Investigation of the Vibration Behavior of a Foil Thrust Bearing Housing Under Angular Disturbance of the Runner

Foil thrust bearings are widely used in high-speed rotating machinery due to their temperature tolerance and contamination-free operation. However, the gas film thickness of the bearing can be weakened by the runner’s runout, which reduces the maximum load capacity of the bearing. To improve the load-carrying capacity of the bearing under runner’s runout, the angular stiffness and damping of the foil thrust bearing housing can be changed to provide angular tracking ability. However, this can result in resonance, which is detrimental to system stability and load-carrying capacity improvement. In this paper, the angular resonance behavior of the bearing housing was investigated theoretically. The results indicate that when the rotor speed is close to the critical speed, the bearing housing experiences angular resonance characterized by a sharp increase in motion amplitude and a sudden phase shift, leading to poor angular tracking ability. By adjusting the critical speed through changes in the angular stiffness, angular damping, and transverse moment of inertia, the angular resonance can be avoided for the bearing system. The results show that there is an optimal angular stiffness for the bearing housing that enables it to have maximum load.