Multiscale analysis and numerical simulation of hydrodynamic inclined fixed pad thrust bearing with ultra low surface separation

Abstract

In the hydrodynamic inclined fixed pad thrust bearing, when the surface separation is ultra low, there will be the special hydrodynamic mode where in the inlet zone occur both the adsorbed boundary layer flows and the intermediate continuum fluid flow i.e. the multiscale flow and in the outlet zone only occurs the physical adsorbed boundary layer flow. This new mode of hydrodynamic bearing has not been addressed before. Here, we present the corresponding multiscale hydrodynamic analysis for this bearing. The inlet zone flow is described by the closed-form explicit multiscale flow equations. The outlet zone flow is described by the nanoscale flow equation. First, the analytical derivations for the pressure distribution and carried load of the bearing were feasibly made by making a reasonable assumption. Then, full numerical solutions to the bearing were obtained to verify the analytical solution. It was found that there are significant differences between the analytically calculated pressure distribution and the numerically solved pressure distribution for the same operating condition; however for the studied different fluid-bearing surface interactions, when the surface separation is relatively large, the analytically derived load equation can be used to calculate the carried load of the bearing. Numerical solutions clearly show that stronger the fluid-bearing surface interaction, higher the generated hydrodynamic pressure in the bearing, and larger the carried load of the bearing. The study not only provides the mathematical tools for studying the bearing but also gives the indication of the strong adsorbed boundary layer effect in this bearing.