Mechanism of Occurrence of Self-Excited Oscillations of a Rotor With a Clearance Between Bearing Holder and Housing

It is well known that, in a rotor system with a radial clearance between a rotating part (ex. shaft) and a static part (ex. guide), a forward rubbing with the same angular speed as the rotational speed ω, a backward rubbing with an angular speed proportional to ω, and various kinds of nonlinear resonances occur. On the contrary, some rotor systems have a clearance between a movable but non-rotating part and a static part. For example, a squeeze-film damper bearing has a clearance between a bearing holder and housing. In such a system, a self-excited oscillation occurs in addition to various kinds of nonlinear resonances. In this paper, the characteristics of this self-excited oscillation are investigated and the mechanism of the occurrence of a self-excited oscillation is clarified by considering energy balance.Copyright © 2011 by ASME