Heat-fluid-solid coupling analysis method for worm and worm gear pair

Abstract

A worm and worm gear pair heat-fluid-solid coupling analysis method comprises the following steps that 1, a heat-fluid-solid coupling simulation analysis model of a worm and worm gear pair is built, and a three-dimensional geometric model is built based on the worm and worm gear meshing principle; 2, parameterized grid division is carried out on the simulation analysis model, a tetrahedral unstructured grid is adopted for a fluid domain, and a worm and worm gear tooth surface area is densified; 3, based on the fluid dynamics theory and an RNG # imgabs0 # turbulence model, establishing an oil-immersed lubricating oil gas two-phase flow transient simulation model, and solving fluid dynamic pressure and a convective heat transfer coefficient through a pressure-speed coupling algorithm; 4, establishing a three-dimensional transient dynamic simulation model based on a solid mechanics theory, combining a temperature-stress coupling field equation, adopting an explicit dynamic algorithm, and iteratively solving thermal deformation and stress strain of the worm and the worm gear through a finite element method; and 5, bidirectionally transmitting the pressure of the fluid domain, the convective heat transfer coefficient and the thermal deformation data of the solid domain through the fluid-solid interface, and carrying out iterative solution until convergence.

Description

Technical Field

[0001] The invention belongs to the technical field of worm and worm gear transmission, and specifically relates to a thermal-fluid-solid coupling analysis method for a worm and worm gear pair. Background Art

[0002] In worm and worm gear transmissions, the main factors that cause the worm and worm gear system to fail are wear, pitting, and bonding. Lubrication and cooling of the worm and worm gear system is an effective way to avoid wear, pitting, and bonding. During the operation of the worm and worm gear system, the relative sliding speed between the worm and worm gear pairs is relatively high, which causes high temperatures to be easily generated between the meshing tooth surfaces of the worm and worm gear, which will inevitably affect the oil immersion lubrication characteristics of the system. At the same time, the internal flow field also directly affects the convective heat transfer and temperature field distribution of the worm and worm gear system, thereby causing structural thermal deformation. The thermal deformation of the gear teeth changes the tooth side clearance and flow field pressure characteristics. Domestic and foreign scholars have conducted a large number of theoretical analyses and experimental verifications on the flow field, structural field, and temperature field distribution of the worm and worm gear system. The analysis method has gradually evolved from a single flow field, temperature field, and structural field analysis to a multi-field coupling analysis. However, the coupling between multiple fields in existing research is mostly one-way, that is, the influence of one physical field on another physical field (for example, only the data of the fluid field is imported into the structural field, but the data in the structural field is not fed back to the fluid field). This fails to couple the interactions of multiple physical fields such as structure, heat, and fluid, resulting in significant deviations between the simulation results and the measured data, making it difficult to support high-reliability design. Especially under extreme working conditions, problems such as bonding and pitting caused by the failure of thermal-mechanical coupling and rupture of the lubricating film are frequent. Therefore, performing a thermal-fluid-solid multi-field coupling analysis of the worm and worm gear pair can more accurately predict the changing states of the flow field, temperature field, and structural field of the worm and worm gear system, so as to more realistically simulate the actual working state of the worm and worm gear, and provide an important reference for further improving the meshing performance, reducing meshing impact, and reducing noise. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a thermal-fluid-solid coupling analysis method for a worm gear pair, which can reflect the mutual influence between the temperature field, flow field and structural field under the actual operation of the worm gear system, and perform a bidirectional coupling analysis between multiple physical fields of the worm gear.

[0004] In order to achieve the above object, the present invention provides the following technical solutions: A thermal-fluid-solid coupling analysis method for a worm gear pair includes the following steps: Step 1: Build a simulation model Establish a thermal-fluid-solid coupling simulation analysis model for a worm gear pair, including the worm, worm gear, and housing, and construct a three-dimensional geometric model based on the worm and worm gear meshing principle; Step 2: Meshing Performing parameterized meshing on the simulation analysis model, using tetrahedral unstructured meshes for the fluid domain and encrypting the tooth surface area of the worm and worm wheel; Step 3: Thermal-fluid coupling analysis of worm and worm gear pairs Based on fluid dynamics theory and RNG Turbulence model, establish a transient simulation model of oil-immersed lubricating oil-gas two-phase flow, and solve the fluid dynamic pressure and convective heat transfer coefficient through the pressure-velocity coupling algorithm; Step 4: Thermo-mechanical coupling analysis of worm and worm gear pairs A three-dimensional transient dynamics simulation model is established based on solid mechanics theory. The temperature-stress coupled field equations are solved simultaneously. An explicit dynamics algorithm is used to iteratively solve the thermal deformation and stress-strain of the worm and worm gear using the finite element method. Step 5: Bidirectional data transmission at the fluid-solid interface The pressure, convective heat transfer coefficient of the fluid domain and thermal deformation data of the solid domain are bidirectionally transferred through the fluid-solid interface to perform a bidirectional thermal fluid-solid coupling analysis, and the solution is iteratively solved until convergence.

[0005] Furthermore, in step 1, the method for constructing the three-dimensional geometric model includes: Generate worm gear tooth surface guide lines in MATLAB; Import the model into Solidworks software and generate the worm and worm gear model through scanning, cutting and Boolean operation.

[0006] Furthermore, in step three, the method steps for thermal-fluid coupling analysis of the worm and worm gear pair are as follows: 31) Import the mesh file of the worm gear pair and check the mesh quality to exclude negative volume and highly distorted mesh; 32) Select pressure-based or density-based solver, set transient time type, and activate RNG Turbulence models, multiphase flow models and energy equations, defining the coupled relationship between flow and heat transfer; 33) Set fluid material properties, including density, viscosity and specific heat capacity; 34) Configure boundary conditions, define the inlet, outlet, wall and symmetry boundary types, set turbulence parameters and associate dynamic mesh parameters; 35) Select the pressure-velocity coupling algorithm, set the relaxation factor and convergence criterion, solve the continuity equation and momentum equation to update the flow field data; 36) Repeatedly solve the momentum equation, energy equation and RNG Turbulence model, monitor the residual curve and the stability of the monitoring points until the convergence conditions are met.

[0007] Furthermore, the RNG The turbulence model defines the eddy viscosity via the following equation: in: is the eddy viscosity; is a constant; is the mass density; is the turbulent kinetic energy; is the turbulent dissipation rate; The RNG The transport equation of the turbulence model is: in: represents the turbulent kinetic energy due to velocity gradient; represents the turbulent kinetic energy induced by buoyancy; The effect of turbulent pulsation expansion behavior on dissipation rate in the flow field is described; 、 and is the model constant; and Respectively and The reciprocal of the effective Prandtl number; Indicates the improvement factor of simulation accuracy; For displacement.

[0008] Furthermore, the continuity equation is: The momentum equation is: The energy equation is: in: is the mass density; is the speed; subscript Indicates the direction of Cartesian coordinates; is the local static pressure; is viscosity; represents the Reynolds stress tensor; is the fluid temperature; is the effective thermal conductivity; is the Laplace operator; is viscous dissipation.

[0009] Furthermore, the heat transfer coupling relationship is: in: is the heat transfer coefficient; is the heat transfer area; is the average temperature difference of heat transfer.

[0010] Furthermore, in step 4, the method steps for thermo-mechanical coupling analysis of the worm and worm gear pair are as follows: 41) Import the mesh file and check the mesh quality indicators including Jacobi and aspect ratio to ensure calculation stability; 42) Define the material constitutive model including elastic modulus, Poisson's ratio and thermal expansion coefficient, and set the physical property parameters; 43) Establish contact pairs and configure friction coefficients, and define displacement and heat flow transfer conditions in the fluid-solid coupling interface area; 44) Apply dynamic load boundary conditions, including worm speed, worm gear resistance torque, fixed support constraint and pressure load constraint; 45) Simultaneously solve the temperature-stress coupled field equations and use explicit dynamics algorithm to iteratively solve thermal deformation, stress strain and temperature distribution; 45) Calculate the total deformation and heat flux density under thermoelastic coupling by finite element method until convergence.

[0011] Furthermore, the explicit dynamics algorithm is a solid part conservation equation, which is expressed as: in: is the density of the solid; is the Cauchy stress tensor; is the body force vector; is the local acceleration vector of the solid domain; The thermal expansion coefficient in the material constitutive model is defined as: in: is the average linear expansion coefficient; is the initial temperature; The initial length is; the temperature change is After that, the material length becomes ; The solution method for the thermal deformation is: in: For temperature changes.

[0012] Furthermore, the stress-strain relationship is: in: 、 and They are 、 and Deformation in the direction; 、 and They are respectively 、 and Directional strain; 、 and They are 、 and Shear strain of the plane; The total deformation is: in: 、 and They are 、 and Stress in direction; 、 and They are 、 and Shear stress in a plane; is the coefficient of thermal expansion; is the elastic modulus; is Poisson's ratio; is the shear modulus, and: .

[0013] Furthermore, the fluid-solid interface satisfies the continuity conditions of displacement, temperature and heat flow, and the coupling control equation is: in: and They are and are the stresses at the interface between the solid part and the fluid part; and are the unit normal vectors at the interface between the solid part and the fluid part respectively; and are the displacements at the interface between the solid part and the fluid part respectively; and are the heat flux at the interface between the solid part and the fluid part respectively; and are the temperatures at the interface between the solid and fluid parts, respectively.

[0014] The beneficial effects of the present invention are: The thermal-fluid-solid coupling analysis method for worm and worm gear pairs of the present invention performs multi-physics field collaborative simulation of the structural field, fluid field, and temperature field of the worm and worm gear pair. It not only considers the frictional heat generation and structural thermal deformation during the meshing process of the worm and worm gear pair, as well as the impact on lubrication characteristics such as oil film thickness and maximum oil temperature rise in the fluid field, but also considers the oil film pressure and heat dissipation of the lubricating oil in the worm and worm gear transmission system, as well as the impact on the temperature distribution and thermal deformation of the structural field. It reveals the complex interactive effects that are difficult to capture in traditional one-way coupling analysis, namely the closed-loop process of frictional heat generation → temperature rise → deformation → contact stress change. Based on the thermal-fluid-solid coupling analysis method for worm and worm gear pairs, the actual working state of the worm and worm gear can be simulated more realistically, providing data support for further optimizing meshing characteristics, reducing dynamic meshing impact, and reducing vibration and noise, and effectively guiding the design of worm and worm gear modification and vibration and noise reduction structures. This comprehensive analysis provides a theoretical basis and technical support for the design of high-precision, high-reliability, and long-life worm and worm gear transmission systems, especially in the fields of precision machinery, new energy vehicle reducers, industrial robots, etc., which has important application significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to make the purpose, technical solutions and beneficial effects of the present invention more clear, the present invention provides the following drawings for illustration: Figure 1 Flowchart of the thermal-fluid-solid coupling analysis method for a worm gear pair according to the present invention; Figure 2 Flowchart for thermal-fluid coupling analysis of worm and worm gear pairs; Figure 3 This is the flow chart of the thermal-mechanical coupling analysis of the worm and worm gear pair; Figure 4 Schematic diagram of thermal-fluid-structure coupling data transfer for a worm gear pair. DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0017] like Figure 1 As shown, the thermal-fluid-solid coupling analysis method for the worm gear pair of this embodiment includes the following steps: Step 1: Build a simulation model A thermal-fluid-solid coupling simulation analysis model of the worm and worm gear pair is established, including the worm, worm gear and housing, and a three-dimensional geometric model is constructed based on the worm and worm gear meshing principle.

[0018] In this embodiment, the method for constructing a three-dimensional geometric model includes: utilizing the worm and worm gear meshing principle to establish a spatial coordinate system, obtaining the corresponding tooth surface equation through coordinate transformation, generating the worm tooth surface guide line in MATLAB, and importing it into Solidworks software to generate a worm and worm gear model through scanning, cutting, and Boolean operations.

[0019] Step 2: Meshing The simulation analysis model is meshed parametrically, a tetrahedral unstructured mesh is used for the fluid domain, and the tooth surface area of the worm and worm wheel is encrypted.

[0020] Specifically, the worm gear pair thermal-fluid-solid coupling simulation analysis model was imported into the pre-processing module of the finite element software for parametric meshing. Mesh quality indicators such as the Jacobi and aspect ratio were checked to ensure computational stability, and each boundary was named. Due to the complex geometry of the fluid domain, the tetrahedral unstructured meshing method was used to mesh the worm gear pair thermal-fluid-solid coupling simulation analysis model. The worm gear tooth surfaces were encrypted with a minimum mesh size of 0.05 mm and a size growth rate of 1.2. Each boundary surface was named.

[0021] Step 3: Thermal-fluid coupling analysis of worm and worm gear pairs Based on fluid dynamics theory and RNG Turbulence model, establish a transient simulation model of oil-immersed lubricating oil-gas two-phase flow, and solve the fluid dynamic pressure and convective heat transfer coefficient through the pressure-velocity coupling algorithm. Specifically, in this embodiment, based on fluid dynamics theory and multiphase flow coupling method, combined with dynamic grid adaptive technology, a simulation model of oil-immersed lubricating oil-gas two-phase flow of worm gear system is established, comprehensively considering the multi-physics field mechanism such as lubricating oil viscosity-temperature effect, tooth surface contact heat source and convective heat transfer, and performing transient numerical solution through the pressure-velocity coupling algorithm to obtain data such as fluid dynamic pressure and convective heat transfer coefficient of the worm gear pair; like Figure 2 As shown, in this embodiment, the method steps for thermal-fluid coupling analysis of the worm and worm gear pair are as follows: 31) Import the mesh file of the worm gear pair and check the mesh quality to exclude negative volume and highly distorted mesh; 32) Select pressure-based or density-based solver, set transient time type, and activate RNG Turbulence models, multiphase flow models and energy equations, defining the coupled relationship between flow and heat transfer; 33) Set fluid material properties, including density, viscosity and specific heat capacity; 34) Configure boundary conditions, define the inlet, outlet, wall and symmetry boundary types, set turbulence parameters and associate dynamic mesh parameters; 35) Select the pressure-velocity coupling algorithm, set the relaxation factor and convergence criterion, solve the continuity equation and momentum equation to update the flow field data; 36) Repeatedly solve the momentum equation, energy equation and RNG Turbulence model, monitor the residual curve and the stability of the monitoring points until the convergence conditions are met.

[0022] The basic control equations of the worm and worm gear thermal-fluid coupling numerical simulation process mainly include the continuity equation, momentum equation (momentum conservation equation) and energy equation (energy conservation equation).

[0023] Specifically, the continuity equation is: The momentum equation is: The energy equation is: in: is the mass density; is the speed; subscript Indicates the direction of Cartesian coordinates; is the local static pressure; is viscosity; represents the Reynolds stress tensor; is the fluid temperature; is the effective thermal conductivity; is the Laplace operator; is viscous dissipation.

[0024] The flow forms of fluid are divided into two forms: laminar flow and turbulent flow. Laminar flow means that the fluid has no radial pulsation and the motion trajectory of the fluid is a smooth curve. Turbulent flow has radial pulsation and the motion trajectory is complex and diverse. Compared with the model, RNG The model extends the dissipation rate The RNG equation improves the ability to predict rapid fluid strain and rotating flow around worm gears. The turbulence model defines the eddy viscosity via the following equation: in: is the eddy viscosity; is a constant; is the mass density; is the turbulent kinetic energy; is the turbulent dissipation rate.

[0025] RNG The transport equation of the turbulence model is obtained through fully developed turbulence. Specifically, the transport equation is: in: represents the turbulent kinetic energy due to velocity gradient; represents the turbulent kinetic energy induced by buoyancy; The effect of turbulent pulsation expansion behavior on dissipation rate in the flow field is described; 、 and is the model constant; and Respectively and The reciprocal of the effective Prandtl number; Indicates the improvement factor of simulation accuracy; For displacement.

[0026] When the worm gear pair rotates, the fluid flows in a turbulent form. The turbulence model RNG should be used in the simulation calculation. The model has good robustness, good accuracy, etc.

[0027] Due to the limitation of the wall, the internal fluid close to the wall and the external fluid close to the free stream have different scales and physical processes, and these layers are called boundary layers. Boundary layers are divided into flow boundary layers and thermal boundary layers. The boundary layer can be divided into laminar boundary layer, transition zone and turbulent boundary layer along the wall direction; it can be divided into laminar bottom layer, mainstream area and turbulent core area in the normal direction of the wall. The boundary layer is mainly a region where momentum is transferred, and is described by the momentum differential equation of the fluid. The velocity gradient in the mainstream area changes very little, and the fluid can be regarded as an ideal fluid, described by the Euler equation, and its heat transfer is mainly based on heat conduction; in the turbulent core area, heat transfer is mainly based on convection; the bottom layer of the turbulent core area is called the laminar bottom layer, and the velocity and temperature gradients are large, and heat conduction is the main mode. Specifically, the heat transfer coupling relationship adopts the basic heat transfer control equation, as follows: in: is the heat transfer coefficient; is the heat transfer area; is the average temperature difference of heat transfer.

[0028] Based on the above-mentioned fluid dynamics theory and dynamic mesh technology, a simulation model of oil-gas two-phase flow in the worm gear system with oil immersion lubrication is established. The motion law of the oil in the worm gear system under oil immersion lubrication, the oil distribution ratio on the tooth surface and the velocity field, the pressure field distribution law, and the convective heat transfer coefficient are obtained through calculation.

[0029] Step 4: Thermo-mechanical coupling analysis of worm and worm gear pairs Based on the theory of solid mechanics, a three-dimensional transient dynamic simulation model is established. The temperature-stress coupling field equations are combined, and an explicit dynamics algorithm is used to iteratively solve the thermal deformation and stress-strain of the worm and worm gear through the finite element method. Specifically, this embodiment establishes a three-dimensional transient dynamic simulation model that takes into account the dynamic load of meshing and the thermal-mechanical coupling effect based on the theory of solid mechanics and the multi-physics field coupling analysis method. The temperature-stress coupling field equations are combined, taking into account the thermal softening effect and thermal expansion deformation; the explicit dynamics algorithm is used to calculate the time-varying contact stress and vibration response, and the friction power consumption is converted into a transient heat source. The stress and strain, thermal deformation, temperature distribution, heat flux density and other data of the worm and worm gear are iteratively solved through the finite element method.

[0030] like Figure 4 As shown, in this embodiment, the method steps for thermal-stiff coupling analysis of the worm and worm gear pair are as follows: 41) Import the mesh file and check the mesh quality indicators including Jacobi and aspect ratio to ensure calculation stability; 42) Define the material constitutive model including elastic modulus, Poisson's ratio and thermal expansion coefficient, and set the physical property parameters; 43) Establish contact pairs and configure friction coefficients, and define displacement and heat flow transfer conditions in the fluid-solid coupling interface area; 44) Apply dynamic load boundary conditions, including worm speed, worm gear resistance torque, fixed support constraint and pressure load constraint; 45) Simultaneously solve the temperature-stress coupled field equations and use explicit dynamics algorithm to iteratively solve thermal deformation, stress strain and temperature distribution; 45) Calculate the total deformation and heat flux density under thermoelastic coupling by finite element method until convergence.

[0031] The explicit dynamics algorithm is the solid part conservation equation, which can be derived from Newton's second law. It quantitatively describes the dynamic behavior of the solid domain and realizes energy transfer and interaction across physical fields by coupling with the fluid equation. Specifically, the solid part conservation equation is expressed as: in: is the density of the solid; is the Cauchy stress tensor; is the body force vector; is the local acceleration vector of the solid domain.

[0032] There is a strong correlation between the temperature field and the structural field of the worm and worm gear. On the one hand, the instantaneous temperature rise on the tooth surface causes the thermal deformation of the worm and worm gear to increase instantly. On the other hand, as the meshing cycle increases, the minimum temperature of the tooth surface gradually increases, which causes the minimum thermal deformation of the tooth surface to gradually increase. Therefore, it is necessary to analyze the deformation law of the worm and worm gear.

[0033] The thermal expansion characteristics of worm gears are measured by the thermal expansion coefficient, which is generally divided into linear expansion coefficient and volume expansion coefficient. The average linear expansion coefficient is usually used to describe the thermal expansion characteristics of the worm gear along its length. That is, in this embodiment, the thermal expansion coefficient in the material constitutive model is defined as: in: is the average linear expansion coefficient; is the initial temperature; The initial length is; the temperature change is After that, the material length becomes .

[0034] The material of the worm gear is usually considered to be isotropic, so when the temperature rise is When , the solution method for the thermal deformation of the worm and worm wheel in all directions is: in: For temperature changes.

[0035] Generally, lubricating oil is applied during actual operation. Considering a series of errors generated during the manufacturing process, a certain gap needs to be left. This gap will be filled with oil. Therefore, the thermal deformation of the tooth profile caused by temperature changes will be subject to extrusion constraints, thereby generating thermal stress. This thermal stress will cause additional deformation due to the elasticity of the object. Therefore, the actual thermal deformation of the worm and worm wheel is the result of the coupling of force, temperature, and displacement. The total deformation of the worm and worm wheel under thermal-elastic coupling is: in: 、 and They are 、 and Stress in direction; 、 and They are 、 and Shear stress in a plane; is the coefficient of thermal expansion; is the elastic modulus; is Poisson's ratio; is the shear modulus, and: Furthermore, the stress-strain relationship is: in: 、 and They are 、 and Deformation in the direction; 、 and They are respectively 、 and Directional strain; 、 and They are 、 and Shear strain of the plane.

[0036] Based on the analysis of the solid governing equations and thermal deformation equations described above, a thermo-solid coupling model was established, and the coupled field transient module was invoked to achieve coupling between the temperature field and the structural field of the worm and worm gear. By solving the transient dynamic coupled thermal analysis, data such as stress and strain, thermal deformation, temperature distribution, and heat flux density during the worm and worm gear meshing process can be obtained.

[0037] Step 5: Data transfer Through the system coupling module in the finite element software, the analysis data of the fluid domain and the analysis data of the solid domain are exchanged and transferred through the interface to perform a two-way thermal fluid-solid coupling analysis. Figure 4 As shown, this embodiment performs a bidirectional thermal fluid-solid coupling analysis by bidirectionally transferring the pressure, convective heat transfer coefficient of the fluid domain and thermal deformation data of the solid domain through the fluid-solid interface, and iterates the solution until convergence.

[0038] Specifically, the fluid-solid interface satisfies the continuity conditions of displacement, temperature, and heat flow, and the coupling control equation is: in: and are the stresses at the interface between the solid part and the fluid part; and are the unit normal vectors at the interface between the solid part and the fluid part respectively; and are the displacements at the interface between the solid part and the fluid part respectively; and are the heat flux at the interface between the solid part and the fluid part respectively; and are the temperatures at the interface between the solid and fluid parts, respectively.

[0039] Through the system coupler, data such as fluid pressure and convective heat transfer coefficient obtained from the flow field simulation calculation are imported into the solid structure analysis through the coupling surface, thereby calculating parameters such as stress, strain, and temperature of the structural simulation. It is believed that the deformation is large enough to affect the original flow field shape, so the deformation displacement is passed back to the flow field simulation calculation, and the flow field data under the new solid shape is calculated again to obtain new fluid pressure and convective heat transfer coefficient data on the coupling surface; this process is repeated until the calculation is completed.

[0040] The above embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. A thermal-fluid-structure coupling analysis method for a worm gear pair, characterized by: The steps include: Step 1: Build a simulation model Establish a thermal-fluid-solid coupling simulation analysis model for a worm gear pair, including the worm, worm gear, and housing, and construct a three-dimensional geometric model based on the worm and worm gear meshing principle; Step 2: Meshing Performing parameterized meshing on the simulation analysis model, using tetrahedral unstructured meshes for the fluid domain and encrypting the tooth surface area of the worm and worm wheel; Step 3: Thermal-fluid coupling analysis of worm and worm gear pairs Based on fluid dynamics theory and RNG Turbulence model, establish a transient simulation model of oil-immersed lubricating oil-gas two-phase flow, and solve the fluid dynamic pressure and convective heat transfer coefficient through the pressure-velocity coupling algorithm; Step 4: Thermo-mechanical coupling analysis of worm and worm gear pairs A three-dimensional transient dynamics simulation model is established based on solid mechanics theory. The temperature-stress coupled field equations are solved simultaneously. An explicit dynamics algorithm is used to iteratively solve the thermal deformation and stress-strain of the worm and worm gear using the finite element method. Step 5: Bidirectional data transmission at the fluid-solid interface The pressure, convective heat transfer coefficient of the fluid domain and thermal deformation data of the solid domain are bidirectionally transferred through the fluid-solid interface to perform a bidirectional thermal fluid-solid coupling analysis, and the solution is iteratively solved until convergence.

2. The thermal-fluid-structure coupling analysis method for a worm gear pair according to claim 1, characterized in that: In the step 1, the method for constructing the three-dimensional geometric model includes: Generate worm gear tooth surface guide lines in MATLAB; Import the model into Solidworks software and generate the worm and worm gear model through scanning, cutting and Boolean operation.

3. The thermal-fluid-structure coupling analysis method for a worm gear pair according to claim 1, characterized in that: In step 3, the method steps for thermal-fluid coupling analysis of the worm and worm gear pair are as follows: 31) Import the mesh file of the worm gear pair and check the mesh quality to exclude negative volume and highly distorted mesh; 32) Select pressure-based or density-based solver, set transient time type, and activate RNG Turbulence models, multiphase flow models and energy equations, defining the coupled relationship between flow and heat transfer; 33) Set fluid material properties, including density, viscosity and specific heat capacity; 34) Configure boundary conditions, define the inlet, outlet, wall and symmetry boundary types, set turbulence parameters and associate dynamic mesh parameters; 35) Select the pressure-velocity coupling algorithm, set the relaxation factor and convergence criterion, solve the continuity equation and momentum equation to update the flow field data; 36) Repeatedly solve the momentum equation, energy equation and RNG Turbulence model, monitor the residual curve and the stability of the monitoring points until the convergence conditions are met.

4. The thermal-fluid-structure coupling analysis method for a worm gear pair according to claim 3, characterized in that: The RNG The turbulence model defines the eddy viscosity via the following equation: in: is the eddy viscosity; is a constant; is the mass density; is the turbulent kinetic energy; is the turbulent dissipation rate; The RNG The transport equation of the turbulence model is: in: represents the turbulent kinetic energy due to velocity gradient; represents the turbulent kinetic energy induced by buoyancy; The effect of turbulent pulsation expansion behavior on dissipation rate in the flow field is described; 、 and is the model constant; and Respectively and The reciprocal of the effective Prandtl number; Indicates the improvement factor of simulation accuracy; For displacement.

5. The thermal-fluid-structure coupling analysis method for a worm gear pair according to claim 3, characterized in that: The continuity equation is: The momentum equation is: The energy equation is: in: is the mass density; is the speed, subscript Indicates the direction of Cartesian coordinates; is the local static pressure; is viscosity; represents the Reynolds stress tensor; is the fluid temperature; is the effective thermal conductivity; is the Laplace operator; is viscous dissipation.

6. The thermal-fluid-structure coupling analysis method for a worm gear pair according to claim 3, characterized in that: The heat transfer coupling relationship is: in: is the heat transfer coefficient; is the heat transfer area; is the average temperature difference of heat transfer.

7. The thermal-fluid-structure coupling analysis method for a worm gear pair according to claim 1, characterized in that: In step 4, the method steps for thermo-mechanical coupling analysis of the worm and worm gear pair are as follows: 41) Import the mesh file and check the mesh quality indicators including Jacobi and aspect ratio to ensure calculation stability; 42) Define the material constitutive model including elastic modulus, Poisson's ratio and thermal expansion coefficient, and set the physical property parameters; 43) Establish contact pairs and configure friction coefficients, and define displacement and heat flow transfer conditions in the fluid-solid coupling interface area; 44) Apply dynamic load boundary conditions, including worm speed, worm gear resistance torque, fixed support constraint and pressure load constraint; 45) Simultaneously solve the temperature-stress coupled field equations and use explicit dynamics algorithm to iteratively solve thermal deformation, stress strain and temperature distribution; 45) Calculate the total deformation and heat flux density under thermoelastic coupling by finite element method until convergence.

8. The thermal-fluid-structure coupling analysis method for a worm gear pair according to claim 7, characterized in that: The explicit dynamics algorithm is the solid part conservation equation, which is expressed as: in: is the density of the solid; is the Cauchy stress tensor; is the body force vector; is the local acceleration vector of the solid domain; The thermal expansion coefficient in the material constitutive model is defined as: in: is the average linear expansion coefficient; is the initial temperature; The initial length is; the temperature change is After that, the material length becomes ; The solution method for the thermal deformation is: in: For temperature changes.

9. The thermal-fluid-structure coupling analysis method for a worm gear pair according to claim 7, characterized in that: The stress-strain relationship is: in: 、 and They are 、 and Deformation in the direction; 、 and They are respectively 、 and Directional strain; 、 and They are 、 and Shear strain of the plane; The total deformation is: in: 、 and They are 、 and Stress in direction; 、 and They are 、 and Shear stress in a plane; is the coefficient of thermal expansion; is the elastic modulus; is Poisson's ratio; is the shear modulus, and: 。 10. The thermal-fluid-structure coupling analysis method for a worm gear pair according to claim 1, characterized in that: The fluid-solid interface satisfies the continuity conditions of displacement, temperature and heat flow, and the coupling control equation is: in: and are the stresses at the interface between the solid part and the fluid part; and are the unit normal vectors at the interface between the solid part and the fluid part respectively; and are the displacements at the interface between the solid part and the fluid part respectively; and are the heat flux at the interface between the solid part and the fluid part respectively; and are the temperatures at the interface between the solid and fluid parts, respectively.

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