0039] like Figure 1As shown, the high-speed jet wind tunnel large-scale model velocity-pressure simulation test of this embodiment includes the following steps:

[0040] S01. Determine the target Mach number M and the target velocity-pressure value Q to be simulated;

[0041] The target Mach number M is set to 2.0, and the target velocity pressure Q is set to 70 kPa.

[0042] S02. Calculate the static pressure P of the jet at the nozzle exit;

[0043] According to Q=0.7•M 2 • P, calculate the corresponding nozzle outlet jet static pressure value P, P=25.30kPa;

[0044] S03. Calculate the total wind tunnel pressure P0;

[0045] According to the isentropic flow equation: P0 = P•(1 + 0.2•M) 2 ) 3.5 Calculate the corresponding total wind tunnel pressure P0, P0 = 194.32 kPa;

[0046] S04. Determine the air tunnel pressure ratio λ1;

[0047] Based on wind tunnel flow field measurements, as follows Figure 2 The curve showing the functional relationship between the high-speed jet wind tunnel Mach number M and the air tunnel start-up pressure ratio λ1 is λ1=f1(M). The air tunnel pressure ratio λ1 is determined to be λ1=2.9012.

[0048] S05. Calculate the total pressure P in the air tunnel. 01 ;

[0049] Based on the pressure ratio λ1 = 2.9012, and the measured atmospheric pressure at the time and place was 94.43 kPa, calculate the total pressure P of the air tunnel. 01 P 01 =Pa•λ1=273.96kPa;

[0050] S06. Calculate the total pressure influence coefficient λ2 of the model blockage degree;

[0051] Based on wind tunnel flow field measurements, as follows Figure 3 The high-speed jet wind tunnel Mach number M and the model blockage degree are shown. The functional relationship curve between the model's blockage degree and the total pressure influence coefficient λ2 is λ2=f2(M, ), to obtain the corresponding blocking degree e m When the coefficient of performance is 0.323, the total pressure influence coefficient of the model blockage degree is λ2 = 1.2231;

[0052] S07. Calculate the total operating pressure P of the wind tunnel after installing the large-scale model. 02 ;

[0053] Based on the total pressure influence coefficient λ2 of the blockage degree, the total pressure P of the air tunnel is... 01 Make corrections and calculate the total operating pressure P of the wind tunnel after installing the large-scale model. 02 P 02 =P 01 •λ2=335.08kPa;

[0054] S08. Calculate the influence coefficient λ3 of the total ejector pressure;

[0055] Calculate the required total ejection pressure influence coefficient λ3, λ3=P0 / P 02 =0.5799;

[0056] S09. Calculate the ejector pressure P 0p ;

[0057] Based on wind tunnel flow field measurements, as follows Figure 4 The high-speed jet wind tunnel Mach number M and ejector pressure P are shown. 0P The functional relationship curve between λ3 and the total ejection pressure influence coefficient λ3 is λ3=f3(M,P). 0P ), calculate the ejector pressure P 0p =690kPa;

[0058] S10. Start the wind tunnel and establish a stable flow field;

[0059] Based on the wind tunnel total pressure P0 = 194.32 kPa and the ejector pressure P 0p =690kPa, start the high-speed jet wind tunnel and establish a stable flow field that meets the needs of large-scale model velocity pressure simulation test;

[0060] S11. Within the allowable error range of velocity and pressure, fine-tune the static pressure matching flow field, optimize the flow field uniformity in the jet uniform region, and conduct a large-scale model velocity and pressure simulation test of the high-speed jet wind tunnel.

[0061] Within the allowable error range of the velocity-pressure simulation, and based on the static pressure matching requirements, the total wind tunnel pressure P0 was fine-tuned to further improve the uniformity of the jet flow field. A large-scale model velocity-pressure simulation experiment was then conducted in the high-speed jet wind tunnel at a determined Mach number M. Finally, at the measured Mach number M1.988, with P0 = 194.7 kPa and P... 0p A uniform flow field was established in the high-speed jet wind tunnel under a pressure of 690 kPa. The actual test velocity and pressure Q = 70.136 kPa. The accuracy of the high-speed jet wind tunnel large-scale model velocity and pressure simulation test fully meets the test requirements.

[0062] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. For those skilled in the art, all features disclosed in the present invention, or all steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for determining the operating parameters of a large-scale model velocity-pressure simulation test in a high-speed jet wind tunnel, characterized in that, Includes the following steps: S01. Determine the target Mach number M and the target velocity-pressure value Q to be simulated; S02. Calculate the static pressure P of the jet at the nozzle exit; According to Q=0.7•M 2 •P, calculate the corresponding nozzle outlet jet static pressure value P; S03. Calculate the total wind tunnel pressure P0; According to the isentropic flow equation: P0 = P•(1 + 0.2•M) 2 ) 3.5 Calculate the corresponding total wind tunnel pressure P0; to achieve accurate simulation of the target velocity-pressure value Q at a given Mach number M, the total wind tunnel pressure P0 must be stably and accurately controlled during the high-speed jet wind tunnel test. 0； S04. Determine the air tunnel pressure ratio λ1; Based on the functional relationship curve λ1=f1(M) between the high-speed jet wind tunnel Mach number M and the air tunnel start-up pressure ratio λ1 obtained from wind tunnel flow field measurement, the air tunnel pressure ratio λ1 is determined. S05. Calculate the total pressure P in the air tunnel. 01 ; Calculate the total pressure P of the air tunnel based on the pressure ratio λ1 and the measured atmospheric pressure Pa. 01 P 01 =Pa•λ1; S06. Calculate the total pressure influence coefficient λ2 of the model blockage degree; Based on the high-speed jet wind tunnel Mach number M and model blockage degree obtained from wind tunnel flow field measurements The functional relationship curve between the model's blockage degree and the total pressure influence coefficient λ2 is λ2=f2(M, ), thus obtaining the total pressure influence coefficient λ2 of the model blockage degree; S07. Calculate the total operating pressure P of the wind tunnel after installing the large-scale model. 02 ; Based on the total pressure influence coefficient λ2 of the model blockage degree, the total pressure P of the air tunnel is... 01 Make corrections and calculate the total wind tunnel pressure P required after installing the large-scale model. 02 P 02 =P 01 •λ2; Calculated total wind tunnel pressure P after installing the large-scale model. 02 The pressure will be much greater than the total wind tunnel pressure P0. To stably and accurately control the total wind tunnel pressure P0, a multi-nozzle ejector is installed in the high-speed jet wind tunnel. While maintaining the total wind tunnel pressure ratio, the ejection pressure P of the multi-nozzle ejector is adjusted. 0P The total operating pressure P of the wind tunnel after the installation of the large-scale model will be... 02 Reduce to the target total pressure P 0； S08. Calculate the influence coefficient λ3 of the total ejector pressure; Calculate the required total ejection pressure influence coefficient λ3, λ3=P0 / P 02 ; S09. Calculate the ejector pressure P 0p ; Based on the high-speed jet wind tunnel Mach number M and ejection pressure P obtained from wind tunnel flow field measurements 0P The functional relationship curve between λ3 and the total ejection pressure influence coefficient λ3 is λ3=f3(M,P). 0P ), calculate the ejector pressure P 0p ; S1 0. Start the wind tunnel and establish a stable flow field; According to the total wind tunnel pressure P0 and ejector pressure P 0p Start the high-speed jet wind tunnel to establish a stable flow field that meets the needs of large-scale model velocity-pressure simulation tests; S11. Within the allowable error range of velocity and pressure, fine-tune the static pressure matching flow field, optimize the flow field uniformity in the jet uniform region, and carry out a large-scale model velocity and pressure simulation test of the high-speed jet wind tunnel; Within the allowable error range of the velocity-pressure simulation, fine-tune the total wind tunnel pressure P0 or the ejector pressure P according to the static pressure matching requirements. 0p To further improve the uniformity of the flow field, a large-scale model velocity-pressure simulation test was conducted in a high-speed jet wind tunnel to determine the Mach number M.

2. The method for determining the operating parameters of a large-scale model velocity-pressure simulation test of a high-speed jet wind tunnel according to claim 1, characterized in that, The ejection pressure P 0p The total pressure is obtained by adjusting the gas collection chamber of the multi-nozzle ejector.

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