Investigation of different parameters on nonlinear dynamic behaviors of vertical rotor system supported by aerostatic bearings

Abstract

A common issue associated with gas bearings is the tendency to generate self-excited vibrations, leading to instability. In this paper, the fluid-structure coupling dynamic model of aerostatic bearing-rotor system is established to address this problem, and a hybrid method including the finite difference method and direct integration method are employed to simultaneously solve the transient Reynolds equation and rotor dynamic equation. Furthermore, based on the orbit of rotor center, frequency spectrum diagram, Poincaré map, waterfall diagram and bifurcation diagram, the effects of rotational speed, rotor mass, orifice diameter and bearing clearance on the nonlinear dynamic behaviors of the bearing-rotor system are investigated. The results reveal that the system has abundant nonlinear behavior with the increasing of rotational speed and rotor mass, including typical half-speed whirl. But the nonlinear vibration of the system can be restricted by selecting appropriate bearing structural parameters, which can provide the theoretical guidance for the design of the aerostatic bearing-rotor system.