Effect of Surface Texturing and Magneto-Rheological Lubricants on the Characteristics of Circular and Three-Lobe Journal Bearings

Multi-lobe journal bearings are highly effective in improving the static and dynamic characteristics required in scenarios characterized by high loads and fluctuating speeds. The present study investigates the combined effects of surface texturing and the adaptive control offered by magneto-rheological (MR) lubricants, specifically comparing the performance of circular and three-lobe journal bearing configurations. The Finite Element Method is used to solve the modified Reynolds equation to obtain the hydrodynamic pressure distribution, with discrete textures applied as cylindrical caps on the bearing pad. The non-Newtonian behavior of the MR lubricant is modeled using the continuous Bingham fluid model. To effectively capture the cavitation phenomenon across these distinct bearing profiles, mass-conserving JFO boundary conditions are employed using switch functions. Parametric optimization indicates optimal non-dimensional values for dimple radius and dimple depth. Furthermore, applying textures to the first half of the bearing pad significantly expanded the hydrodynamic pressure region. The results demonstrate that combining cylindrical cap textures with a three-lobe configuration and MR fluid yields a higher minimum film thickness and improved direct stiffness coefficients compared to the circular baseline. Although this configuration results in marginal power losses due to increased viscous damping from the texturing and MR effect, this trade-off provides a viable solution for utilizing the adaptive behavior of these lubricants to suppress vibrations in high-speed machinery