MOLECULAR FREE PATH EFFECTS IN GAS LUBRICATED SLIDER BEARINGS.

Variational formulation is derived for the steady state compressible Reynolds equation under slip-flow conditions. Finite element techniques and a numerical procedure, using Newton-Raphson iteration method to solve the non-linear finite element equations, are described. These techniques are applied to conventional slider bearings and the effects of the molecular mean free path (MMFP) for a wide range of the compressibility numbers ( LAMBDA equals 1 similar 10**4) are shown. Then, MMFP effects for different bearing configurations are compared. As a result, it is found that non-dimensional load W is useful for estimating MMPF effects. The load or velocity versus spacing characteristics are calculated for a cylindrical slider bearing. These calculations reveal that when spacing decreases with velocity for a constant load, MMFP effects increase monotonously. However, when spacing decreases with an increase in load at a constant velocity, MMPF effects only increase slightly. The new calculation procedure developed here has wide applicabilities, converges rapidly and saves computer memory.