基于稀薄效应的微气体径向轴承稳态性能

针对微气体轴承给出参考努森数的定义，根据空气不同温度时的黏度，得到参考努森数的分布范围；考虑气体稀薄效应，给出基于Burgdorfer一阶滑移速度边界的微气体径向轴承润滑Reynolds方程的修正形式; 采用有限差分法求解修正的Reynolds方程，得到不同参考努森数$Kn_0$, 轴承数以及轴颈偏心率情况下轴承的压力分布、无量纲承载能力及偏位角. 数值分析表明:随气体稀薄程度的增强，气体径向轴承的压力明显降低，无量纲承载力降低，而轴承偏位角增大. 当偏心率小于0.6时，轴承偏位角变化平缓，受$Kn_0$数的影响不明显. 当轴承数较小时，气体稀薄程度对轴承的无量纲承载力、偏位角影响较小. 

STEADY CHARACTERISTICS OF MICRO GAS JOURNAL BEARINGS BASED ON RAREFACTION EFFECT

The reference Knudsen number is defined for micro gasjournal bearings and its value range is obtained according to the viscositydata of air at different temperatures. With gas rarefaction effect, modifiedReynolds equation for micro gas journal bearings is presented based onBurgdorfer's first order slip boundary condition. The finite differencemethod is used to solve the modified Reynolds equation, and pressure, loadcapacity and journal attitude angle of the bearing are obtained at differentreference Knudsen numbers, bearing numbers and journal eccentricityratios.Numerical results show that with the increase of gas rarefaction, bearingpressure and non-dimensional load capacity decrease obviously, and journalattitude angle increase. When the journal eccentricity ratio is less than0.6, journal attitude angle changes insignificantly and the influence on itfrom the reference Knudsen number is unobvious. Moreover, when the bearingnumber is small, the influence of gas rarefaction on non-dimensional loadcapacity and journal attitude angle is also insignificant.