Abstract:

Based on the fractal geometry theory，the surface topography including surface roughness and waviness of the end faces of the sealing rings and its change during the frictional wear of mechanical seals were characterized by the fractal parameters with independent dimension.The effect of change of surface topography on leakage path was analyzed.A permissible-leakage-rate-based method of predicting seal life of mechanical seals was developed by using Navier-Stokes equation，and the seal life of a 108 mechanical seal in diesel oil pump was predicted by this method.The 108 mechanical seal worked for 11500 h in 0.8 MPa diesel oil when the pressure on seal face pg was 1.1 MPa，the fractal dimension D was 1.5607，scale amplitude G was 2.0298×10^-9m，and the calculated leakage rate Q reached 2.95 cm³•h^-1.The seal life exceeded 1400 h as calculated for volatile matter permissible leakage given in API and STLE and the mechanical seal was in dangerous state.The research results indicate that accurately predicting seal life of mechanical seals is essential.The method of predicting seal life of mechanical seals put forward in this paper can be used to make scheduled maintenance and achieve safe，reliable service of mechanical seals.