Effects of the shape of surface micropores on the performance of a face seal

Abstract

A mathematical model is developed for the prediction of performance of a mechanical face seal with regular microstructure on its surface in the form of pores. Pores of right circular cylindrical, hemispherical and exponential profiles have been considered. A two dimensional steady state Reynolds equation is solved to get the hydrodynamic pressure distribution on an imaginary control area around a single pore. Consequently, the seal performance parameters such as seal clearance, friction torque and leakage across the seal are calculated. A parametric analysis is done for right circular cylindrical pores for a range of sealed pressure, pore size and pore ratio. Increase of pore ratio improves the seal performance up to a pore ratio of 12%, beyond which no improvement of the seal performance is possible. The optimum pore size depends on the sealed pressure as well as on the pore profile. Through a comparison of the performance of face seals with different pore profiles hemispherical pores are recommended for enhancement of performance. For any pore profile, the seal performance improves with the increase of pore depth as long as the depth is less than 1.5 times of the pore radius. Keywords: Face seal, seal performance, surface micropore, pore profile, pore ratio.DOI: 10.3329/jme.v38i0.897 Journal of Mechanical Engineering Vol.38 Dec. 2007 pp.25-31