Numerical simulation study on the fluid excitation force on a nuclear fuel rod with a spacer grid

Abstract

Fluid excitation force is the driving source of grid-to-rod fretting (GTRF) wear, which is an important mechanism of nuclear fuel failure and breakage. In the present work, the fluid excitation force on a nuclear fuel rod was calculated and analyzed by the computational fluid dynamics (CFD) method, including time domain and frequency domain analysis. The cases of different turbulence models, inlet velocity, mixing vanes, and clamping structures were simulated and compared to study the mechanism of the generation of fluid force. The result shows that the SST k-ω model with a resolved near wall region mesh can capture the fluctuation of fluid excitation force, that the necessary condition for the generation of fluid force is enough inlet velocity and mixing vanes or clamping structures equipped, and that the necessary condition for the fluctuation of fluid force is enough inlet velocity and clamping structures.