Effect of Hydrodynamic Thrust Bearings on Lateral Shaft Vibrations

Abstract

A computational method for the prediction of static and dynamic characteristic data of tilting pad and fixed pad thrust bearings for high surface velocities and high thermal loads is developed and verified. Furthermore, a convenient model is presented, which allows the determination of the dynamic coefficients for the gyrating movement of the thrust collar, where it is sufficient using the purely axial dynamic single pad coefficients only. Introducing these coefficients into an accordingly modified rotor dynamics program, the lateral vibrations of a high speed rotor with sliding bearings are calculated and a considerable effect of the thrust bearings is shown. These theoretical results are also verified experimentally through vibration measurements at a high speed rotor test rig.