Subharmonic, Quasi-Periodic and Chaotic Motions of a Rigid Rotor Supported by an Eccentric Squeeze Film Damper

Abstract

This paper analyses the complexity of the unbalance response possible with a simple rigid rotor supported by an eccentric squeeze film damper. The damper forces are obtained from the ‘π’ film short bearing approximation to the Reynolds equation and a fourth-order Runge-Kutta integration is used to evaluate the rotor response. Poincaré maps, rotor trajectories, bifurcation diagrams and power spectra are used to elucidate and to illustrate the diversity of the system behaviour. It is shown that for a large unbalance and static eccentricity ratio, the system can exhibit undesirable jump phenomenon and subharmonic, quasi-periodic and even chaotic motions, which limit the operating conditions at which dampers should be used.