Effect of surface roughness and micropolar lubricants on performance of capillary compensated hole-entry hybrid journal bearing

In the present study, the combined influence of surface roughness and Micropolar lubricants on the performance of a hole-entry type hybrid journal bearing is investigated. The Reynolds equation governing Micropolar lubrication for the journal bearing system is suitably modified to incorporate the effects of surface roughness. The resulting governing equations are solved by coupling the capillary restrictor flow equation with a finite element formulation. Different magnitudes of surface roughness and Micropolar lubricant parameters are considered for various surface roughness patterns in order to comprehensively evaluate their impact on the bearing performance characteristics. The analysis demonstrates that surface roughness, when used in conjunction with Micropolar lubricants, significantly alters the hydrodynamic behavior of the bearing. Specifically, the results reveal an 18.9% reduction in bearing flow rate, a 5% increase in the minimum fluid film thickness, and a pronounced enhancement in the stiffness and damping coefficients for a bearing with a longitudinal surface roughness pattern operating under Micropolar lubrication, compared to an equivalent smooth bearing lubricated with a Newtonian fluid. These findings highlight the potential advantages of employing Micropolar lubricants and engineered surface textures in improving the dynamic and load-carrying performance of hybrid journal bearings.