Research on Vibration Transmission Characteristics of Thrust Bearings in Rim-Driven Thrusters Based on Variational method

With the advancement of shaft-less pump-jet technology, stringent requirements for vibration and noise reduction necessitate addressing excitations from flow non-uniformity and rotor imbalance which induce thrust oscillations and radiated noise. This study investigates the rotor vibration response under such excitations and the force transmission of thrust bearings to mitigate structural coupling. A transient rotor-bearing system model is established to compare the performance of water-lubricated tilting pad thrust bearings with spherical pivot versus rubber cushion supports. To accurately model transient bearing lubrication beyond traditional equivalent models, a computationally efficient semi-numerical semi-analytical method based on variational principles is introduced for solving the Reynolds equation. Noise measurements on a rim-driven thruster demonstrate differing acoustic radiation for each bearing configuration, validating the simulations. The results indicate that the bearing support design significantly influences vibration transmission and noise output, providing critical insights for optimizing the dynamic quietness of shaft-less.