Performance analysis of circular and lemon bore hydrodynamic journal bearing considering surface roughness and shear thinning effect

Abstract

This article presents numerical simulations of rough surface circular and lemon bore journal bearing operating with non-Newtonian shear thinning lubricant, in turbulent regime. Numerical simulations of bearing have been performed by finite element solution of modified Reynolds equation for non-Newtonian lubricant. Rabinowitsch fluid model is used to define the shear-thinning nature of lubricant. Surface roughness has been modelled using the average film thickness model proposed by Patir and Chang. The effects of orientation of surface roughness, turbulent flow (Reynolds number), and fluid flow coefficient are investigated on film pressure, minimum film thickness, frictional torque, and stiffness coefficients of bearing. It has been found that lemon bore bearing outperforms circular bearing in terms of the above-mentioned performance indices. Turbulent flow condition is a notice to provide a higher value of minimum film thickness, stiffness, and damping coefficients but at the expense of higher frictional torque. Roughness on the bearing surface tends to offer a high value of film thickness but also enhances frictional torque. It has been found that the transverse orientation of surface roughness is favourable for a higher value of stiffness coefficients.