Thermohydrodynamic Analysis of Thrust-Bearing With Circular Pads Running on Bubbly Oil (BTHD-Theory)

Abstract

This paper considers the steady-state bubble-thermohydrodynamic behavior of rigid circular pad thrust bearing and presents an iterative numerical scheme to solve the governing equations. The Reynolds equation, the energy equation of the oil film, and the heat conduction equation of the pad are converted by means of finite difference method and solved numerically. The air/gas bubbles included in the lubricant are assumed to be evenly dispersed. The variation in the oil density and viscosity due to bubble presence as well according to pressure differentials and temperature rise is considered. The surface tension of the bubbles is taken into account in the analysis. Typical graphs showing the influence of the bubble content on the most important design criteria of the bearing: load W, friction loss F, pressure center location Xp and temperature rise within the oil film are presented. The load carrying capacity, outlet temperature or friction loss does not change much with increasing bubble content. The pressure distributions predicted in earlier work by To̸nder [1–4] etc. is confirmed. The pressure center location, however, shifts more downstream, making the bearing more unstable for smaller loads.