Unsteady flow loading of fuel assemblies in Pressurised Water Reactors power plants is a potential cause of deformation and of fretting wear damage. Inside a fuel assembly, rods are arranged in 17 × 17 bundles. The rod diameter is equal to about 9 mm, and the gap between two rods is equal to about 2 mm. Each rod is several meters long, and mixing grids are arranged every 0.4 m. The axial flow velocity is equal to about 5 m/s, so that the Reynolds number reaches 5 × 105 in the reactor configuration. Due to the complexity of the turbulent flow pattern, an accurate description of the fluid-structure interaction is still a challenging task, and only a few data about this issue are available today in literature. Recent Computational Fluid Dynamics results are revisited from the point of view of classical axial turbulence-induced vibrations. The unsteady pressure force Power Spectral Densities are determined, a convective velocity is derived, and an estimation of the axial correlation length for the pressure force is given. The results agree reasonably well with the scientific literature.
CFD Estimation of the Unsteady Fluid Force Along a Fuel Rod Downstream a Mixing Grid
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Moussou, P, Benhamadouche, S, & Bodel, C. "CFD Estimation of the Unsteady Fluid Force Along a Fuel Rod Downstream a Mixing Grid." Proceedings of the ASME 2011 Pressure Vessels and Piping Conference. Volume 4: Fluid-Structure Interaction. Baltimore, Maryland, USA. July 17–21, 2011. pp. 251-259. ASME. https://doi.org/10.1115/PVP2011-57337
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