Abstract: The second-generation intact stability criteria of International Maritime Organization (IMO) has entered the trial period. This paper focuses on the surf-riding/ broaching stability failure mode in irregular waves. It reproduce the process of the surf-riding/broaching phenomenon through massive repeated numerical simulations with different speeds, wave directions, wave spectrum truncation ranges and metacentric heights (GM) by adopting a six degrees of freedom (6-DoF) numerical modeling. Hilbert transform is used to calculate the instantaneous wave velocity to identify the ‘speed increase’ state, and the probability of ‘speed increase’, broaching, excessive yawing and rolling are quantitatively studied. It is found that the occurrence of ‘speed increase’ is closely related to the surf-riding, and its probability estimates increase with the increase of the ship speed. Most ships capsize after experiencing a relatively long and continuous duration of ‘speed increase’, and the wave spectrum frequency truncation has a great impact on the probability estimates of ‘speed increase’. However, the probability estimates of broaching after ‘speed increase’ increase sharply with the increase of the wave angle for the ships at the same speed. The total duration of broaching can account for 30% to 50% of the total duration of ‘speed increase’ at high speed when the wave angle reaches 30 degrees. With the increase of the ship speed, the proportion of the duration of broaching in the total time of excessive yawing gradually increases to 60% to 80%, indicating that the yawing at high speed is mainly caused by broaching. The same as the variation of the probability of broaching after ‘speed increase’, the probability estimates of excessive rolling also increases with the increase of wave angle. The quantitative probability estimates of the ‘speed increase’, broaching and excessive yawing and rolling can provide technical support for the application of the second generation intact stability criteria of IMO.

Key words: the second generation intact stability criteria, surf-riding/broaching, ship form parameters, probability estimate

摘要： 国际海事组织（IMO）船舶第二代完整稳性衡准进入试用期,该文针对不规则波中的骑浪/横甩稳性失效模式开展研究,采用六自由度数值模型,选取具有不同航速、浪向、波浪谱截断区域和GM值,进行大量的重复数值模拟,再现了船舶发生骑浪/横甩现象的过程。文中使用希尔伯特变换计算瞬时波速来识别增速状态,定量研究了船舶发生增速、横甩、显著艏摇和横摇的概率。研究发现,增速的发生与骑浪密切相关,其概率估计是随着航速的增加而增大,多数船舶在经历相对较长的持续增速后倾覆; 同时,波浪谱频率截断范围对增速的概率估计有较大影响。在同一航速下,增速后横甩的概率评估随着浪向角的增大而急剧增加,当浪向角达到30°时,在高航速下,横甩的总持续时间可占增速总持续时间的30%~50%。随着航速的增加,发生横甩的时间在显著艏摇总时间的占比逐渐增大至60%~80%,表明船舶在高航速下发生的艏摇主要是由横甩造成。与增速后横甩的概率变化规律相同,显著横摇的概率估计值均随浪向角增加而增加。该文定量研究增速、横甩、显著艏摇和横摇的概率评估,为IMO船舶二代完整稳性衡准的应用提供了技术支撑。

关键词: 第二代完整稳性衡准, 骑浪/横甩, 船型参数, 概率评估