Free-fall water entry of a variable deadrise angle aluminium wedge: An experimental study

This study is aimed to investigate the impact-induced loads on an aluminium wedge with stiffened panels. A three-dimensional aluminium wedge with 4 mm bottom plate thickness and the deadrise angle varies from 20 to 30 degrees along the length is allowed to fall freely into still water. Starboard side of the wedge was stiffened with longitudinal and transverse stiffeners, while the portside was unstiffened to allow the hydroelastic response. A series of experiments on the water entry of the wedge has been carried out and the tests for 25 cm drop height are discussed in the paper. To study the hydrodynamic loads, sixteen pressure sensors are used across the wedge surface. Four accelerometers are mounted along the keel of the wedge and measure the vertical acceleration. The pressure on the wedge bottom for both sides, vertical acceleration, velocity, and position are examined. Three phases of the water entry problem including pre-impact, impact, and post-impact are studied. The repeatability analysis of the test process is carried out and is demonstrated that the measured pressure and accelerations are repeatable. Based on the experimental results, the effect of elasticity and deadrise angle is significant on impact-induced loads and acceleration.