Combined influence of couple stress lubricant,recess geometry and method of compensation on the performance of hydrostatic circular thrust pad bearing

Abstract

This study concerns with the theoretical investigation to show the influence of recess geometry and method of compensation on the performance of recessed hydrostatic circular thrust pad bearing operating with couple stress lubricant. Modified Reynolds equation for couple stress lubricant has been derived using Stokes microcontinuum theory. Stokes theory describes the behavior of fluids consisting of long chain polymer additives having sizes comparable to that of the fluid film thickness. Finite element method technique and commercially available software MATLAB 2013 have been used to solve the modified Reynolds equation and, thus, performance characteristics of bearing have been computed. The performance of capillary- and orifice-compensated hydrostatic thrust pad bearings performance have been compared vis-à-vis to different geometric shapes of recess. Each recess shape has identical ratio of bearing pad area to recess area. It has been observed that the couple stress additives have significant positive influence on the static and dynamic performance of the compensated hydrostatic thrust pad bearing provided that restrictors operates with lower values of the restrictor deign parameter $({\mathrm{CS}¯}_2)$ . Limiting values of 10 and 5 for restrictor design parameter $({\mathrm{CS}¯}_2)$ have been noticed for capillary and orifice restrictor; beyond these values of ${\mathrm{CS}¯}_2$ , use of couple stress lubricant on the performance of hydrostatic thrust pad bearing become insignificant.