Bidirectional fluid-structure interaction FVM numerical calculation method considering radiation

Abstract

The invention provides a numerical calculation method of a bidirectional fluid-structure interaction (FVM) considering radiation. The numerical calculation method comprises the following steps: establishing a non-uniform participating medium radiation transmission numerical model based on a CCFVM, establishing a CCFVM numerical model considering radiation fluid-structure interaction heat transfer, and establishing a CVFVM numerical model considering bidirectional fluid-structure interaction stress; and constructing a numerical framework of the radiation-considered bidirectional fluid-solid coupling FVM, and developing a solving program. The advantages of the CCFVM in flow field calculation and the advantages of the CVFVM in structure field calculation are fully utilized, a unified grid model is adopted, and errors caused by data mapping between different numerical value methods are avoided.

Description

Technical Field

[0001] The present invention relates to a multi-physical field coupling numerical calculation technology, specifically a bidirectional fluid-solid coupling numerical calculation method based on a unified finite volume method and considering radiation. Background Art

[0002] Fluid-solid interaction is an interdisciplinary subject of fluid-solid interaction and is a multi-physics coupling problem. For multi-physics coupling problems, the commonly used numerical calculation methods are unified method and hybrid method.

[0003] The hybrid method uses two or more numerical methods to simulate different regions or physical fields. For example, the Monte Carlo method is used to solve the radiation intensity field, and the Boltzmann method is used to solve the flow field. Since the hybrid method uses different numerical methods for different physical fields, the data transfer at the coupling point requires approximation or difference processing, which will lead to the generation of calculation errors and increase the possibility of calculation divergence. The unified method uses the same numerical method for different physical fields and establishes a unified numerical framework for multi-physical field coupling. For example, FVM is used to solve the radiation intensity field, flow field and solid field at the same time. Since the unified method uses a unified numerical method to solve different physical fields, it can be calculated based on the same grid, and the coupling surface does not require special processing. The generation of coupling surface processing errors is avoided, and the calculation is not easy to diverge.

[0004] The present invention establishes a numerical model of radiation heat transfer of non-uniform participating media based on CCFVM, a numerical model of fluid-solid coupling heat transfer considering radiation based on CCFVM, and a numerical model of fluid-solid coupling stress based on CVFVM. By utilizing the difference between the numerical models of CCFVM and CVFVM, a unified numerical framework is established based on the same set of grids, and the dynamic grid technology is introduced to establish a finite volume numerical model of bidirectional fluid-solid coupling considering radiation based on the unified finite volume method, and a complete calculation program of the finite volume numerical model of bidirectional fluid-solid coupling considering radiation based on the unified finite volume method is developed using C++ language.

[0005] The symbols in this application mean: FVM: finite volume method, CVFVM: grid-type finite volume method, CCFVM: grid-centred finite volume method. Summary of the invention

[0006] Aiming at the problems of incomplete consideration of coupling effect in existing fluid-solid coupling heat transfer and additional errors introduced by coupling surface data processing, the present invention proposes a bidirectional fluid-solid coupling FVM numerical calculation method considering radiation.

[0007] In the first step, the radiation source term and the wall radiation heat flux density calculated from the radiation intensity field in the numerical model of radiation transfer of non-uniform participating media established based on CCFVM are first brought into the fluid-solid coupling heat transfer numerical model established based on CCFVM; then the temperature field calculated from the fluid-solid coupling heat transfer numerical model established based on CCFVM is used to update the radiation physical property parameters of the non-homogeneous participating media in the radiation intensity field; finally, the radiation physical property parameters of the non-homogeneous participating media in the radiation intensity field are used to update the radiation intensity field in the numerical model of radiation transfer of non-uniform participating media established based on CCFVM, and finally the establishment of the CCFVM numerical model considering radiation fluid-solid coupling heat transfer is realized;

[0008] In the second step, the solid structure field temperature and fluid force on the fluid-solid coupling surface calculated by the CCFVM numerical model considering radiation fluid-solid coupling heat transfer are first introduced into the solid structure field stress calculation of the fluid-solid coupling stress numerical model based on CVFVM, and the flow-induced vibration numerical model and thermal-solid coupling numerical model based on CVFVM are established; the above models are then used to solve the thermal stress and stress distribution of the structural field, and a one-way fluid-solid coupling numerical calculation considering radiation based on CVFVM is established;

[0009] In the third step, the coupling surface displacement obtained by numerical calculation of the one-way fluid-solid coupling based on CVFVM considering radiation is transferred to the flow field grid of the CCFVM numerical model considering radiation fluid-solid coupling heat transfer, and the dynamic mesh technology is introduced to establish the CVFVM numerical model of bidirectional fluid-solid coupling stress.

[0010] The fourth step is to establish a numerical calculation method for the bidirectional fluid-solid coupling FVM considering radiation based on the CCFVM numerical model considering radiation fluid-solid coupling heat transfer established in the first step and the CVFVM numerical model of bidirectional fluid-solid coupling stress established in the third step, and develop the numerical calculation program for the bidirectional fluid-solid coupling FVM considering radiation using C++ language.

[0011] (1) Establishment of a numerical model of radiation transmission in inhomogeneous participating media based on CCFVM

[0012] The following steps are used to establish a calculation method for the numerical model of radiation transfer in non-uniform participating media based on CCFVM.

[0013] The first step is to calculate the radiation heat transfer of non-uniform participating media based on the method. The method has the radiation heat transfer phenomenon of non-uniform participating media. The medium inhomogeneity refers to the changes of absorption coefficient, scattering coefficient and refractive index with temperature and time and space. At the same time, the changes of radiation physical parameters of the medium will affect heat transfer.

[0014] The second step is the calculation of thermal radiation based on CCFVM.

[0015] The third step is to discretize the radiation transfer equation based on CCFVM, store the radiation physical property parameters in the unit center, discretize the solid angle based on CCFVM, calculate the solid angle correlation coefficient and the surface unit coefficient, introduce the change of radiation physical property parameters into the discretization process, and realize the calculation of radiation heat transfer based on CCFVM discretized spatial solid angle and control equation.

[0016] The fourth step is to calculate the unit radiation source term and the wall radiation heat flux density and store the calculation results at the unit center.

[0017] (2) Establishment of CCFVM numerical model considering radiation fluid-solid coupling heat transfer

[0018] The following steps are used to establish the calculation method of the CCFVM numerical model considering radiation fluid-solid coupling heat transfer.

[0019] In the first step, based on the fluid-solid coupling heat transfer numerical model established by CCFVM, when the temperature is high, it is necessary to calculate the radiation heat transfer.

[0020] The second step is the calculation based on the CCFVM numerical model considering radiation fluid-solid coupling heat transfer.

[0021] In the third step, the fluid-solid coupled heat transfer numerical model established based on CCFVM is separated from the heat conduction equation and the energy equation, the material physical properties are defined at the center of the grid, and the surface unit coefficients in the discrete equations are calculated.

[0022] The fourth step is to form a calculation coefficient matrix. The radiation source term calculated in the fourth step of (1) is added to the control equation. The fluid subdomain and the solid subdomain are discretized using a unified method, and the coefficients of the two domains are stored in the same matrix to form a unified set of algebraic equations.

[0023] The fifth step is to use the synchronous iterative solution method combined with the implicit algorithm to establish the CCFVM numerical model calculation method for fluid-solid coupled heat transfer considering radiation, and use the C++ language to compile the solution program.

[0024] (3) Establishment of the CVFVM numerical model of bidirectional fluid-solid coupling stress

[0025] The calculation method of the fluid-solid coupling stress CVFVM numerical model is established using the following steps.

[0026] The first step is to establish the calculation of the fluid-solid coupling stress numerical model based on CVFVM, including the solid structure stress caused by the pulsating pressure of the flow field and the solid structure thermal stress caused by the temperature field. The solid structure field temperature and fluid force on the fluid-solid coupling surface calculated by the CCFVM numerical model considering radiation fluid-solid coupling heat transfer are introduced into the solid structure field stress calculation of the fluid-solid coupling stress numerical model based on CVFVM, and the flow-induced vibration numerical model and thermal-solid coupling numerical model based on CVFVM are established;

[0027] In the second step, based on the CVFVM discrete thermal elastic equation, the variables to be solved are stored at the unit nodes, and the physical parameters are stored at the unit center. The pulsating pressure of the fluid-solid coupling boundary flow field and the unit center temperature of the solid structure field calculated by the CCFVM numerical model of fluid-solid coupling heat transfer considering radiation are extracted;

[0028] The third step is to form a coefficient matrix;

[0029] In the fourth step, the iterative solution method is used to solve the flow-induced vibration numerical model based on CVFVM, and the direct solution method is used to solve the thermal-solid coupling numerical model based on CVFVM. The above models are then used to solve the thermal stress and stress distribution of the structural field, and a unidirectional fluid-solid coupling numerical model based on CVFVM considering radiation is established.

[0030] In the fifth step, the coupling surface displacement obtained by numerical calculation of the one-way fluid-solid coupling based on CVFVM considering radiation is transferred to the flow field mesh of the CCFVM numerical model considering radiation fluid-solid coupling heat transfer, and feedback is loaded to the flow field boundary. The dynamic mesh technology is introduced to update the flow field mesh, and the dynamic mesh technology is introduced to establish the CVFVM numerical model of bidirectional fluid-solid coupling stress.

[0031] (4) Establishment of numerical calculation of bidirectional fluid-structure interaction FVM considering radiation

[0032] Based on the CCFVM numerical model considering radiation fluid-solid coupling heat transfer and the CVFVM numerical model of bidirectional fluid-solid coupling stress established in the above steps, a numerical calculation method for bidirectional fluid-solid coupling FVM considering radiation is established, and the numerical calculation program for the bidirectional fluid-solid coupling FVM considering radiation is developed using C++ language.

[0033] The technical problem solved by the present invention is to establish a numerical model of bidirectional fluid-solid coupling FVM considering radiation, which can avoid the data mapping error caused by solving different physics with different numerical methods. By using the numerical model based on bidirectional fluid-solid coupling FVM considering radiation, the radiation intensity field, flow field, temperature field and solid structure field can be calculated based on the same set of grids. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Technology Roadmap

[0035] Figure 2 Schematic diagram of the numerical model of bidirectional fluid-structure interaction FVM considering radiation

[0036] Figure 3 Schematic diagram of FVM control volume (taking a two-dimensional grid as an example, the thick solid line is the grid boundary, the solid dots are the grid nodes, and the hollow dots are the grid centers)

[0037] Figure 4Schematic diagram of a heat exchanger, where a) is the solid subdomain and (b) is the fluid subdomain

[0038] Figure 5 Schematic diagram of heat exchanger mesh division

[0039] Figure 6 Heat exchanger temperature spatial distribution diagram DETAILED DESCRIPTION

[0040] The numerical calculation method of the bidirectional fluid-solid coupling FVM considering radiation is applicable to the single solution or coupled solution of one or more physical fields including radiation intensity field, flow field, temperature field, and structural stress field. The following is a numerical model of a bidirectional fluid-solid coupling FVM based on radiation in a simple gas-gas heat exchanger as a specific embodiment for explanation.

[0041] The simple gas-gas heat exchanger includes a solid subdomain 1 composed of a shell 101, and a fluid subdomain 2 composed of a low-temperature gas 201 and a high-temperature gas 202. Due to the different materials of the solid subdomain 1 and the fluid subdomain 2, the effects of radiation heat transfer on their heat transfer processes are also different. For the solid subdomain 1, its absorption coefficient is relatively large, and the radiation energy is absorbed after propagating a short distance in it, so it is called an opaque medium; for the low-temperature gas 201 and the high-temperature gas 202 in the fluid subdomain 2, their absorption coefficient and scattering coefficient are very small, and they neither absorb nor scatter the radiation energy, so they are called transparent media. For this reason, when solving the fluid-solid coupled heat transfer, it is first determined whether radiation heat transfer needs to be considered in each domain. The low-temperature gas 201 and the high-temperature gas 202 in the fluid subdomain 2 are participating media, and the influence of radiation heat transfer needs to be considered. The heat exchanger shell 101 in the solid subdomain 1 is an opaque medium, and the influence of radiation heat transfer does not need to be considered. A numerical model of radiation transfer of non-uniform participating media is established based on CCFVM, and the grid is used as the control body to discretize the equations (such as Figure 3 The grid is surrounded by grid nodes ABCD). When the spatial solid angle of the grid unit is discretized, the number of discrete solid angles is stored in advance, and then the coefficient related to the solid angle in the equation is calculated and stored in the center of each unit. The physical parameters are stored in the center of the grid unit. The physical parameters of the grid surface are required in the discrete control equation, and the parameters of the grid surface are obtained by the difference of the values ​​of the centers of adjacent units, so as to consider the spatial distribution of the participating medium, realize the CCFVM processing of the radiation transmission problem of the non-uniform participating medium, and use CCFVM to establish the radiation intensity field in the numerical model of radiation transmission of the non-uniform participating medium to calculate the radiation source term and the wall radiation heat flux density at the center of each unit, which is used for the subsequent calculation of the CCFVM fluid-solid coupling heat transfer numerical model.

[0042] When calculating the fluid-solid coupling heat transfer numerical model based on CCFVM, since it is necessary to establish the fluid-solid coupling heat transfer numerical model based on CCFVM to separate the heat conduction equation and the energy equation, the material physical parameters and initial temperature are stored at the unit center; this processing method is consistent with the discretization of the non-uniform participating medium radiation transmission numerical model based on CCFVM, and both obtain the physical parameters on the grid surface by the value difference of the grid center. The continuity equation and momentum equation are solved by the SIMPLE algorithm, and the velocity and pressure in the entire fluid subdomain 2 are obtained by using a suitable turbulence model. Then, it is determined whether each subdomain needs to consider the influence of radiation heat transfer. For the subdomains that need to be considered, the unit center radiation source items calculated in the previous article are extracted and added to the corresponding coefficient matrix. The coefficients of each subdomain are stored in a unified coefficient matrix, and a group of energy equations considering radiation including solid subdomain 1 and fluid subdomain 2 are constructed. At the same time, the unit center temperature in each subdomain is solved to complete the calculation of the CCFVM numerical model of fluid-solid coupling heat transfer considering radiation.

[0043] The calculation of the fluid-solid coupling stress numerical model based on CVFVM includes the thermal stress distribution of the solid structure field caused by the temperature space-time distribution and the stress distribution of the solid structure field caused by the flow field pressure. Because the calculation of the fluid-solid coupling stress numerical model based on CVFVM requires the extraction of the unit center temperature using the CVFVM discrete thermoelastic equation, which is exactly consistent with the unit center temperature obtained by solving the CCFVM numerical model considering radiation fluid-solid coupling heat transfer, so the error caused by data mapping can be avoided. Solving the thermoelastic equation obtains the displacement field of the solid subdomain 1 composed of the shell 101, and then solving the constitutive equation to obtain the thermal stress field. The unit center temperature (solid structure field temperature) of the solid subdomain 1 and the fluid force on the fluid-solid coupling surface calculated by the CCFVM numerical model of fluid-solid coupling heat transfer considering radiation in the previous article are loaded into the solid structure field, and the fluid-solid coupling stress numerical model based on CVF VM is solved to obtain the thermal stress field and stress field of the solid subdomain 1.

[0044] Finally, the coupling surface displacement obtained by the numerical calculation of the one-way fluid-solid coupling based on CVFVM considering radiation is mapped to the flow field grid as the flow field boundary calculation condition. The dynamic mesh technology is introduced to update the mesh of the fluid subdomain 2, and the flow field is recalculated to complete the calculation of the CVFVM numerical model of bidirectional fluid-solid coupling stress.

[0045] The numerical calculation method of the bidirectional fluid-solid coupling FVM considering radiation is as follows: a numerical model of radiation transmission of non-uniform participating media is established based on CCFVM, a numerical model of heat transfer of fluid-solid coupling considering radiation is established, and a numerical model of CVFVM of bidirectional fluid-solid coupling stress is established, a numerical framework of bidirectional fluid-solid coupling FVM considering radiation is constructed, and a solution program is developed. The advantages of CCFVM in flow field calculation and CVFVM in structural field calculation are fully utilized, and a unified grid model is adopted to avoid errors caused by data mapping between different numerical methods.

Claims

1. A two-way fluid-structure interaction FVM numerical calculation method considering radiation, characterized by: In the first step, the radiation source term and the wall radiation heat flux density calculated from the radiation intensity field in the numerical model of non-uniform participating medium radiation transfer based on CCFVM are introduced into the fluid-solid coupling heat transfer numerical model based on CCFVM. Then, the temperature field calculated by the fluid-solid coupling heat transfer numerical model established based on CCFVM is used to update the radiation intensity field and the radiation physical property parameters of the heterogeneous participating medium. Finally, the radiation intensity field of the non-homogeneous participating medium radiation physical property parameters will be updated and calculated based on the CCFVM to establish the radiation intensity field in the non-uniform participating medium radiation transmission numerical model, and finally the CCFVM numerical model considering the radiation fluid-solid coupling heat transfer will be established; In the second step, the solid structure field temperature and fluid force on the fluid-solid coupling surface calculated by the CCFVM numerical model considering radiation fluid-solid coupling heat transfer are first introduced into the solid structure field stress calculation of the fluid-solid coupling stress numerical model based on CVFVM, and the flow-induced vibration numerical model and thermal-solid coupling numerical model based on CVFVM are established; the above models are then used to solve the thermal stress and stress distribution of the structural field, and a one-way fluid-solid coupling numerical calculation considering radiation based on CVFVM is established; The third step is to transfer the coupling surface displacement obtained by numerical calculation of one-way fluid-solid coupling based on CVFVM considering radiation to the flow field grid of the CCFVM numerical model considering radiation fluid-solid coupling heat transfer, and introduce the dynamic mesh technology to establish the CVFVM numerical model of bidirectional fluid-solid coupling stress. The fourth step is to establish a numerical calculation method for the bidirectional fluid-solid coupling FVM considering radiation based on the CCFVM numerical model considering radiation fluid-solid coupling heat transfer established in the first step and the CVFVM numerical model of bidirectional fluid-solid coupling stress established in the third step, and develop the numerical calculation program for the bidirectional fluid-solid coupling FVM considering radiation using C++ language.

2. The method for numerical calculation of bidirectional fluid-structure coupling FVM considering radiation according to claim 1 is characterized in that: The following steps are used to establish a numerical model calculation method for radiation transfer in non-uniform participating media based on CCFVM; The first step is to calculate the radiation heat transfer of non-uniform participating media based on the method. The method has the radiation heat transfer phenomenon of non-uniform participating media. The medium non-uniformity refers to the spatiotemporal changes of the absorption coefficient, scattering coefficient, and refractive index with temperature. At the same time, the changes of the radiation physical parameters of the medium will affect the heat transfer. The second step is the calculation of thermal radiation based on CCFVM; The third step is to discretize the radiation transfer equation based on CCFVM, store the radiation physical property parameters in the unit center, discretize the solid angle based on CCFVM, calculate the solid angle correlation coefficient and the surface unit coefficient, introduce the change of radiation physical property parameters into the discretization process, and realize the calculation of radiation heat transfer based on CCFVM discretized space solid angle and control equation; The fourth step is to calculate the unit radiation source term and the wall radiation heat flux density and store the calculation results at the unit center.

3. The method for numerical calculation of bidirectional fluid-structure interaction FVM considering radiation according to claim 1 is characterized in that: The calculation method of the CCFVM numerical model considering radiation fluid-solid coupling heat transfer is established using the following steps: The first step is to establish a fluid-solid coupling heat transfer numerical model based on CCFVM. When the temperature is high, it is necessary to calculate the radiation heat transfer; The second step is the calculation based on the CCFVM numerical model considering radiation fluid-solid coupling heat transfer; The third step is to separate the heat conduction equation and energy equation based on the fluid-solid coupling heat transfer numerical model established by CCFVM, define the material property parameters at the center of the grid, and calculate the surface unit coefficients in the discrete equations; The fourth step is to form a calculation coefficient matrix. The radiation source term calculated in the fourth step of (1) is added to the control equation. The fluid subdomain and the solid subdomain are discretized using a unified method, and the coefficients of the two domains are stored in the same matrix to form a unified set of algebraic equations. In the fifth step, the synchronous iterative solution method is combined with the implicit algorithm to establish the CCFVM numerical model calculation method for fluid-solid coupled heat transfer considering radiation, and the solution program is compiled using C++ language.

4. The method for numerical calculation of bidirectional fluid-structure coupling FVM considering radiation according to claim 1 is characterized in that: The calculation method of the fluid-solid coupling stress CVFVM numerical model is established using the following steps: The first step is to establish a numerical model of fluid-solid coupling stress calculation based on CVFVM, including the solid structure stress caused by the pulsating pressure of the flow field and the solid structure thermal stress caused by the temperature field; The solid structure field temperature and fluid force on the fluid-solid coupling surface calculated by the CCFVM numerical model considering radiation fluid-solid coupling heat transfer are introduced into the solid structure field stress calculation of the fluid-solid coupling stress numerical model based on CVFVM, and the flow-induced vibration numerical model and thermal-solid coupling numerical model based on CVFVM are established. In the second step, based on the CVFVM discrete thermal elastic equation, the variables to be solved are stored at the unit nodes, and the physical parameters are stored at the unit center; and the pulsating pressure of the fluid-solid coupling boundary flow field and the unit center temperature of the solid structure field calculated by the CCFVM numerical model of fluid-solid coupling heat transfer considering radiation are extracted; The third step is to form a coefficient matrix; The fourth step is to use the iterative solution method to solve the flow-induced vibration numerical model based on CVFVM, and the direct solution method to solve the thermal-solid coupling numerical model based on CVFVM. Then, the above models are used to solve the thermal stress and stress distribution of the structural field, and a one-way fluid-solid coupling numerical model considering radiation based on CVFVM is established. In the fifth step, the coupling surface displacement obtained by numerical calculation of the one-way fluid-solid coupling based on CVFVM considering radiation is transferred to the flow field mesh of the CCFVM numerical model considering radiation fluid-solid coupling heat transfer, and feedback is loaded to the flow field boundary. The dynamic mesh technology is introduced to update the flow field mesh, and the dynamic mesh technology is introduced to establish the CVFVM numerical model of bidirectional fluid-solid coupling stress.

5. A two-way fluid-structure coupling FVM numerical calculation method considering radiation according to claims 1-4, characterized in that: Based on the CCFVM numerical model of fluid-solid coupling heat transfer considering radiation and the CVFVM numerical model of bidirectional fluid-solid coupling stress, a numerical calculation method of bidirectional fluid-solid coupling FVM considering radiation is established, and a numerical calculation program of the bidirectional fluid-solid coupling FVM considering radiation is developed using C++ language.

6. The use of a two-way fluid-structure coupling FVM numerical calculation method considering radiation according to claims 1-5 is applied to the calculation of a simple gas-gas heat exchanger model, characterized in that: When the numerical model of radiation transfer of inhomogeneous participating media is established based on CCFVM, the low-temperature gas (201) and the high-temperature gas (202) in the fluid subdomain (2) are participating media, and the influence of radiation heat transfer needs to be considered. The heat exchanger shell (101) in the solid subdomain (1) is an opaque medium, and the influence of radiation heat transfer does not need to be considered. VM is used to calculate the fluid-solid coupling stress numerical model. It is necessary to use the CVFVM to separate the thermal elastic equation and extract the unit center temperature, which is exactly the same as the unit center temperature obtained by solving the CCFVM numerical model considering radiation fluid-solid coupling heat transfer. The solid subdomain (1) unit center temperature (solid structure field temperature) and the fluid force on the fluid-solid coupling surface calculated by the CCFVM numerical model considering radiation are loaded into the solid structure field to solve the fluid-solid coupling stress numerical model established based on CVFVM, and the thermal stress field and stress field of the solid subdomain (1) are obtained. The coupling surface displacement obtained by the unidirectional fluid-solid coupling numerical calculation based on CVFVM considering radiation is mapped to the flow field grid as the flow field boundary calculation condition, and the dynamic grid technology is introduced to update the fluid subdomain (2) grid, recalculate the flow field, and complete the calculation of the CVFVM numerical model of bidirectional fluid-solid coupling stress.

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