Analysis of nonlinear dynamic for micro gas lubricated spiral groove thrust bearing-rotor system

The molecular gas film lubrication model was employed to study the effect of rarefaction in the micro gas spiral groove thrust bearing. The generalized Reynolds equation and the kinetic equation were coupled in the time domain and solved simultaneously by the direct numerical method, and then the transient displacement and transient velocity of the micro rotor at any time were obtained. The effects of gas rarefaction and the spiral groove parameters on the nonlinear dynamic behavior of micro gas lubricated spiral groove thrust bearing-rotor system were investigated, and the critical values of axial disturbance corresponding to the different rotation speeds were further obtained. The results show that the micro bearing-rotor system presents better stability when the gas rarefaction is considered. The higher the rotational speedis, the lower the critical value of axial disturbance becomes. It is also shown that the optimum spiral groove parameters for enhancing the micro-bearing load capacity are not beneficial for the system stability.