Numerical simulation and validation of flow-induced vibration of the slender rod using one-way fluid-solid interaction

The vibration induced by the cooling fluid flow around the fuel rods in the fuel Assembly of nuclear reactors causes the rods to be destroyed and eventually leak due to the fretting wear in the place of contact with their supports for a long time. In this paper, the vibration caused by axial fluid flow around a specific rod is numerically simulated. In this study, the fluid flow is modeled using the Large Eddy Simulation (LES) turbulence model in the FLUENT software. The fluid-structure interaction is also modeled using the ANSYS coupling system. To validate the implemented numerical model, the test results of the reported brass rod vibration similar to the studied problem in this research are used. Due to the long execution time of the two-way fluid-structure interaction simulations with a high grid number, the one-way fluid-structure interaction method is proposed. The results of simulations show that the one-way fluid-structure interaction method can be used in cases where the vibration amplitude of the structure is less than the height of the viscous layer. Also, this method reduces the simulation time by ۸۰%. By conducting a grid independence study, the results of the brass rod model showed that the grid is finer, the simulation results are closer to the test results. So that the difference between simulation and laboratory data has decreased from ۹ microns to less than ۲ microns in the present research.

Keywords:

Flow-induced vibration , One-way fluid-structure interaction , LES turbulence model