Wall-Modeled Large Eddy Simulation of the Flow Through PWR Fuel Assemblies at Re_H = 66 000—Validation on CALIFS Experimental Setup

The EDF aims to identify what causes fuel assembly vibrations in pressurized water reactors. The present work focuses on the validation of pressure fluctuations along the central rod of a 5 × 5 configuration for wall-modeled large eddy simulations. New experiments, called CALIFS, have been carried out by the Atomic Energy Commission (CEA) on a 5 × 5 mixing vane grid (MVG) in the framework of the Fuel Assembly EDF/CEA/FRAMATOME tripartite project. In addition to pressure drop and velocity measurements using particle image velocimetry, pressure measurements have been performed along the central rod. The computational domain is representative of a span of the experimental mock-up composed of a 5 × 5 rod bundle equipped with a split-type MVG. The hydraulic Reynolds number is equal to 66 000 and periodic boundary conditions are imposed in the streamwise direction. The mesh is fully hexahedral and conformal. Computations give very satisfactory results for the pressure drop, the mean velocity, and the Reynolds stresses at different locations. The root-mean-square of the pressure along the central rod is also compared to experimental data at different heights. The behavior is in very good agreement up to five hydraulic diameters downstream of the MVG.