Numerical Simulation of Two‐Lobe Journal Bearing Operating With Magnetorheological Lubricant

ABSTRACT This article investigates the synergistic effect of surface texturing and Magneto‐rheological (MR) lubricants on the steady‐state and dynamic performance indices of two‐lobe journal bearings. MR lubricants, composed of magnetic particles in mineral oil, offer tunable viscosity through applied magnetic fields. The study employs a generalised Reynolds equation, incorporating a continuous Bingham fluid model to capture the lubricant's non‐linear behaviour. The Dave model has been used to describe the shear stress of commercially available MRF122EG lubricant, as a function of volume fraction of magnetic particles and magnetic field. Surface textures, comprising arrays of spherical and conical cap dimples in various circumferential configurations, are analysed. The Reynolds equation is solved using a finite element approach coupled with the Newton–Raphson method, and a mass‐conserving algorithm addresses gaseous cavitation. Optimal surface texture configurations for maximising direct stiffness parameters are determined, revealing that partial texturing in the first half of the bearing is most effective. The study further examines the influence of dimple shape, texture configuration and MR lubricant on the performance of circular and two‐lobe journal bearings. Journal center trajectories are predicted by solving the equation of motion using the fourth‐order Runge–Kutta method. The key findings indicate that the combined application of MR lubricant and partial surface texturing in the first half of two‐lobe bearings enhances direct stiffness parameters by up to 781.9%. Threshold speed, a critical design parameter, is significantly improved (89.3%) in two‐lobe bearings through surface texturing and MR effects. Two‐lobe journal bearings with MR lubricants exhibit smaller and more stable journal center trajectories and limit cycles, indicating enhanced dynamic stability. Consequently, for applications requiring enhanced stability and performance, first half partially textured surface two‐lobe journal bearings with MR lubricants should be preferred.