Hydrodynamic Performance Analysis of Herringbone-Textured Floating Ring Bearing for Locomotive Turbochargers

Abstract

Abstract. Floating ring bearings (FRBs) are widely employed in high-speed locomotive turbochargers to address rotor-bearing instabilities that arise under extreme rotational speeds, whereas conventional fluid-film bearings encounter challenges due to nonlinear behavior and instability. The surface texturing with various patterns has been explored for conventional bearing performance improvement, while its application to FRBs remains limited. This study numerically investigates the performance of a bio-inspired herringbone-textured floating ring bearing (HTFRB) in terms of static, dynamic, and stability characteristics. The static performance parameters (load-carrying capacity, power loss, side leakage, and coefficient of friction) of HTFRB are evaluated by solving the Reynolds equation for inner and outer layers using the finite difference method with a successive over-relaxation algorithm. Dynamic coefficients (stiffness and damping) are obtained through the solution of perturbed Reynolds equations. The resulting dynamic coefficients are used to assess the stability parameters, namely the equivalent stiffness coefficient, whirl frequency ratio, and critical mass of the rotor. The parametric analysis studies the effect of key herringbone texture parameters (helix angle, groove depth, groove width ratio, and the number of grooves) on bearing performance. The results reveal that bio-inspired HTFRB exhibits superior performance across different geometrical configurations and rotor speeds. The stability analysis confirms the robustness of rotor-HTFRB system, with positive equivalent stiffness coefficients, negative whirl frequency ratios, and a critical mass of the rotor significantly exceeding its actual mass, even under varying speeds and dynamic conditions. The study demonstrates that HTFRB effectively suppresses external disturbances and enhances operational reliability, providing a promising solution for high-speed turbocharger rotor-bearing systems.