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.

Theoretical and experimental investigation of the effect of oil aeration on the load-carrying capacity of a hydrodynamic journal bearing

“…Despite the above, there have been relatively few published studies concerned with the effect of air bubbles on hydrodynamic bearing performance. Theoretical work by Abdel-Latif et al [1] considered the effect of aerated oil in circular thrust bearings. Later Chamniprasart et al [2] developed a theoretical model for journal bearings lubricated by aerated oil, based on a modified Reynolds equation, and Nikolajsen [3,4] developed a theoretical model based on viscosity and density values that were modified to account for the presence of air bubbles.…”

Drag Reduction by Dimples on Surfaces in Plane–Plane Contact Lubrication

“…However, a previous study pointed out that bubbles cannot be avoided in journal bearing lubrication, especially in starved lubrication conditions [10], and some studies proved that the bubbles in the film were beneficial to the load carrying capacity [11][12][13][14], which was attributed to the viscosity increase because of the entrained bubbles [15]. However, on the other hand, some researchers gave a contradictory result that the bubbles had little effect on load capacity [16][17][18][19]. In the previous research, the bubbles were small and were entrained in the lubricant; the research focus was the effect of the bubbles on the lubricant viscosity.…”

A lubrication model and static characteristics analysis for bubbly oil lubricated journal bearings based on theory of multiphase mixtures

“…In the first method, the bubbly oil mixture is regarded as a single component lubricating medium. Considering different factors such as air content [4,5], surface tension, shear rate [6][7][8][9], temperature, the equivalent viscosity model of the mixture is established based on the equivalent principle of viscous force. Although the equivalent model has the advantages of simple model and easy numerical calculation, such models can not describe the interface effect between phases and the state.…”