Nonlinear Response of Gas-Lubricated Shrouded Rayleigh-Step Thrust Pad

Abstract

The quasi-static pressure characteristics of a gas-lubricated thrust bearing with shrouded Rayleigh-step pads are determined for a time-varying film thickness. The axial response of the thrust bearing to an axial forcing function or an axial rotor disturbance is investigated by treating the gas film as a spring having nonlinear restoring and damping forces. These forces are related to the film thickness by a power relation. The nonlinear equation of motion in the axial mode is solved by the Ritz–Galerkin method as well as by direct numerical integration. Results of the nonlinear response by both methods are compared with the response based on the linearized equation.