Analyzing Short Porous Hydrodynamic Journal Bearing Numerically Considering Micropolar Lubrication and Isotropic Roughness

Abstract

In present days of high speed machines and machinery, the aim to reduce the energy loses becomes a major aspect of research for economic reasons and long-term reliability. It is known that an industrial nation can save about 1% of gross national product by better tribological exercises. Many modern machines use porous bearings for its ability to act as a lubricant reservoir. The lubricant used in the open adverse operating situations gets contaminated with worn-out particles and dust, and can be better studied by micropolar lubrication theory. Moreover, machined surfaces always have some degree of roughness which adds to the loss of energy. The present work aims at clubbing the effect of roughness in hydrodynamic lubrication using micropolar fluid with a thin porous bush assuming the velocity slip of lubricant film at the porous bush and fluid film junction. The governing equation for fluid pressure in the porous matrix and hydrodynamic film zone are developed following Darcy’s equation and hydrodynamic micropolar lubrication theory, considering Christensen’s stochastic model of roughness. The bearing is approximated as a short one. Modified Reynold’s equation is numerically solved to compute fluid film pressure in steady-state condition. Friction parameters and non-dimensional load capacity in terms of roughness parameters and porous bearing characteristics are presented in case of Newtonian and micropolar fluids.