Dynamic Stability of Externally Pressurized Gas Bearings

Abstract

A feedback loop model is presented us to study instability phenomena in externally pressurized gas bearings. The main features in the theoretical analysis are the compressibility of the fluid and molecular transit times in the bearing gap. The proposed theory is based upon a separate handling of disturbances due to gap thickness variations and pressure changes. The analysis shows, that the dynamic pressure distribution in the gap plays an important role in the overall bearing stability. Comparisons between theoretical and experimental observations are highlighted; reference is made to Turnblade’s stability chart. The proposed analysis gives some additional information with regard to the relative importance of some bearing parameters.