Session: 06-05-01 Marine Hydrodynamics

Submission Number: 153493

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

Hydrodynamic impact problems frequently occur in natural hazards, marine engineering, and water sports, particularly where structures interact with water at high velocities. Prolonged exposure to such high-intensity impacts poses a serious threat to structural integrity. Therefore, accurate prediction of impact loads is crucial for both scientific research and engineering applications. In open ocean environments, air bubbles are naturally introduced through processes such as biological activity, wave breaking, snowmelt, and foam, further complicating the problem. The presence of these bubbles alters water entry dynamics, making theoretical analysis insufficient to fully capture the impact characteristics. Consequently, experimental investigations remain the most reliable method for studying water entry under aerated conditions. In this study, a series of wedge water entry experiments, both in pure and aerated water, were conducted at the State Key Laboratory of Ocean Engineering (SKLOE) at Shanghai Jiao Tong University. A custom-designed test apparatus was employed, and a bubble generator was used to create a stable and uniformly distributed bubble field. The aeration level, or void fraction, was measured using a wire-mesh sensor. By comparing the impact loads in pure water and aerated conditions, the study reveals the effects of varying void fractions on the spatial and temporal distribution of impact pressure. The effects of aeration on the impact pressure during wedge water entry were evident in both the reduction of peak impact pressure and the extension of pressure duration. The visualisation of the flow during wedge water entry further demonstrated the significant influence of aeration on water entry dynamics, particularly on the development of water jets and splashes. Furthermore, a statistical analysis of the impact pressure was conducted, with the objective of examining the relationships between void fraction, peak impact pressure, and impact duration. Finally, the peak pressures were fitted to probabilistic models, including the two-parameter Weibull distribution and the Generalized Extreme Value (GEV) distribution. This research represents the first experimental study on the impact load characteristics of a wedge in aerated conditions. These findings offer novel insights into the complex behavior of impact loads under aerated conditions and contributes valuable data for the further exploration of water entry dynamics.

Presenting Author: Wencheng Wu Shanghai Jiao Tong University

Presenting Author Biography: Wencheng Wu received his Bachelor's degree in Naval Architecture and Ocean Engineering from Shanghai Jiao Tong University, Shanghai, China, in 2022. He is currently pursuing a Ph.D. degree with the School of Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China. His research focuses on the characteristics of impact loads considering air-water mixtures.