On the Design of Thrust Bearings Using a CFD Technique

Abstract

A computational fluid dynamics (CFD) technique is used to examine fully submerged three-dimensional thrust bearings, including the effects of fluid inertia in both the thin film clearance and the groove. Making use of the advantage of the CFD technique, the present paper focuses on the optimum design of thrust bearings in terms of film ratio and fore-region volume size, given the bearing geometry. In contrast to the traditional lubrication analysis where inlet and outlet conditions were assumed to be known (ambient in most cases), the present investigation uses the so-called “spatial” periodic condition which is a more realistic approach to a practical situation. Load capacity and drag on the runner are obtained and compared among solutions of different bearing models. It is found that the flow within the groove significantly affects the load generated in the thin film clearance. Its effect on the drag developed in the film clearance is marginal. As the film ratio increases, the drag on the runner monotonically decreases for all groove configurations and Reynolds numbers investigated here. However, the load goes through a maximum value when the film ratio is about 2.4. The investigation also reveals that the pressure center on the pad is noticeably shifted toward the leading edge by the presence of the flow in fore-region volume. Introduction is also provided regarding the effect of flow in the groove on pressure distribution, inlet flowrate and side leakage.