Numerical study on the effect of lateral vibration frequency on the flow and heat transfer characteristics inside annular fuel elements

Lateral vibrations, commonly experienced in oceanic environments, exert a significant impact on offshore nuclear power platforms. Therefore, it is crucial to investigate the thermal and hydraulic performance of fuel elements under vibrating conditions. In this study, a computational fluid dynamics (CFD) approach is utilized, incorporating a mathematical model of fluid–solid coupling. Through numerical simulations, the flow and heat transfer within an internally and externally cooled annular fuel element under lateral vibration conditions are analyzed. Various parameters are examined with vibration frequencies ranging from 0 to 100 Hz. The vibration was observed to increase the average pressure drop in the flow channel, with the highest average pressure drop occurring at frequencies up to 5 Hz. The velocities in the radial section of the inner and outer runners exhibit symmetric distribution. The optimal uniformity of the synergy angle α is achieved at a vibration frequency of f = 5 Hz. As the vibration frequency reaches 100 Hz, the average synergy angle α approaches 90° at different time intervals. Lateral vibration results in a consecutive decrease in the heat transfer coefficient in the direction of coolant flow, and it also leads to an overall increase in the average heat transfer coefficient of the coolant.