Effects of pore geometry on face seal performance

Abstract

Surfaces covered with rmcropores have recently become a topic of interest as an effective means for better lubrication and friction reduction in thrust bearings, mechanical seals, piston rings, and other machine parts. The surface structure of the sliding faces plays a vital role in their performances. Surface pores on face seal surfaces are developed during different kinds of manufacturing operations and surface treatments and their shapes may be different. Moreover, different kinds of surface textures may be deliberately machined on the seal surface through modem techniques. It is, therefore, essential to investigate how pores! asperities of different shapes affect the hydrodynamic behavior of face seal In the present work, performance of mechanical face seals with pores! asperities of square and exponential shapes is investigated. Mathematical models are developed for different pore geometry to allow the performance prediction of liquid non-contacting face seals with regular microsurface structure in the forms of rectangular and exponential pores. Seal performance such as equilibrium face separation, friction torque and leakage across the seal are calculated and presented for a range of sealed pressure, pore size and pore ratio of the annular ring surface area. An optimum pore size is found that depend on corresponding to the maximum axial stiffness and minimum friction torque.