An Experimental Study on the Impact Pressure Characteristics of a Symmetrical Wedge in Pure and Aerated Water Entry

Offshore impact load standards are currently based on pure water conditions. However, open oceans typically contain air bubbles, making it essential to understand the effects of water-air mixtures on impact loads. Water entry experiments with a 20° deadrise angle wedge were conducted in both pure and aerated water. Utilising a custom-designed apparatus and a bubble generator, this study established a stable and uniformly distributed bubble field, with void fractions measured by a wire-mesh sensor. The spatiotemporal distribution of dimensionless impact pressures was carefully investigated. The results indicated that the impact pressures are higher along the centreline than those at the edge, emphasizing the necessity of considering three-dimensional flow effects in water entry impacts. Additionally, the area-averaged Zhao & Faltinsen model exhibited good agreement with the measured peak pressures. Introducing aeration significantly reduced peak impact pressures, attributed to the lower density of the air-water mixture and the buffering effect of air bubbles. These results provide new insights into the behaviour of impact loads under aerated conditions and offer valuable data for further exploration of water entry dynamics.