Aeration effects on water-structure impacts:Part 1. Drop Plate Impact

Abstract

Current offshore engineering design codes for wave loading are based on pure water, but wave impacts often involve aerated flow, either as a result of air entrapment as the wave overturns or due to impact with a wave that is already broken. Therefore, it is necessary to develop a new understanding of how design codes should incorporate water-air mixture for wave impact. The experimental study investigates aeration effects on wave impacts by means of (i) slamming impacts of a square flat plate onto a pure and aerated water surface, with zero degree deadrise angle presented in this paper; (ii) wave impacts on a truncated vertical wall in pure and aerated water those will be presented in the companion paper. From the experiment studies it were found that there was a significant reduction in the peak impact loads (both pressure and force) for impact in aerated water compared to that in pure water. There was also a significant reduction in the first phase of the pressure and force impulse for aerated water. The variation of impulsive loadings is less sensitive than the peak loadings for impacts. Implications for design are that maximum instantaneous loads may be conservative in the presence of aerated water.