Performance of Multiscale Hydrodynamic Step Bearing with Inhomogeneous Surfaces

In the hydrodynamic step bearing, when the lubricating film thickness is as low as the adsorbed layer thickness on the surface, the adsorbed layer effect on the bearing pressure should be evident.Different interactions can be formed between the fluid and the static surface, in the bearing inlet and outlet zones, respectively.In this paper, the multiscale calculation was made for the pressures generated in this type of step bearing when the continuum film exists between the adsorbed layers. The calculation outcomes show that the hydrodynamic pressures and loads of the bearing for the S(strong)-M(medium)-S(strong) and S(strong)-W(weak)-S(strong) fluid-bearing surface interaction types exceed significantly those for the S(strong)-S(strong)-S(strong) fluid-bearing surface interaction type if the bearing clearance in the outlet zone is smaller than 100nm (and over 20nm).The results indicate that for higher hydrodynamic pressures in the bearing, the interaction between the fluid and the static surface in the outlet zone is stronger than that in the inlet zone.