Stability of Multirecess Hydrostatic Journal Bearings

Abstract

An analysis which predicts that multirecess hydrostatic journal bearings exhibit dynamic instability at and above a certain speed of shaft rotation is summarized. This instability is characterized by the centre of the shaft exercising vibrations in a closed orbit of high eccentricity at a frequency equal to one half of the critical shaft speed. Futhermore, this frequency corresponds to the natural frequency of the system at zero eccentricity in the absence of shaft rotation. An expression for the critical speed of an orifice compensated bearing with four recesses is given and an experimental verification of these predictions is presented.