Theoretical prediction of hydrodynamic effect by tailored boundary slippage

Abstract

Abstract

Classical sliding bearings usually rely on the converging geometrical wedge to generate desirable hydrodynamic lubricating effects. This article proposes a novel approach to the generation of efficient hydrodynamic effects in sliding bearings, including those running without the apparently indispensable geometrical wedge. In the new bearing prototype, the stationary bounding surface is modified in such a way that lubricant boundary slippage occurs in the upstream region. It results in a smaller flow resistance in the inlet than in the outlet. Thus, a hydrodynamic effect is generated. To theoretically validate the proposed idea, a one-dimensional model with the critical shear-stress criterion of slippage is built and closed-form solutions are obtained. The result shows a triangular distribution of pressure similar to that of Rayleigh bearings. The load capacity and friction behaviour are studied under different critical shear stresses and surface-tailored parameters. In addition, it is shown that even with a diverging gap, positive hydrodynamic pressure can also be produced through tailored boundary slippage.