Research On Lubrication Characteristics Of Microporous Face Of Mechanical Seal Considering Surface Roughness

With the rapid development of the shipbuilding industry,the requirements for the reliability of ship operation are gradually improved,but once the stern shaft seal fails,it is easy to cause major accidents.Therefore,the research on the sealing performance of marine stern shaft has important theoretical significance and practical application value.Taking the marine stern shaft mechanical seal as the research object,the numerical analysis model of the rough microporous seal face is established considering the roughness of the seal face and the existence of micropores.The thermal fluid solid coupling simulation of the seal structure is carried out by using the finite element software.The influence of the seal parameters on the seal performance under different working conditions is studied,and the test bench is built and verified.The main research contents are as follows(1)For the study of the mechanical seal face with micro pores considering the surface roughness,W-M fractal function is used to calculate the two-dimensional and three-dimensional seal face roughness morphology,and the influence of different parameters on the roughness is analyzed.According to the structural parameters of the end face,a description equation of the thickness of the mechanical seal end surface is established considering the surface roughness and the micropore.The corresponding membrane pressure control equation is deduced based on the simplified Reynolds equation.The finite difference method and the MATLAB software are used to compile and calculate the iterative procedure to obtain the liquid film pressure.Complete the calculation of sealing parameters under different working conditions.The results show that the increase of rotation speed,medium pressure and surface roughness will lead to the increase of opening force,leakage rate and liquid film stiffness,and the increase of rotation speed and surface roughness will also lead to the increase of friction torque,but the medium pressure has little effect on the friction torque.(2)Firstly,the mechanical seal ring model of microporous end face is established by using Solid Works software.The heat flux of end face calculated by friction coefficient with different surface roughness is taken as the boundary condition of coupled temperature field analysis.The fluid field and structure field are coupled.After completing the thermal fluid solid coupling analysis,the coupled temperature field and pressure field nephogram under different working conditions are obtained,and the micro flow field is drawn The temperature and pressure curves of hole center path were compared and analyzed.The results show that the increase of rotation speed and friction coefficient will increase the contact pressure of liquid film and the temperature of seal end face,which will increase the clearance of seal end face,resulting in the increase of leakage and the deformation of seal end face,which will affect the stability of mechanical seal.The increase of medium pressure will lead to the increase of liquid film contact pressure,the increase of opening force and the temperature of microporous seal face.(3)According to the actual conditions,the experimental platform is designed and built to verify the theoretical calculation and simulation results.The test results show that: with the increase of sealing device speed and sealing medium pressure,the end face temperature also increases,and the increase rate is related to the increase rate of corresponding parameters;the leakage also increases rapidly with the increase of speed,but the influence of working medium pressure on the leakage is limited,and only fluctuates with the change of medium pressure.The increase of roughness will also increase the leakage and reduce the sealing performance,but the effect is small.The data are consistent with the laws of theoretical calculation and simulation calculation.