Method and system for simulating payload aerodynamic characteristics

Abstract

The present invention relates to the field of aerodynamic simulation technology, and provides a method and system for simulating aerodynamic characteristics of a payload, wherein the method includes: establishing a three-dimensional solid model of the payload; establishing a finite element numerical model of the payload; establishing a finite element numerical model of the flow field around the payload to form a simulation numerical model; setting the material properties and physical properties of the flow field; configuring a theoretical model and calculation method of a solver simulation software for solving the flow field based on computational fluid dynamics; inputting the simulation numerical model into the solver simulation software, and running the solver simulation software to obtain simulation results of the flow field characteristics of the payload and its surroundings and simulation results of the aerodynamic parameters of the payload. The present invention can effectively solve the problems of high experimental cost, low cost-effectiveness and easy error generation in traditional solutions. The obtained simulation results are crucial to optimizing the aerodynamic shape of the payload and improving flight stability, and can provide a basis for the stability evaluation of the subsequent parachute-payload system.

Description

Technical Field

[0001] The present invention relates to the technical field of aerodynamic simulation, and in particular to a method and system for simulating aerodynamic characteristics of a payload. Background Art

[0002] Before the payload is deployed and the parachute is opened, its own stability is the prerequisite for reliable parachute opening and the key to achieving stability of the parachute-payload system and accurate landing point. The key to the stable flight of the payload lies in whether its aerodynamic shape can ensure its static stability during flight. When optimizing its aerodynamic shape, wind tunnel tests are often used.

[0003] Wind tunnel testing is expensive and cost-ineffective, and the size of the model is also limited by the size of the wind tunnel. Depending on the measurement accuracy, certain errors will also occur to some extent. Summary of the invention

[0004] The purpose of the present invention is to solve at least one technical problem in the background technology and to provide a method and system for simulating aerodynamic characteristics of a payload.

[0005] To achieve the above object, the present invention provides a method for simulating aerodynamic characteristics of a payload, comprising:

[0006] According to the actual size of the payload, a three-dimensional solid model of the payload is established;

[0007] Import the three-dimensional solid model into the finite element modeling software to establish a finite element numerical model of the payload;

[0008] Based on the finite element numerical model of the payload, a finite element numerical model of the flow field is established around the payload, and the finite element numerical model of the payload and the finite element numerical model of the flow field together form a simulation numerical model;

[0009] Based on the finite element numerical model of the flow field, setting material properties and physical properties of the flow field;

[0010] Theoretical models and calculation methods for solving flow field based on computational fluid dynamics solver simulation software;

[0011] The simulation numerical model is input into the solver simulation software, and the solver simulation software is run to obtain simulation results of flow field characteristics of the payload and its surroundings and simulation results of aerodynamic parameters of the payload.

[0012] According to one aspect of the present invention, the three-dimensional solid model is imported into the finite element modeling software to establish the finite element numerical model of the payload as follows:

[0013] The three-dimensional solid model of the payload is imported into the finite element modeling software Hypermesh for meshing, and the three-dimensional solid model of the payload is divided into tetrahedral unstructured grids to form a finite element numerical model of the payload.

[0014] According to one aspect of the present invention, the finite element numerical model of the flow field around the payload is established based on the finite element numerical model of the payload, comprising:

[0015] First, five layers of boundary layer transition grids are arranged in the flow field near the surface close to the payload;

[0016] Then the remaining flow field is divided into two parts. The inner computational domain close to the payload is divided into tetrahedral unstructured grids, and the outer computational domain away from the payload is divided into hexahedral grids.

[0017] According to one aspect of the present invention, the material properties and physical properties of the flow field are:

[0018] The material properties of the fluid in the flow field are set to ideal gas, the physical properties are set to 1 standard atmospheric pressure, and the temperature is set to 25°C.

[0019] According to one aspect of the present invention, the theoretical model and calculation method of the solver simulation software for solving the flow field based on computational fluid dynamics configuration include:

[0020] Governing equations:

[0021] The movement of fluids must follow the three conservation laws of mass conservation, momentum conservation, and energy conservation. The integral form of the Navier-Stokes equations is applied to the volume V and vector area element dA of any control body in the flow field. Its vector form in the Cartesian coordinate system is:

[0022] ;

[0023] In the formula, vector W is the conserved variable, Fc is the convection flux, Fv is the source term, V is the control volume, and dA is the surface element;

[0024] W, Fc, Fv and Q are:

[0025] ;

[0026] In the formula, is the density, u, v, w are the velocities in three directions respectively, E is the total energy, , where e is the internal energy per unit mass and v is the velocity vector;

[0027] ;

[0028] Where V is the inversion velocity perpendicular to the surface element dA, p is the pressure, and H is the total enthalpy. , and are the components of the external normal vector n of the surface element along the three directions;

[0029] Among them, the expressions of V and H are:

[0030] ;

[0031] ;

[0032] ;

[0033] in, ;

[0034] ;

[0035] ;

[0036] ;

[0037] ;

[0038] ;

[0039] ;

[0040] ;

[0041] ;

[0042] In the formula, is the viscous stress, is the thermal conductivity, T is the temperature, is the dynamic viscosity;

[0043] ;

[0044] In the formula, fe is the body force, fex, fey, and fez are the components of fe in three directions respectively. is the heat flux density;

[0045] Turbulence Models:

[0046] Using the SA turbulence model, the transport variables in the SA turbulence model is a quantity related to eddy viscosity. Outside the viscous sublayer and viscosity coefficient Equal, transport variable The transport equation is:

[0047] ;

[0048] In the formula, is the turbulent viscosity generation term, is the turbulent viscous dissipation term caused by wall blockage and viscous damping near the wall, It is a custom item. and is a constant, is the viscosity coefficient, and its calculation formula is as follows:

[0049] ;

[0050] in, ;in is a constant;

[0051] Turbulent viscosity generation term The expression is:

[0052] ;

[0053] in, ;

[0054] ;

[0055] , ;;

[0056] ;

[0057] ;

[0058] In the formula, , k and is a constant, d is the distance from the wall, S is the deformation tensor, is the laminar rotation tensor, where the subscripts i and j are indices of the three dimensions (x, y, z) in the Cartesian coordinate system;

[0059] Turbulent viscosity dissipation term The expression is:

[0060] ;

[0061] in, ;

[0062] ;

[0063] ;

[0064] ;

[0065] In the formula, , is a constant;

[0066] Boundary conditions:

[0067] The boundary conditions include: wall boundary conditions, pressure far-field boundary conditions at infinity, and symmetric boundary conditions. The wall boundary uses a no-slip adiabatic wall, and the inlet uses a non-reflecting boundary condition. For subsonic flow, there are two Riemann invariant equations corresponding to the waves entering and leaving the computational domain:

[0068] ;

[0069] ;

[0070] In the formula, represents the fluid velocity along the boundary normal, c is the local sound speed, is the specific heat ratio of the fluid, represents the incoming flow value at infinity, and m represents the number of grid unit center points in the computational domain. From the above two equations, we can get The expressions of and c are as follows:

[0071] ;

[0072] ;

[0073] use , c, tangential velocity and entropy can be used to solve the values ​​of pressure, velocity and density on the boundary.

[0074] According to one aspect of the present invention, the simulation numerical model is input into the solver simulation software, and the solver simulation software is run to obtain simulation results of flow field characteristics of the payload and its surroundings and simulation results of aerodynamic parameters of the payload, including:

[0075] Input the simulation numerical model into FLUENT computational fluid dynamics simulation software and run the FLUENT computational fluid dynamics simulation software;

[0076] Obtain the flow field characteristics around the payload from the FLUENT computational fluid dynamics simulation software;

[0077] Parameters characterizing the aerodynamic characteristics of the payload are extracted from the FLUENT computational fluid dynamics simulation software, including: drag coefficient, lift coefficient, pitch moment coefficient and pressure center coefficient.

[0078] To achieve the above object, the present invention also provides a payload aerodynamic characteristics simulation system, comprising:

[0079] A three-dimensional solid model building module is used to build a three-dimensional solid model of the payload according to the actual size of the payload;

[0080] Payload finite element numerical model building module, which imports the three-dimensional solid model into the finite element modeling software to build the finite element numerical model of the payload;

[0081] A simulation numerical model building module is used to build a finite element numerical model of the flow field around the payload based on the finite element numerical model of the payload, and the finite element numerical model of the payload and the finite element numerical model of the flow field together form a simulation numerical model;

[0082] A flow field property setting module, which sets material properties and physical properties of the flow field based on a finite element numerical model of the flow field;

[0083] A simulation configuration module, which configures the theoretical model and calculation method of the solver simulation software for solving the flow field based on computational fluid dynamics;

[0084] The simulation module inputs the simulation numerical model into the solver simulation software, and runs the solver simulation software to obtain simulation results of flow field characteristics of the payload and its surroundings and simulation results of aerodynamic parameters of the payload.

[0085] To achieve the above objectives, the present invention also provides an electronic device, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the computer program implements the above-mentioned method for simulating aerodynamic characteristics of a payload when executed by the processor.

[0086] To achieve the above object, the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the method for simulating aerodynamic characteristics of a payload as described above is implemented.

[0087] According to the scheme of the present invention, the numerical simulation method involved in the present invention can greatly reduce the test cost, and the calculation result is consistent with the actual situation, which effectively solves the problems of high test cost, low cost-effectiveness and easy error in traditional schemes.

[0088] According to the scheme of the present invention, the method for simulating the aerodynamic characteristics of a payload involved in the present invention can effectively simulate and predict the dynamic changes of the flow field around the payload, and can obtain parameters characterizing its aerodynamic characteristics. The influence of different aerodynamic shapes on the aerodynamic characteristics of the payload can be analyzed through the aerodynamic characteristic parameters, which is very important for optimizing the aerodynamic shape of the payload and improving flight stability. The obtained aerodynamic parameters can provide a basis for the stability evaluation of the subsequent parachute-payload system. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 A flowchart schematically showing a method for simulating aerodynamic characteristics of a payload according to an embodiment of the present invention;

[0090] Figure 2a , Figure 2b Schematically showing a mesh division diagram of a finite element numerical model of a payload and a flow field according to an embodiment of the present invention;

[0091] Figure 3 A diagram schematically showing flow field characteristics around a payload according to an embodiment of the present invention;

[0092] Figure 4a-4d The figures schematically show a comparison of aerodynamic parameters of payloads with different aerodynamic shapes according to an embodiment of the present invention. DETAILED DESCRIPTION

[0093] The present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the present invention, rather than implying any limitation on the scope of the present invention.

[0094] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0095] Figure 1 A flowchart schematically shows a method for simulating aerodynamic characteristics of a payload according to an embodiment of the present invention. Figure 1 As shown, in this embodiment, the method for simulating aerodynamic characteristics of a payload includes:

[0096] According to the actual size of the payload, a three-dimensional solid model of the payload is established;

[0097] Import the three-dimensional solid model into the finite element modeling software to establish a finite element numerical model of the payload;

[0098] Based on the finite element numerical model of the payload, a finite element numerical model of the flow field is established around the payload, and the finite element numerical model of the payload and the finite element numerical model of the flow field together form a simulation numerical model;

[0099] Based on the finite element numerical model of the flow field, set the material properties and physical properties of the flow field;

[0100] Theoretical models and calculation methods for solving flow field based on computational fluid dynamics solver simulation software;

[0101] The simulation numerical model is input into the solver simulation software, and the solver simulation software is run to obtain the simulation results of the flow field characteristics of the payload and its surroundings and the simulation results of the aerodynamic parameters of the payload.

[0102] Further, according to one embodiment of the present invention, the three-dimensional solid model is imported into the finite element modeling software, and the finite element numerical model of the payload is established as follows:

[0103] The three-dimensional solid model of the payload is imported into the finite element modeling software Hypermesh for meshing, and the three-dimensional solid model of the payload is divided into tetrahedral unstructured grids to form a finite element numerical model of the payload.

[0104] Further, according to an embodiment of the present invention, based on the finite element numerical model of the payload, a finite element numerical model of the flow field around the payload is established as follows:

[0105] A finite element numerical model of the flow field is built around the finite element numerical model of the payload, including:

[0106] First, five layers of boundary layer transition grids are arranged in the flow field near the surface close to the payload;

[0107] Then the remaining flow field is divided into two parts. The inner computational domain close to the payload is divided into tetrahedral unstructured grids, and the outer computational domain away from the payload is divided into hexahedral grids.

[0108] Specifically, in this embodiment, in order to ensure that the aerodynamic parameters of the payload are accurately obtained, the grid of the flow field calculation domain near the payload should be dense enough, and the calculation domain of the flow field should be large enough to avoid the reflection of pressure waves in the flow field at the boundary causing instability in numerical calculations. However, if the calculation domain is too large and the grid is too dense, it will cause insufficient computer resources. Therefore, the present invention divides the calculation domain into two layers. The closer the part is to the payload, the denser the grid is, and the farther away from the payload, the sparser the grid is. CFD grid generation technology can generate structured grids and unstructured grids. The calculation results of structured grids are more accurate and can achieve boundary fitting of the region. However, structured grid generation technology is unable to cope with complex flow regions. The generation speed of unstructured grids is much faster than that of structured grids, and the shape adaptability is very strong, which is beneficial to shorten the calculation cycle for complex calculation regions. Based on the above considerations, the present invention arranges 5 layers of boundary layer transition grids near the surface of the payload, divides the inner calculation domain into tetrahedral unstructured grids, and divides the outer calculation domain into hexahedral grids, such as Figure 2a and Figure 2b As shown, Figure 2a It shows that 5 layers of boundary layer transition grids are arranged near the payload surface. Figure 2bThe overall grid structure of the finite element numerical model of the payload and its surrounding flow field is shown.

[0109] Further, according to an embodiment of the present invention, the material properties and physical properties of the flow field are set as follows:

[0110] The material properties of the fluid in the flow field are set to ideal gas, the physical properties are set to 1 standard atmospheric pressure, and the temperature is set to 25°C.

[0111] Further, according to an embodiment of the present invention, starting from the basic physical laws of fluid mechanics, the control equations for solving the flow field are determined. By discretizing in space and time, the continuous flow quantity is replaced by variables of a finite number of discrete nodes and a set of algebraic equations that need to be satisfied between the variables is established, and numerical solutions are performed using a computer, and finally numerical approximate solutions to various flow problems are obtained. Specifically, in this embodiment, the theoretical model and calculation method of the solver simulation software for solving the flow field based on computational fluid dynamics (CFD) are configured, including:

[0112] Governing equations:

[0113] The movement of fluids must follow the three conservation laws of mass conservation, momentum conservation, and energy conservation. The integral form of the Navier-Stokes equations is applied to the volume V and vector area element dA of any control body in the flow field. Its vector form in the Cartesian coordinate system is:

[0114] ;

[0115] In the formula, vector W is the conserved variable, Fc is the convection flux, Fv is the source term, V is the control volume, and dA is the surface element;

[0116] W, Fc, Fv and Q are:

[0117] ;

[0118] In the formula, is the density, u, v, w are the velocities in three directions respectively, E is the total energy, , where e is the internal energy per unit mass and v is the velocity vector;

[0119] ;

[0120] Where V is the inversion velocity perpendicular to the surface element dA, p is the pressure, and H is the total enthalpy. , and are the components of the external normal vector n of the surface element along the three directions;

[0121] Among them, the expressions of V and H are:

[0122] ;

[0123] ;

[0124] ;

[0125] in, ;

[0126] ;

[0127] ;

[0128] ;

[0129] ;

[0130] ;

[0131] ;

[0132] ;

[0133] ;

[0134] In the formula, is the viscous stress, is the thermal conductivity, T is the temperature, is the dynamic viscosity;

[0135] ;

[0136] In the formula, fe is the body force, fex, fey, and fez are the components of fe in three directions respectively. is the heat flux density;

[0137] Turbulence Models:

[0138] The turbulence model directly determines the calculation results of aerodynamic parameters. The two most commonly used turbulence models are the Spalart-Allmaras model (SA turbulence model) and the standard Model". From the perspective of flow field mesh, the mesh near the wall of SA turbulence model only needs to be comparable to the model, and does not need to be very fine. From the perspective of transport variable gradient, SA turbulence model is better than "standard The gradient of the "SA turbulence model" is much smaller, making the SA turbulence model insensitive to numerical errors and achieving higher accuracy. Since the payload flight trajectories discussed in the present invention are all in the subsonic range, the SA turbulence model can better calculate the turbulence problems involved.

[0139] In this embodiment, the SA turbulence model is used, and the transport variables in the SA turbulence model are is a quantity related to eddy viscosity. Outside the viscous sublayer and viscosity coefficient Equal, transport variable The transport equation is:

[0140] ;

[0141] In the formula, is the turbulent viscosity generation term, is the turbulent viscous dissipation term caused by wall blockage and viscous damping near the wall, It is a custom item. and is a constant, is the viscosity coefficient, and its calculation formula is as follows:

[0142] ;

[0143] in, ;in is a constant;

[0144] Turbulent viscosity generation term The expression is:

[0145] ;

[0146] in, ;

[0147] ;

[0148] , ;

[0149] ;

[0150] ;

[0151] In the formula, , k and is a constant, d is the distance from the wall, S is the deformation tensor, is the laminar rotation tensor, where the subscripts i and j are indices of the three dimensions (x, y, z) in the Cartesian coordinate system;

[0152] Turbulent viscosity dissipation term The expression is:

[0153] ;

[0154] in, ;

[0155] ;

[0156] ;

[0157] ;

[0158] In the formula, , is a constant;

[0159] In this embodiment, , , , , , , , .

[0160] Boundary conditions:

[0161] The boundary conditions include: wall boundary conditions, pressure far-field boundary conditions at infinity, and symmetric boundary conditions. The wall boundary uses a no-slip adiabatic wall, and the inlet uses a non-reflecting boundary condition. For subsonic flow, there are two Riemann invariant equations corresponding to the waves entering and leaving the computational domain:

[0162] ;

[0163] ;

[0164] In the formula, represents the fluid velocity along the boundary normal, c is the local sound speed, is the specific heat ratio of the fluid, represents the incoming flow value at infinity, and m represents the number of grid unit center points in the computational domain. From the above two equations, we can get The expressions of and c are as follows:

[0165] ;

[0166] ;

[0167] use , c, tangential velocity and entropy can be used to solve the values ​​of pressure, velocity and density on the boundary.

[0168] In addition, since the payload model is mirror-symmetric, symmetric boundary conditions are used to divide the model into 1 / 2, which can greatly reduce the number of grid divisions and improve the calculation speed.

[0169] Further, according to an embodiment of the present invention, the simulation numerical model is input into the solver simulation software, and the solver simulation software is run to obtain the simulation results of the flow field characteristics of the payload and its surroundings and the simulation results of the aerodynamic parameters of the payload, including:

[0170] Input the simulation numerical model into FLUENT computational fluid dynamics simulation software, solve it in the density solution basis, set the initial conditions such as the flow velocity and angle of attack of the fluid in the system according to actual needs, and run FLUENT computational fluid dynamics simulation software for simulation;

[0171] The flow field characteristics around the payload are obtained from the FLUENT computational fluid dynamics simulation software, such as Figure 3 As shown;

[0172] Parameters characterizing the aerodynamic characteristics of the payload are extracted from the FLUENT computational fluid dynamics simulation software, including: drag coefficient, lift coefficient, pitch moment coefficient and pressure center coefficient.

[0173] In this embodiment, Figure 4a-4d The aerodynamic parameter comparisons of the payloads under different aerodynamic shapes are given respectively, that is, the payloads with different aerodynamic shapes (flat head payload, concave head payload and convex head payload) can obtain different aerodynamic characteristic parameters through the above simulation.

[0174] According to the above scheme of the present invention, the numerical simulation method involved in the present invention can greatly reduce the experimental cost, and the calculation results are consistent with the actual situation, which effectively solves the problems of high experimental cost, low cost-effectiveness and easy error in traditional schemes.

[0175] According to the above scheme of the present invention, the payload aerodynamic characteristics simulation method involved in the present invention can effectively simulate and predict the dynamic changes of the flow field around the payload, and can obtain parameters characterizing its aerodynamic characteristics. The influence of different aerodynamic shapes on the aerodynamic characteristics of the payload can be analyzed through the aerodynamic characteristic parameters, which is very important for optimizing the aerodynamic shape of the payload and improving flight stability. The obtained aerodynamic parameters can provide a basis for the stability evaluation of the subsequent parachute-payload system.

[0176] Furthermore, in order to achieve the above-mentioned object, the present invention also provides a payload aerodynamic characteristics simulation system, characterized in that it comprises:

[0177] A three-dimensional solid model building module is used to build a three-dimensional solid model of the payload according to the actual size of the payload;

[0178] Payload finite element numerical model building module, which imports the three-dimensional solid model into the finite element modeling software to build the finite element numerical model of the payload;

[0179] A simulation numerical model building module, based on the finite element numerical model of the payload, builds a finite element numerical model of the flow field around the payload, and the finite element numerical model of the payload and the finite element numerical model of the flow field together form a simulation numerical model;

[0180] The flow field property setting module sets the material properties and physical properties of the flow field based on the finite element numerical model of the flow field;

[0181] A simulation configuration module, which configures the theoretical model and calculation method of the solver simulation software for solving the flow field based on computational fluid dynamics;

[0182] The simulation module inputs the simulation numerical model into the solver simulation software, and runs the solver simulation software to obtain the simulation results of the flow field characteristics of the payload and its surroundings and the simulation results of the aerodynamic parameters of the payload.

[0183] Further, according to one embodiment of the present invention, the three-dimensional solid model is imported into the finite element modeling software, and the finite element numerical model of the payload is established as follows:

[0184] The three-dimensional solid model of the payload is imported into the finite element modeling software Hypermesh for meshing, and the three-dimensional solid model of the payload is divided into tetrahedral unstructured grids to form a finite element numerical model of the payload.

[0185] Further, according to an embodiment of the present invention, based on the finite element numerical model of the payload, a finite element numerical model of the flow field around the payload is established as follows:

[0186] A finite element numerical model of the flow field is built around the finite element numerical model of the payload, including:

[0187] First, five layers of boundary layer transition grids are arranged in the flow field near the surface close to the payload;

[0188] Then the remaining flow field is divided into two parts. The inner computational domain close to the payload is divided into tetrahedral unstructured grids, and the outer computational domain away from the payload is divided into hexahedral grids.

[0189] Specifically, in this embodiment, in order to ensure that the aerodynamic parameters of the payload are accurately obtained, the grid of the flow field calculation domain near the payload should be dense enough, and the calculation domain of the flow field should be large enough to avoid the reflection of pressure waves in the flow field at the boundary causing instability in numerical calculations. However, if the calculation domain is too large and the grid is too dense, it will cause insufficient computer resources. Therefore, the present invention divides the calculation domain into two layers. The closer the part is to the payload, the denser the grid is, and the farther away from the payload, the sparser the grid is. CFD grid generation technology can generate structured grids and unstructured grids. The calculation results of structured grids are more accurate and can achieve boundary fitting of the region. However, structured grid generation technology is unable to cope with complex flow regions. The generation speed of unstructured grids is much faster than that of structured grids, and the shape adaptability is very strong, which is beneficial to shorten the calculation cycle for complex calculation regions. Based on the above considerations, the present invention arranges 5 layers of boundary layer transition grids near the surface of the payload, divides the inner calculation domain into tetrahedral unstructured grids, and divides the outer calculation domain into hexahedral grids, such as Figure 2a-2b As shown, Figure 2a It shows that 5 layers of boundary layer transition grids are arranged near the payload surface. Figure 2b The overall grid structure of the finite element numerical model of the payload and its surrounding flow field is shown.

[0190] Further, according to an embodiment of the present invention, the material properties and physical properties of the flow field are set as follows:

[0191] The material properties of the fluid in the flow field are set to ideal gas, the physical properties are set to 1 standard atmospheric pressure, and the temperature is set to 25°C.

[0192] Further, according to an embodiment of the present invention, starting from the basic physical laws of fluid mechanics, the control equations for solving the flow field are determined. By discretizing in space and time, the continuous flow quantity is replaced by variables of a finite number of discrete nodes and a set of algebraic equations that need to be satisfied between the variables is established, and numerical solutions are performed using a computer, and finally numerical approximate solutions to various flow problems are obtained. Specifically, in this embodiment, the theoretical model and calculation method of the solver simulation software for solving the flow field based on computational fluid dynamics (CFD) are configured, including:

[0193] Governing equations:

[0194] The movement of fluids must follow the three conservation laws of mass conservation, momentum conservation, and energy conservation. The integral form of the Navier-Stokes equations is applied to the volume V and vector area element dA of any control body in the flow field. Its vector form in the Cartesian coordinate system is:

[0195] ;

[0196] In the formula, vector W is the conserved variable, Fc is the convection flux, Fv is the source term, V is the control volume, and dA is the surface element;

[0197] W, Fc, Fv and Q are:

[0198] ;

[0199] In the formula, is the density, u, v, w are the velocities in three directions respectively, E is the total energy, , where e is the internal energy per unit mass and v is the velocity vector;

[0200] ;

[0201] Where V is the inversion velocity perpendicular to the surface element dA, p is the pressure, and H is the total enthalpy. , and are the components of the external normal vector n of the surface element along the three directions;

[0202] Among them, the expressions of V and H are:

[0203] ;

[0204] ;

[0205] ;

[0206] in, ;

[0207] ;

[0208] ;

[0209] ;

[0210] ;

[0211] ;

[0212] ;

[0213] ;

[0214] ;

[0215] In the formula, is the viscous stress, is the thermal conductivity, T is the temperature, is the dynamic viscosity;

[0216] ;

[0217] In the formula, fe is the body force, fex, fey, and fez are the components of fe in three directions respectively. is the heat flux density;

[0218] Turbulence Models:

[0219] The turbulence model directly determines the calculation results of aerodynamic parameters. The two most commonly used turbulence models are the Spalart-Allmaras model (SA turbulence model) and the standard Model". From the perspective of flow field mesh, the mesh near the wall of SA turbulence model only needs to be comparable to the model, and does not need to be very fine. From the perspective of transport variable gradient, SA turbulence model is better than "standard The gradient of the "SA turbulence model" is much smaller, making the SA turbulence model insensitive to numerical errors and achieving higher accuracy. Since the payload flight trajectories discussed in the present invention are all in the subsonic range, the SA turbulence model can better calculate the turbulence problems involved.

[0220] In this embodiment, the SA turbulence model is used, and the transport variables in the SA turbulence model are is a quantity related to eddy viscosity. Outside the viscous sublayer and viscosity coefficient Equal, transport variable The transport equation is:

[0221] ;

[0222] In the formula, is the turbulent viscosity generation term, is the turbulent viscous dissipation term caused by wall blockage and viscous damping near the wall, It is a custom item. and is a constant, is the viscosity coefficient, and its calculation formula is as follows:

[0223] ;

[0224] in, ;in is a constant;

[0225] Turbulent viscosity generation term The expression is:

[0226] ;

[0227] in, ;

[0228] ;

[0229] , ;

[0230] ;

[0231] ;

[0232] In the formula, , k and is a constant, d is the distance from the wall, S is the deformation tensor, is the laminar rotation tensor, where the subscripts i and j are indices of the three dimensions (x, y, z) in the Cartesian coordinate system;

[0233] Turbulent viscosity dissipation term The expression is:

[0234] ;

[0235] in, ;

[0236] ;

[0237] ;

[0238] ;

[0239] In the formula, , is a constant;

[0240] In this embodiment, , , , , , , , .

[0241] Boundary conditions:

[0242] The boundary conditions include: wall boundary conditions, pressure far-field boundary conditions at infinity, and symmetric boundary conditions. The wall boundary uses a no-slip adiabatic wall, and the inlet uses a non-reflecting boundary condition. For subsonic flow, there are two Riemann invariant equations corresponding to the waves entering and leaving the computational domain:

[0243] ;

[0244] ;

[0245] In the formula, represents the fluid velocity along the boundary normal, c is the local sound speed, is the specific heat ratio of the fluid, represents the incoming flow value at infinity, and m represents the number of grid unit center points in the computational domain. From the above two equations, we can get The expressions of and c are as follows:

[0246] ;

[0247] ;

[0248] use , c, tangential velocity and entropy can be used to solve the values ​​of pressure, velocity and density on the boundary.

[0249] In addition, since the payload model is mirror-symmetric, symmetric boundary conditions are used to divide the model into 1 / 2, which can greatly reduce the number of grid divisions and improve the calculation speed.

[0250] Further, according to an embodiment of the present invention, the simulation numerical model is input into the solver simulation software, and the solver simulation software is run to obtain the simulation results of the flow field characteristics of the payload and its surroundings and the simulation results of the aerodynamic parameters of the payload, including:

[0251] Input the simulation numerical model into FLUENT computational fluid dynamics simulation software, solve it in the density solution basis, set the initial conditions such as the flow velocity and angle of attack of the fluid in the system according to actual needs, and run FLUENT computational fluid dynamics simulation software for simulation;

[0252] The flow field characteristics around the payload are obtained from the FLUENT computational fluid dynamics simulation software, such as Figure 3 As shown, Figure 3 The flow field pressure distribution within the symmetry plane of the payload is shown;

[0253] Parameters characterizing the aerodynamic characteristics of the payload are extracted from the FLUENT computational fluid dynamics simulation software, including: drag coefficient, lift coefficient, pitch moment coefficient and pressure center coefficient.

[0254] In this embodiment, Figure 4a-4d The aerodynamic parameter comparisons of the payloads under different aerodynamic shapes are given respectively, that is, the payloads with different aerodynamic shapes (flat head payload, concave head payload and convex head payload) can obtain different aerodynamic characteristic parameters through the above simulation.

[0255] According to the above scheme of the present invention, the numerical simulation method involved in the present invention can greatly reduce the experimental cost, and the calculation results are consistent with the actual situation, which effectively solves the problems of high experimental cost, low cost-effectiveness and easy error in traditional schemes.

[0256] According to the above scheme of the present invention, the payload aerodynamic characteristics simulation method involved in the present invention can effectively simulate and predict the dynamic changes of the flow field around the payload, and can obtain parameters characterizing its aerodynamic characteristics. The influence of different aerodynamic shapes on the aerodynamic characteristics of the payload can be analyzed through the aerodynamic characteristic parameters, which is very important for optimizing the aerodynamic shape of the payload and improving flight stability. The obtained aerodynamic parameters can provide a basis for the stability evaluation of the subsequent parachute-payload system.

[0257] Furthermore, to achieve the above-mentioned purpose, the present invention also provides an electronic device, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the method for simulating the aerodynamic characteristics of a payload as described above is implemented.

[0258] Furthermore, to achieve the above-mentioned purpose, the present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the method for simulating aerodynamic characteristics of a payload as described above is implemented.

[0259] Those skilled in the art will appreciate that the modules and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0260] 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 equipment can refer to the corresponding processes in the aforementioned method implementation methods, and will not be repeated here.

[0261] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0262] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0263] In addition, each functional module in the embodiment of the present invention may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0264] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the energy-saving signal sending / receiving method of each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical disks.

[0265] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

[0266] It should be understood that the size of the serial numbers of each step in the content of the invention and the implementation methods of the present invention does not absolutely mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation methods of the present invention.

Claims

1. A method for simulating aerodynamic characteristics of a payload, characterized in that: include: According to the actual size of the payload, a three-dimensional solid model of the payload is established; Import the three-dimensional solid model into the finite element modeling software to establish a finite element numerical model of the payload; Based on the finite element numerical model of the payload, a finite element numerical model of the flow field is established around the payload, and the finite element numerical model of the payload and the finite element numerical model of the flow field together form a simulation numerical model; Setting material properties and physical properties of the flow field based on the finite element numerical model of the flow field; Theoretical models and calculation methods for solving flow field based on computational fluid dynamics solver simulation software; Inputting the simulation numerical model into the solver simulation software, and running the solver simulation software to obtain simulation results of flow field characteristics of the payload and its surroundings and simulation results of aerodynamic parameters of the payload; The three-dimensional solid model is imported into the finite element modeling software to establish the finite element numerical model of the payload: The three-dimensional solid model of the payload is imported into the finite element modeling software Hypermesh for meshing, and the three-dimensional solid model of the payload is divided into tetrahedral unstructured meshes to form a finite element numerical model of the payload; The finite element numerical model of the flow field around the payload is established based on the finite element numerical model of the payload, including: First, the flow field near the surface of the payload is arranged with 5 layers of boundary layer transition grids; Then the remaining flow field is divided into two parts. The inner computational domain close to the payload is divided into tetrahedral unstructured grids, and the outer computational domain away from the payload is divided into hexahedral grids.

2. The method for simulating aerodynamic characteristics of a payload according to claim 1, characterized in that: The material properties and physical properties of the flow field are set as follows: The material properties of the fluid in the flow field are set to ideal gas, the physical properties are set to 1 standard atmospheric pressure, and the temperature is set to 25°C.

3. The method for simulating aerodynamic characteristics of a payload according to claim 1, characterized in that: The theoretical model and calculation method of the solver simulation software for solving the flow field based on computational fluid dynamics configuration include: Governing equations: The movement of fluids must follow the three conservation laws of mass conservation, momentum conservation, and energy conservation. The integral form of the Navier-Stokes equations is applied to the volume V and vector area element dA of any control body in the flow field. Its vector form in the Cartesian coordinate system is: In the formula, vector W is a conserved variable, F c is the convective flux, F v is the source term, V is the control volume, and dA is the surface element; W.F. c 、F v and Q are: W=(ρρuρvρwρE) T ; In the formula, ρ is the density, u, v, w are the velocities in three directions respectively, E is the total energy, In the formula, e is the internal energy per unit mass, and v is the velocity vector; F c =(ρVρVu+pn x ρVv+pn y ρVw+pn z pHV) T ; Where V is the inversion velocity perpendicular to the surface element dA, p is the pressure, H is the total enthalpy, and n is x 、n y and n z are the components of the external normal vector n of the surface element along the three directions; Among them, the expressions of V and H are: V=v·n=n x u+n y v+n z w; in, In the formula, τ ij (i=x,y,z; j=x,y,z) is the viscous stress, κ is the thermal conductivity, T is the temperature, and μ is the dynamic viscosity; In the formula, f e is the body force, f ex 、f ey 、f ez f e The components in the three directions of is the heat flux density; Turbulence Models: Using the SA turbulence model, the transport variables in the SA turbulence model is a quantity related to eddy viscosity. Outside the viscous sublayer and viscosity coefficient μ t Equal, transport variable The transport equation is: In the formula, G ν is the turbulent viscosity generation term, Y ν is the turbulent viscous dissipation term caused by wall blockage and viscous damping near the wall, It is a custom item. and C b2 is a constant, μ t is the viscosity coefficient, and its calculation formula is as follows: in, Among them C ν1 is a constant; Turbulent viscosity generation term G ν The expression is: in, S≡|Ω ij |+C prod ,min(0,|S ij |-Oh ij |); In the formula, C b1 , k and C prod is a constant, d is the distance from the wall, S is the deformation tensor, Ω ij is the laminar rotation tensor, where the subscripts i and j are indices of the three dimensions (x, y, z) in the Cartesian coordinate system; Turbulent viscosity dissipation term Y ν The expression is: in, g=r+C ω2 (r 6 -r); In the formula, C ω2 , C ω3 is a constant; Boundary conditions: The boundary conditions include: wall boundary conditions, pressure far-field boundary conditions at infinity, and symmetric boundary conditions. The wall boundary uses a no-slip adiabatic wall, and the inlet uses a non-reflecting boundary condition. For subsonic flow, there are two Riemann invariant equations corresponding to the waves entering and leaving the computational domain: Where, ν n represents the fluid velocity along the boundary normal, c is the local sound speed, γ is the fluid specific heat ratio, ∞ represents the incoming flow value at infinity, and m represents the number of grid unit center points in the computational domain. From the above two equations, ν can be obtained n The expressions of and c are as follows: Using ν n , c, tangential velocity and entropy can be used to solve the values ​​of pressure, velocity and density on the boundary.

4. The method for simulating aerodynamic characteristics of a payload according to any one of claims 1 to 3, characterized in that: The simulation numerical model is input into the solver simulation software, and the solver simulation software is run to obtain simulation results of flow field characteristics of the payload and its surroundings and simulation results of aerodynamic parameters of the payload, including: Input the simulation numerical model into FLUENT computational fluid dynamics simulation software and run the FLUENT computational fluid dynamics simulation software; Obtain the flow field characteristics around the payload from the FLUENT computational fluid dynamics simulation software; Parameters characterizing the aerodynamic characteristics of the payload are extracted from the FLUENT computational fluid dynamics simulation software, including: drag coefficient, lift coefficient, pitch moment coefficient and pressure center coefficient.

5. Payload aerodynamic characteristics simulation system, characterized in that: include: A three-dimensional solid model building module is used to build a three-dimensional solid model of the payload according to the actual size of the payload; Payload finite element numerical model building module, which imports the three-dimensional solid model into the finite element modeling software to build the finite element numerical model of the payload; A simulation numerical model building module is used to build a finite element numerical model of the flow field around the payload based on the finite element numerical model of the payload, and the finite element numerical model of the payload and the finite element numerical model of the flow field together form a simulation numerical model; A flow field property setting module, which sets material properties and physical properties of the flow field based on a finite element numerical model of the flow field; A simulation configuration module, which configures the theoretical model and calculation method of the solver simulation software for solving the flow field based on computational fluid dynamics; A simulation module, inputting the simulation numerical model into the solver simulation software, and running the solver simulation software to obtain simulation results of flow field characteristics of the payload and its surroundings and simulation results of aerodynamic parameters of the payload; The three-dimensional solid model is imported into the finite element modeling software to establish the finite element numerical model of the payload: The three-dimensional solid model of the payload is imported into the finite element modeling software Hypermesh for meshing, and the three-dimensional solid model of the payload is divided into tetrahedral unstructured meshes to form a finite element numerical model of the payload; The finite element numerical model of the flow field around the payload is established based on the finite element numerical model of the payload, including: First, the flow field near the surface of the payload is arranged with 5 layers of boundary layer transition grids; Then the remaining flow field is divided into two parts. The inner computational domain close to the payload is divided into tetrahedral unstructured grids, and the outer computational domain away from the payload is divided into hexahedral grids.

6. An electronic device, characterized in that The method comprises a processor, a memory and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the method for simulating aerodynamic characteristics of a payload as claimed in any one of claims 1 to 4 is implemented.

7. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for simulating aerodynamic characteristics of a payload according to any one of claims 1 to 4 is implemented.

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