A Study of the Effect of Various Recess Shapes on Hybrid Journal Bearing Performance Using Computational Fluid Dynamics and Response Surface Method

Abstract

Hybrid bearings are mostly used in high-speed and load situations due to their better stability and loading capacity. They are typically designed with recess grooves to enhance both static and dynamic performance of the bearing. Previous theoretical studies on the influence of the recess geometrical shapes often utilize the Reynolds equation method. The aim of this paper is to analytically study the influence of various recess geometrical shapes on hybrid journal bearings. A three-dimensional (3D) computational fluid dynamics (CFD) model of a hybrid journal bearing is built, and a new method of response surface model is employed to determine the equilibrium position of the rotor. Based on the response surface model, an optimization scheme is used to search around the equilibrium position to get an accurate solution. The current analysis includes the geometries of rectangular, circular, triangular, elliptical, and annular shaped recesses. All these different shapes are studied assuming the same operating conditions, and static properties are used as the indices of the bearing performance. This study proposes a new design process using a CFD method with the ability of calculating the equilibrium position. The flow rate, fluid film thickness, and recess flow pattern are analyzed for various recess shapes. The CFD model is validated by published experimental data. The results show that the response surface model method is fast and robust in determining the rotor equilibrium position, even though a 3D-CFD model is utilized. The results suggest that recess shape is a dominant factor in hybrid bearing design.