Abstract: In order to find out the mechanism of the micro self-vibration of aerostatic thrust bearing, large eddy simulation(LES) is used to analyze the flow field of the bearing with pocketed orifice-type restrictor. The results show that there are complicated vortexes near orifice outlet. Gas pressure and velocity change gradually from the centre to the edge of the vortexes. It is the repetition of the generation and crack of vortexes causes gas pressure to fluctuate with gas flow inside the bearing and induces the bearing to be micro self-vibration. By comparing to the calculation results of standard k-ε model, the correctness of LES is validated. Moreover, the mechanism of vortexes induce the micro self-vibration of aerostatic thrust bearing is validated by comparing to the flow field of aerostatic thrust bearing with inherently orifice-type restrictor. The results also indicate that there exists a maximum value of the magnitude of pressure fluctuation with the increases of film thickness. Therefore, the film thickness of the maximum pressure fluctuation should not be close to that of the maximum stiffness in order to make the bearings with better stiffness and less self-vibration simultaneously.

Key words: Aerostatic bearing, Large eddy simulation, Micro self-vibration, Vortex