AUTHOR=Lu Chuan , Du Zhaohui 

TITLE=Large eddy simulation of a turbulent flow in a 5 x 5 rod bundle with a mixing vane spacer grid

JOURNAL=Frontiers in Energy Research

VOLUME=Volume 12 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2024.1334200

DOI=10.3389/fenrg.2024.1334200

ISSN=2296-598X

ABSTRACT=In fuel assemblies of pressurized water reactors (PWRs), mixing-vane spacer grids are extensively employed to array fuel rods and to enhance inter-subchannel and intra-subchannel mixing. Turbulent flow downstream of spacer grids is essential knowledge to support the design of spacer grid and mixing vane. As a high-fidelity approach for turbulence simulation, large eddy simulation (LES) results are assessed with the high-resolution flow field measured with particle image velocimetry (PIV). The LES results reveal mixing vane effect on vortex structures and Reynolds stresses. The mechanism of vortex generation at the mixing vanes and development downstream of the spacer grid are visualized by Q-criterion. The distributions of root mean square fluctuating velocity and Reynolds stresses decay fast downstream of the spacer grid. The secondary flow intensity downstream of the spacer grid predicted by LES is evaluated and follows the exponentially decaying law with distance from the spacer grid.