Simplified Prediction of Stability Limit for Oil Bearing Rotor Systems

Abstract

This paper describes the vibration analyses of a flexible rotor system supported by oil bearings and the simplified prediction method for the rotational speed limits of the self-excited vibration induced by the fluid force in bearings. In the vibration analyses, the equations of motion for the rotor system are simplified and modeled as a two-degree-of-freedom system with parallel and flexural modes and eigenvalue calculations for the stability analyses are conducted. The rotational speed limits for the instability of the system obtained by the present method are compared with the calculation and experimental results in the references to discuss the validity of the present method.