Method and device for obtaining transition characteristics of high-enthalpy ablation wall boundary layer

Abstract

The present application relates to a method and device for obtaining high-enthalpy ablation wall boundary layer transition characteristics, applied in the field of aerospace technology, the method comprising: obtaining flow parameters and boundary condition parameters; determining the equivalent roughness height based on the actual roughness height of each position of the wall, and determining the dimensionless roughness height of each position; constructing the first correction factor and the second correction factor of each position according to the dimensionless roughness height and the equivalent roughness height; calculating the first time scale and the second time scale in the symbol-Wang transition mode, updating the first time scale to the product of the first time scale and the first correction factor, and updating the second time scale to the product of the second time scale and the second correction factor; based on the flow parameters and the boundary condition parameters, simulating the high-enthalpy ablation wall boundary layer flow transition of the high-speed aircraft by using the modified symbol-Wang transition mode, and obtaining the transition starting position and the position of the turbulent flow region distribution. The transition starting position and the development trend can be accurately predicted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aerospace technology, and in particular to a method and device for obtaining boundary layer transition characteristics of a high-enthalpy ablation wall. BACKGROUND

[0002] Under hypersonic flight conditions, the surface of a vehicle produces ablation due to severe aerodynamic heating effects, and then forms irregularly distributed rough structures. This distributed roughness significantly affects the stability of the boundary layer, leading to early transition, a sharp rise in heat flux and friction coefficient, and directly threatening the stability and structural integrity of the thermal protection system. Compared with the boundary layer in the laminar state, the thermal conductivity and shear stress in the turbulent state are significantly enhanced.

[0003] In related technologies, a transition model based on the RANS (Reynolds Average Navier-Stokes) framework is used for flow prediction, with the SST-γ-Reθ model as a representative. Since it is based on subsonic flow assumptions, it has the defects of too many empirical coefficients, poor prediction ability for hypersonic flow, and lack of adaptability to high-enthalpy flow, making it difficult to accurately depict roughness-induced transition behavior on high-temperature ablation walls. SUMMARY

[0004] To solve the above technical problems, the present application provides a method and device for obtaining boundary layer transition characteristics of a high-enthalpy ablation wall.

[0005] According to a first aspect of the present application, a method for obtaining boundary layer transition characteristics of a high-enthalpy ablation wall is provided, comprising:

[0006] Obtaining the incoming flow parameters of a high-speed vehicle and the boundary condition parameters of the high-speed vehicle;

[0007] Determining the equivalent roughness height based on the actual roughness height of each position of the high-speed vehicle wall, and determining the dimensionless roughness height of each position based on the wall feature information of each position and the equivalent roughness height;

[0008] Constructing a first correction factor and a second correction factor for each position according to the dimensionless roughness height of each position and the equivalent roughness height; wherein the first correction factor and the second correction factor are both greater than 1;

[0009] Calculating a first time scale corresponding to a first mode and a second time scale corresponding to a second mode in the Zhang-Wang transition model, updating the first time scale to the product of the first time scale and the first correction factor, and updating the second time scale to the product of the second time scale and the second correction factor;

[0010] Based on the inflow parameters and boundary condition parameters, high-enthalpy ablation wall boundary layer flow transition of the high-speed aircraft is simulated by using the corrected symbol-Wang transition mode to obtain a transition starting position and a position of a turbulent flow region distribution.

[0011] Optionally, the first correction factor and the second correction factor of each position are configured according to the dimensionless roughness height of each position and the equivalent roughness height, including:

[0012] The first time scale amplification factor corresponding to the first mode and the second time scale amplification factor corresponding to the second mode are configured according to the equivalent roughness height;

[0013] The first correction factor of each position is configured according to the first time scale amplification factor and the dimensionless roughness height of each position;

[0014] The second correction factor of each position is configured according to the second time scale amplification factor and the dimensionless roughness height of each position.

[0015] Optionally, the first time scale amplification factor corresponding to the first mode and the second time scale amplification factor corresponding to the second mode are configured according to the equivalent roughness height, including:

[0016] The first time scale amplification factor corresponding to the first mode is configured according to the formula: ;

[0017] The second time scale amplification factor corresponding to the second mode is configured according to the formula: ;

[0018] Wherein, , , and is a calibrated constant, k r is an equivalent sand height.

[0019] Optionally, the first correction factor of each position is configured according to the first time scale amplification factor and the dimensionless roughness height of each position, including:

[0020] The first correction factor of each position is determined according to the formula: ;

[0021] The second correction factor of each position is configured according to the second time scale amplification factor and the dimensionless roughness height of each position, including:

[0022] The second correction factor of each position is determined according to the formula: ​​​determining the second correction factor of each position ;

[0023] wherein, represents the dimensionless roughness height of each position, represents a calibrated constant.

[0024] Optionally, the method for obtaining the high-enthalpy ablative wall boundary layer transition characteristics further comprises:

[0025] simulating the high-enthalpy ablative wall boundary layer transition of the high-speed vehicle by using a chemical reaction kinetics model containing multi-component real gas, and determining the volume fraction of each component.

[0026] Optionally, the method for obtaining the high-enthalpy ablative wall boundary layer transition characteristics further comprises:

[0027] correcting the wall boundary condition in the boundary condition parameters by using a Knopp roughness correction mode to obtain corrected boundary condition parameters;

[0028] simulating the high-enthalpy ablative wall boundary layer transition of the high-speed vehicle by using the modified Zhu-Wang transition mode based on the flow parameters and the boundary condition parameters, and obtaining the transition starting position and the position of the turbulent flow region, specifically comprising:

[0029] simulating the high-enthalpy ablative wall boundary layer transition of the high-speed vehicle by using the modified Zhu-Wang transition mode based on the flow parameters and the corrected boundary condition parameters, and obtaining the transition starting position and the position of the turbulent flow region.

[0030] Optionally, based on the wall feature information of each position and the equivalent roughness height, the dimensionless roughness height of each position is determined, comprising:

[0031] According to the formula: , the dimensionless roughness height of each position is determined ;

[0032] wherein, represents the equivalent roughness height, represents the friction velocity, represents the shear stress on the wall.

[0033] According to the second aspect of the present application, a device for obtaining high-enthalpy ablative wall boundary layer transition characteristics is provided, comprising:

[0034] an input data acquisition module for acquiring the flow parameters of a high-speed vehicle and the boundary condition parameters of the high-speed vehicle;

[0035] a roughness height determination module, configured to determine an equivalent roughness height based on actual roughness heights of the high-speed aircraft wall surface at different positions, and determine a dimensionless roughness height at each position based on wall surface feature information at the position and the equivalent roughness height;

[0036] a correction factor construction module, configured to construct a first correction factor and a second correction factor at each position according to the dimensionless roughness height at the position and the equivalent roughness height; wherein the first correction factor and the second correction factor are both greater than 1;

[0037] a Gort-Wang transition mode correction module, configured to calculate a first time scale corresponding to a first mode and a second time scale corresponding to a second mode in the Gort-Wang transition mode, update the first time scale to a product of the first time scale and the first correction factor, and update the second time scale to a product of the second time scale and the second correction factor;

[0038] a transition characteristic acquisition module, configured to simulate high-enthalpy ablation wall boundary layer flow transition of the high-speed aircraft based on the corrected Gort-Wang transition mode, according to the flow parameters and the boundary condition parameters, and acquire a transition starting position and a position of a turbulent flow region distribution.

[0039] Optionally, the correction factor construction module is specifically configured to construct a first time scale amplification factor corresponding to the first mode and a second time scale amplification factor corresponding to the second mode according to the equivalent roughness height, construct the first correction factor at each position according to the first time scale amplification factor and the dimensionless roughness height at the position, and construct the second correction factor at each position according to the second time scale amplification factor and the dimensionless roughness height at the position.

[0040] Optionally, the correction factor construction module is specifically configured to construct the first time scale amplification factor corresponding to the first mode and the second time scale amplification factor corresponding to the second mode according to the equivalent roughness height by the following steps:

[0041] according to the formula: ; the first time scale amplification factor corresponding to the first mode is constructed ;

[0042] according to the formula: ; the second time scale amplification factor corresponding to the second mode is constructed ;

[0043] wherein, , , and denote calibrated constants, k r is an equivalent sand height.

[0044] Optionally, the correction factor construction module is specifically configured to construct a first time scale amplification factor corresponding to a first modal according to the equivalent roughness height and a second time scale amplification factor corresponding to a second modal according to a formula: to determine the first correction factor of each position according to a formula: to determine the second correction factor of each position ;

[0045] wherein, represents the dimensionless roughness height of each position, represents a calibrated constant.

[0046] Optionally, the high-enthalpy ablation wall boundary layer transition characteristic acquisition device further comprises:

[0047] The component volume fraction determination module is configured to simulate the high-enthalpy ablation wall boundary layer flow transition of the high-speed vehicle by using a chemical reaction kinetics model containing a multi-component real gas, and determine the volume fraction of each component.

[0048] Optionally, the high-enthalpy ablation wall boundary layer transition characteristic acquisition device further comprises:

[0049] The boundary condition correction module is configured to correct the wall boundary condition in the boundary condition parameter by using a Knopp roughness correction mode to obtain a corrected boundary condition parameter.

[0050] The transition characteristic acquisition module is specifically configured to simulate the high-enthalpy ablation wall boundary layer flow transition of the high-speed vehicle by using the corrected Shi-Wang transition mode based on the flow parameter and the corrected boundary condition parameter, and acquire the transition starting position and the position of the turbulent flow region distribution.

[0051] Optionally, the roughness height determination module is specifically configured to determine the equivalent roughness height based on the actual roughness height of each position of the wall surface of the high-speed vehicle, and determine the dimensionless roughness height of each position according to a formula: ;

[0052] wherein, represents the equivalent roughness height, represents the friction velocity, represents the shear stress on the wall surface.

[0053] ​According to a third aspect of the present application, an electronic device is provided, comprising: a processor configured to execute a computer program stored in a memory, the computer program, when executed by the processor, implements the method for obtaining high-enthalpy ablation wall boundary layer transition characteristics according to the first aspect.

[0054] According to a fourth aspect of the present application, a computer readable storage medium is provided, having stored thereon a computer program, the computer program, when executed by a processor, implements the method for obtaining high-enthalpy ablation wall boundary layer transition characteristics according to the first aspect.

[0055] According to a fifth aspect of the present application, a computer program product is provided, which, when running on a computer, causes the computer to execute the method for obtaining high-enthalpy ablation wall boundary layer transition characteristics according to the first aspect.

[0056] The technical solution provided by the embodiments of the present application has the following advantages compared with the prior art:

[0057] On the basis of the S-W transition model, a roughness-modulated disturbance time scale amplification mechanism is introduced, that is, a first correction factor and a second correction factor related to the equivalent roughness height and the dimensionless roughness height are constructed, and the first correction factor and the second correction factor are used to amplify the time scale in the S-W transition model. In this way, the influence of the rough wall on the first mode (TS wave) and the second mode (Mack wave) can be accurately described, thereby improving the prediction accuracy of the model on the boundary layer transition position and development trend. Through verification of multiple typical working conditions (such as a flat plate, a blunt cone, and a return capsule), the accuracy of the present application in simulating roughness-induced transition is superior to that of the existing mainstream models, can provide more reliable data support for aircraft thermal protection design, and can be popularized to the engineering fields of hypersonic aerodynamic layout optimization and boundary layer control, and has high engineering practical value. BRIEF DESCRIPTION OF DRAWINGS

[0058] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate an embodiment consistent with the present application and, together with the description, serve to explain the principles of the application.

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, brief introductions will be given below to the drawings needed to be used in the embodiments or prior art descriptions, and obviously, other drawings can also be obtained by those skilled in the art without any creative labor on the basis of these drawings.

[0060] Figure 1 A flow chart of the method for obtaining high-enthalpy ablation wall boundary layer transition characteristics in the embodiments of the present application;

[0061] Figure 2Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0062] Figure 3 Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 2 Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0063] Figure 4 Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0064] Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 5A Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0065] Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 5B Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0066] Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 6 Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 5A Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 5B Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0067] Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 7 Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0068] Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 8A Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0069] Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 8B Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0070] Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 8C Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0071] Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 8D Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0072] Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 8E Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0073] Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 9 Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application;

[0074] Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; Figure 10 Grid sketch of incompressible flow rough flat boundary layer flow example in embodiments of the present application; DETAILED DESCRIPTION

[0075] In order to enable a more clear understanding of the above-mentioned objects, features and advantages of the present application, the following will further describe the schemes of the present application. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0076] In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the present application, but the present application can also be implemented in other manners different from those described herein; obviously, the embodiments described in the specification are only a part of the embodiments of the present application, and not all the embodiments.

[0077] Reference is made to Figure 1 , Figure 1 A flow chart of the method for obtaining the boundary layer transition characteristics of the high-enthalpy ablation wall surface in the embodiments of the present application can include the following steps.

[0078] In step S102, the free-stream parameters of the high-speed vehicle and the boundary condition parameters of the high-speed vehicle are obtained.

[0079] The free-stream parameters of the high-speed vehicle describe the free-stream state without disturbance, mainly including Mach number, free-stream velocity, free-stream static pressure, free-stream static temperature, free-stream density, Reynolds number, etc. The boundary condition parameters of the high-speed vehicle are used to define the physical constraints of the calculation domain or experimental model, and the boundary condition parameters include wall boundary conditions, inflow boundaries and outflow boundaries, etc.

[0080] In step S104, the equivalent roughness height is determined based on the actual roughness height of each position of the high-speed vehicle wall surface, and the dimensionless roughness height of each position is determined based on the wall surface feature information and the equivalent roughness height of each position.

[0081] Considering the influence of the wall roughness, the embodiments of the present application model based on the equivalent sand height. Specifically, for the influence of the flow resistance, friction loss, etc. caused by the distributed roughness unit with irregular height, shape and distribution, if it is the same as the influence of the rough sand wall surface with a certain uniform height as a whole, the sand height is taken as the equivalent roughness height of the original rough wall surface. That is, the statistical physical quantity equivalent roughness height is used to represent the roughness degree of the distributed roughness unit of the entire surface. For example, the average value of the actual roughness height of each position of the high-speed vehicle wall surface can be taken as the equivalent roughness height.

[0082] Since the flow scales in the boundary layer are not completely the same, the inner scale can be used to measure, , which represents the friction velocity, represents the shear stress on the wall surface. Even if the equivalent roughness height is equal for the whole flow field, the flow will be affected differently at different locations of the flow field, and therefore, to reflect the influence of different locations, the dimensionless roughness height may be used to measure. Alternatively, the dimensionless roughness height of each location can be determined according to the formula: ; wherein, represents the equivalent roughness height, i.e. the scale of the inner layer of the boundary layer measures the influence of the sand height.

[0083] Step S106, constructing the first correction factor and the second correction factor of each location according to the dimensionless roughness height and the equivalent roughness height of each location.

[0084] Experimental studies and numerical simulations of isolated roughness show that isolated roughness elements can increase the amplitude and frequency of the incoming flow disturbance wave. This feature can be reflected by changing the time scale of the non-turbulent fluctuations in the Gomberg-Wang transition model. In view of the influence of roughness and disturbance frequency, a relationship between and can be constructed:

[0085] ;

[0086] ;

[0087] wherein, represents the first correction factor, represents the first time scale corresponding to the first mode in the Gomberg-Wang transition model, represents the first time scale corresponding to the first mode in the modified Gomberg-Wang transition model, represents the second correction factor, represents the second time scale corresponding to the second mode in the Gomberg-Wang transition model, represents the second time scale corresponding to the second mode in the modified Gomberg-Wang transition model.

[0088] It can be seen that the first correction factor and the second correction factor are both related to , i.e. the correction factors of different locations are different. And the first correction factor and the second correction factor are both greater than 1, respectively used to amplify the first time scale and the second time scale.

[0089] Optionally, the first time scale amplification factor corresponding to the first mode and the second time scale amplification factor corresponding to the second mode can be constructed according to the equivalent roughness height. The first time scale amplification factor and the second time scale amplification factor respectively represent the coefficients used when amplifying the first time scale and the second time scale, and the same mode uses the same coefficient.

[0090] Then, the first correction factor of each position is constructed according to the first time scale amplification factor and the dimensionless roughness height of each position. The second correction factor of each position is constructed according to the second time scale amplification factor and the dimensionless roughness height of each position. Since the dimensionless roughness height of each position is different, the correction factor of the same mode at different positions is also different. By constructing the correction factor in this way, not only the differences between different modes can be reflected, but also the differences between different positions can be reflected, and the accuracy is higher.

[0091] The logarithm of the transition position flow direction coordinate and the Reynolds number of the flow have an approximately linear relationship, so the correction factor can be constructed with reference to the relationship.

[0092] Optionally, the first time scale amplification factor corresponding to the first mode can be constructed according to the formula: The second time scale amplification factor corresponding to the second mode can be constructed according to the formula: ; wherein, , , and are calibrated constants, which are obtained by numerical fitting according to experimental values, k r is the equivalent roughness height. For example, = 0.0085, = 0.137, = 0.215, = 0.064.

[0093] The first correction factor of each position is determined according to the formula: The second correction factor of each position is determined according to the formula: ; wherein, is the dimensionless roughness height of each position, is a calibrated constant, for example, = 2.3.

[0094] ​​​​Step S108, calculating the first time scale corresponding to the first mode and the second time scale corresponding to the second mode in the Smith-Paterson transition model, updating the first time scale as the product of the first time scale and the first correction factor, and updating the second time scale as the product of the second time scale and the second correction factor.

[0095] The Smith-Paterson transition model contains transport equations of three turbulent variables, turbulent kinetic energy k, unit dissipation rate of k and intermittency factor , wherein k and ω The difference between the transport equation and the SST turbulent model is that the effective viscosity coefficient is used instead of the eddy viscosity in the SST turbulent model, and the transport equation of the increased is expressed as:

[0096]

[0097] wherein, is the body derivative of the corresponding turbulent variable, denotes the fluid micro-cluster density, including , and , respectively representing the differential scales of three directions of the three-dimensional coordinate system, denotes the generation term of , and the expression is:

[0098] ;

[0099] wherein, d is the object distance, is the kinematic viscosity, E u is the average kinetic energy of the fluid at the current position relative to the wall surface, f(Tu) is a function of the incoming turbulent degree Tu , and the expression is:

[0100]

[0101] F onset is a function for controlling the start of transition, and is defined as:

[0102]

[0103] is the effective length scale, and its dimensionless form is:

[0104] ;

[0105] ;

[0106] where, are the first, second and third length scales, respectively, is the modulus of the current position vorticity, S is the modulus of the strain rate tensor.

[0107] effective viscosity coefficient The modulus of the effective viscosity coefficient is based on Warren's study, which takes into account the influence of non-turbulent fluctuations, and its expression is:

[0108] ;

[0109] where, is the non-turbulent fluctuation viscosity coefficient:

[0110]

[0111] where, is the time scale of the disturbance mode, The modulus of the effective viscosity coefficient considers different modes, including the first mode, the second mode and the cross-flow mode, and distinguishes the action area of the modes by the current position relative Mach number :

[0112]

[0113] where U represents the current position main flow velocity, represents the disturbance phase velocity, and a is the current position sound speed.

[0114] In the boundary layer region of the two-dimensional boundary layer where the current position relative Mach number is greater than 1, the most unstable mode in the high-order mode is the second mode, so the mode ignores the high-order mode except the second mode, and the time scale modulus form is:

[0115]

[0116] where, is the time scale of the first mode, is the time scale of the second mode, which is constructed by the effective length scale :

[0117] ;

[0118] ;

[0119] U(y s ) represents the velocity at the generalized inflection point in the boundary layer, and the generalized inflection point has:

[0120]

[0121] C1~ C10 are mode constants, and the corresponding numerical values are shown in Table 1:

[0122] Table 1

[0123]

[0124] After the time scale of the first mode and the time scale of the second mode are calculated according to the above formula, the result of multiplying the first time scale by the first correction factor is taken as the final first time scale, and the result of multiplying the second time scale by the second correction factor is taken as the final second time scale.

[0125] For a three-dimensional boundary layer, there is often a cross-flow unstable wave in the spanwise direction. The cross-flow mode time scale can be solved according to the following formula: ;

[0126] wherein, W is the cross-flow velocity, e represents the outer edge of the boundary layer, is the velocity of the outer edge of the boundary layer, is the kinematic viscosity of the outer edge of the boundary layer, , , .

[0127] The total time scale T is calculated according to the formula: .

[0128] In step S110, the high-enthalpy ablation wall boundary layer flow transition of the high-speed aircraft is simulated based on the inflow parameters and the boundary condition parameters by using the modified S-W transition mode, so as to obtain the transition starting position and the position of the turbulent flow region distribution.

[0129] After the S-W transition mode is modified, the high-enthalpy ablation wall boundary layer flow transition of the high-speed aircraft can be simulated by using the modified S-W transition mode, so as to obtain the transition starting position and the position of the turbulent flow region distribution.

[0130] Optionally, the wall boundary condition in the boundary condition parameters can be modified by using the Knopp roughness correction mode first, so as to obtain the modified boundary condition parameters. Specifically, the wall boundary condition of the original SST turbulence mode is:

[0131]

[0132] wherein, represents the value of the turbulent kinetic energy on the wall, represents the value of the specific dissipation rate on the wall, = 0.075, represents the height of the first layer of grids.

[0133] ​​After the wall boundary condition in the boundary condition parameter is corrected by using the Knopp roughness correction model, the following is obtained:

[0134]

[0135] The transition function is:

[0136]

[0137] =0.41, .

[0138] As can be seen from the expression, the model reverts to the smooth wall boundary condition of the SST model when the equivalent roughness height is 0. When the dimensionless roughness height is greater than 90, the transition function takes the maximum value 1, at this time, it corresponds to the fully rough condition; when the dimensionless roughness height takes a value between 0 and 90, the transition function takes an intermediate value between the hydraulically smooth and fully rough conditions.

[0139] Then, based on the inflow parameters and the corrected boundary condition parameters, the high-enthalpy ablation wall boundary layer flow transition of a high-speed aircraft is simulated by using the corrected transition model, so as to obtain the transition starting position and the position of the turbulent flow region distribution. In this way, the influence of the roughness caused boundary layer lifting and transition advance on the starting position and development process (i.e. the range of γ from 0 to 1 and the region where γ is equal to 1) of the boundary layer transition of the ablation rough wall of the aircraft under high-enthalpy and hypersonic speed conditions can be more accurately measured.

[0140] The embodiment of the present application has good performance in incompressible flow, hypersonic flow (full Mach number section) and high-enthalpy flow.

[0141] Referring to Figure 2 , Figure 2 is a schematic diagram of a grid for incompressible flow rough plate boundary layer flow. In Figure 2 , the wall friction coefficients of different roughness heights can be seen from Figure 3 . Figure 4 is a comparison diagram of transition prediction position and experimental value, including the calculation results corresponding to Langel, Dassler and TRANS solver (i.e. the embodiment of the present application) respectively. As can be seen, the calculation result of the embodiment of the present application is most consistent with the experimental value.

[0142] Figure 5A and Figure 5B are rough cone models, which are uniform conical sand, and the absolute heights of the two roughnesses are 14 mil and 25 mil respectively. The comparison results of the transition prediction positions and experimental values of the two roughnesses can be seen from Figure 6It can be seen that the embodiments of the present invention can effectively simulate the effect of different roughness on the advance of transition.

[0143] In real-world scenarios, roughness typically occurs in high-temperature environments, where chemical reactions are common. Therefore, the real gas effect can be considered, and a chemical reaction kinetic model incorporating multi-component real gases can be used to simulate the boundary layer flow transition at the high-enthalpy ablation wall of a high-speed aircraft, determining the volume fraction of each component.

[0144] A chemical reaction kinetic model can be a five-component chemical reaction kinetic model:

[0145]

[0146] Where M is the catalyst, which can be any one of the five components; R1, R2, and R3 are decomposition reactions; and R4 and R5 are exchange reactions. The equations involving ns components and nR chemical reactions can be expressed as the following general formula:

[0147] ;

[0148] in, Components The molar concentration is expressed as:

[0149] ;

[0150] and They are the first In the first reaction The stoichiometric coefficients of the components on both sides of the chemical formula. For the first The density of the components, For the first The molar mass of each component.

[0151] The forward chemical reaction rate is given by the Arrhenius equation:

[0152] ;

[0153] in, Let T represent the forward chemical reaction rate of the j-th chemical reaction equation, and let C represent the temperature. r , and There are three fitting parameters.

[0154] Indicates the rate of the reverse reaction:

[0155] ;

[0156] Chemical reaction equilibrium constant is expressed as:

[0157] ;

[0158] wherein A1, A2, A3, A4 and A5 are a set of fitting parameters of equilibrium constant corresponding to the reaction process, and the five reactions correspond to multiple sets of fitting parameters of equilibrium constant.

[0159] wherein Z = 10000 / T, the molar concentration of component In the first reaction, the molar concentration change rate is :

[0160] ;

[0161] The mass generation rate of component (nR reactions) is: ;

[0162] The pressure of the mixed gas is : ;

[0163] The gas constant of each component of the mixed gas is : ;

[0164] wherein the universal gas constant R0 is 8.314 J / molK, and M i is the molar mass of component i . The constant volume specific heat and enthalpy of each component are calculated by Palmer's fitting polynomial with 8 empirical parameters a1 to a8, and the internal energy of the mixed gas is calculated by the mass fraction weighted constant volume specific heat of each component.

[0165] ;

[0166] ;

[0167] wherein is the zero-point energy of component, and the total constant volume specific heat and the total enthalpy of the mixed gas are calculated as shown below:

[0168] ;

[0169] ;

[0170] wherein represents the mass fraction of component i , represents the mass fraction of componenti Specific heat at constant pressure of the mixture, Absolute enthalpy per unit mass of the mixture i Absolute enthalpy per unit mass of the mixture Mass generation rate of the mixture.

[0171] The total energy expression of the mixture gas is:

[0172]

[0173] Wherein, The gas pressure is represented by P, The total density of the mixture gas is represented by ρ, The density of component i is represented by ρi, E represents the total energy of the mixture gas, and U, V, W represent the velocities in three directions.

[0174] The conservation form of the NS equation group of the multi-component is:

[0175]

[0176] Wherein, q is a conservation variable, f, g, h are respectively the viscous fluxes in x, y, z directions, , , The viscous fluxes in x, y, z directions are respectively, The Reynolds number of the incoming flow at infinity is represented by Re, and S represents the generation rate of the component, that is, the reaction rate.

[0177] The molar concentration, mass fraction and internal energy of different gas components change, and these changes not only affect the mass conservation equation of each component, but also affect the total enthalpy and total energy through the changes of the reaction enthalpy and specific heat capacity of the component, thereby being directly coupled into the energy conservation equation.

[0178] Taking the air dissociation chemical reaction in the blunt head region of high-enthalpy flow as an example for simulation, the temperature field near the head stagnation point of two kinds of gas models is compared as shown in Figure 7 It can be seen that the shock position calculated by using the real gas model is closer to the wall surface than the calorically perfect gas, and the gas temperature after the shock is also smaller than the calorically perfect gas, which is consistent with the theory. Figure 8A~Figure 8E The volume fraction of each component in the blunt head region of high-enthalpy flow can be used to verify the accuracy of the calculation result.

[0179] The method for obtaining the transition characteristics of the high-enthalpy ablation wall boundary layer of the embodiment of the application couples the modified Sun-Wang transition mode with the real gas multi-component chemical reaction model, is suitable for high-temperature aerodynamic heat environment with a Mach number of 6 or more, can reflect the thermal-mechanical coupling behavior of the shock-wave-boundary-layer interference region, and significantly enhances the physical consistency.

[0180] ​​It should be noted that although the various steps of the methods of the present disclosure are described in a particular order in the drawings, this is not required or implied as the steps must be performed in that particular order, or that all of the steps shown must be performed to achieve the desired result. Additionally or alternatively, certain steps can be omitted, multiple steps can be combined into a single step, a single step can be broken into multiple steps, etc.

[0181] The embodiment of the present application also provides an acquisition device for boundary layer transition characteristics of high-enthalpy ablation wall surface, which is shown in Figure 9 The acquisition device 900 for boundary layer transition characteristics of high-enthalpy ablation wall surface comprises:

[0182] An input data acquisition module 902 is configured to acquire the inflow parameters of the high-speed vehicle and the boundary condition parameters of the high-speed vehicle.

[0183] A roughness height determination module 904 is configured to determine the equivalent roughness height based on the actual roughness height of each position of the wall surface of the high-speed vehicle, and determine the dimensionless roughness height of each position based on the wall surface feature information of each position and the equivalent roughness height.

[0184] A correction factor construction module 906 is configured to construct the first correction factor and the second correction factor of each position according to the dimensionless roughness height and the equivalent roughness height of each position; wherein the first correction factor and the second correction factor are both greater than 1.

[0185] A Zhong-Wang transition mode correction module 908 is configured to calculate the first time scale corresponding to the first mode and the second time scale corresponding to the second mode in the Zhong-Wang transition mode, update the first time scale to the product of the first time scale and the first correction factor, and update the second time scale to the product of the second time scale and the second correction factor.

[0186] A transition characteristic acquisition module 910 is configured to simulate the high-enthalpy ablation wall surface boundary layer flow transition of the high-speed vehicle by using the corrected Zhong-Wang transition mode based on the inflow parameters and the boundary condition parameters, and acquire the transition starting position and the position of the turbulent flow region distribution.

[0187] Optionally, the correction factor construction module 906 is specifically configured to construct the first time scale amplification factor corresponding to the first mode and the second time scale amplification factor corresponding to the second mode according to the equivalent roughness height, construct the first correction factor of each position according to the first time scale amplification factor and the dimensionless roughness height of each position, and construct the second correction factor of each position according to the second time scale amplification factor and the dimensionless roughness height of each position.

[0188] Optionally, the correction factor construction module 906 is specifically configured to construct the first time scale amplification factor corresponding to the first mode and the second time scale amplification factor corresponding to the second mode according to the equivalent roughness height by the following steps:

[0189] According to the formula: ; the first time scale amplification factor corresponding to the first mode is constructed ;

[0190] According to the formula: ; the second time scale amplification factor corresponding to the second mode is constructed ;

[0191] wherein, , , and denotes a calibrated constant, k r is the equivalent sand height.

[0192] Optionally, the correction factor construction module 906 is specifically configured to construct the first time scale amplification factor corresponding to the first mode and the second time scale amplification factor corresponding to the second mode according to the equivalent roughness height . According to the formula: ; the first correction factor of each position is determined According to the formula: ; the second correction factor of each position is determined ;

[0193] wherein, denotes the dimensionless roughness height of each position, denotes a calibrated constant.

[0194] Optionally, the high-enthalpy ablation wall boundary layer transition characteristic acquisition device 900 further comprises:

[0195] The component volume fraction determination module is configured to simulate the high-enthalpy ablation wall boundary layer flow transition of the high-speed aircraft by using a chemical reaction kinetics model containing a multi-component real gas, and determine the volume fraction of each component.

[0196] Optionally, the high-enthalpy ablation wall boundary layer transition characteristic acquisition device 900 further comprises:

[0197] The boundary condition correction module is configured to correct the wall boundary condition in the boundary condition parameter by using the Knopp roughness correction mode to obtain the corrected boundary condition parameter.

[0198] The transition characteristic acquisition module 910 is specifically configured to simulate high-enthalpy ablation wall boundary layer flow transition of the high-speed aircraft based on the incoming flow parameters and the corrected boundary condition parameters, and to acquire a transition starting position and a position of a turbulent flow region distribution by using the corrected symbol-king transition mode.

[0199] Optionally, the roughness height determination module 904 is specifically configured to determine an equivalent roughness height based on an actual roughness height of each position of the wall surface of the high-speed aircraft, and to determine a dimensionless roughness height of each position according to a formula:

[0200] wherein, k represents the equivalent roughness height, represents a friction velocity, represents a shear stress on the wall surface.

[0201] The specific details of each module or unit in the above device have been described in detail in the corresponding method, and thus will not be described here again.

[0202] It should be noted that although several modules or units of the device for action execution are mentioned in the above detailed description, such a division is not mandatory. In fact, according to the embodiments of the present application, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided into a plurality of modules or units.

[0203] The present application also provides an electronic device, comprising: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to execute the above-mentioned high-enthalpy ablation wall boundary layer transition characteristic acquisition method in the present example embodiment.

[0204] Referring to Figure 10 , Figure 10 is a structural schematic diagram of the electronic device in the present application embodiment, and the present application embodiment does not limit the specific implementation of the electronic device.

[0205] As Figure 10 shown, the electronic device can include: a processor 1002, a communication interface 1004, a memory 1006, and a communication bus 1008.

[0206] The processor 1002, the communication interface 1004, and the memory 1006 complete mutual communication through the communication bus 1008.

[0207] The communication interface 1004 is configured to communicate with other electronic devices or servers.

[0208] ​​​The processor 1002 is configured to execute the program 1010, and particularly configured to execute the steps in the above method embodiments.

[0209] Specifically, the program 1010 can include program codes containing computer operation instructions.

[0210] The processor 1002 can be a central processing unit, or a specific integrated circuit, or one or more integrated circuits configured to implement the embodiments of the present application.

[0211] The one or more processors included in the electronic device can be processors of the same type, such as one or more CPUs; or processors of different types, such as one or more CPUs and one or more ASICs.

[0212] The memory 1006 is configured to store the program 1010. The memory 1006 can include a high-speed RAM memory, and can also include a non-volatile memory, such as at least one disk memory.

[0213] The program 1010 can be specifically configured to cause the processor 1002 to execute the steps in the above method embodiments of obtaining the high-enthalpy ablation wall boundary layer transition characteristics.

[0214] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and modules can refer to the corresponding process descriptions in the foregoing method embodiments, which will not be described herein.

[0215] In the embodiments of the present application, a computer readable storage medium is also provided, which stores a computer program. The computer program is executed by a processor to implement the above method of obtaining high-enthalpy ablation wall boundary layer transition characteristics.

[0216] It should be noted that the computer-readable storage medium shown in the present application may, for example, be, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or apparatus, or any combination of the above. More specific examples of computer-readable storage media can include, but are not limited to, an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, device or apparatus. The program code contained on the computer-readable storage medium can be transmitted in any suitable medium, including but not limited to wireless, wire, optical cable, radio frequency, etc., or any suitable combination of the above.

[0217] In the embodiments of the present application, a computer program product is also provided, which, when running on a computer, enables the computer to execute the above-mentioned method for obtaining high-enthalpy ablation wall boundary layer transition characteristics.

[0218] It should be noted that in this paper, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the element.

[0219] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for obtaining the characteristics of the boundary layer transition of a high-enthalpy ablation wall, characterized in that, The method comprises: obtaining the flow parameters of a high-speed vehicle and boundary condition parameters of the high-speed vehicle; determining an equivalent roughness height based on the actual roughness height of each position of the wall surface of the high-speed vehicle, and determining a dimensionless roughness height of each position based on the wall surface feature information of each position and the equivalent roughness height; constructing a first correction factor and a second correction factor of each position according to the dimensionless roughness height of each position and the equivalent roughness height; wherein the first correction factor and the second correction factor are both greater than 1; calculating a first time scale corresponding to a first mode and a second time scale corresponding to a second mode in a first mode-wang transition mode, updating the first time scale to a product of the first time scale and the first correction factor, and updating the second time scale to a product of the second time scale and the second correction factor; simulating high-enthalpy ablation wall boundary layer flow transition of the high-speed vehicle based on the flow parameters and the boundary condition parameters by using the modified first mode-wang transition mode to obtain a transition starting position and a position of a turbulent flow region.

2. The method of claim 1, wherein the method further comprises: The method further comprises: constructing a first time scale amplification factor corresponding to the first mode and a second time scale amplification factor corresponding to the second mode according to the equivalent roughness height; constructing the first correction factor of each position according to the first time scale amplification factor and the dimensionless roughness height of each position; constructing the second correction factor of each position according to the second time scale amplification factor and the dimensionless roughness height of each position.

3. The method according to claim 2, wherein the method is characterized by: The method further comprises: According to the formula: ; construct a first time scale amplification factor corresponding to the first modal ; According to the formula: ; construct a second time scale amplification factor corresponding to the second modal ; wherein , , and denote calibrated constants, k r is the equivalent sand height.

4. The method of claim 2, wherein the method further comprises: simulating high-enthalpy ablation wall boundary layer flow transition of the high-speed vehicle by using a chemical reaction kinetics model containing multi-component real gas to determine the volume fraction of each component. According to the formula: ; determine the first correction factor for each position ; The method further comprises: According to the formula: ; determine a second correction factor for each position ; wherein, represents the dimensionless roughness height at each location, represents a constant that is calibrated.

5. The method of claim 1, wherein the method further comprises: correcting the wall boundary condition in the boundary condition parameters by using a Knopp roughness correction mode to obtain a corrected boundary condition parameter; The method further comprises:

6. The method of claim 1, wherein the method further comprises: simulating high-enthalpy ablation wall boundary layer flow transition of the high-speed vehicle based on the flow parameters and the boundary condition parameters by using the modified first mode-wang transition mode to obtain a transition starting position and a position of a turbulent flow region. The method further comprises: simulating high-enthalpy ablation wall boundary layer flow transition of the high-speed vehicle based on the flow parameters and the boundary condition parameters by using the modified first mode-wang transition mode to obtain a transition starting position and a position of a turbulent flow region. The method further comprises:

7. The method of claim 1, wherein the method further comprises: The device comprises: The dimensionless roughness height at each location is determined according to the formula: , where h is the height of the surface at the location, and h is the average height of the surface. ; wherein, represents the equivalent roughness height, represents the friction velocity, represents the shear stress on the wall.

8. A device for obtaining the boundary layer transition characteristics of a high-enthalpy ablation wall, characterized in that, ​ The input data acquisition module is configured to acquire the incoming flow parameters of the high-speed vehicle and boundary condition parameters of the high-speed vehicle. The roughness height determination module is configured to determine an equivalent roughness height based on actual roughness heights of the high-speed vehicle wall surface at different positions, and determine a dimensionless roughness height at each position based on wall surface feature information at the position and the equivalent roughness height. The correction factor construction module is configured to construct a first correction factor and a second correction factor at each position according to the dimensionless roughness height at the position and the equivalent roughness height, wherein the first correction factor and the second correction factor are both greater than 1. The transition characteristic acquisition module is configured to simulate high-enthalpy ablation wall boundary layer flow transition of the high-speed vehicle based on the incoming flow parameters and the boundary condition parameters, and acquire a transition starting position and a position of a turbulent flow region by using the modified Gort-Young transition model. The correction factor construction module is specifically configured to construct a first time scale amplification factor corresponding to the first mode and a second time scale amplification factor corresponding to the second mode according to the equivalent roughness height, construct the first correction factor at each position according to the first time scale amplification factor and the dimensionless roughness height at the position, and construct the second correction factor at each position according to the second time scale amplification factor and the dimensionless roughness height at the position.

9. The device of claim 8, wherein the device is configured to determine the transition location by determining a location of a point of inflection of the temperature profile. The correction factor construction module is specifically configured to construct the first time scale amplification factor corresponding to the first mode and the second time scale amplification factor corresponding to the second mode according to the equivalent roughness height by the following steps:

10. The device of claim 9, wherein the device is configured to determine the transition location by determining a location of a point of inflection of the temperature profile. ​ According to the formula: ; construct a first time scale amplification factor corresponding to the first modal ; According to the formula: ; construct a second time scale amplification factor corresponding to the second modal ; wherein, , , and denote constants to be calibrated, k r is the equivalent sand height.

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