The influence of aeration and compressibility on slamming loads during cone water entry

Abstract

The problem of the impact between a rigid body and a gas-liquid mixture is relevant to various engineering applications, including the design of breakwaters and LNG containers. In the present study, the specific problem of the impact of a rigid cone upon the surface of an aerated liquid is investigated. Numerical simulations of water entry of cones with different dead-rise angles (7° and 15°) were performed using an explicit finite element method. The air-water mixture is modelled as a homogeneous fluid with a specific equation of state. In addition, experimental tests of the impact of a cone with a dead-rise angle of 7° on the surface of bubbly water were performed. The air volume fraction was measured prior to the impact tests using optical probes technique, and the instantaneous impact force on the cone was measured using strain gauges. The results highlight a significant reduction of the impact load with the increase of the air volume fraction. Moreover, the numerical results show that this reduction is also dependent on the impact velocity. This phenomenon is found to be related to the nonlinearity of the equation of state of the air-water mixture.