On the Fluid Mechanics of the Inherent Restrictor

Abstract

Hydrostatic thrust bearings commonly employ a sharp-edged asymmetric inlet, generally referred to as an inherent restrictor. For gas and liquid metal bearings, this inlet configuration offers significant advantages and is of definite practical interest. In this paper, an approximate solution is obtained for the laminar flow past the sharp-edged asymmetric inlet to a channel flow or a bearing film, using a simple integral method. The results exhibit important features of the oblique flow disturbance associated with inherent restrictors, including the occurrence of a separation bubble highly destabilizing to laminar flow. From this solution, a first approximation to the inlet pressure loss generated by the separation-induced local breakdown of laminar flow is calculated through the use of energy and momentum theorems. The predicted Reynolds number dependent pressure loss coefficient shows substantial agreement with available experimental data.