Turbulent Non-axial Flow in Rod Bundles

Abstract

CFD studies were performed to evaluate the flow field, the turbulent statistics and pressure losses in rod bundles in cross flow with slope angle of $90^\circ , 45^\circ$ and $30^\circ$ between main flow and the axis of the rods. Due to the presence of non-isotropic turbulence in rod bundles, Large Eddy Simulations (LES) are used. This approach is first justified by mesh convergence studies of a single rod in cross flow, simulated by two popular linear eddy viscosity turbulence models. Then the LES approach is validated by comparing the calculations of $90^\circ$ cross flow to results known from the literature: the well-known experiment of Simonin et al. (1986) for a triangular rod arrangement and the very fine calculations of Iacovides et al. (2014) for inline rod arrangements. Comparison to the CEA experimental program EOLE is discussed which was performed with inclined rod bundles. The calculated pressure losses for $90^\circ , 45^\circ$ and $30^\circ$ slope angles and two Reynolds numbers where compared to the experiments. Mean velocity profiles and turbulent statistics are presented.