Stability Analysis For a Novel Design of Low Impedance Hydrodynamic Bearing

Abstract

An important problem in rotordynamics which researchers and bearing designers face is that of system stability. One of the causes of rotordynamic instability is oil whirl. This is an instability phenomena associated with the operating characteristics of the journal bearing and hence depends on the design of the bearings and the operating conditions in which it performs. This paper presents a theoretical stability analysis of a rigid rotor supported by a novel design of hydrodynamic oil film bearing. The novel bearing incorporates recesses in the bearing surface which are linked to a hydraulic accumulator and have been shown to offer superior unbalance response performance to conventional designs. However, their stability characteristics have not been investigated before. The paper describes a theoretical investigation using linearised oil film coefficients. Results are presented in the form of stability maps showing the variation of system stability with operating characteristics. The results obtained for the novel bearing are also compared with those obtained for conventional bearings.