Heterogeneous geometric equivalence-based anisotropic physical field simulation modeling method and system for complex tube bundle structure of water-cooled wall of boiler

Abstract

The invention discloses an anisotropic physical field simulation modeling method and system for a complex tube bundle structure of a boiler water-cooled wall based on heterogeneous geometric equivalence, and the method comprises the steps: geometrically mapping a hollow circular tube structure with a complex curvature into a regular rectangular entity unit, and carrying out the modeling of an anisotropic physical field of the complex tube bundle structure of the boiler water-cooled wall based on the principles of energy conservation, rigidity conservation and thermal resistance conservation. And a set of complete virtual anisotropic material constitutive model is deduced and established. The model is based on path extension and section correction theories in the tangential direction (X direction), introduces logarithmic thermal resistance equivalence and circular ring curved beam rigidity theories in the radial direction (Y direction), and adopts a bearing area scaling criterion in the axial direction (Z direction); therefore, the equivalent simplified model is highly consistent with an original physical structure in macroscopic thermal resistance, structural rigidity, thermal deformation and three-dimensional shearing behaviors. By means of the method, engineering personnel can reduce the calculation freedom degree by a plurality of orders of magnitude on the premise that the accuracy of key physical characteristics is not sacrificed, and the efficiency of thermal fatigue life evaluation and structure optimization design of the water cooling wall of the supercritical boiler is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the fields of computer-aided engineering (CAE), computational mechanics, and energy and power equipment design technology. Specifically, it relates to an anisotropic equivalent physical field simulation modeling method for complex tube-fin structures such as water-cooled walls of power plant boilers and heat transfer tube bundles of nuclear power plant steam generators. This method is particularly suitable for the analysis of heat conduction, thermal expansion, and thermal stress coupling of large-scale tube bundle structures under high temperature and high pressure conditions. Background Technology

[0002] Industrial Background and Technological Challenges In modern large-scale thermal power plants, the furnace water-cooled walls of supercritical and ultra-supercritical boilers are core pressure-bearing components. Water-cooled walls are typically constructed by welding thousands of steel pipes (with an outer diameter of tens of millimeters) together with flat steel (fins), forming a massive membrane wall structure. During boiler start-up, shutdown, and variable load operation, the water-cooled walls are subjected to the combined effects of high-temperature radiation from the furnace flame, convective cooling of the working fluid within the pipes, and mechanical loads, easily generating complex three-dimensional temperature and thermal stress fields.

[0003] To ensure the safe operation of the boiler, accurate finite element simulation of the water-cooled walls is essential. However, significant geometric and computational challenges arise in engineering practice: Multi-scale geometric contradictions: The overall height of the furnace can reach 60-100 meters, and the width can reach tens of meters, while the wall thickness of the water-cooled tubes is only 5-8 millimeters. If a three-dimensional solid model containing all the details of the curved surfaces of the circular tubes were to be built, the number of meshes would reach billions, which is almost an impossible task under the current computing hardware conditions.

[0004] Meshing is difficult: there is a complex geometric transition at the connection between the circular tube and the fin. Using a tetrahedral mesh will introduce a large number of nodes, while using a hexahedral mesh requires extremely high topology cutting skills and is prone to generating distorted elements, which affects computational convergence.

[0005] Physical field anisotropy: Water-cooled walls exhibit significant geometric directionality. Along the tube axis (Z-direction), there is a continuous fluid channel; along the tangential direction (X-direction), there is a periodic tube-fin-tube structure; and along the radial direction (Y-direction), there is a hollow, thin-walled structure. This geometric non-uniformity leads to strong anisotropy in macroscopic thermal conduction and stiffness characteristics.

[0006] Existing technology and its limitations To address the above issues, existing simplified modeling methods mainly include: Shell element simplification method: The water-cooled wall is simplified into a planar shell element.

[0007] Disadvantages: Shell elements typically assume a linear temperature distribution or no gradient along the thickness direction, making it difficult to accurately simulate the radial thermal stress generated by the huge temperature difference (up to 50℃-100℃) between the inside and outside of the tube wall; and it is difficult to handle the application of convection heat transfer boundary conditions for the fluid inside the tube.

[0008] Isotropic homogenization method: The tube-fin structure is equivalent to an isotropic plate of a certain thickness.

[0009] Disadvantages: Forcibly assuming material isotropy can lead to serious physical distortions. For example, when a real circular tube is subjected to radial compression, its stiffness is much less than that of a solid plate due to the presence of a hollow structure. If it is treated as isotropic, the radial stiffness will be greatly overestimated, resulting in larger calculated results for constraint reaction force and thermal stress, which can mislead the design.

[0010] Porous media models are commonly used in fluid calculations, but lack mature constitutive relation descriptions in solid mechanics analysis.

[0011] Therefore, there is an urgent need for a new modeling method that can both geometrically simplify the complex "circular tube + fin" into a regular "rectangular solid" (which is convenient for dividing into a high-quality hexahedral mesh) and endow it with special anisotropic material properties so that the simplified model can perfectly reproduce the response of the original structure in terms of thermal and mechanical behavior. Summary of the Invention

[0012] To address the problems existing in the prior art, this invention provides a method and system for anisotropic physical field simulation modeling of complex tube bundle structures in boiler water-cooled walls based on heterogeneous geometric equivalence. Through rigorous physical derivation, the hollow circular tube is equivalent to anisotropic solid flat plate. This method can significantly reduce the number of meshes (by more than 90%), greatly shorten the computation time, while maintaining high-accuracy prediction of temperature fields (especially radial gradients) and stress fields (especially structural flexibility).

[0013] Core logic of the technical solution The core idea of ​​this invention is "geometric simplification and property compensation." Geometrically, a circular tube is "flattened" into a flat plate. The resulting deviations in physical response (such as shorter heat transfer paths, larger load-bearing area, and stiffer structural rigidity) are precisely compensated for by artificially modifying material properties (reducing thermal conductivity and elastic modulus). Since the geometric characteristics of a circular tube are completely different in the X, Y, and Z directions, this compensation must be orthotropic.

[0014] This invention establishes the following equivalence criteria: (1) In-plane tangential (X direction): Path and section correction In the X direction, heat or force must be transferred along the curved wall of the circular tube.

[0015] Physical phenomenon: Compared to the straight path of the equivalent rectangle, the actual path is curved, and the actual heat conduction / load bearing section is the annular section of the pipe wall.

[0016] Equivalent strategy: In order to simulate the resistance of a long arc path on a straight path, the thermal conductivity of the equivalent material must be adjusted according to the dimensional parameters of the circular tube and the equivalent flat plate. and modulus .

[0017] (2) Thickness / Radial (Y direction): Structural stiffness and logarithmic thermal resistance Thermal equivalence: The thermal conductivity of the cylindrical wall follows a logarithmic law. However, flat surfaces follow a linear pattern. Adjustments are necessary. This allows both to pass through the same heat flow under the same boundary temperature difference.

[0018] Mechanical Equivalence: When a circular tube is subjected to radial compression, its deformation mechanism is not material compression, but rather the bending of the ring (curved beam). Compared to a solid homogeneous material of the same size, a hollow tube is more easily "flattened." If the modulus of the matrix material is used directly, the equivalent solid plate would be too stiff. This invention utilizes curved beam theory to calculate the radial stiffness of the ring and assigns it to the equivalent plate. This makes It is typically 4 to 6 orders of magnitude smaller than the matrix modulus, thus accurately replicating the "soft" characteristics of hollow tubes.

[0019] (3) Axial direction (Z direction): Area scaling In the Z direction, the structure is continuous, with the main difference being the cross-sectional area.

[0020] Equivalent strategy: To ensure the total axial force and total axial heat flow To maintain balance, the base properties need to be scaled according to the ratio of "actual circular tube cross-sectional area / equivalent rectangular cross-sectional area".

[0021] (4) The integrity of Poisson's ratio To ensure the stability of finite element calculations, the Maxwell-Betti reciprocity theorem must be used. We rigorously derive the sub-Poisson ratio to avoid calculation errors caused by the non-positive definiteness of the stiffness matrix.

[0022] Based on the above equivalence criteria, the present invention adopts the following technical solution: An anisotropic physical field simulation modeling method for complex tube bundle structures in boiler water-cooled walls based on heterogeneous geometric equivalence includes the following steps: S1. Parameter Acquisition and Geometric Definition: Acquire the original geometric parameters and matrix material properties of the target water-cooled wall tube bundle structure; the original geometric parameters include the outer radius of the circular tube. Inner radius of the circular tube fin thickness and the dimensions of the inter-tube fins; the physical properties of the matrix material include isotropic thermal conductivity. Elastic modulus Poisson's ratio Material density and coefficient of thermal expansion Simultaneously, the geometric target parameters of the simplified equivalent model are defined, wherein the simplified equivalent model is the width. Thickness is The solid rectangular plate structure, and the simplified equivalent model is divided into two layers of flat plates in the thickness direction, with a virtual thermal boundary layer in the middle to simulate the cooling effect of the working fluid inside the pipe. S2. Calculation of equivalent parameters in the in-plane tangential direction (X direction): Based on the physical fact that heat flow and stress are transmitted along the arc path of the circular tube wall, the equivalent tangential thermal conductivity is derived and calculated by setting the total thermal resistance and total mechanical compliance of the original circular tube along the arc path to be equal to the total thermal resistance and total mechanical compliance of the equivalent rectangular plate along the straight path. and equivalent tangential elastic modulus ; S3. Calculation of equivalent parameters in the radial direction (Y direction) of thickness: Equivalent equations are established based on the differences between radial heat transfer and structural deformation mechanisms; For thermal conductivity, the equivalent radial thermal conductivity is calculated by setting the radial logarithmic thermal resistance of the original circular tube cross-section equal to the linear thermal resistance in the thickness direction of the equivalent rectangular plate cross-section. ; Regarding mechanical properties, based on the theory of circular ring curved beam deformation, the equivalent radial elastic modulus is calculated by setting the closed-loop stiffness of the original circular tube under radial compression equal to the solid stiffness of the equivalent rectangular plate under thickness compression. ; S4. Calculation of Axial (Z-direction) and Shear Equivalent Parameters: Based on the principle of conservation of cross-sectional bearing capacity, an area scaling factor is introduced by comparing the effective bearing area of ​​the original circular tube cross-section with the cross-sectional area of ​​the equivalent rectangular plate. Calculate the equivalent axial elastic modulus Equivalent axial thermal conductivity And the equivalent shear modulus involving the axial plane; S5. Construction and verification of multidimensional coupling parameters: The rectangular plate structure of the simplified equivalent model has anisotropic Poisson's ratio. The direction of the principal Poisson's ratio is determined according to the mechanical response. Then, based on the Maxwell-Betti reciprocity theorem of orthogonal anisotropic material mechanics, the secondary Poisson's ratio is derived from the calculated principal elastic modulus. A symmetric stiffness matrix is ​​constructed to ensure the stability of numerical calculation. S6. Simulation Model Generation and Solution: Establish the geometric model of the simplified equivalent model in the finite element analysis software, assign the anisotropic material parameters obtained from steps S2 to S5 to the model, apply the thermo-mechanical boundary conditions corresponding to the actual working conditions to solve the problem, and map the calculation results back to the original structure for evaluation. In step S2, the equivalent tangential thermal conductivity and equivalent tangential elastic modulus The calculation formulas are as follows: in, The formula, which represents the average radius of the circular tube, reflects a comprehensive correction for the effects of path extension and cross-sectional area change.

[0023] In step S3, the equivalent radial thermal conductivity The calculation formula is: This formula ensures that the temperature difference from the surface to the center of the equivalent rectangular plate remains consistent with the temperature difference from the outer wall to the inner wall of the original tube at the same heat flux density.

[0024] In step S3, the equivalent radial elastic modulus The formula is derived based on structural stiffness rather than material compressive stiffness, utilizing the radial stiffness formula for a circular ring. The resulting calculation formula is as follows: This parameter is significantly smaller than the matrix modulus. This is to simulate the mechanical properties of hollow tubes that are prone to flattening and deformation.

[0025] In step S4, the equivalent axial elastic modulus Equivalent axial thermal conductivity The calculation is performed using the area equivalence method, and the formula is as follows: The equivalent shear modulus is also scaled according to the above area ratio. .

[0026] In step S5, the construction of the anisotropic Poisson's ratio satisfies the following constraints: Poisson's ratio: ; The formula for calculating Poisson's ratio is as follows: This is to ensure the symmetry of the stiffness matrix and the correct transmission of the Poisson effect in thermal stress calculations.

[0027] The thermal expansion coefficients of the simplified equivalent model are set to be isotropic to those of the base material in the X, Y, and Z directions. Equal, that is To reproduce the free thermal deformation behavior under unconstrained conditions; the density of the simplified equivalent rectangular plate is set as the density of the matrix material. Scaling is performed proportionally based on volume fraction, i.e. .

[0028] A boiler water-cooled wall simulation system for implementing the method includes: Geometric preprocessing module: used to read the parameters of the water-cooled wall tube bundle structure, automatically identify the tube diameter, wall thickness and fin parameters, and generate the geometric model of the rectangular plate in the corresponding simplified equivalent model; Anisotropic parameter calculation engine: Built-in anisotropic equivalent derivation algorithm, which automatically calculates the anisotropic material property table that varies with temperature based on the material library data and geometric parameters input by the user; Finite element solution interface module: Converts the generated geometric model and material property table into an input file format that can be recognized by a general finite element solver, and automatically sets orthogonal anisotropic material cards; The result reconstruction module is used to read the nodal temperature and displacement results of the simplified model and restore the stress distribution cloud map of the original circular tube structure based on the inverse mapping algorithm.

[0029] The general-purpose finite element solver used is ANSYS or ABAQUS.

[0030] A computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of the method described thereon.

[0031] This invention addresses the challenges of large-scale power plant boiler water-cooled walls and other thermo-mechanically coupled systems composed of numerous tube-fin structures. It aims to solve the technical difficulties of traditional all-solid finite element models, such as excessively large mesh sizes, low computational efficiency, and the inability of traditional homogenization methods to accurately capture radial gradients. This invention geometrically maps a hollow circular tube structure with complex curvature to a regular solid rectangular plate structure. Based on the principles of energy conservation, stiffness conservation, and thermal resistance conservation, a complete virtual anisotropic material constitutive model is derived and established. This model is based on path extension and section correction theory in the tangential direction (X-direction), introduces logarithmic thermal resistance equivalence and circular toroidal beam stiffness theory in the radial direction (Y-direction), and adopts a load-bearing area scaling criterion in the axial direction (Z-direction). This ensures a high degree of consistency between the equivalent simplified model and the original physical structure in terms of macroscopic thermal resistance, structural stiffness, thermal deformation, and three-dimensional shear behavior. Compared with existing technologies, this invention has the following advantages: Extremely high computational efficiency: It transforms complex curved surface meshes into regular hexahedral meshes, reducing the degrees of freedom by several orders of magnitude.

[0032] Excellent convergence: It eliminates sharp-corner meshes at the connection between the circular tube and the fin, avoids stress singularities, and achieves extremely stable computational convergence.

[0033] Accurate physical reproduction: Through anisotropic constitutive modeling, the huge radial temperature difference and radial structural flexibility of the water-cooled wall are accurately captured, overcoming the shortcomings of traditional homogenization models.

[0034] Seamless integration: The calculated parameters can be directly input into commercial software such as ANSYS and ABAQUS without the need for secondary development of the solver. Attached Figure Description

[0035] Figure 1 This is a schematic diagram comparing the original structure and the equivalent simplified structure of the water-cooled wall. Detailed Implementation

[0036] The implementation of this invention will be described in detail below with specific physical derivation. This embodiment takes a water-cooled wall of a supercritical boiler as an example, assuming that ANSYS or ABAQUS is used as the simulation platform.

[0037] 1. Geometric Model Construction and Mapping refer to Figure 1 The upper part shows the original cylindrical tube-fin structure, and the lower part shows the simplified double-layer flat plate-fin structure. The original outer diameter is marked in the figure. , inner diameter With equivalent thickness The correspondence.

[0038] The original water-cooled wall consisted of multiple parallel circular tubes and connecting fins.

[0039] Original parameters: tube outer radius Inner radius of the pipe Pipe spacing Matrix material properties: .

[0040] Equivalent model definition: Each circular tube region is simplified into a double-layer flat plate unit, while the fin region retains its original structure and parameters.

[0041] Equivalent width: .

[0042] Equivalent thickness: Double-layer structure: To simulate fluid cooling inside the pipe, the equivalent plate is divided into two layers of equal thickness in the thickness direction (see...). Figure 1 The lower side), the middle interface is defined as the "virtual inner wall surface", and a convective heat transfer coefficient is applied. and fluid temperature .

[0043] 2. Derivation of anisotropy parameters in the X direction In the X direction (parallel to the furnace wall surface), heat flow or stress needs to be transmitted along the curved wall of the circular tube. This path is longer than the straight path in the equivalent rectangle, and its thermally conductive / stress-bearing cross-sectional area is also different from that of the equivalent rectangle.

[0044] Therefore, the most accurate equivalent method is to ensure that the total thermal resistance (for thermal conduction) or total mechanical compliance (for elasticity) of the original circular tube and the equivalent rectangular plate are exactly equal in the X direction.

[0045] According to Fourier's law of thermal conductivity and Hooke's law, thermal resistance and mechanical flexibility The expression for (the reciprocal of stiffness) is identical in form: Thermal resistance: Mechanical flexibility: therefore, and The derivation process is exactly the same.

[0046] 1) Calculate the thermal resistance and compliance in the X direction of the original circular tube. In the original circular tube structure, the path lengths for heat conduction and load bearing are not straight. It is not the length of the semicircle, but the length of the semicircle. Therefore, the average radius is used. The arc length at that point is used as the feature path: Meanwhile, the effective cross-sectional area for load bearing and heat transfer is the pipe wall cross-section (assuming a unit length of pipe axial direction). ): Therefore, the formulas for calculating the thermal resistance and flexibility of the original circular tube are: 2) Calculate the thermal resistance and compliance in the X direction of the equivalent rectangular plate. In the equivalent rectangular plate, the length of the heat conduction and load-bearing path is equal to the width of the equivalent rectangle. The thermally conductive and load-bearing cross-sectional areas are the equivalent rectangular cross-sectional areas (assuming a unit length of...). ). Therefore, the formula for calculating the thermal resistance / compliance of the equivalent rectangle is: 3) Solving for equivalent parameters By order and ,get: Solving for the given information yields the following results: and The final formula: 3. Derivation of anisotropy parameters in the Y direction The Y-direction involves transmission from the outer surface towards the center, which is the core challenge of this invention.

[0047] 3.1 Equivalent thermal conductivity In the Y direction (perpendicular to the furnace wall surface), heat is drawn from the outer surface of the circular tube. Transmitted to inner surface (i.e., the central cooling surface of the simplified equivalent model). This process is typical radial heat conduction. It must be ensured that the thermal resistance of the equivalent rectangle from the outer surface to the central surface is equal to the thermal resistance of the original circular tube from the outer wall to the inner wall.

[0048] According to the radial heat conduction formula of a standard hollow cylinder Only consider width Within the region, the thermal resistance of the upper half of the pipe wall (i.e., half of the total heat flow path through the circular pipe), (assuming a unit length of Its thermal resistance is: For an equivalent rectangular region, heat transfer occurs along the thickness direction of the plate (path length). ,width The thermal resistance is: Solve for the equivalent thermal conductivity by assuming both thermal resistances are equal: Solving for the given information yields: 3.2 Equivalent elastic modulus The mechanical behavior of a circular tube in the y-direction is that of a closed torus curved beam. When the circular tube is subjected to radial compression, it is not that the material is compressed, but rather that it undergoes "elliptic" deformation, and its stiffness is much lower than the material's inherent compressive stiffness. Its resistance to flattening mainly comes from structural bending, rather than material compression. This invention will use a stiffness formula based on the theory of torus curved beams for derivation.

[0049] Based on elasticity theory, its stiffness formula under small deformation is: Among them, the pipe wall thickness Average radius of circular tube Substituting, we get: For the equivalent rectangle (width) ,thickness The total stiffness under compression in the Y direction (assuming a unit length of length) )for: make Solve : Solving for: Significant effect: due to The numerator is a small cube, and the calculated value is... Usually more The difference is 4 to 6 orders of magnitude smaller. This makes the simplified equivalent model very "soft" in the radial direction, which can truly reflect the stress level of the hollow tube when thermal expansion is limited, avoiding the artificially high thermal stress caused by excessive radial stiffness in the traditional model.

[0050] 4. Derivation of anisotropy parameters in the Z direction 4.1 Axial equivalent thermal conductivity Z-direction heat conduction area of ​​the original circular tube Z-direction heat conduction area of ​​equivalent rectangle Before and after equivalence Solving for the results 4.2 Axial equivalent elastic modulus Similar to the solution for thermal conductivity, the equivalent stiffness in the Z direction is conserved before and after the equivalence.

[0051] Z-direction bearing area of ​​the original circular tube Z-direction bearing area of ​​the equivalent rectangle The solution yields: 5. Other physical properties 5.1 Shear modulus: Shear modulus describes a material's resistance to angular deformation. For water-cooled wall structures, the original circular tube cross-sectional area is scaled based on a ratio of the effective load-bearing area. Simplified equivalent model rectangular cross-sectional area Define volume fraction Therefore, the shear modulus of the water-cooled wall model after equivalent calculation based on volume fraction is: 5.2 Density: To ensure that the models before and after equivalence have the same quality, the density of the equivalent structure is also scaled proportionally based on the volume fraction. Therefore, the density of the anisotropic plate after equivalence is... 5.3 Poisson's ratio To ensure that finite element software (such as ANSYS) can solve the problem, the stiffness matrix must be symmetric, i.e., satisfying: The direction (axial direction) is the primary direction of force on the pipe, and the material is continuous steel. When in... When a tube is stretched axially, it will naturally contract in the X and Y directions due to the inherent properties of steel. The Y direction has the lowest stiffness, and when the tube is compressed in the Y direction, it is usually insufficient to cause significant lateral expansion in the X or Z directions.

[0052] Therefore, the principal Poisson ratio is set. .

[0053] Then calculate the required sub-Poisson's ratio: 5.4 Coefficient of thermal expansion The coefficient of thermal expansion is an inherent property of materials. For a component made of a single, homogeneous, isotropic material, regardless of its geometry, the thermal strain caused by temperature changes when unconstrained is the same at all points and in all directions. The goal of the equivalent model is to reproduce this free expansion; therefore, the equivalent coefficient of thermal expansion is equal to the coefficient of thermal expansion of the material itself, i.e.: 6. Simulation Verification and Implementation Process Implementation steps: 1) Data entry: Input the geometric parameters of the water-cooled wall into the calculation script.

[0054] 2) Parameter generation: The script calculates the orthogonal anisotropy parameters based on the above formula.

[0055] 3) Modeling: Create a rectangular plate in the software that alternates between simplified equivalent regions and inherent fin regions.

[0056] 4) Assign weights: Create an anisotropic material model and fill in the calculated values.

[0057] 5) Thermal boundary: Apply fluid convection load to the middle surface of the double-layer plate (simulating the inside of the tube); apply heat flux density to the outer surface of the plate (simulating the furnace flame).

[0058] 6). Solution: Perform thermo-mechanical coupling calculations.

[0059] 7. Conclusion This invention provides a systematic, physics-based equivalent modeling method for complex tube bundle structures. By cleverly constructing anisotropic material properties, a simple rectangular mesh acquires the thermal and mechanical responses of a complex circular tube structure. This not only solves the computational bottleneck problem in simulating ultra-large-scale water-cooled walls, but also significantly improves the physical realism of thermal stress calculations by correcting radial stiffness, possessing extremely high engineering application value.

Claims

1. A simulation modeling method for anisotropic physical fields of complex tube bundle structures in boiler water-cooled walls based on heterogeneous geometric equivalence, characterized in that, The method includes the following steps: S1. Parameter Acquisition and Geometric Definition: Acquire the original geometric parameters and matrix material properties of the target water-cooled wall tube bundle structure; the original geometric parameters include the outer radius of the circular tube. Inner radius of the circular tube fin thickness and the dimensions of the inter-tube fins; the physical properties of the matrix material include isotropic thermal conductivity. Elastic modulus Poisson's ratio Material density and coefficient of thermal expansion Simultaneously, the geometric target parameters of the simplified equivalent model are defined, wherein the simplified equivalent model is the width. Thickness is The solid rectangular plate structure, and the simplified equivalent model is divided into two layers of flat plates in the thickness direction, with a virtual thermal boundary layer in the middle to simulate the cooling effect of the working fluid inside the pipe. S2. Calculation of equivalent parameters in the in-plane tangential direction (X direction): Based on the physical fact that heat flow and stress are transmitted along the arc path of the circular tube wall, the equivalent tangential thermal conductivity is derived and calculated by setting the total thermal resistance and total mechanical compliance of the original circular tube along the arc path to be equal to the total thermal resistance and total mechanical compliance of the equivalent rectangular plate along the straight path. and equivalent tangential elastic modulus ; S3. Calculation of equivalent parameters in the radial direction (Y direction) of thickness: Equivalent equations are established based on the differences between radial heat transfer and structural deformation mechanisms; For thermal conductivity, the equivalent radial thermal conductivity is calculated by setting the radial logarithmic thermal resistance of the original circular tube cross-section equal to the linear thermal resistance in the thickness direction of the equivalent rectangular plate cross-section. ; Regarding mechanical properties, based on the theory of circular ring curved beam deformation, the equivalent radial elastic modulus is calculated by setting the closed-loop stiffness of the original circular tube under radial compression equal to the solid stiffness of the equivalent rectangular plate under thickness compression. ; S4. Calculation of Axial (Z-direction) and Shear Equivalent Parameters: Based on the principle of conservation of cross-sectional bearing capacity, an area scaling factor is introduced by comparing the effective bearing area of ​​the original circular tube cross-section with the cross-sectional area of ​​the equivalent rectangular plate. Calculate the equivalent axial elastic modulus Equivalent axial thermal conductivity And the equivalent shear modulus involving the axial plane; S5. Construction and verification of multidimensional coupling parameters: The rectangular plate structure of the simplified equivalent model has anisotropic Poisson's ratio. The direction of the principal Poisson's ratio is determined according to the mechanical response. Then, based on the Maxwell-Betti reciprocity theorem of orthogonal anisotropic material mechanics, the secondary Poisson's ratio is derived from the calculated principal elastic modulus. A symmetric stiffness matrix is ​​constructed to ensure the stability of numerical calculation. S6. Simulation Model Generation and Solution: Establish the geometric model of the simplified equivalent model in the finite element analysis software, assign the anisotropic material parameters obtained from steps S2 to S5 to the model, apply the thermo-mechanical boundary conditions corresponding to the actual working conditions to solve the problem, and map the calculation results back to the original structure for evaluation.

2. The method according to claim 1, characterized in that, In step S2, the equivalent tangential thermal conductivity and equivalent tangential elastic modulus The calculation formulas are as follows: in, The formula, which represents the average radius of the circular tube, reflects a comprehensive correction for the effects of path extension and cross-sectional area change.

3. The method according to claim 1, characterized in that, In step S3, the equivalent radial thermal conductivity The calculation formula is: This formula ensures that the temperature difference from the surface to the center of the equivalent rectangular plate remains consistent with the temperature difference from the outer wall to the inner wall of the original tube at the same heat flux density.

4. The method according to claim 1, characterized in that, In step S3, the equivalent radial elastic modulus The formula is derived based on structural stiffness rather than material compressive stiffness, utilizing the radial stiffness formula for a circular ring. The resulting calculation formula is as follows: This parameter is significantly smaller than the matrix modulus. This is to simulate the mechanical properties of hollow tubes that are prone to flattening and deformation.

5. The method according to claim 1, characterized in that, In step S4, the equivalent axial elastic modulus Equivalent axial thermal conductivity The calculation is performed using the area equivalence method, and the formula is as follows: The equivalent shear modulus is also scaled according to the above area ratio. .

6. The method according to claim 1, characterized in that, In step S5, the construction of the anisotropic Poisson's ratio satisfies the following constraints: Poisson's ratio: ; The formula for calculating Poisson's ratio is as follows: This is to ensure the symmetry of the stiffness matrix and the correct transmission of the Poisson effect in thermal stress calculations.

7. The method according to claim 1, characterized in that, The thermal expansion coefficients of the simplified equivalent model are set to be isotropic to those of the base material in the X, Y, and Z directions. Equal, that is To reproduce the free thermal deformation behavior under unconstrained conditions; the density of the simplified equivalent rectangular plate is set as the density of the matrix material. Scaling is performed proportionally based on volume fraction, i.e. .

8. A boiler water-cooled wall simulation system for implementing the method according to any one of claims 1 to 7, characterized in that, include: Geometric preprocessing module: used to read the parameters of the water-cooled wall tube bundle structure, automatically identify the tube diameter, wall thickness and fin parameters, and generate the geometric model of the rectangular plate in the corresponding simplified equivalent model; Anisotropic parameter calculation engine: Built-in anisotropic equivalent derivation algorithm, which automatically calculates the anisotropic material property table that varies with temperature based on the material library data and geometric parameters input by the user; Finite element solution interface module: Converts the generated geometric model and material property table into an input file format that can be recognized by a general finite element solver, and automatically sets orthogonal anisotropic material cards; The result reconstruction module is used to read the nodal temperature and displacement results of the simplified model and restore the stress distribution cloud map of the original circular tube structure based on the inverse mapping algorithm.

9. The boiler water-cooled wall simulation system according to claim 1, characterized in that, The general-purpose finite element solver used is ANSYS or ABAQUS.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method steps as described in any one of claims 1 to 7.

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