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

Abstract

The invention belongs to the technical field of high-speed wind tunnel tests, and discloses a high-speed jet flow wind tunnel large-scale model velocity pressure simulation test operation parameter determination method, which comprises the steps of determining a target Mach number M and a target velocity pressure value Q needing to be simulated; calculating a jet static pressure value P of a nozzle outlet; calculating the total pressure P0 of the wind tunnel; determining an air wind tunnel pressure ratio lambda1; calculating the total pressure P01 of the air wind tunnel; calculating a model blocking degree total pressure influence coefficient lambda2; calculating the total operation pressure P02 of the wind tunnel after the installation of the large-scale model; calculating an injection total pressure influence coefficient lambda3; the injection pressure P0p is calculated; starting the wind tunnel and establishing a stable flow field; and carrying out static pressure matching flow field fine tuning in a speed pressure allowable error range, optimizing the uniformity of the flow field in a jet flow uniform region, and carrying out a high-speed jet flow wind tunnel large-scale model speed pressure simulation test. According to the method, the total pressure P0 and the injection pressure P0P of the wind tunnel can be selected under the condition that the Mach number M is determined, accurate simulation of the Mach number M and the velocity pressure is achieved, and the method has engineering practical value.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-speed wind tunnel tests, and in particular relates to a method for determining operating parameters of a large-scale model speed-pressure simulation test in a high-speed jet wind tunnel. Background Art

[0002] High-speed jet tunnels, a unique structural form of high-speed wind tunnel, have experienced significant development since the mid-20th century. Free from the strict wall restrictions of closed-section wind tunnel test sections, high-speed jet tunnels allow for relatively large model obstructions and offer flexible model support and test equipment layouts. These tunnels are particularly well-suited for conducting specialized wind tunnel tests, such as aircraft structural integrity and functional feasibility testing. They are primarily used to verify the deformation and sealing of aircraft components, cowling separation, and dynamic deployment of wings, rudders, and parachutes, addressing numerous specialized aerodynamic challenges encountered during aircraft development.

[0003] To establish a stable test flow field in a high-speed wind tunnel, two conditions must be met: nozzle profile and pressure ratio. Once the Mach number M is determined, the nozzle profile is determined; the pressure ratio is the ratio of the total pressure in the wind tunnel's stable section to the pressure behind the test chamber. As a special direct current transient wind tunnel, the high-speed jet wind tunnel has the same starting total pressure as the operating total pressure, and the pressure behind the test chamber can refer to the local atmospheric pressure. In smaller (usually less than 5%) conventional tests, the corresponding air-to-air wind tunnel pressure ratio λ1 can be determined based on the functional relationship between the test Mach number M and the air-to-air wind tunnel pressure ratio λ1 obtained from wind tunnel debugging, and the total wind tunnel pressure can be calculated with reference to the local measured atmospheric pressure value to carry out the test.

[0004] However, in the functional verification tests such as deformation and sealing of aircraft components, separation of hood, dynamic deployment of wings / rudders / parachute, etc., it is usually required to use the aircraft to develop the original object or a large-scale test model with high flow similarity and mass distribution similarity. The blockage degree of the large-scale test model is The blockage degree of large-scale test models in high-speed jet wind tunnels is generally much higher than that of conventional high-speed wind tunnel tests. In the subsonic domain, this has exceeded 60%, and in the supersonic domain, it has exceeded 30%. Large-scale test models have a significant impact on the startup performance of high-speed jet wind tunnels, the test airflow velocity and pressure, and the static pressure of the test chamber. In particular, they have a significant impact on the wind tunnel total pressure P0, a key parameter in wind tunnel test operation.

[0005] In order to achieve the purpose of functional assessment and verification test, it is necessary to simulate the flight Mach number M conditions while accurately simulating the structural load and response of the aircraft under flight conditions. That is, the wind tunnel test speed and pressure must be consistent with the flight speed and pressure. Under the determined target Mach number M, the high-speed jet wind tunnel needs to select the appropriate wind tunnel total pressure P0, the injection pressure P 0PThe combination can realize the accurate simulation of velocity pressure in large-scale model test. If the total pressure of wind tunnel P0 and the ejection pressure P 0P Improper combination selection may, on the one hand, make it difficult to establish the target Mach number M flow field in the high-speed jet wind tunnel, cause shock wave oscillation, and affect the test safety; on the other hand, it may cause the uniform area 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 purpose and affecting the 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 speed-pressure simulation test at a certain 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 operating parameters of a large-scale model velocity-pressure simulation test in a high-speed jet wind tunnel, so as to overcome the defects of the prior art.

[0008] The method for determining operating parameters of a large-scale model velocity-pressure simulation test in a high-speed jet wind tunnel of the present invention comprises the following steps: S01. Determine the target Mach number M and the target speed and pressure value Q to be simulated; S02. Calculate the static pressure value P of the jet at the nozzle outlet; According to Q=0.7•M 2 •P, calculate the corresponding nozzle exit jet static pressure value P; S03. Calculate the total wind tunnel pressure P0; According to the isentropic flow relationship: P0=P•(1+0.2•M 2 ) 3.5 , calculate the corresponding wind tunnel total pressure P0; S04. Determine the air-to-air tunnel pressure ratio λ1; According to the functional relationship curve λ1=f1(M) between the high-speed jet wind tunnel Mach number M and the empty wind tunnel starting pressure ratio λ1 obtained by wind tunnel flow field measurement, the empty wind tunnel pressure ratio λ1 is determined; S05. Calculate the total pressure P in the empty wind tunnel 01 ; Calculate the total pressure P in the wind 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; According to the high-speed jet wind tunnel Mach number M and model blockage obtained by wind tunnel flow field comparison The functional relationship curve of the total pressure influence coefficient λ2 of the model blockage degree is λ2=f2(M, ), the total pressure influence coefficient of the model blockage degree λ2 is obtained; S07. Calculate the total operating pressure P of the wind tunnel after installing the large-scale model02 ; According to the total pressure influence coefficient λ2 of the model blockage degree, the total pressure of the air wind tunnel P 01 Make corrections and calculate the total wind tunnel pressure P required after installing the large-scale model 02 , P 02 =P 01 •λ2; S08. Calculate the total ejection pressure influence coefficient λ3; Calculate the required total ejection pressure influence coefficient λ3, λ3=P0 / P 02 ; S09. Calculate the injection pressure P 0p ; According to the wind tunnel flow field measurement, the high-speed jet wind tunnel Mach number M and the ejection pressure P 0P The functional relationship curve of the total ejection pressure influence coefficient λ3 is λ3=f3(M,P 0P ), calculate the ejection pressure P 0p ; S10. Start the wind tunnel and establish a stable flow field; According to the total pressure of the wind tunnel P0, the injection pressure P 0p Start the high-speed jet wind tunnel to establish a stable flow field suitable for large-scale model speed and pressure simulation tests; S11. Fine-tune the static pressure matching flow field within the allowable error range of velocity and pressure, optimize the flow field uniformity in the jet uniformity zone, and conduct large-scale velocity and pressure simulation tests of high-speed jet wind tunnel models. Within the allowable error range of velocity-pressure simulation, fine-tune the wind tunnel total pressure P0 or the ejection pressure P according to the static pressure matching requirements. 0p To further improve the uniformity of the flow field, a large-scale model speed and pressure simulation test was carried out in a high-speed jet wind tunnel to determine the Mach number M.

[0009] Furthermore, the injection pressure P 0p It is obtained by adjusting the total pressure of the multi-nozzle ejector gas collecting chamber.

[0010] The method for determining the operating parameters of the large-scale model speed-pressure simulation speed-pressure test of the high-speed jet wind tunnel of the present invention can select the appropriate wind tunnel total pressure P0 and ejection pressure P under the determined Mach number M. 0P The combination can realize the accurate simulation of the experimental Mach number M and velocity pressure when using a large-scale model. It is simple, reliable and has practical engineering value. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a flow chart of the method for determining operating parameters of a large-scale model velocity-pressure simulation test in a high-speed jet wind tunnel according to the present invention; Figure 2 is the functional relationship curve between the Mach number M of the high-speed jet wind tunnel and the starting pressure ratio λ1 of the empty wind tunnel; Figure 3 is the Mach number M of the high-speed jet wind tunnel and the model blockage Functional relationship curve of total pressure influence coefficient λ2 of model blockage degree; Figure 4 is the high-speed jet wind tunnel Mach number M, the ejection pressure P 0P Functional relationship curve with the total ejection pressure influence coefficient λ3. DETAILED DESCRIPTION

[0012] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0013] Example: The high-speed jet wind tunnel of this embodiment consists of a gas source spherical tank, a pressure regulating valve, a stabilization section, a nozzle, a test chamber, a super-expansion section (including an inlet collector), an ejector, a sub-expansion section, a muffler, and connecting pipes. By controlling the opening of the main air inlet pressure regulating valve, the high-pressure gas ejected from the gas source spherical tank is regulated. The gas is rectified in the stabilization section and accelerated in the nozzle section to achieve the required test flow field conditions in the test chamber. By controlling the opening of the ejector air inlet pressure regulating valve, the high-pressure gas ejected from the gas source spherical tank reaches a stable pressure in the ejector plenum chamber and is ejected through the ejector nozzle, thereby injecting and aspirating the main airflow and achieving the purpose of regulating the test chamber pressure conditions. Finally, the test gas is discharged from the muffler through the expansion section.

[0014] The high-speed jet wind tunnel large-scale model speed pressure simulation test of this embodiment shows that the model blockage is 0.323, the test Mach number M is 2.0, the target test velocity pressure Q is 70kPa, and when the nominal Mach number of the high-speed jet wind tunnel is M2.0, the measured Mach number M at the nozzle outlet is 1.988; the injection pressure P 0P The adjustment range is: 420kPa≤P 0P ≤1100kPa.

[0015] like Figure 1 As shown, the high-speed jet wind tunnel large-scale model speed pressure simulation test of this embodiment includes the following steps: S01. Determine the target Mach number M and the target speed and pressure value Q to be simulated; Take the target Mach number M as 2.0 and the target velocity pressure Q as 70 kPa; S02. Calculate the static pressure value P of the jet at the nozzle outlet; According to Q=0.7•M 2 •P, calculate the corresponding static pressure value of the nozzle outlet jet P, P = 25.30kPa; S03. Calculate the total wind tunnel pressure P0; According to the isentropic flow relationship: P0=P•(1+0.2•M 2 ) 3.5, calculate the corresponding wind tunnel total pressure P0, P0=194.32kPa; S04. Determine the air-to-air tunnel pressure ratio λ1; According to the wind tunnel flow field measurement, Figure 2 The functional relationship curve of the high-speed jet wind tunnel Mach number M and the empty wind tunnel starting pressure ratio λ1 is shown as λ1=f1(M), and the empty wind tunnel pressure ratio λ1 is determined, λ1=2.9012; S05. Calculate the total pressure P in the empty wind tunnel 01 ; According to the pressure ratio λ1=2.9012, the measured atmospheric pressure at that time was 94.43kPa, and the total pressure of the wind tunnel P was calculated. 01 , P 01 =Pa•λ1=273.96kPa; S06. Calculate the total pressure influence coefficient λ2 of the model blockage degree; According to the wind tunnel flow field measurement, Figure 3 The high-speed jet wind tunnel Mach number M and model blockage are shown The functional relationship curve of the total pressure influence coefficient λ2 of the model blockage degree is λ2=f2(M, ), and the corresponding blocking degree e is obtained m =0.323, the total pressure influence coefficient of the model blockage degree λ2=1.2231; S07. Calculate the total operating pressure P of the wind tunnel after installing the large-scale model 02 ; According to the total pressure influence coefficient λ2 of the blockage degree, the total pressure of the air wind tunnel P 01 Correction is made to calculate the total pressure P of the wind tunnel after installing the large-scale model. 02 , P 02 =P 01 •λ2=335.08kPa; S08. Calculate the total ejection pressure influence coefficient λ3; Calculate the required total ejection pressure influence coefficient λ3, λ3=P0 / P 02 =0.5799; S09. Calculate the injection pressure P 0p ; According to the wind tunnel flow field measurement, Figure 4 The high-speed jet wind tunnel Mach number M and ejection pressure P shown 0P The functional relationship curve of the total ejection pressure influence coefficient λ3 is λ3=f3(M,P 0P ), calculate the ejection pressure P 0p =690kPa; S10. Start the wind tunnel and establish a stable flow field; According to the total pressure of the wind tunnel P0 = 194.32kPa, the injection pressure P0p =690kPa, start the high-speed jet wind tunnel to establish a stable flow field suitable for large-scale model speed and 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 area, and conduct large-scale model velocity and pressure simulation tests in a high-speed jet wind tunnel.

[0016] Within the allowable error range of velocity-pressure simulation, according to the static pressure matching requirements, the wind tunnel total pressure P0 was fine-tuned to further improve the uniformity of the jet flow field, and a large-scale model velocity-pressure simulation test was carried out in a high-speed jet wind tunnel to determine the Mach number M. Finally, under the measured Mach number M1.988, at P0=194.7kPa, P 0p =690kPa, a uniform flow field in the high-speed jet wind tunnel was established. The actual test velocity pressure Q=70.136kPa. The accuracy of the velocity and pressure simulation test of the large-scale model of the high-speed jet wind tunnel fully met the test requirements.

[0017] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the description and implementation methods. For those familiar with the art, all features disclosed in the present invention, or all steps in the disclosed methods or processes, 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 operating parameters of a large-scale model velocity-pressure simulation test in a high-speed jet wind tunnel, characterized in that: The following steps are involved: S01. Determine the target Mach number M and the target speed and pressure value Q to be simulated; S02. Calculate the static pressure value P of the jet at the nozzle outlet; According to Q=0.7•M 2 •P, calculate the corresponding nozzle exit jet static pressure value P; S03. Calculate the total wind tunnel pressure P0; According to the isentropic flow relationship: P0=P•(1+0.2•M 2 ) 3.5 , calculate the corresponding wind tunnel total pressure P0; the wind tunnel total pressure P0 can achieve accurate simulation of the target speed pressure value Q under the determined Mach number M. The wind tunnel total pressure P0 must be stably and accurately controlled during the high-speed jet wind tunnel test. 0； S04. Determine the air-to-air tunnel pressure ratio λ1; According to the functional relationship curve λ1=f1(M) between the high-speed jet wind tunnel Mach number M and the empty wind tunnel starting pressure ratio λ1 obtained by wind tunnel flow field measurement, the empty wind tunnel pressure ratio λ1 is determined; S05. Calculate the total pressure P in the empty wind tunnel 01 ; Calculate the total pressure P in the wind 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; According to the high-speed jet wind tunnel Mach number M and model blockage obtained by wind tunnel flow field comparison The functional relationship curve of the total pressure influence coefficient λ2 of the model blockage degree is λ2=f2(M, ), the total pressure influence coefficient of the model blockage degree λ2 is obtained; S07. Calculate the total operating pressure P of the wind tunnel after installing the large-scale model 02 ; According to the total pressure influence coefficient λ2 of the model blockage degree, the total pressure of the air wind tunnel P 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 It will be much greater than the total pressure of the wind tunnel P0. In order to stably and accurately control the total pressure of the wind tunnel P0, a multi-nozzle ejector is set in the high-speed jet wind tunnel. Under the premise of maintaining the wind tunnel pressure ratio to the total pressure, the ejection pressure P0 of the multi-nozzle ejector is adjusted. 0P , the total pressure of the wind tunnel after installing the large-scale model P 02 , down to the target total pressure P 0； S08. Calculate the total ejection pressure influence coefficient λ3; Calculate the required total ejection pressure influence coefficient λ3, λ3=P0 / P 02 ; S09. Calculate the injection pressure P 0p ; According to the wind tunnel flow field measurement, the high-speed jet wind tunnel Mach number M and the ejection pressure P 0P The functional relationship curve of the total ejection pressure influence coefficient λ3 is λ3=f3(M,P 0P ), calculate the ejection pressure P 0p ; S1 0. Start the wind tunnel and establish a stable flow field; According to the total pressure of the wind tunnel P0, the injection pressure P 0p Start the high-speed jet wind tunnel to establish a stable flow field suitable for large-scale model speed and pressure simulation tests; S11. Fine-tune the static pressure matching flow field within the allowable error range of velocity and pressure, optimize the flow field uniformity in the jet uniformity zone, and conduct large-scale velocity and pressure simulation tests of high-speed jet wind tunnel models. Within the allowable error range of velocity-pressure simulation, fine-tune the wind tunnel total pressure P0 or the ejection pressure P according to the static pressure matching requirements. 0p To further improve the uniformity of the flow field, a large-scale model speed and pressure simulation test was carried out in a high-speed jet wind tunnel to determine the Mach number M.

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

Images