Structural improvement of tilting-pad thrust bearings in nuclear reactor coolant pumps based on thermal elastohydrodynamic lubrication analysis

As a core supporting component of a nuclear main pump, the tilting-pad thrust bearing carries a large axial load, and its lubrication performance directly affects the operational reliability of the pump. This study develops a fluid–structure coupled thermal elastohydrodynamic lubrication model for an oil-lubricated point-supported tilting-pad thrust bearing by considering the contact effect at the pad-back pivot. Within each physical time step, partitioned iterative coupling is implemented between the oil-film lubrication field and the thermoelastic deformation field of the pad. Based on this model, improved schemes for the pad pivot position and pad surface profile are determined, and the lubrication performance of the bearing under extreme accident conditions is evaluated. The results show that thermoelastic deformation of the pad significantly affects the distributions of oil-film pressure, film thickness, and temperature. Considering the maximum oil-film pressure, minimum oil-film thickness, and maximum oil-film temperature, the bearing investigated in this study exhibits the best comprehensive lubrication performance when the radial offset coefficient is 0.51, the circumferential offset coefficient is 0.57, and the height of the parabolic pad surface profile is 6 μm. The optimized structure also improves the pressure and film thickness distributions during coast-down condition, thereby enhancing the oil-film safety margin. This study provides a theoretical basis and numerical method support for thermal elastohydrodynamic lubrication analysis, structural parameter optimization, and transient shutdown safety evaluation of tilting-pad thrust bearings in reactor coolant pumps.