Nonlinear Modeling of Tilting-pad Bearings with Squeeze Film Dampers and Application to Flexible Rotor Analysis

摘要

Linearized bearing and squeeze film damper models have limits when the rotor undergoes severe unbalance conditions or large shaft vibrations. This paper presents a nonlinear modeling approach for a complex rotor-bearing system, consisting of both tilting-pad bearings with squeeze film dampers as well as an assembly method for linear flexible rotors to simulate behavior of shaft-bearing system under severe unbalance conditions. By solving Reynolds equations derived from a tilting-pad bearing model and a finite length squeeze film damper model, the pressure profile is calculated using an approximate finite element method. The bearing/damper forces are then calculated based upon the shaft instantaneous position and velocity, and updated at each time step. The transient response of system, including coupled motions of the shaft, the bearing pads/pivots, and the dampers, is solved using a 4th Runge-Kutta integration method. The nonlinear transient behavior of a flexible eight-stage compressor...........