Dynamic analysis of textured surface three-lobe hydrodynamic journal bearing operating with electro-rheological lubricant

This study investigates the effectiveness of surface texturing for enhancing steady-state and dynamic performance of three-lobe journal bearings using electrorheological (ER) lubricants. ER fluids consist of dielectric particles suspended in non-conductive oil. The fluid flow in bearing clearance is modeled by generalized Reynolds equation. The non-linear characteristics of lubricant are captured using continuous Bingham fluid model. Surface textures are designed with arrays of spherical and conical dimples arranged in various circumferential configurations. The Reynolds equation is solved using finite element approach and Newton-Raphson method, incorporating a mass-conserving algorithm to address gaseous cavitation in film. Different surface texture configurations are analysed to maximize bearing's direct stiffness parameters. The findings indicate that partial texturing in first half of the bearing maximizes these stiffness parameters. The study further examines impact of dimple shape, surface texture configuration, and applied electric field on the performance of circular and three-lobe journal bearings. The equation of motion for journal is solved using fourth-order Runge-Kutta method to predict journal's center trajectories. The application of ER lubricant and partial surface texturing in three-lobe journal bearing enhances direct stiffness parameter by 339.3% and increases damping parameter by 43%. The threshold speed, a crucial design factor for journal bearings is significantly improved (72.8%) through surface texturing and ER effect in three-lobe bearings. Moreover, three-lobe journal bearings utilizing ER lubricants demonstrate smaller and more stable linear motion trajectories of journal. Under simulated conditions, designers should consider textured surface three-lobe journal bearings with ER lubricants for enhanced stability and performance.