Numerical Investigation of Compressible Flow within Aerostatic Journal Bearing.

Abstract

Aerostatic journal bearings are employed in a lot of engineering fields because of the high endurance under severe conditions in current technology. However, it is difficult to investigate the flowfield experimentally, since the flow region of an aerostatic journal bearing is formed by a clearance of micron order. The present study numerically clarifies the flow in a pressurized journal bearing with a circular slot restrictor and the effect of a slit which is used to measure the static pressure. In this study, the flowfield is assumed to be laminar and compressible, and thus the compressible Navier-Stokes equations, equation of continuity and energy equation are solved. The static pressure distributions obtained by our computations are in good agreement with the experimental data, especially under the conditions of small bearing clearances. Furthermore, it is shown that a shock wave is formed around the impinging region at large mass flow rates, and the influence of a static pressure slit should be taken into account to estimate the static pressure reasonably.