船舶與海洋工程畢業(yè)設(shè)計外文翻譯--常規(guī)貨船的橫搖阻尼在池田方法基礎(chǔ)上的一個簡單預(yù)測方法及其局限性-展示頁
2025-05-26 18:35本頁面
【正文】 (in Japanese) 九、 Y. Himeno, Prediction of Ship Roll Damping一 State of the Art, Report of Department of Naval Architecture amp。A Simple Prediction Formula of Roll Damping of Conventional Cargo Ships on the Basis of lkeda39。s Method and Its Limitation Yuki Kawahara, Kazuya Maekawa and Yoshiho Ikeda Department of Marine System Engineering, Osaka Prefecture University, Sakai 5998531’ Japan Since 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, Ikeda’s one is widely used in many ship motion puter 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 puter code to predict it on the basis of Ikeda， s method, too. On the basis of the predicted roll damping by Ikeda’s 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, midship 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 ponent, eddy ponent, bilge keel ponent. ??Introduction In 1970s, strip methods for predicting ship motions in 5degree of freedoms in waves have been established. The methods are based on potential flow theories (UrsellTasai method, source distribution method and so on), and can predict pitch, heave, sway and yaw motions of ships in waves in fairly good accuracy. In roll motion, however, the strip methods do not work well because of significant viscous effects on the roll damping. Therefore, some empirical formulas or experimental data are used to predict the roll damping in the strip methods. To improve the prediction of roll motions by these strip methods, one of the authors carried out a research project to develop a roll damping prediction method which has the same concept and the same order of accuracy as the strip methods which are based on hydrodynamic forces acting on strips. The review of the prediction method was made by Himeno [5] and Ikeda [6， 7] with the puter program. The prediction method, which is now called Ikeda’s method, divides the roll damping into the frictional (BF), the wave (Bw)， the eddy (Be) and the bilge keel (Bbk) ponents at zero forward speed, and at forward speed, the lift (Bi) is added. Increases of wave and friction ponents due to advance speed are also corrected on the basis of experimental results. Then the roll damping coefficient B44 (= roll damping moment
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