Thermo-solid Coupling Simulation Analysis And Performance Optimization Of Mechanical Dynamic Seal

Mechanical seal has been widely used in many fields such as industrial manufacture,chemical industry production and aerospace due to its advantages like stable performance,long service life,small leakage,broad scope of application,etc.However,rotary friction of dynamic seal in mechanical seal easily results in local high temperature of seal faces.On one hand,sharp increase in temperature can make liquid film between seal faces fail to work due to flash evaporation,and on the other hand,it can cause thermal-mechanical cone deformation of seal faces and result in leakage at dynamic seal faces,seriously influencing overall performance of mechanical seal units.Therefore,research on the temperature fields and face deformation of dynamic seal has important practical significance and application value towards optimization of work performance of dynamic seal.This paper establishes transient and quasi-static finite-element simulation models of dynamic seal based on the thermo-solid coupling method.Advantages of such models lie in that thermal expansion of materials can be considered,as temperature change and structural deformation are always interacted,so as to accurately simulate the rotary friction between seal faces under practical conditions.With both models,accurate temperature distribution of seal faces,as well as stable axial displacement values of nodes are obtained,based on which,simulation analysis of flow distribution of liquid film between seal faces is carried out to correctly evaluate work performance of dynamic seal.Major research contents of this paper include:(1)Verification of the thermo-solid coupling simulation method for rotary frictionRelevant setting parameters of the thermo-solid coupling finite-element model are obtained by taking rotary friction of two rings as the theoretical contrast model,and adjusting related parameters of the finite-element model to get simulation results consistent with theoretical values,which lays a foundation for subsequent establishment of the finite-element model for rotary friction of dynamic seals based on the thermal-solid coupling method.(2)Transient simulation analysis of thermal-solid coupling of dynamic seal temperature fieldsThe transient simulation model for thermal-solid coupling of dynamic seal temperature fields is established by reasonably exerting loads and boundary conditions,as well as by defining convective heat transfer coefficients of various surfaces.Accurate temperature distribution at dynamic sealing areas is obtained through simulation results,which provides temperature boundary conditions for subsequent establishment of the quasi-static simulation model for thermal-solid coupling of dynamic sealing face deformation.(3)Quasi-static simulation analysis of thermal-solid coupling of dynamic seal face deformationStable temperature values of various nodes in the transient model are added,as temperature boundary conditions,into the transient model that deletes rotary loads,by programming with MATLAB.Based on above,the quasi-static simulation model for thermal-solid coupling of dynamic seal face deformation is established.Stable axial displacement values of seal faces are obtained through simulation results,which provides a base for subsequent establishment of the liquid film model used for analysis of the relevant flow field.(4)Simulation analysis of the flow field of liquid filmThe finite-element model of liquid film is established by determining thickness distribution of liquid film between seal faces through superposition of microscopic clearance and macroscopic cone clearance between seal faces.The simulation model of the liquid film flow field is established in the software of FLUENT by defining flowing status of liquid film,and exerting boundary conditions of various surfaces.Work status of liquid film is judged through simulation results,and work performance of dynamic seal is evaluated.(5)Analysis of factors influencing dynamic seal performanceWith a single variable and multiple simulated work conditions,studies are conducted regarding influences of spring specific pressure,rotary speed,and pressure of sealing media on dynamic seal performance,which provides certain reference for the parameter selection of dynamic seal during the design.