Effect of effective viscosity on characteristics of microscale gas journal bearings

According to 1st order slip velocity boundary, modified Reynolds equation for microscale gas journal bearings is presented with consideration of effective viscosity of gas under rarefied condition. Modified Reynolds equation is solved using the finite difference method. Non-dimensional pressure distribution, load capacity and attitude angle for microscale gas journal bearings under different reference Knudsen number (the ratio of molecular mean free path to the minimum of gas film thickness), bearing number and eccentricity ratio are obtained. Numerical analysis demonstrates that when the bearing number is constant, the pressure and load capacity decrease and attitude angle changes inversely with the reference Knudsen number increasing. The larger the eccentricity ratio, the larger the change of attitude angle from effective viscosity. When eccentricity ratio is less than 0.6, attitude angle changes softly and the effect of effective viscosity is unobvious. When eccentricity ratio is constant, the influence of effective viscosity on non-dimensional load capacity and attitude angle becomes large with bearing number increasing, and this influence is more prominent with larger reference Knudsen number.