Dynamic Performance of Asymmetric Herringbone-Groove Journal Bearings Lubricated with Gallium-Based Liquid Metal

To address lubricant film oscillation and rotor whirl instability caused by unreasonable bearing configurations in X-ray tubes, this study systematically investigated the dynamic performance of asymmetrically distributed herringbone-groove journal bearings lubricated with gallium-based liquid metal. On the basis of hydrodynamic lubrication theory and turbulence effects, an unsteady dynamic Reynolds equation and a perturbation pressure differential equation are established. The physical definitions and coordinate transformation relationships of the lubricant film stiffness and damping coefficients are clarified. Comparative analyses of symmetric and asymmetric bearing structures are conducted on the COMSOL Multiphysics platform under varying eccentricities, rotational speeds, bearing clearances, and groove depths. Compared with the symmetric design, the asymmetric structure generates a significantly higher damping peak in the medium-to-high eccentricity range, achieving an optimal combination of high stiffness and moderate damping. A stable, directional, high-pressure zone can form at zero eccentricity, which actively guides the lubricant to establish a steady hydrodynamic film under misaligned operating conditions. This study provides theoretical support for the optimal design of high-speed bearing systems.