Ship Slamming in Waves

点击翻译按钮获取中文摘要

The objective of the proposed research program is to improve numerical tools to predict ship slamming in waves. New experiments will be carried out to gain insight into the physics of water impact in waves and to provide experimental data for validation studies. A ship travelling in extreme seas can experience large-amplitude motions with its bow frequently out of water and re-entering water due to its weight. This phenomenon is called slamming, which can result in high impulsive loads on ship structures. Slamming is a concern of structural integrity for ships in large waves. It is important to predict the loads due to slamming in waves in ship design. Although great progress has been made in solving slamming problems, most studies have been focused on 2-D sections entering into calm water using numerical and experimental methods. Recent studies have been extended to 3-D bodies into calm water and some of them are on experimental tests. The understanding of 3-D slamming in waves for a ship with 6-DOF motions is however limited. The proposed research program will focus on the prediction of ship slamming in waves by improving the numerical methods and by carrying out model tests. The research is summarized as follows: (1) A constrained interpolation profile (CIP)-based finite difference method will be further developed to compute water entry of ships into waves; (2) Model tests will be carried out in Memorial's deep tank and towing tank for two ship models (3-D), one planing hull and one container ship hull, entering calm water and waves. Water entries of the ship models with constant vertical velocities and free-fall motions along with different initial attitudes will be examined. Scale effects will also be investigated. Model test results, including the flow fields, pressures and loads on ship models, will be used to validate the numerical methods. Since the experimental data for 3-D ship slamming into waves is very rare, efforts will be made to provide high-quality model test data for benchmark and validation studies. Uncertainty analysis will be carried out to quantify uncertainties in model tests; (3) Based on extensive 2-D and 3-D studies using the improved CIP tool and the experimental data, a new semi-analytical model will be developed by considering factors such as 3-D effect, wave effect and the initial attitude of ship. The semi-analytical model will be integrated into the panel-free method-based time-domain ship motion program, MAPS, to simulate large-amplitude ship motions in large waves involving slamming. Through the proposed research, highly qualified personnel in the area of marine hydrodynamics with strong computational and experimental skills will be trained. The proposed research, especially the numerical methods and the benchmark experimental data for ship slamming in waves, will contribute nationally and internationally to the field of ship hydrodynamics.