Investigating flow and heat transfer characteristics in a fuel bundle with split-vane pair grids by CFD methodology

Abstract

In this paper, a computational fluid dynamics (CFD) methodology is proposed to investigate the thermal–hydraulic characteristics in a rod bundle with split-vane pair grids. The SST k–ω turbulence model is primarily adopted in the present CFD model. Thickness of grids is considered in order to precisely simulate their effects in reduction of the effective flow area and increase of the flow velocity and the heat transfer capability. In addition, the uniform heat generation rate is also used to model the heat generation rate within the fuel rod, rid of constant heat flux assumption as the previous simulation works. Existing data of Nusselt (Nu) number distributions in the axial and azimuthal directions obtained by Holloway et al. (2008) have been employed to validate the CFD model. The Nu decreasing trend downstream of a split-vane pair grid and the Nu variation around the circumferential surface of rod can be explained by the predicted flow characteristics, including flow swirling, detachment, separation, etc.