Liquid-Lubricated Spiral Spherical-Groove Bearings: Static and Dynamic Characteristics and Hybrid Surrogate Model-Based Rotor Response Prediction

Liquid-lubricated spherical spiral-groove hydrodynamic bearings (SSGB) sustain composite loads under high-speed conditions. This study establishes a numerical framework for SSGB lubrication and proposes a physics-guided hybrid surrogate model to accelerate rotor dynamic analysis. The spherical Reynolds equation is solved via the finite-difference method to determine pressure distributions and dynamic coefficients. Results indicate SSGB exhibits quasi-isotropic behavior, with load capacity and stiffness increasing linearly with rotational speed. Direct stiffness rises with groove depth but varies non-monotonically with groove width ratio, whereas damping generally declines as these geometric parameters increase. The developed surrogate model achieves high prediction accuracy (R2=0.9969). Embedding this model into rotor equations reveals typical soft-spring nonlinearities: deeper grooves increase critical speed and resonance amplitude, while excessive groove width ratios trigger amplitude jumps and system instability. This work provides an efficient approach for predicting the dynamic response of complex rotor-bearing systems.