Characteristics of micro-gas journal bearings based on kinetic theory

According to Poiseuille and Couette flow rate correctors, Q˜p(D,α1,α2) and Q˜C(D,α1,α2), the modified molecular gas lubrication (MMGL) equation is applied for the analysis of micro-gas journal bearings. The effects of gas rarefaction are considered for arbitrary inverse Knudsen numbers (D) and non-symmetric accommodation coefficients (AC) conditions (α1≠α2). The combined effects of Q˜p(D,α1,α2) and Q˜C(D,α1,α2) on the performance of micro-gas journal bearings are firstly discussed. The results show that the surface property (AC) of moving surface affects the bearing performance more significantly than that of stationary surface does. The load carrying capacity increases as the AC of moving surface increases or the inverse Knudsen number increases.

Research highlights
► This manuscript deals with the modeling and analysis of micro-gas journal bearings.
► The modeling of the gas film includes the effects of gas rarefaction (Knudsen number and accommodation coefficients, AC).
► The MMGL equation is first applied in the micro-gas bearing analysis.
► As compared to published paper (almost all in the slip flow regime), the present model is applicable to arbitrary conditions (from free molecular flow, transition flow to slip flow regime) and any combinations of ACs of the two lubricating surfaces.
► The effects of non-symmetric ACs on the bearing performance are first considered in this manuscript.