Fluid-structure interactions during the high speed water entry of a plate

The water entry of a flat plate at high horizontal velocity (30 to 46 m/s) is experimentally investigated with focus on the fluid-structure interaction aspects. Several test conditions has been examined by varying the vertical to horizontal velocity ratio, the pitch angle, the plate thickness and material (aluminium and CFRP panels). Measurements are performed in terms of strains, loads and local pressures. By comparing the data measured at the same test condition but different plate stiffness it is shown that the total load increases significantly, up to 40%, in presence of large deformations of the plate, whichever is the origin, elastic or permanent. This result highlights the relevance of the scaling issues in fluid-structure interaction, and the need of performing full scale tests in order to get correct estimates. In addition to the advancement in the physical understanding, thanks to the high level of test repeatability, the data can be also used as a solid reference for detailed validation of computational approaches.