THE PERFORMANCE OF A MICRO GAS BEARING WITH VELOCITY SLIP AT THE SOLID BOUNDARY

Abstract

Considering the velocity slip effect of the gas film at the solid boundary, the performance of a micro gas bearing is given. For the length scale of the micro gas bearing, the gas flow in the bearing is dominated by the slip regime instead of the continuum one. With different slip models, the modified Reynold's equations are obtained. Solving the Reynold's equation with finite difference method, the bearing forces are compared between the different models, and the second order slip model is found to fit the microelectromechanical systems (MEMS) case very well. Adopting the second order slip model, the dynamical coefficients and the stable threshold speed of the system are estimated based on the linear bearing force. And the dynamical response of the micro gas bearing is acquired with fourth-rank Runge–Kutta method. Compared with the results of the second order slip flow, the continuum flow overestimates the dynamical coefficients and underestimates the threshold speed. What is more, the period of the journal oscillation rose for the slip effect.