A Study on Estimation Method of Sloshing Loads on Actual Ship Tanks

船舶在海浪中的运动是六自由度随机运动。因此，船舶运动引起的液舱内液体晃荡行为应视为三维非线性现象，从而成为一个较为复杂的理论分析问题。本文的目的是建立一种合理的估算实际船舶液舱晃荡载荷的方法。主要结论如下：1.本文提出了一种分析三维晃动问题的方法。该方法采用摄动展开法简化边界元法的算法，并考虑了船舶六自由度的全部运动。使用该方法，可以分析在规则波或不规则波（即海浪）中前进的船舶上的罐中的晃动现象。2.本文提出了一种计算具有绝对随机变量的非线性响应最大值概率分布的方法。利用这种方法，可以对满液棱柱形储罐壁面上产生的动水压力进行统计预报.作为应用实例，给出了某巨型油轮棱柱形液舱的各种数值模拟结果。2.结果表明，综合运用上述计算方法，可以估算实船液舱的晃荡载荷。

A ship in sea waves behaves randomly in six degrees of freedom. Therefore, the sloshing behavior of fluids in ship tanks, which is excited by ship motions, should be treated as a three-dimensional and non-linear phenomenon, then it becomes a fairly complicated problem in the rational analysis. It is the purpose of this work to establish a rational method for estimation of the sloshing loads on actual ship tanks. The conclusions are as follows.1. A method is proposed for analysis of a three-dimentional sloshing problem. In this method, an algorithm of the boundary element method which is simplified by use of perturbation expansion is introduced, and all of the ship motions which have six degrees of freedom is considered. Using this method, it is possible to analyze a sloshing phenomenon in tanks on a ship which advances in regular waves or irregular waves(i.e. sea waves).2. A method is proposed for calculations of the probability distribution of the maxima of non-linear response with absolutes of random variables. Using this method, it is possible to make a statistical prediction of the hydrodynamic pressure induced on the walls of the full-filled prismatic tanks.3. The results of various numerical simulations for prismatic tanks on a gigantic oil tanker are illustrated as application examples of the calculations by 1. and 2.. As a result, it is recognized that we can estimate the sloshing loads on actual ship tanks by application of combined use of preceding calculation methods.