镍矿运输船沉没机理的数值模拟分析

Numerical simulations on the mechanisms of the capsizing of bulk nickel ore carrier

近几年来,多条装运红土镍矿的船舶在南中国海倾覆沉没,引起业界的震惊。红土镍矿是一种非常特殊的矿物质,在运输过程中,如果船舶遭遇风浪,或船舶本身长时间的振动,都会导致该矿石的表面液化。液化后的混合液体具有较强粘性,可以形成自由液面。但由于现存的用于计算船舶自由液面的方法不适合于具有较大粘性的液体,因而无法解释运输该种货物船舶倾覆沉没的原因。所以,该文采用数学建模的方法,对运输红土镍矿的船舶进行了模拟计算。得出的结论是当流体的惯性力大于流体的粘性剪力时,粘性流体对船舶的作用力矩随时间的变化总趋势是逐渐增大。当流体产生的横向惯性力远大于流体的剪切阻力时,流体将会挣脱剪切阻力的束缚,迅速滑向船舶的一侧,使船舶的横稳性迅速消失,最终导致船舶很快倾覆沉没。

A number of bulk nickel ore carriers capsizing in South China Sea have made shipping industry shocked. Clay lateritic nickel ore is characterized by liquefaction on the surface under the influence of waves or long time vibrations during transportation. The blending liquid after liquefied is highly viscous and can generate free surface. However, the existing methods based on the calculation of GM values fail in explain- ing the capsizing of the carriers during transportation. In this paper, the mathematical modeling is adopted to make a thorough analysis to the mechanisms of capsizing. The results show that the imbalance of the shear force leads to the free movements of the liquid cargoes as the inertial force of the liquid cargoes is greater than that of the shear stress, and thus caused a loss of stability. Finally, the increasing external mo- ments result in the capsizing.