Stability Considerations for a Gas-Lubricated Tilting Pad Bearing—Part 2: Analytical Refinements and Stability Data

Abstract

A method for generating the film response of a single gas-lubricated tilting pad journal bearing is derived and it is shown how the results can be used to provide both steady-state and stability data for a three pad bearing. The nature of tilting pad bearing stability is discussed with the aid of frequency response plots, mode shape computations and two illustrative limiting cases. In the first, the bearing pivots are locked and the shaft is free to translate; in the second, the rotor is restrained from translating but the pads are free to pitch. Finally, a design example is given and a comparison is made between a three shoe bearing with design data based on the step-jump method and a four shoe bearing with design data based on the frequency response method.