Whirl Instabilities in Pressure Step Bearings

Abstract

The effect on the stability of a dynamically loaded journal bearing of introducing a pressure step is examined by calculating numerically the whirl orbits described by the journal for a range of values of physical effects. In all full film cases the configuration is unstable in that the orbits spiral outwards to the bearing case; the tightness of the spiral is, however, much influenced by parameter values. The presence of appropriate cavitation permits a degree of stability, with the existence of stable whirl orbits. Cavity position and extent are vitally important to the stability characteristics, a result one would expect to be true of more realistic cavitation models than the single one used here.