Flow Visualization, Hydrodynamics, and Structural Response of a Flexible Wedge in Water Entry Experiments

Abstract

_ In this article, a free-falling flexible wedge into calm water is experimentally studied to understand the relationship between the spray root, peak pressure, and structural response. High-speed cameras are employed to record the spray root propagation, whereas hydrodynamic loading is measured with an array of pressure transducers. Stereoscopic-Digital Image Correlation (S-DIC) is used to measure deflection on the bottom of the wedge during the impact. Experiments are conducted from different drop heights to study the effect of impact velocity. Results are interpreted in light of an experimental data set of a rigid wedge of comparable dimensions. The comparison between the rigid and flexible wedges shows that due to fluid-structure interaction, the evolution of the spray root on a flexible wedge is slightly delayed compared to the rigid one. Introduction Nowadays, high-speed planing craft are widely used in commercial, recreational, and naval applications. As the growth in utilization of these vessels is observed, naval architects strive to improve the overall performance while the safety metrics are adequately maintained. One of the major concerns that challenges both the performance and structural strength of small high-speed craft is hull slamming. Once the vessel is subject to incoming waves, the hull repeatedly becomes airborne and then impacts the water surface. These slams cause operators to reduce the speed, and the maneuverability of the vessel is also influenced. Additionally, slamming can lead to the serious injury of sailors in rough sea conditions. Severe motion of the vessel because of the impact may also adversely affect the operability of equipment on board, meaning that autonomous vessels are still vulnerable to these types of loading events. As a result, it is crucial to study and understand the slamming in high-speed craft in order to mitigate its negative effects.