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原文传递 Numerical Prediction of Green Water and Loads on Ships

论文题名：	Numerical Prediction of Green Water and Loads on Ships
关键词：	Green water;relative wave motion;radiation and diffraction;reverse dam break flow;CFX;simulation;Newton's formulation
摘要：	The green water problem has been known in the maritime world for a long time.Although there are much advanced experimental facilities available throughout the world in the form of towing tanks. But since it is expensive to carry out model tests, a reliable and efficient numerical tool for Green water prediction is always needed.Thus present work aims at developing a numerical method that can predict the Green water loads on ships and offshore structures. The work was divided into two main parts. At first the relative wave elevation was calculated taking into account all the factors that have there influence on relative wave motion. The importance of radiation and diffraction waves in overall wave elevation has also been explained in detail and results have been compared for various wave headings and positions along the surface of a cylinder and ship models. The results were calculated for a fixed cylinder, an FPSO model and an S-175 ship model. Hydrostar was used to predict the sea keeping characteristics for ship models in frequency domain at zero forward speed, later these results were transformed into time domain calculation of the said parameters.In the second part of the research work, the water flow onto the deck and the resulting loads on ship's deck and deck structure were calculated. Once the relative wave elevation and the freeboard exceedance were known, Dam break flow was used to calculate the resulting water heights and velocities at certain point on deck. The freeboard exceedance is taking as a time dependant variable for more realistic results. In order to cater for the water that is reflected back from the structure, a reverse dam flow method was introduced, the comparison of reverse dam flow results is also explained in detail. Finally the Newton's second law was used to formulate the expressions for vertical and horizontal loads on deck. The deck's vertical velocity and acceleration were also taken into account in load calculations. The same scenario was also simulated using CFX software, in that the process was simplified by assuming the ship's deck to be fixed.Computed numerical results for all the above mentioned factors were compared with relevant available experimental data and software based simulations, and a favorable agreement is found.
作者：	Imran Aziz
专业：	Naval Architecture
导师：	Wen Yang Duan
授予学位：	硕士
授予学位单位：	哈尔滨工程大学
学位年度：	2007
正文语种：	中文