Rheodynamic lubrication of an externally pressurized converging thrust bearing using visco plastic fluids

Abstract

The modern world of the mechanical industry is conventionally in pursuit of machines that have been designed to withstand the high operating speed and heavy load -carrying capacities. Hence the bearing in these machines is subject to high operating speed, heavy load, increased mechanical shearing forces, and a continual surge in pressure. As a result, the lubrication of modern machines is a challenge and an emerging interest among Tribologists around the world. Generally, lubricants are classified into two types namely Newtonian and Non-Newtonian. It has been ascertained that the study related to NonNewtonian lubricants has been trending among accomplished researches worldwide. Tribologists explicitly use Non-Newtonian lubricants, characterized by a yield value called visco-plastic lubricants such as Bingham Plastics, Herschel-Bulkley fluids, and Casson fluids. There are different constitutive equations (or models) to represent Bingham fluids such as the twoconstant Bingham model, the Biviscosity model, and the Papanastasiou model. In this study, the most widely used two-constant model of Bingham fluid has been considered. Further, a generalization of the two-constant Bingham model has been theorized for Herschel-Bulkley fluids. Further, most of the researches on the thrust bearing, both experimental and theoretical have been carried out either with parallel-plates or porous plates. Only a few studies explore the bearings with converging plates. In this scenario, the present study gives a theoretical overview of the performance of an externally pressurized converging circular thrust bearing using Bingham plastics, Casson fluid, and HerschelBulkley fluids as lubricants. This study aims to examine the combined effects of fluid inertia, the angle of convergence and Non-Newtonian characteristics of the lubricants based on the performance of an externally pressurized converging circular thrust bearing, by taking into consideration the variable film thickness. newline