肥大船の船首船底部に働く波浪衝撃圧に関する研究 (続報)

抄録

Following the previous report, the hydrodynamic impact pressure on the forward flat bottom of a full form ship in waves has been studied. In this report we assume that the two types of impacts may be occured depending on the relative angle between ship bottom and wave surface at the moment of impact. One is the so-called Wagner type impact and the other is the Bagnold type impact which will be accompanied by the trapped air between the ship bottom and wave surface at the moment of impact. The results are summerized as follows, 1) From the drop tests onto the calm water, it is shown that in the case of Wagner type impact the maximum pressure acting on the two-dimensional model may be proportional to the square of the impact velocity, whereas in the Bagnold type impact it may be proportional to the impact velocity. 2) The occurence of the two types of impacts in waves can be classified by the sign of the relative angle at the moment when ship bottom touches on a wave surface. 3) The Bagnold type impact causes a severe impact acceleration, and its effects will have to be taken into account in the problem of whipping. 4) The occurence of the Bagnold type impact increases drastically in case of shallow fore draft, when it is less than 3%L.