Accurate calculation method of arc heating aerodynamic thermal test parameters

Abstract

A method for accurately calculating arc heating aerodynamic thermal test parameters is provided. The method is based on the total enthalpy and heat flux required to be simulated in the arc heating ground simulation test, combined with the iterative analysis of the thermophysical parameters of the ground test airflow, to provide a fast and effective method for calculating the arc heating test state. The method can achieve accurate conversion between aerodynamic thermal parameters (total enthalpy and heat flux) and arc heating equipment operating parameters (mass flow rate) within seconds, thereby improving the evaluation accuracy of the arc heating aerodynamic thermal ground test and increasing the efficiency of the model aerodynamic thermal ground test.

Description

Technical Field

[0001] The invention relates to a ground test of an arc heater, and in particular to accurate calculation of arc heating aerodynamic thermal test parameters, and belongs to the research field of ground aerodynamic thermal test of aircraft. Background Art

[0002] The arc heating aerodynamic thermal test uses arc heating equipment to break through the air medium, establish an arc channel, heat the incoming air medium, and obtain the aerodynamic thermal environment of the aircraft re-entry after accelerated expansion through the nozzle. The main simulated aerodynamic thermal parameters are generally total enthalpy and heat flow. The first step in conducting an arc heating aerodynamic thermal test is to evaluate the aerodynamic thermal parameters of the surface of the heat protection material during the aircraft re-entry, and convert them into the parameters required for the operation of the arc heating equipment itself. One of the key parameters is the mass flow required by the arc heating equipment. At present, the mainstream calculation methods include traditional engineering algorithms and CFD numerical algorithms: the traditional engineering algorithm is based on simple assumptions, directly applies the thermophysical parameters of air at room temperature, and performs table lookup calculations, which has low calculation efficiency. At the same time, due to the large difference between the thermophysical parameters of air at high temperature and the normal temperature state, the method obtains inaccurate mass flow parameters of the arc heating equipment. The aerodynamic thermal parameters (total enthalpy, heat flow) obtained by guiding the actual debugging of the arc heating equipment based on the calculation parameters are often far from the target values, which greatly increases the difficulty of subsequent debugging; the CFD numerical algorithm is to grid the flow field of the arc heating equipment from the nozzle inlet to the outlet through CFD numerical calculation, and use the computer to calculate the flow field, which can obtain the one-dimensional / two-dimensional / three-dimensional distribution of the airflow field of the arc heating test, and can accurately convert the aerodynamic thermal parameters and the equipment operation parameters. However, the calculation time required for this method often ranges from several hours to several days, and it is impossible to quickly and effectively evaluate the arc heating test status, which is not conducive to the preliminary preparation and evaluation of the test. It is necessary to conduct research to quickly and accurately calculate the arc heating aerodynamic thermal test status and realize the efficient implementation of the aerodynamic thermal test of engineering models. Summary of the invention

[0003] The purpose of the present invention is to develop a method for accurately calculating the parameters of an arc heating aerodynamic thermal test. The method is based on the total enthalpy and heat flux that need to be simulated in the arc heating ground simulation test, combined with the iterative analysis of the thermal physical properties of the ground test airflow, to provide a fast and effective arc heating test state calculation method, which can achieve accurate conversion between aerodynamic thermal parameters (total enthalpy and heat flux) and arc heating equipment operating parameters (mass flow rate) within a few seconds, thereby improving the evaluation accuracy of the arc heating aerodynamic thermal ground test and improving the efficiency of the model aerodynamic thermal ground test.

[0004] The above-mentioned object of the present invention is mainly achieved through the following technical scheme: A method for accurately calculating the parameters of an arc heating aerodynamic heat test comprises the following steps:

[0005] (1) Input the aerodynamic thermal parameters to be simulated in the arc heating test: total enthalpy H0, heat flux q, select the nozzle, and determine the nozzle throat-exit area ratio A / A*;

[0006] (2) Assume an initial total pressure value P0 and an initial specific heat ratio γ0;

[0007] (3) According to the total pressure value P0, combined with the total enthalpy H0, and based on the thermochemical equilibrium calculation, the total temperature T0 is obtained; according to the specific heat ratio γ0, combined with the above-selected nozzle throat-exit area ratio A / A*, the Mach number Ma at the nozzle outlet can be calculated;

[0008] (4) Based on the Mach number Ma obtained above, given the specific heat ratio γ0, the static temperature to total temperature ratio T of the nozzle is obtained i / T0, static pressure to total pressure ratio P i / P0, combined with the above-mentioned total temperature T0 and initial total pressure P0, the static temperature T of the nozzle outlet is obtained i and static pressure P i ;

[0009] (5) Under the assumption of balanced flow or freezing flow, the specific heat ratio γ, Prandtl number Pr, and viscosity coefficient μ of the nozzle outlet airflow are all functions of the local static temperature and static pressure γ(P, T), Pr(T, P), and μ(T, P). i and static pressure P i , we can get the specific heat ratio γ i , Prandtl number Pr i , viscosity coefficient μ i The value of

[0010] (6) According to the specific heat ratio γ obtained above i , Prandtl number Pri, viscosity coefficient μ i The velocity V at the nozzle outlet is calculated i , static enthalpy H 静焓i , recovery enthalpy H 恢复焓i and reference enthalpy H 参考焓i ;

[0011] (7) Based on all the parameters obtained above, the total enthalpy H0 and the mass flow rate m required for the arc heating test simulation are preliminarily calculated. i , and obtain the total pressure P of the arc heater test 0_i ;

[0012] (8) Determine the calculated total pressure P 0_i and specific heat ratio γ i Is it converged? If it is converged, the calculation is terminated. The mass flow rate m at this time is i That is the flow value m:m required for the arc heating test i=m; otherwise, the total pressure P 0_i and specific heat ratio γ i Instead of the initial total pressure P0 and the initial specific heat ratio γ0 given in step (2), the calculation is restarted from step (3) until the iteratively calculated total pressure P 0_i and specific heat ratio γ i convergence.

[0013] Preferably, the value range of the initial total pressure P0 is 0.001 MPa-20 MPa; the value range of the initial specific heat ratio γ0 is 1.1-1.4.

[0014] The method of the present invention covers the parameter calculation of three main types of tests, namely, stationary point, flat plate and wing leading edge tests of aircraft thermal protection ground assessment tests.

[0015] Preferably, the value of the initial specific heat ratio γ0 satisfies:

[0016] H0≤9000kJ / kg:

[0017] γ0=1.41-5.36e-5×H0-1.05e-8×H0 2 +3.13e-12×H0 3 -1.71e-16×H0 4

[0018] H0>9000kJ / kg:

[0019] γ0=2.52-3.03e-4×H0+2.62e-8×H0 2 -1.12e-12×H0 3 +2.38e-17×H0 4 -1.99e-22×H0 5

[0020] Preferably, steps (1)-(8) are processed into modular units based on excel, matlab or C software development, and the input of the modular unit is the three parameters in step (1). After the input is completed, the calculation of the aerodynamic thermal test parameters can be automatically completed within a few seconds.

[0021] The method of the invention is applicable to the calculation of operating parameters of arc heaters in existing aircraft heat protection material arc heating ground tests, and converts the aerodynamic thermal parameters of aircraft reentry into operating parameters of arc heating equipment.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention provides a fast and effective method for calculating the state of an arc heating test based on the precise calculation of the ground test of the arc heating equipment and the iterative analysis of the thermophysical parameters of the airflow in the ground test. The method can achieve accurate conversion between aerodynamic thermal parameters (total enthalpy and heat flux) and arc heating equipment operating parameters (mass flow rate) within a few seconds.

[0024] (2) The precise calculation method of the arc heating aerodynamic thermal test parameters of the present invention has been packaged in an engineering package. In actual calculation, it is only necessary to input the required simulated aerodynamic thermal parameters (total enthalpy and heat flow) to instantly obtain the mass flow parameters required by the arc heating test equipment.

[0025] (3) Compared with the traditional estimation method, the accurate calculation method of the arc heating aerodynamic thermal test parameters of the present invention can greatly improve the calculation accuracy of the arc heating operating flow, thereby improving the evaluation capability of the existing arc heating ground test.

[0026] (4) The method for accurately calculating the parameters of the arc heating aerodynamic thermal test of the present invention is a fast and effective method for engineering calculation of arc heating tests. Compared with the simulation evaluation that takes several hours to several days for CFD numerical calculations, the method of the present invention can output results within seconds while ensuring accurate calculations, thereby greatly improving the efficiency of test status evaluation.

[0027] (5) The calculation method of the present invention is based on Excel, Matlab or C software development environment. Only the three parameters in step (1) need to be input to automatically complete the rapid and accurate calculation of the aerodynamic thermal test parameters within a few seconds.

[0028] (6) The precise calculation method of arc heating aerodynamic thermal test parameters can quickly and accurately calculate the operating parameters of the arc heater in the arc heating ground test of existing aircraft thermal protection materials, quickly convert the aerodynamic thermal parameters of the aircraft reentry into the operating parameters of the arc heating equipment, and maximize the evaluation efficiency of the arc heating aerodynamic thermal test status. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the method for accurately calculating the parameters of the arc heating aerodynamic heat test of the present invention.

[0030] Figure 2-Figure 4 They are respectively the changing trends of γ(P, T), Pr(T, P) and μ(T, P) in the accurate calculation method of arc heating aerodynamic thermal test parameters of the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0032] The method for accurately calculating the parameters of the arc heating aerodynamic heat test includes the following steps:

[0033] (1) Input the aerodynamic thermal parameters to be simulated in the arc heating test: total enthalpy H0, heat flux q, select the nozzle, and determine the nozzle throat-exit area ratio A / A*;

[0034] (2) Assume an initial total pressure value P0 and an initial specific heat ratio γ0;

[0035] The value range of the initial total pressure P0 is 0.001MPa-20MPa; the value range of the initial specific heat ratio γ0 is 1.1-1.4.

[0036] (3) According to the total pressure value P0, combined with the total enthalpy H0, and based on the thermochemical equilibrium calculation, the total temperature T0 is obtained; according to the specific heat ratio γ0, combined with the above-selected nozzle throat-exit area ratio A / A*, the Mach number Ma at the nozzle outlet can be calculated;

[0037]

[0038] (4) Based on the Mach number Ma obtained above, given the specific heat ratio γ0, the static temperature to total temperature ratio T / T0 and the static pressure to total pressure ratio P / P0 of the nozzle can be obtained. Combined with the total temperature T0 obtained above, the static temperature T and static pressure P at the nozzle outlet can be obtained;

[0039]

[0040]

[0041] (5) Under the assumption of balanced flow or freezing flow, the specific heat ratio γ, Prandtl number Pr, and viscosity coefficient μ of the nozzle outlet airflow are all functions of the local static temperature and static pressure γ(P, T), Pr(T, P), and μ(T, P). Based on the static temperature T and static pressure P obtained above, the specific heat ratio γ can be obtained. i , Prandtl number Pr i , viscosity coefficient μ i The value of .

[0042] Figure 2-Figure 4 They are respectively the changing trends of γ(P, T), Pr(T, P) and μ(T, P) in the accurate calculation method of arc heating aerodynamic thermal test parameters of the present invention.

[0043] (6) Based on the specific heat ratio γ obtained above i , Prandtl number Pri, viscosity coefficient μ i The nozzle outlet velocity V can be further calculated. i , static enthalpy H 静焓i , recovery enthalpy H 恢复焓i and reference enthalpy H 参考焓i ;

[0044] Vi =Ma(γ i RT) 0.5

[0045] H 静焓i =f(T,P)

[0046]

[0047]

[0048] In laminar flow, n = 1 / 2; in turbulent flow, n = 1 / 3;

[0049] (7) Based on all the parameters obtained above, the mass flow rate m required for the arc heating test to simulate the above aerodynamic thermal parameters (total enthalpy H0, heat flow q) can be preliminarily calculated: i , and obtain the total pressure P of the arc heater test 0_i ;

[0050] The mass flow rate of the arc-heated flat plate free jet test is determined as follows:

[0051]

[0052] L is the distance from the nozzle throat to the nozzle outlet;

[0053] The total pressure is determined as follows:

[0054]

[0055] (8) Determine the calculated total pressure P 0_i and specific heat ratio γ i Whether it converges, if it converges, the calculation is terminated and the mass flow rate m is obtained. i This is the flow rate required for the arc heating test; otherwise, the total pressure P 0_i and specific heat ratio γ i Substituting the given initial total pressure P0 and initial specific heat ratio γ0, the calculation is restarted from step (3) until the iteratively calculated total pressure P 0_i and specific heat ratio γ i convergence.

[0056] The parameters of step 1 above are manually input by a person, and all other steps are automatically iterated by the background program, which can realize the rapid calculation of arc heating pneumatic thermal test parameters within a few seconds.

[0057] The above description is only the best specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

[0058] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. Accurate calculation method of arc heating aerodynamic heat test parameters, characterized by The following steps are involved: (1) Input the aerodynamic thermal parameters to be simulated in the arc heating test: total enthalpy H0, heat flux q, select the nozzle, and determine the nozzle throat-exit area ratio A / A*; (2) Assume an initial total pressure value P0 and an initial specific heat ratio γ0; The value of the initial specific heat ratio γ0 satisfies: H0≤9000kJ / kg: γ0=1.41-5.36e-5×H0-1.05e-8×H0 2 +3.13e-12×H0 3 -1.71e-16×H0 4 H0>9000kJ / kg: γ0=2.52-3.03e-4×H0+2.62e-8×H0 2 -1.12e-12×H0 3 +2.38e-17×H0 4 -1.99e-22×H0 5 ; (3) According to the total pressure value P0, combined with the total enthalpy H0, and based on the thermochemical equilibrium calculation, the total temperature T0 is obtained; according to the specific heat ratio γ0, combined with the above-selected nozzle throat-exit area ratio A / A*, the Mach number Ma at the nozzle outlet can be calculated; (4) Based on the Mach number Ma obtained above, given the specific heat ratio γ0, the static temperature to total temperature ratio T of the nozzle is obtained i / T0, static pressure to total pressure ratio P i / P0, combined with the above-mentioned total temperature T0 and initial total pressure P0, the static temperature T of the nozzle outlet is obtained i and static pressure P i ; (5) Under the assumption of balanced flow or freezing flow, the specific heat ratio γ, Prandtl number Pr, and viscosity coefficient μ of the nozzle outlet airflow are all functions of the local static temperature and static pressure γ(P, T), Pr(T, P), and μ(T, P). i and static pressure P i , we can get the specific heat ratio γ i , Prandtl number Pr i , viscosity coefficient μ i The value of (6) According to the specific heat ratio γ obtained above i , Prandtl number Pr i , viscosity coefficient μ i The velocity V at the nozzle outlet is calculated i , static enthalpy H 静焓i , recovery enthalpy H 恢复焓i and reference enthalpy H 参考焓i ; (7) Based on all the parameters obtained above, the total enthalpy H0 and the mass flow rate m required for the arc heating test simulation are preliminarily calculated. i , and obtain the total pressure P of the arc heater test 0_i ; (8) Determine the calculated total pressure P 0_i and specific heat ratio γ i Is it converged? If it is converged, the calculation is terminated. The mass flow rate m at this time is i That is the flow value m:m required for the arc heating test i =m; Otherwise, the total pressure P 0_i and specific heat ratio γ i Instead of the initial total pressure P0 and the initial specific heat ratio γ0 given in step (2), the calculation is restarted from step (3) until the total pressure P after iterative calculation is 0_i and specific heat ratio γ i convergence.

2. The method for accurately calculating arc heating aerodynamic heat test parameters according to claim 1 is characterized in that: The value range of the initial total pressure P0 is 0.001MPa-20MPa; the value range of the initial specific heat ratio γ0 is 1.1-1.

4.

3. The method for accurately calculating arc heating aerodynamic heat test parameters according to claim 1 is characterized in that: It is applicable to the parameter calculation of three main types of tests: stationary point, flat plate and wing leading edge tests for aircraft thermal protection ground assessment tests.

4. The method for accurately calculating arc heating aerodynamic heat test parameters according to claim 1 is characterized in that: Steps (1)-(8) are processed into modular units based on excel, matlab or C software development. The input of the modular unit is the three parameters in step (1). After the input is completed, the calculation of the aerodynamic thermal test parameters can be automatically completed within a few seconds.

5. The method for accurately calculating arc heating aerodynamic heat test parameters according to claim 1 is characterized in that: It is suitable for calculating the operating parameters of arc heaters in ground tests of arc heating of existing aircraft thermal protection materials, and converting the aerodynamic thermal parameters of aircraft reentry into the operating parameters of arc heating equipment.

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