Hydroelastic impacts with aerated water
P.R. Wellens (TU Delft - Mechanical Engineering)
M.M. Bockstael (Maritime Research Institute Netherlands (MARIN))
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Abstract
Green water can enact impact loads on deck structures of ships sailing through heavy seas. The water that flows on deck likely has some air entrained, originating from wave breaking. We call that entrained air aeration, and the water aerated water. The maximum pressures in impacts with aerated water can be reduced compared to pressures in water without air. A novel set of experiments was devised in order to study controlled hydroelastic impacts on models of deck structures in the presence of aeration. The plates, with varying stiffness, could take on different angles with respect to the flow direction of the water front. The water front could have different angles, so that a relative angle between water front and plate could be defined. The tests were conducted without aeration and with 4 different percentages of air in water (by volume). The impacts were measured by means of force gauges and pressure gauges, the water front was registered by means of resistive free surface gauges and a set of high-speed cameras. The deformations of the plates were measured by means of laser distance meters. Impacts following from the same starting configuration were repeated so that variations could be studied.