船舶与海洋工程毕业设计外文中英文翻译.doc

船舶与海洋工程毕业设计外文翻译 题 目 7500吨干货船技术设计 总体方案及第三部分 专 业 船舶与海洋工程 班 级 学 生 指导教师 重庆交通大学 2013年 A Simple Prediction Formula of Roll Damping of Conventional Cargo Ships on the Basis of lkedas Method and Its Limitation Yuki Kawahara Kazuya Maekawa and Yoshiho Ikeda Department of Marine System Engineering Osaka Prefecture University Sakai 599-8531 JapanSince the roll damping of ships has significant effects of viscosity it is difficult to calculate it theoretically Therefore experimental results or some prediction methods are used to get the roll damping in design stage of ships Among some prediction methods Ikedas one is widely used in many ship motion computer programs Using the method the roll damping of various ship hulls with various bilge keels can be calculated to investigate its characteristics To calculate the roil damping of each ship detailed data of the ship are needed to input Therefore a simpler prediction method is expected in primary design stage Such a simple method must be useful to validate the results obtained by a computer code to predict it on the basis of Ikedas method too On the basis of the predicted roll damping by Ikedas method for various ships a very simple prediction formula of the roll damping of ships is deduced in the present paper Ship hull forms are systematically changed by changing length beam draft mid-ship sectional coefficient and prismatic coefficient It is found however that this simple formula can not be used for ships that have high position of the center of gravity A modified method to improve accuracy for such ships is proposed Key words Roll damping simple prediction formula wave component eddy component bilge keel component IntroductionIn 1970s strip methods for predicting ship motions in 5-degree of freedoms in waves have been established The methods are based on potential flow theories Ursell-Tasai method source distribution method and so on and can predict pitch heave sway and y