STATIC SEALING PERFORMANCE OF GAS MECHANICAL SEALS INCLUDING SURFACE-ROUGHNESS AND RAREFACTION EFFECTS

The combined problems of contacting rough surfaces and pressure-induce d flow in their interface are formulated and solved. The analysis is v alid for thin gas films, where rarefactiom effects are significant. Th e effects of the face loading, surface roughness, material properties and operating conditions on the static sealing performance of mechanic al gas seals are investigated. It is found that, as the surface roughn ess and the Knudsen number increase, the leakage also increases. For v ery low leakages, corresponding to high face loading, the effect of th e Knudsen number on the leakage is still significant but the effect of the surface roughness diminishes. A semi-empirical model that relates the leakage with the face loading and the other relevant parameters i s developed. This model favorably compares with available experimental data and provides a simple tool for evaluating static sealing perform ance of mechanical gas seals.