SHIP-WAVE IMPACT GENERATED SEA SPRAY: PART 1 - FORMULATING LIQUID WATER CONTENT AND SPRAY CLOUD DURATION

摘要

When a wave impacts a ship, a cloud of water spray may form. This spray water, in cold climates, significantly contributes to the deposition of icing on the ship. Estimation of the spray flux is a first step towards predicting the marine icing. The amount of spray water, termed as liquid water content (LWC), the time of ship exposure to the spray cloud in a spray event known as spray duration, and the frequency at which the spray is generated are all important parameters required to define the spray flux. Most of the spray flux formulas found in the literature are based on field observations of small fishing vessels. Moreover, they consider meteorological and oceanographic parameters only and ignore the characteristic behaviors of the vessel. These formulas are therefore not applicable to any size and type of vessel. This paper develops methods to quantify the spray properties in terms that can be applied to vessels of any size. Formulas to estimate two crucial spray properties, LWC and spray duration, are derived based on the energy conservation principles and by non-dimensional analysis. The formulas take into account the ship's principal particulars, its operating conditions, and the environmental parameters. The formulas are validated against full-scale field measurement from a Russian fishing trawler, MFV Narva, and a medium-size US coast guard vessel, USCGC Midgett. Reasonable agreements are found in both cases.