Effect of Pore Ensemble Statistics on Load Support of Mechanical Seals With Pore-Covered Faces

Abstract

A mathematical model was developed for predicting the performance of laser-textured seals with pores. A solution of the two-dimensional steady-state Reynolds equation was given for rectangular and exponential pores, as well as expressions for the hydrodynamic pressure distribution over the control cell and for the cell load support. The difference between the two pore shapes can be reduced from a factor of multiple times to 30 percent at most—if the pore volume is kept constant. It was also shown that the total hydrodynamically induced load-carrying capacity can be obtained with accuracy, even if the pore radius of the seal surface is assumed to vary over a wide interval about its mean value, as it does in reality. Diameters in an ensemble of over 4 · 104 pores were run at random for 500 seal faces. It was established for the first time that load support of an ensemble exceeds by 22 percent the one determined for N identical pores. The model for the entire pore population as an ensemble with size variation is more realistic, and substantiates the possibilities and advisability of pore size diversity, hitherto considered undesirable in the pore production process. In general, the pore ensemble is an essential aspect in exact determination of the load support and better insight into the tribologic behavior of pore-covered surfaces.