Pressure Drop Due to Inertia Forces in Step Bearings

Abstract

A study of the pressure distribution in a step bearing is presented, including inertia effects, by assuming that (1) a simplified pressure differential equation, (2) a global momentum balance or (3) an energy equation can be written in the vicinity of the step. All three methods give comparable results for small and moderate film thickness ratios, while satisfactory agreement with existing numerical data and some experimental data may be emphasized. It is pointed out that under certain circumstances, such as strong reverse flow occurring for larger film thickness ratios, the flow is decelerated instead of being accelerated across the step. As a consequence a pressure rise instead of a pressure drop may occur due to inertia, reaching a limiting value equal to half of the dynamic head corresponding to the sliding velocity (when the minimum film thickness in the land area becomes very small).