Nonlinear Vibration and Bifurcation Analysis for a Rotor with Seal and Bearing Excitations

Abstract

This paper presents the nonlinear coupling vibration and bifurcation of a rotor system excited by both seal and journal bearing excitations. The rotor system is modeled as a Jeffcott rotor. The nonlinear transverse vibration of the Jeffcott rotor with labyrinth seal and two supporting journal bearings are investigated. The seal force with multiple parameters is presented by the Muszynska’s model [1, 2]. The excitation of unsteady oil-film forces is used based on the model proposed by Zhang [3]. In light of numerical computation, the Runge-Kutta method is used to determine the vibration responses at the disc center and the two bearings. When the rotation speed and the seal pressure change, bifurcation diagrams are shown, which prove the complexity of the rotor motions. There is an example with two different seal pressure pointing out the multiple periodic bifurcations. The complex bifurcation behavior explains inherent interactions between forces of oil-film and seal, which indicates much more intricate rotor dynamics than the one with either of the excitations alone.