STUDY OF LOADING CRITERION FOR LIQUEFIED NATURAL GAS CARRIER

提出了一种系统的方法来估算与液化天然气船（LNG船）的操作和设计有关的装载标准。该方法由三种数值方法组成，并与LNG船液货舱内液体晃动的研究密切相关：首先，提出了三种基于边界元法（BEM）、随机选择法（RCM）和有限差分法（FDM）的液货舱内液体晃动的数值计算方法;本文对一系列任意形状的储罐，即圆形储罐、球形储罐、带折流板的矩形储罐等进行了数值计算，本文首先讨论了液体晃荡准则的计算方法，并讨论了编制液体晃荡准则时应注意的几个问题，然后对这些方法进行了独立的改进，以检验LNG船从超浅舱到满液舱的大装载系数范围内的装载准则。并建立了一套系统的加载准则估算方法。为了验证该方法的有效性，进行了一系列的模型试验。数值计算结果与实验结果吻合较好。2.结果表明，该方法可用于LNG船任意积载系数的装载准则估算。3.这是一个悬而未决的问题，以确认所提出的方法是否可以投入实际使用。

A systematic method is proposed for the purpose of estimating the loading criterion which has relation to the operation and the design of cargo tanks of liquefied natural gas carrier (LNG carrier). The method consists of three numerical methods and is closely related with investigations of liquid sloshing in cargo tanks of LNG carrier.Firstly, three numerical methods are presented for the sloshing problem on the basis of Boundary Element Method (BEM), Random Choice Method (RCM) and Finite Difference Method (FDM). Numerical computations are executed for a series of arbitrarily shaped tanks, that is to say, circular tank, spherical tank, rectangular tank fitted with baffle plates etc., in any conditions, and several problems for programming those sloshing codes are discussed.Then, those methods are improved independently in order to examine the loading criterion for wide range of stowage factor of LNG carrier (from super shallow to full filled liquid tank). And, they construct a systematic method for estimating loading criterion. Furthermore, a series model experiments are carried out, in order to the usefulness of the proposed method.The following results are obtained, 1. Numerical and experimental results are shown to be good agreement. 2. It is shown that the proposed method is useful for estimating loading criterion for any stowage factor of LNG carrier. 3. It is a pending question to confirm whether the proposed method can be put into practical use.