二阶滑移边界对微型气浮轴承稳态性能的影响

考虑微型气浮轴承的尺寸特征，内部气流不再满足连续流的假设，根据Knudsen数可确定内部气流为滑移流. 分别利用一阶速度滑移模型和二阶速度滑移模型对连续流的状态方程进行修改，得到一阶滑移流和二阶滑移流机制下修正的雷诺方程. 利用有限差分法对连续流、一阶滑移流和二阶滑移流的雷诺方程分别求解，得出相应的承载力和偏位角. 经过对比分析，发现采用滑移流模型得到的轴承的稳态力学性能与连续流机制的结果存在较大差异，一阶滑移流与二阶滑移流间的差异随偏心率增加而增加. 说明在MEMS环境下必须考虑滑移流效应对微型气浮轴承稳态力学性能的影响. 在大偏心率工作状态下，二阶滑移流模型能够得到最好的结果.

The effects of second-order slip-flow on the steady performance of micro gas bearing

The effects of slip flow on the steady mechanical performances of the micro gas bearing are discussed. Considering the dimensional characters of the micro bearing and judging from the flow's Knudsen number,the flow in the bearing is in the slip regime instead of the continuous regime.The modified Reynold's equations of first-order slip-flow and second-order slip-flow for the micro gas bearing are obtained.Solving the Reynold's equations for the continuous regime and the two slip regimes with the finite difference method(FDM),the gas pressure distributions,the non-dimensionai load capacities and attitude angles are obtained.The comparisons of the load capacities and attitude angles between the three regimes are made,and it is shown that the mechanical performance with the slip regime distinctly differs with that of the continuous regime.An analysis illustrates that the slip flow regime has great effects on the steady mechanical performances of the micro bearing.The second-order slip-flow model can produce a good result for high eccentricity ratio operation.