Simulation method for sealing performance of ceramic grid plate based on thermal-fluid-structure coupling analysis

Abstract

The application discloses a ceramic grid sealing performance simulation method based on thermal fluid-solid coupling analysis, and specifically implements the following steps: step 1, a three-dimensional model of ceramic grid sealing is constructed; step 2, the constructed three-dimensional model of ceramic grid sealing is imported into finite element simulation software, and the three-dimensional model of ceramic grid sealing is regionally divided, divided into a fluid domain and a solid domain, and meshed; step 3, a ceramic grid sealing flow field is set and flow field simulation is performed; and step 4, data obtained through the flow field simulation in step 3 is imported into the solid domain of a structure simulation module to perform solid simulation, and stress, strain and displacement of the ceramic grid and a wall surface are obtained. The application solves the problem that in the prior art, directly meshing the gap between the ceramic grid and the adhered wall surface can easily lead to deviation of simulation results.

Description

Technical Field

[0001] This invention belongs to the technical field of thermal-fluid-structure interaction simulation methods for ceramic grid sealing, and relates to a simulation method for ceramic grid sealing performance based on thermal-fluid-structure interaction analysis. Background Technology

[0002] Aerospace vehicles often encounter extreme temperatures, high pressures, and complex dynamic environments during flight. To ensure stability during high-speed flight, high-performance and reliable sealing systems are essential. The internal working environment of aero-engine nozzles is high-temperature and high-pressure, and there are gaps between rotating and stationary components within the nozzle. Sealing effectively prevents the leakage of high-temperature combustion gases and cooling media. The quality of the seal directly determines the engine's performance, efficiency, and safety. Poor sealing can lead to high-temperature gas leakage, reducing thrust output, increasing fuel consumption, and potentially causing overheating and damage to surrounding components. Furthermore, for nozzles employing thrust vectoring technology, a good seal is fundamental to ensuring flexible nozzle movement and achieving super-maneuverability, while leakage of cooling gases directly affects the cooling effect of hot-end components, jeopardizing engine life and reliability. Therefore, advanced sealing technology is a key element in improving the thrust-to-weight ratio, economy, and safety of aero-engines.

[0003] Ceramic grid seals are a type of contact seal used in aero-engine nozzle sealing. They primarily consist of ceramic grids, bridging elements, springs, a sealing cavity, and a wall surface. Multiple ceramic grids are connected to a compression spring via bridging elements. When the wall surface to be sealed shifts, the thrust generated by the spring pushes the bridging elements and ceramic grids, bringing the grids close to the sealing surface, thus achieving a seal. This type of seal can self-seal if there is a pressure difference between the internal and external pressures. It is heat-resistant, does not easily oxidize, does not easily experience frictional wear, has a low leakage rate, good resilience, and good vibration resistance.

[0004] Ceramic grilles possess initial sealing and self-sealing capabilities, but leaks can still occur at a microscopic scale. Leakage paths in ceramic grille seals can be categorized into gap leaks and contact leaks. Gap leaks occur primarily between the top of the ceramic grille and the separating wall, and between the front end of the sealing grille and the adjacent engine separating wall; these two paths are relatively frequent and constitute the main leakage paths. Contact leaks occur between ceramic grilles and are the same length and width as the grilles themselves.

[0005] Finite element method (FEM) simulation is currently the primary method for studying the performance of ceramic grid seals, including leakage. It offers advantages such as controllable accuracy, visualized results, and low cost. In reality, the gap between the ceramic grid and the mating wall is approximately 0.01 mm. Direct modeling makes it difficult to define the fluid domain, and errors in mesh generation can easily occur, leading to deviations in the simulation results. Summary of the Invention

[0006] The purpose of this invention is to provide a simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis, which solves the problem in the prior art that directly dividing the gap between the ceramic grid plate and the mating wall surface into meshes can easily lead to deviations in the simulation results.

[0007] The technical solution adopted in this invention is a simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis, which is implemented according to the following steps:

[0008] Step 1: Construct a 3D model of the ceramic grid plate seal; Step 2: Import the constructed three-dimensional model of the ceramic grid seal into the finite element simulation software, and divide the three-dimensional model of the ceramic grid seal into fluid domain and solid domain and perform mesh generation. Step 3: Set up the flow field for the ceramic grid sealing and perform flow field simulation; Step 4: Import the data obtained from the flow field simulation in Step 3 into the solid domain of the structural simulation module to perform solid simulation and obtain the stress, strain and displacement of the ceramic grid plate and the wall.

[0009] Furthermore, the three-dimensional model of the ceramic grid seal includes the wall, the ceramic grid, and the fluid domain. The three-dimensional model of the ceramic grid seal conforms to the actual size of the ceramic grid seal structure and the gap between the ceramic grid and the wall is enlarged tenfold for modeling. The fluid domain of the three-dimensional model of the ceramic grid seal is all the areas through which air flows from the inlet to the outlet.

[0010] Furthermore, in step 2, when dividing the region, the ceramic grid plate and the wall surface are divided into a solid domain, and the fluid domain is divided into a pure fluid domain and a porous medium domain. The porous medium domain is the gap between the ceramic grid plate and the wall surface, and the pure fluid domain is the fluid domain excluding the porous medium domain. All surfaces in contact with the fluid and the ceramic grid plate and the wall surface are defined as fluid-structure interaction surfaces.

[0011] Furthermore, in step 2, when meshing, meshes are generated for the pure fluid domain, the porous medium region, and the solid domain, and the hexahedral-dominated method is used to refine the mesh of the fluid-structure interaction surface.

[0012] Further, in step 3, the flow field of the ceramic grid sealing is set in the flow field setting module. When setting the flow field of the ceramic grid sealing, air is selected as the fluid material, and the density parameter of air is changed from a constant to a piecewise linear value. Then, at least two temperature points and two intermediate points are selected between 25-1000℃. Then, the air density function curve from 25℃ to 1000℃ is fitted with the temperature change. The same settings are made for the heat capacity, viscosity, and thermal conductivity parameters. At least two temperature points and two intermediate points are selected between 25-1000℃. Then, the air specific heat capacity, viscosity, and thermal conductivity function curves from 25℃ to 1000℃ with the temperature change are fitted respectively. The porous medium region is changed from the solid to the fluid interior, and the resistance coefficient of the porous medium is calculated according to the formula of the porous medium resistance coefficient. It is divided into viscous resistance coefficient and inertial resistance coefficient. Then the resistance coefficient and porosity of the porous medium are set. Change the inlet type to a pressure inlet, set the pressure to 0.6 MPa, the inlet temperature to 600℃, the initialization scheme to standard initialization, set the number of steps to 1000, start the simulation, and obtain the flow field simulation data, including the flow field pressure cloud map, velocity cloud map, trace cloud map, temperature cloud map, and leakage rate.

[0013] Furthermore, given porosity = 1, the formula for the viscous resistance coefficient of porous media is:

[0014] in, h In a real-world scenario, the porous media region refers to the gap width between the ceramic grid and the wall, expressed in meters (m). μ The value is the aerodynamic viscosity, expressed in Pa·s.

[0015] Because the Reynolds number of the fluid in the narrow gap is small, the inertial drag is set to 10. 4 .

[0016] Further, step 4 specifically involves: importing the data obtained from the flow field simulation in step 3 into the solid domain of the structural simulation module, inserting the imported geometric temperature and pressure into the imported load, and selecting the fluid-structure interaction surface as the data transmission surface to complete the transmission of the flow field simulation data to the structural simulation module. Fixed constraints are applied to the wall surface and the top surface of the ceramic grid, while elastic supports are applied to the bottom surface of the ceramic grid. The foundation stiffness is set to 0.5 N / m. 3 After adding total stress, total strain, and total displacement to the solution options, start the solid simulation to obtain the stress, strain, and displacement of the ceramic grid plate and the wall.

[0017] Furthermore, steps 3-4 are repeated to obtain the stress, strain, and displacement of the ceramic grid plate and wall under different working conditions by setting different data.

[0018] Furthermore, it also includes optimizing the mesh density, porous media resistance parameters, and calculation step size based on the simulation results. Specifically, if the simulated leakage result is more than 5 g / s / m higher than the actual value, the mesh density is increased or the viscous resistance coefficient in the porous media resistance coefficient is increased; if the simulated leakage result is more than 5 g / s / m lower than the actual value, the viscous resistance coefficient in the porous media resistance coefficient is decreased; if the calculation results do not converge, the number of calculation steps is increased.

[0019] The beneficial effects of this invention are: A simulation method for ceramic grid sealing performance based on thermo-fluid-structure interaction analysis is provided. By introducing a porous medium, this method solves the problem in existing technologies where directly meshing the gap between the ceramic grid and the mating wall can easily lead to deviations in the simulation results. This simulation method can also obtain results under different operating conditions by changing the inlet pressure and inlet temperature, allowing for a direct assessment of the ceramic grid seal performance under various conditions. Attached Figure Description

[0020] Figure 1 This is a flowchart of the simulation method for the sealing performance of ceramic grid plates based on thermal-fluid-structure interaction analysis according to the present invention; Figure 2 This is a three-dimensional geometric model of the ceramic grid plate seal in Embodiment 7 of the present invention; Figure 3 This is a fluid domain division diagram of the ceramic grid plate seal in Embodiment 7 of the present invention; Figure 4 This is a solid domain partitioning diagram of the ceramic grid plate seal in Embodiment 7 of the present invention; Figure 5 This is a fluid domain mesh partitioning diagram of the ceramic grid plate seal in Embodiment 7 of the present invention; Figure 6 This is a solid domain mesh partitioning diagram of the ceramic grid plate seal in Embodiment 7 of the present invention; Figure 7 This is a flow field pressure cloud diagram of the ceramic grid seal in Embodiment 7 of the present invention; Figure 8 This is a flow field velocity cloud map of the ceramic grid seal in Embodiment 7 of the present invention; Figure 9 This is a flow field trace cloud diagram of the ceramic grid seal in Embodiment 7 of the present invention; Figure 10 This is a flow field temperature cloud map of the ceramic grid seal in Embodiment 7 of the present invention; Figure 11 This is a displacement diagram of the solid domain sealed by the ceramic grid plate in Embodiment 7 of the present invention. Detailed Implementation

[0021] The following detailed description is provided in conjunction with specific implementation methods.

[0022] Example 1 This invention presents a simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis, the process of which is as follows: Figure 1 As shown, the specific steps are as follows: Step 1: Construct a 3D model of the ceramic grid plate seal; Step 2: Import the constructed three-dimensional model of the ceramic grid seal into the finite element simulation software, and divide the three-dimensional model of the ceramic grid seal into fluid domain and solid domain and perform mesh generation. Step 3: Set up the flow field for the ceramic grid sealing and perform flow field simulation; Step 4: Import the data obtained from the flow field simulation in Step 3 into the solid domain of the structural simulation module to perform solid simulation and obtain the stress, strain and displacement of the ceramic grid plate and the wall.

[0023] Example 2 Based on Example 1, the three-dimensional model of the ceramic grid seal includes the wall, the ceramic grid, and the fluid domain. The three-dimensional model of the ceramic grid seal conforms to the size of the actual ceramic grid seal structure and the gap between the ceramic grid and the wall is enlarged tenfold for modeling. The fluid domain of the three-dimensional model of the ceramic grid seal is all the areas through which air flows from the inlet to the outlet.

[0024] Each ceramic grid plate is 18mm long, 12mm wide, and 3mm thick. The fluid domain is 12.2mm long, 9mm wide, and 32.1mm high. The gas inlet and outlet are 3mm high.

[0025] Example 3 Based on Example 2, when dividing the region in step 2, the ceramic grid plate and the wall surface are divided into solid domains, and the fluid domain is divided into pure fluid domains and porous media domains. The porous media domain is the gap between the ceramic grid plate and the wall surface, and the pure fluid domain is the fluid domain excluding the porous media domain. All surfaces in contact with the fluid and the ceramic grid plate and the wall surface are defined as fluid-structure interaction surfaces.

[0026] In step 2, meshing is performed on the pure fluid domain, the porous medium region, and the solid domain. The fluid domain has approximately 540,000 meshes, and the solid domain has approximately 370,000 meshes. The hexahedral-dominated method is used to refine the mesh on the fluid-structure interaction surface.

[0027] Example 4 Based on Example 3, in step 3, the flow field of the ceramic grid sealing is set in the flow field setting module. When setting the flow field of the ceramic grid sealing, the continuity equation, mass conservation equation and momentum conservation equation in the finite element simulation software are enabled by default, while the energy conservation equation needs to be manually enabled. After enabling, the inlet temperature can be set.

[0028] Using air as the fluid material, the density parameter of air was modified from a constant to a piecewise linear value. Then, at least two temperature points, including two endpoints and two intermediate points, were selected between 25 and 1000℃. The air density function curve was then fitted from 25℃ to 1000℃ as a function of temperature. The same settings were applied to the heat capacity, viscosity, and thermal conductivity parameters, selecting at least two endpoints and two intermediate temperature points between 25 and 1000℃. The specific heat capacity, viscosity, and thermal conductivity function curves of air as a function of temperature were then fitted from 25℃ to 1000℃. The porous medium region is changed from the solid to the fluid interior, and the resistance coefficient of the porous medium is calculated according to the formula of the resistance coefficient of the porous medium. Then the resistance coefficient and porosity of the porous medium are set. Change the inlet type to a pressure inlet, set the pressure to 0.6 MPa, the inlet temperature to 600℃, the initialization scheme to standard initialization, set the number of steps to 1000, start the simulation, and obtain the flow field simulation data, including the flow field pressure cloud map, velocity cloud map, trace cloud map, temperature cloud map, and leakage rate.

[0029] The formula for calculating the continuity of gas flow is:

[0030]

[0031]

[0032] In the formula, λ The mean free path of the molecule is m; L t denoted as the characteristic size of the flow region, in meters (m); k is the Boltzmann constant, 1.381 × 10⁻⁶. -23 J / K; T Let K be the gas temperature. p σ is the gas pressure, Pa; σ is the diameter of an air molecule, 3.53 × 10⁻⁶. -10 m; A The cross-sectional area of ​​the flow path is m 2 ; Z Let be the length of the perimeter line where the fluid contacts the wall at the cross-section, in meters (m). V For the leakage path volume m 3 ; S The total surface area of ​​the solid wall in contact with the fluid is m. 2 .

[0033] The mass conservation equation is:

[0034] In the formula, ρ The fluid density is expressed in kg / m³. This is the velocity vector.

[0035] The momentum conservation equation is:

[0036] Expanding the formula into a third-order equation yields the component equations for the three directions:

[0037] In the formula, p For pressure, N; μ The viscosity is the fluid dynamic viscosity, Pa·s; g For gravity, N.

[0038] The energy conservation equation is:

[0039] In the formula, ρ The fluid density is expressed in kg / m³. T Temperature, °C; Specific heat capacity at constant pressure, J / (kg·K); k The thermal conductivity is W / (m·K); This is the viscous dissipation term, W / m³.

[0040] Since the system defaults to the porous media region being solid, the porous media region is changed from solid to fluid interior, and the resistance coefficient and porosity of the porous media are set. The derivation of the formula for the viscous resistance coefficient of porous media with porosity = 1 is as follows: For a laminar flow channel with parallel narrow slits on both walls, the volumetric flow rate per unit width is related to the pressure gradient as follows:

[0041] in, h In a real-world scenario, the porous media region refers to the gap width between the ceramic grid and the wall, expressed in meters (m). μ Aerodynamic viscosity, expressed in Pa·s. dp This is the change in pressure, expressed in Pa. dx This represents the change in distance along the flow direction, expressed in meters (m).

[0042] The average speed can be obtained as:

[0043] Darcy's Law is:

[0044] Comparing the two equations yields the equivalent permeability: .

[0045] The formula for the viscous drag coefficient of porous media is:

[0046] in, h In a real-world scenario, the porous media region refers to the gap width between the ceramic grid and the wall, expressed in meters (m). μ The value is the aerodynamic viscosity, expressed in Pa·s.

[0047] Because the Reynolds number of a narrow-gap fluid is small, the inertial drag can be set to 10. 4 .

[0048] The Knudsen number (Kn) can be used to calculate the flow continuity of the sealing gas in the ceramic grid sealing gap. Kn < 0.01 indicates a continuous flow region, where the gas can be considered a continuous medium; 0.01 ≤ Kn < 0.1 indicates a slip flow region, requiring correction using slip boundary conditions; 0.1 ≤ Kn < 10 indicates a transitional flow region, where the continuous medium theory fails; Kn ≥ 10 indicates a free molecular flow region, where molecules mainly collide with the wall. The formula for calculating the Kn number is as follows:

[0049]

[0050]

[0051] In the formula, λ The mean free path of the molecule is m; L t denoted as the characteristic size of the flow region, in meters (m); k is the Boltzmann constant, 1.381 × 10⁻⁶. -23 J / K; T Let K be the gas temperature. p σ is the gas pressure, Pa; σ is the diameter of an air molecule, 3.53 × 10⁻⁶. -10 m; A The cross-sectional area of ​​the flow path is m 2 ; Z Let be the length of the perimeter line where the fluid contacts the wall at the cross-section, in meters (m). V Let m be the volume of the leakage path. 3 ; S The total surface area of ​​the solid wall in contact with the fluid is m. 2 .

[0052] The flow state of the sealing gas in the ceramic grid sealing gap can be determined by the Reynolds number (Re). If the Reynolds number Re between parallel plates is less than 1000, the fluid is in a laminar flow state.

[0053]

[0054] In the formula, ρ Fluid density, kg / m³ 3 ; v The average flow velocity of the fluid is given in m / s. L t The characteristic length of the flow region is in meters (m). μ ρ is the fluid dynamic viscosity, Pa·s.

[0055] In a ceramic grid-sealed fluid domain, fluid flow between planes must also satisfy the mass conservation equation, momentum conservation equation, and energy conservation equation. The mass conservation equation is:

[0056] In the formula, ρ The fluid density is expressed in kg / m³. This is the velocity vector.

[0057] The momentum conservation equation is:

[0058] Expanding the formula into a third-order equation yields the component equations for the three directions:

[0059] In the formula, p For pressure, N; μ The viscosity is the fluid dynamic viscosity, Pa·s; g For gravity, N.

[0060] The energy conservation equation is:

[0061] In the formula, ρ The fluid density is expressed in kg / m³. T Temperature, °C; Specific heat capacity at constant pressure, J / (kg·K); k The thermal conductivity is W / (m·K); This is the viscous dissipation term, W / m³.

[0062] Example 5 Based on Example 4, step 4 specifically involves: importing the data obtained from the flow field simulation in step 3 into the solid domain of the structural simulation module, inserting the imported geometric temperature and pressure into the imported load, and selecting the fluid-structure interaction surface as the data transmission surface to complete the transmission of the flow field simulation data to the structural simulation module. Fixed constraints are applied to the wall surface and the top surface of the ceramic grid, while elastic supports are applied to the bottom surface of the ceramic grid. The foundation stiffness is set to 0.5 N / m. 3 After adding total stress, total strain, and total displacement to the solution options, start the solid simulation to obtain the stress, strain, and displacement of the ceramic grid plate and the wall.

[0063] Example 6 Based on Example 5, steps 3-4 are repeated to obtain the stress, strain, and displacement of the ceramic grid plate and wall under different working conditions by setting different data.

[0064] It also includes optimizing the grid density, porous media resistance parameters, and calculation step size based on the simulation results. Specifically, if the simulated leakage rate is more than 5 g / s / m higher than the actual value, the grid density is increased or the viscous resistance coefficient in the porous media resistance coefficient is increased. If the simulated leakage rate is more than 5 g / s / m lower than the actual value, the viscous resistance coefficient in the porous media resistance coefficient is decreased. If the calculation results do not converge, the number of calculation steps is increased.

[0065] Example 7 Based on Example 6, the three-dimensional model of the ceramic grid plate seal in step 1 is established in three-dimensional modeling software, such as... Figure 2 As shown. Because the contact gap between the ceramic grid plate and the wall surface is very small, making mesh generation difficult, the gap is enlarged tenfold, and the fluid domain within the enlarged gap is designed as a porous medium region, such as... Figure 3 As shown, a hexahedral-dominant method was used to mesh the fluid and solid domains of the ceramic grid seal, and the mesh was refined at the coupling surfaces, as shown. Figures 5-6 As shown.

[0066] In step 3, the porous medium region is set as the fluid interior, and the porous medium resistance coefficient is defined. The derivation process of the formula for the viscous resistance coefficient of the porous medium is as follows: For a laminar flow channel with parallel narrow slits on both walls, the volumetric flow rate per unit width is related to the pressure gradient as follows:

[0067] in, h In a real-world scenario, the porous media region refers to the gap width between the ceramic grid and the wall, expressed in meters (m). μ Aerodynamic viscosity, expressed in Pa·s. dp This is the change in pressure, expressed in Pa. dx This represents the change in distance along the flow direction, expressed in meters (m).

[0068] The average speed can be obtained as:

[0069] Darcy's Law is:

[0070] Comparing the two equations yields the equivalent permeability:

[0071] The formula for the viscous drag coefficient of porous media is:

[0072] in, h In a real-world scenario, the porous media region refers to the gap width between the ceramic grid and the wall, expressed in meters (m). μ The value is the aerodynamic viscosity, expressed in Pa·s.

[0073] Because the Reynolds number of a fluid in a narrow gap is small, the inertial drag can be set to a small number, such as 10. 4 The porosity is taken as 1.

[0074] The inlet pressure was set to 0.6 MPa, the inlet temperature to 600℃, and the outlet pressure to 0.1 MPa. These parameters can be adjusted as needed. The SIMPLE method was used for calculation, with standard initialization. The calculation began after 1000 steps. After the calculation, pressure, velocity, trace, and temperature contour maps of the ceramic grid sealing flow field were obtained, as shown below. Figures 7-10 As shown, the leakage rate is 5.6074 (g / s·m).

[0075] Step four, the analysis of the solid structure based on finite element simulation software, first involves importing the calculation parameters of the fluid domain into the structural calculation module, selecting the fluid-structure interaction surface and applying the pressure and temperature generated by the corresponding fluid surface, setting fixed and elastic supports, and calculating the deformation of the ceramic grid plate, such as... Figure 11 As shown, the deformation trend of the ceramic grid plate can be seen from the deformation amount, which can be used to determine whether it meets the sealing requirements under this working condition.

Claims

1. A simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis, characterized in that, The specific steps are as follows: Step 1: Construct a 3D model of the ceramic grid plate seal; Step 2: Import the constructed three-dimensional model of the ceramic grid seal into the finite element simulation software, and divide the three-dimensional model of the ceramic grid seal into fluid domain and solid domain and perform mesh generation. Step 3: Set up the flow field for the ceramic grid sealing and perform flow field simulation; Step 4: Import the data obtained from the flow field simulation in Step 3 into the solid domain of the structural simulation module to perform solid simulation and obtain the stress, strain and displacement of the ceramic grid plate and the wall.

2. The simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis according to claim 1, characterized in that, The three-dimensional model of the ceramic grid seal includes the wall, the ceramic grid, and the fluid domain. The three-dimensional model of the ceramic grid seal conforms to the size of the actual ceramic grid seal structure and the gap between the ceramic grid and the wall is enlarged by ten times for modeling. The fluid domain of the three-dimensional model of the ceramic grid seal is all the areas through which air flows from the inlet to the outlet.

3. The simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis according to claim 2, characterized in that, In step 2, when dividing the region, the ceramic grid plate and the wall surface are divided into a solid domain, and the fluid domain is divided into a pure fluid domain and a porous medium domain. The porous medium domain is the gap between the ceramic grid plate and the wall surface, and the pure fluid domain is the fluid domain excluding the porous medium domain. All surfaces in contact with the fluid and the ceramic grid plate and the wall surface are defined as fluid-structure interaction surfaces.

4. The simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis according to claim 3, characterized in that, In step 2, meshing is performed on the pure fluid domain, porous medium region, and solid domain, and the mesh is refined on the fluid-structure interaction surface using a hexahedral-dominant method.

5. The simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis according to claim 4, characterized in that, In step 3, the flow field for sealing the ceramic grid plate is set in the flow field setting module. When setting the flow field for sealing the ceramic grid plate, air is selected as the fluid material. The density parameter of air is changed from a constant to a piecewise linear value. Then, at least two temperature points and two intermediate points are selected between 25-1000℃. Then, the air density function curve from 25℃ to 1000℃ is fitted with the temperature change. The same settings are made for the heat capacity, viscosity, and thermal conductivity parameters. At least two temperature points and two intermediate points are selected between 25-1000℃. Then, the air specific heat capacity, viscosity, and thermal conductivity function curves from 25℃ to 1000℃ with the temperature change are fitted respectively. The porous medium region is changed from the solid to the fluid interior, and the resistance coefficient of the porous medium is calculated according to the formula of the porous medium resistance coefficient. It is divided into viscous resistance coefficient and inertial resistance coefficient. Then the resistance coefficient and porosity of the porous medium are set. Change the inlet type to a pressure inlet, set the pressure to 0.6 MPa, the inlet temperature to 600℃, the initialization scheme to standard initialization, set the number of steps to 1000, start the simulation, and obtain the flow field simulation data, including the flow field pressure cloud map, velocity cloud map, trace cloud map, temperature cloud map, and leakage rate.

6. The simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis according to claim 5, characterized in that, The porosity is 1, and the formula for the viscous resistance coefficient of the porous medium is: in, h In a real-world scenario, the porous media region refers to the gap width between the ceramic grid and the wall, expressed in meters (m). μ The aerodynamic viscosity is expressed in Pa·s. Due to the small Reynolds number of the narrow-gap fluid, the inertial resistance is set to 10 4 .

7. The simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis according to claim 6, characterized in that, Step 4 specifically involves: importing the data obtained from the flow field simulation in step 3 into the solid domain of the structural simulation module, inserting the imported geometric temperature and pressure into the imported load, and selecting the fluid-structure interaction surface as the data transmission surface to complete the transmission of the flow field simulation data to the structural simulation module. The fixed constraint is set for the wall surface and the top surface of the ceramic grid plate, the elastic support is set for the bottom surface of the ceramic grid plate, and the foundation stiffness is set to 0.5 N / m 3 After adding the total stress, total strain and total displacement in the solving options, the solid simulation is started, and the stress, strain and displacement of the ceramic grid plate and the wall surface are obtained.

8. The simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis according to claim 7, characterized in that, It also includes repeating steps 3-4 to obtain the stress, strain, and displacement of the ceramic grid plate and wall under different working conditions by setting different data.

9. The simulation method for the sealing performance of ceramic grid plates based on thermo-fluid-structure interaction analysis according to claim 8, characterized in that, It also includes optimizing the grid density, porous media resistance parameters, and calculation step size based on the simulation results. Specifically, if the simulated leakage result is more than 5 g / s / m larger than the actual value, the grid density is increased or the viscous resistance coefficient in the porous media resistance coefficient is increased. If the simulated leakage result is more than 5 g / s / m smaller than the actual value, the viscous resistance coefficient in the porous media resistance coefficient is decreased. If the calculation results do not converge, the number of calculation steps is increased.

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