STUDY OF LOADING CRITERION FOR LIQUEFIED NATURAL GAS CARRIER

提出了一种系统的方法来估计与液化天然气运输船的操作和货舱设计有关的装载准则。该方法由三种数值方法组成，与LNG运输船货舱内液体晃动的研究密切相关。首先，在边界元法（BEM）、随机选择法（RCM）和有限差分法（FDM）的基础上，提出了求解晃动问题的三种数值方法。对任意形状的圆形罐、球形罐、装有挡流板的矩形罐等一系列罐体在任意条件下进行了数值计算，并讨论了这些罐体晃动编码的几个问题。然后，分别对这些方法进行了改进，研究了LNG运输船大范围（从超浅到满液舱）载载系数的装载判据。并建立了一套系统的荷载准则估计方法。此外，还进行了一系列的模型实验，以验证所提方法的有效性。得到了以下结果：1。数值与实验结果吻合较好。2. 结果表明，该方法适用于LNG运输船任意载载系数的装载准则估计。3. 所提出的方法能否付诸实际应用还是个悬而未决的问题。

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.