The End Part Of The Porous Mechanical Seal Characteristics

Mechanical seals with micro-pores are new type ones.Micro-pores are etched on one face of the seal. They have excellent lubrication ability and good seal performance. But mostly research work is about the full seal face with mico-pores , even so, there is little literature about dynamics of the full seal face with mico-pores. Mechanical seals of partial face with mico-pores are promising ones,which has good lubrication ablity of the same as the full seal face with mico-pores,but overcomes the disadvantage of high leakage of the full seal face with mico-pores. The liquid film pressure distribution between the seal rings and the influence on seal performance by seal stucture parameters and operation parameters are deeply investigated by solving the steady-state Reynolds equation using finite difference method.Furtherly, the dynamics model of the mechanical seals under axial perturbation is setted up,and the vibration characteristics of both liquid film between the mate rings and the stationary ring are investigated.The main contents and conclusions are as follows:1. An analytical model has been developed to investigate fluid hydrodynamics between seal rings of mechanical seals of partial face with mico-pores. According to the characteristic of symmetry, the liquid film pressure over one radial pore column can characterize one over the integrated seal face. By means of dimensionless variables, the nondimensional steady-state Reynolds equation to the problem of the mechanical seals of partial face with mico-pores is obtained2. The nondimensional steady-state Reynolds equation is solved by finite difference method. The computing method is programed by Visual basic. Meanwhile, three dimensional liquid film pressure distribution are showed by Matlab.3. The influcences of structure parameters and operating parameters on the mechanical seal performances of the partial face with micro-pores are deeply analyzed by means of programs,with results as follows: (1) The average pressure between the seal rings achieves maximum when the micro-pore area density is about 0.2 and the ratio of micro-pore depth to diameter is about 0.02.(2) The seal performes well when the structure parameters are in the range of follows:micro-pore area density is about 0.2,the ratio of micro-pore depth to diameter is within 0.015～0.02 and the ratio of porous width to annular width is in the range of 0.5～0.6.. (3) The seal performes well when the rotation speed is above 2000 rpm and the viscosity is above 0.015Pa·s,. (4)Comparing with the full face with micro-pores, the opening forcing and fluid flim stiffness of the paritial face with micro-pores are smaller, but the leakage of paritial pores is much smaller than that of the full face with micro-pores.4. The axial vibration model of the mechanical seal is setted up and the model is analytically solved. The rules of seal rings movement and the characteristics of liquid film vibration under axial forced vibration have been obtained. The vibration characteristics of seal rings is analytied with considering liquid film damping and without considering liquid film damping, the results indicating that the liquid film damping must be considered when the liquid film under axial forced vibration. The result indicates that the liquid film swing has not reached 0.5 microns, though the axial perturbation swing reached 300 microns.