Design And Application Of Squeeze Film Dampers For Turbomachinery Stabilization

Abstract

This study investigates the steady-state and transient response of the squeeze film damper bearing. Both the steady-state and transient equations for the hydrodynamic bearing forces are derived. The steady-state equations are used to determine the damper equivalent stiffness and dampening coefficients. These coefficients are used to find the damper configuration which will provide the optimum support characteristics based on a stability analysis of the rotor-bearing system. The effects of end seals and caveated fluid film are included. The transient analysis of rotor-bearing systems is performed by coupling the dampening and rotor equations and integrating forward in time. The effects of unbalance, cavitation and retainer springs are included in the analysis. Methods of determining the stability of a rotor-bearing system under the influence of aerodynamic forces and internal shaft friction are discussed. Particular emphasis is placed on solving the system characteristic frequency equation and stability maps produced using this method are presented. The study shows that for optimum stability and low force transmissibility the squeeze bearing should operate at an eccentricity ration of e<0.4.