随机风浪中破损船横摇与瘫船倾覆概率计算

Calculation of Rolling and Capsizing Probability of Dead Ship in Random Wind and Waves

现有的瘫船稳性研究主要围绕完整船进行计算,而针对破损船瘫船稳性的研究较少.为评估处于瘫船状态的破损船在随机横风横浪中的安全性,计算第三类舱室破损形式船舶的倾覆概率,并与完整船比较.建立单自由度横摇运动模型,应用CFD方法计算横摇阻尼系数,在时域内模拟船舶在风浪联合作用下的横摇运动,并运用蒙特卡洛方法计算破损船舶的倾覆概率.结果表明:船舶大角度横摇时由于复原力矩和阻尼力矩的非线性,横摇幅值不再服从瑞利分布,且船舶破损后的倾覆概率较完整船增大.破损船舶不对称浸水形式比对称浸水形式更危险,船舶处于横摇的临界区域时倾覆概率会大幅增加.舱室破损虽然会增大横摇阻尼系数,但会造成复原力臂曲线急剧下降,对船舶稳性产生不利影响.

The existing research on the stability of dead ships mainly focuses on the calculation of intact ships,while the research on the stability of damaged ships in the dead ship condition is less.In order to evaluate the safety of damaged ship in the dead ship condition under random beam wind and waves,the capsizing probability of the third type of cabin damaged ship was calculated and compared with the intact ship.By establishing a single-degree-of-freedom roll motion model,the roll damping coefficient was calculated by CFD method.The roll motion of a ship under the combined action of wind and waves was simulated in time domain,and the capsizing probability of a damaged ship was calculated by Monte Carlo method.The results show that,due to the nonlinearity of restoring moment and damping moment,the rolling amplitude no longer obeys Rayleigh distribution,and the capsizing probability of damaged ship is higher than that of intact ship.Asymmetric flooding of damaged ships is more dangerous than symmetric flooding,and the probability of capsizing will greatly increase when the ship is in the critical area of rolling.Although the cabin damage will increase the roll damping coefficient,it will cause the curve of restoring force arm to drop sharply,which will adversely affect the stability of the ship.