A Study of the Effect of Various Recess Shapes on Hybrid Journal Bearing Using CFD and Response Surface Method

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 and most of the research focuses on thrust bearings. The aims of this paper is to analytically study the influence of various recess geometrical shapes on hybrid journal bearings. A 3-D 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 the response surface model, an optimization scheme is used to search around the equilibrium position to get a more accurate solution. The current analysis includes the recess geometry of rectangular, circular, triangular, elliptical and annular shapes. All these different shapes are studied assuming the same operating and loading conditions and bearing static properties are used as the indices of the bearing performance. The flow rate, fluid film thickness and recess flow pattern are analyzed for various recess shapes. The CFD model for the baseline bearing is validated against experimental data. The results show that the response surface model method is fast and robust in determining the rotor equilibrium position even though a 3-D CFD model is utilized. The results suggest that recess shape is a dominant factor in hybrid bearing design. This study proposed a new design process for a 3-D CFD bearing model with the ability of calculating equilibrium position and is expected to be useful to bearing designers.