Dynamic Characteristics of Viscoelastic Supported Air Foil Thrust Bearing Under Axial Whirl

摘要

Dynamic characteristics are very important to gas foil bearing when bearing-rotor system is running in disturbance statuses. Three types of disturbance statuses including axial whirl, cylindrical whirl and conical whirl are introduced in this paper, and axial whirl is mainly discussed because this disturbance condition has obvious influence for dynamic characteristics. Based on the governing equations represented disturbance condition, dynamic characteristics including stiffness and damping coefficients are obtained by Finite Difference Method (FDM). The results show that dynamic coefficients in axial whirl are negative numbers, so load capacity of foil thrust bearing will decrease when axial whirl takes place; generally, absolute values of the dynamic coefficients are increase when structural stiffness and damping increase; absolute values of the dynamic coefficients become bigger when ramp ratio decreases and bearing number increase. In order to reduce the influence of disturbance statuses, the foil thrust bearings should have high ramp ratio and low bearing number.