Numerical investigation on flow-induced vibration and heat transfer of fuel rods in a small pitch-diameter ratio (P/D) channel

Abstract

The Korea Atomic Energy Research Institute developed a dual-cooled annular fuel rod bundle structure to enhance the core power of the nuclear reactor and improve its heat transfer efficiency. The structure also reduced the pitch-diameter ratio (P/D) of the channel. In this study, a four-subchannel model is taken as the research object, and the Reynolds stress model (RSM) is applied to calculate the flow-solid-thermal tri-physical field coupling for a typical bare rod beam channel. The accuracy of the numerical calculation method used in this study was first verified by comparing it with the experimental data in the literature. Then, the channel flow field under different P/D conditions was simulated, and the formation conditions and influencing factors of the vortex-street structure were studied. Axial flow-induced vibrations of a cylindrical structure in a channel were investigated using a weak coupling algorithm. Finally, the influence of the vortex-street structure on the heat transfer efficiency of the fluid in the channel is discussed. The results show that the anisotropy-based RSM turbulence model can accurately capture the vortex-street structure in small P/D channels. When P/D < 1.050, a stable vortex-street structure appeared in the channel, which led to the stable micro-amplitude vibration of the cylindrical structure in the channel. The presence of the vortex-street structure significantly improves the heat transfer efficiency of the fluid in the channel.