Multiscale Hydrodynamic Journal Bearing with Ultra Low Surface Separation

When the hydrodynamic journal bearing works under excessively heavy loads, there will be the mixed hydrodynamic regime. In the local area, due to the ultra low surface separation, there is only the physically adsorbed boundary layer lubrication; in the other areas, the hydrodynamic is multiscale contributed by both the adsorbed boundary layer non-continuum flows and the intermediate continuum fluid flow. The present study first gives different governing equations respectively for different flow regimes, and then derives the film pressure and carried load of the bearing. The calculations show that in the condition of ultra low surface clearances, the boundary adsorbed layer effect normally very significantly increases the film pressure and the load-carrying capacity of the bearing, and this increase can be more than 3 orders when the fluid-bearing surface interaction is strong.