追波中の船の大振幅前後揺れと波乗り現象 : その3 位相面解析による検討

概要

論文の詳細を見る
In the previous papers, the surf-riding of a ship in the regular following waves was examined by the self-running model tests^<5)6)>as well as the numerical simulations^<7)>. It was clarified that the surf-riding occurs when the ship speed including the steady oscillatory component due to the surging motion, after the decay of the transitional motion, reaches the phase velocity of the wave. The numerical simulation showed that conceming the occurrence of the surf-riding there exist three ranges of the ship speed for the fixed wave condition. Under the critical speed V_<lcr>, the ship never makes the surf-riding but invariably makes the periodic surging motion. At the speed between V_<lcr> and another critical speed V_1, the ship sometimes makes the periodic surging motion and sometimes makes the surf-riding motion. Which motion occurs is dependent on the initial conditions of the ship position relative to the wave trough and the surging velocity of the ship. Over the critical speed V_1, the ship always drops into the surf-riding condition. It was also shown that for the low wave height, the critical speed V_<icr>. coincides with another critical speed V_1. It was not clarified how the critical speed V_1 appears. In order to make clear totally the non-linear phenomenon like the surf-riding, it is not sufficient to repeat the numerical simulations for the various initial conditions. It is necessary to use the common method of a phase plane analysis for the non-linear ordinary differential equation which expresses the surf-riding motion. In the present paper, the author examines the mechanism of the surf-riding by means of the phase plane analysis and clarifies how the speed range is separated into three parts and how the wave parameter affects the separation. The method is presented to obtain the above critical speed V_1, which may be termed as the unconditional critical speed for the occurrence of the surf-riding. It is important to know the speed at which the ship can escape from dangerous surf-riding condition. The speed is named as the pull out speed following the analogy with the pull out torque of the synchronous motor, and the chart to obtain the pull out speed is also presented. Showing the analogy with other physical phenomena such as the Josephson effect in the superconductivity, the synchronous motor and the driven damped pendulum, the surf-riding is suggested to be one of the fundamental non-linear phenomenon in the physical science.
社団法人日本船舶海洋工学会の論文

追波中の船の大振幅前後揺れと波乗り現象 : その3 位相面解析による検討

スポンサーリンク

概要

著者

関連論文

スポンサーリンク