Statistical characterization on slamming and green water impact onto a chemical tanker in extreme sea conditions

Abstract

Characteristics of slamming and green water impact onto a chemical tanker in extreme waves are investigated using statistical analysis based on the model test data. Three extreme wave sequences which contain single real-world waves, the New Year wave, Three sisters waves and Yura wave are considered. The temporal variation of the wave surface elevation generated in the tests, along with the measured heave, pitch motions, and vertical bending moments amidships, are compared and analysed in relation to the probability of exceedance for the maxima and minima. The Weibull and Generalized Extreme Value (GEV) models are used to fit the peaks. Slamming pressures on various locations are discussed by comparing the time signals and analysing the peaks using the analytical distribution models for the three extreme waves. The green water column height and associated loading on the deck are presented and compared as well. Discussions are also provided for the results of slamming and green water impacts for the ship with a medium forward speed in the New Year waves. Statistical values including the largest peak, the mean of 1/10th, and 1/3rd highest value of the identified peaks on the pressures are calculated. In addition to the temporal variation of the slamming pressures, the statistical values of the peaks on 32 locations (26 on the bow and 6 on the stern) are calculated, providing insights on both the time variations and the distributions of the pressures.