A Bi-Directional Gas Thrust Bearing

Abstract

A gas bearing with a bi-directional hydrodynamic geometry is presented and analyzed. The configuration considered is an equally spaced set of alternating land and radial groove sectors, together forming a bearing surface. The typical operating gap of the bearing is very small and a predominant laminar viscous flow field is assumed. The Reynolds equation is therefore used to describe the flow field. A parametric study of the controlling equations shows that four dimensionless geometric parameters in conjunction with the bearing number fully define the problem. A simplified one-dimensional and a more complete two-dimensional steady-state analyses are performed to optimize the governing parameters for maximum load carrying capacity and maximum film stiffness. This study shows that the performance prediction capability of the one-dimensional model is overly conservative and not satisfactory, but that its parametric optima are in favorable agreement with the two-dimensional analysis results. The load carrying capacity of the bi-directional bearing is shown to be comparable to that of a Rayleigh step or plain slider bearing. This design offers the great advantage of independence of direction of shaft rotation.