Implementation of Time-Transient and Step-Jump Dynamic Analyses of Gas-Lubricated Bearings

Abstract

The dynamic analysis of gas-bearing systems are discussed from two points of view. The “Time-Transient” method which has been previously reported in a number of papers [1] [2] couples the lubrication and dynamic equations and integrates forward in time, to provide a time history of the motions of the system in its various degrees of freedom. The “Step-Jump” approach determines the system response due to a sudden impulse from an assumed stable operating position. The two theoretical approaches are discussed qualitatively. Implementation is presented by way of sample problems, including a fixed and resiliantly mounted hybrid journal bearing system and an elastic gimbal mounted Rayleigh-Step thrust bearing. The advantages, disadvantages and complementary characteristics of each method are presented. Details of the Step-Jump analysis for the hybrid bearing are included as an Appendix.