二代稳性衡准纯稳性丧失直接评估方法研究(二)

针对国际海事组织(IMO)正在制定的船舶第二代完整稳性衡准中的纯稳性丧失直接评估衡准,本文提出了纵荡-横荡-横摇-首摇4自由度运动耦合的标准数学模型,进行了纯稳性丧失直接评估.该方法首先基于MMG操纵性标准方法,构建纵荡-横荡-横摇-首摇4自由度运动方程,同时考虑了舵控制方程,其次在纵荡、横荡、横摇、首摇方程右边考虑时域波浪力/力矩,且横摇方程右边进一步考虑了粘性横摇阻尼力矩和波浪中复原力臂变化.最后采用ONR内倾船进行了尾斜浪中纯稳性丧失直接数值计算,为纯稳性丧失直接稳性评估衡准的应用奠定了基础.

Study on direct stability assessment method of pure loss of stability for the second generation intact stability criteria

The guidelines for direct stability assessment of pure loss of stability are currently under development at the International Maritime Organization (IMO) for the second generation intact stability criteria. This study intends to provide a standard mathematical model with surge-sway-roll-yaw coupled motions for predicting pure loss of stability. Firstly, one Maneuvering Modeling Group (MMG) standard method for ship maneuvering predictions is referenced for establishing 4 degrees of freedom (DOF) mathematical model with surge-sway-roll-yaw coupled motions and a control equation for keeping course. Secondly, excite wave forces in time domain are taken into account in the 4 DOF mathematical model, and nonlinear roll damping and roll restoring variation is considered in the roll motion. Finally, some crucial terms for predicting pure loss of stability in stern-quartering waves are numerically investigated with the ONR tumblehome vessel for developing the second generation intact stability criteria,