Hydraulic coupling effects are essential for the fuel assembly dynamic behavior in reactor operation and under accident conditions when the fuel structures are subjected to external excitations by core barrel motions or inlet mass flow variations. A representative testing in a flow test loop, thus, requires the consideration of several fuel assemblies in a row to assess the associated FSI effects in a relevant manner. Since the existing flow test facility at AREVA Erlangen is designed for testing of a single integral fuel structure, a scaling approach is applied to enable forthcoming flow tests in a row of scaled fuel structures. The validity of the derived scaling principles for the static and dynamic FSI characteristic is demonstrated via benchmarking flow tests between an integral bundle and a scaled down sub bundle structure of an AREVA fuel design. On an analytical level, it is shown that the implementation of a dynamic FSI coupled CFD model is capable to reproduce the dynamic behavior of the scaled fuel design in the flow tests in a quantitative and consistent fashion. This rigorous FSI modeling approach is based on the detailed flow test geometry without any adjustable parameters and, therefore, features predictive qualities for the development of simplified FSI approaches.
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