骑浪横甩运动操纵耐波耦合模型与统计分析方法研究

Surf-riding and broaching are one of the main causes of the ship dynamic stability failure in following and quartering seas. It is also one of the five stability failure modes in the new generation probability-based Intact Stability Code. However, due to the strong nonlinearity, the research on the statistical property of surf-riding and broaching still faces obstacles such as the inaccuracy of the numerical model and the uncertainty on non-Gaussian probability distributions of identical variables(speed, yaw and roll). In this research, in order to overcome the limitation of the traditional method on system dimensions and coupling factors, the numerical continuation method based on the extended state-space model is proposed and improved to account for time-varying dynamics of the multi-DOF system. Based on this method, the coupling and interacting mechanisms among different degrees of freedoms and factors are analyzed quantitatively to determine the governing factors which are then measured through captive model tests. Thus, a maneuvering and seakeeping coupled 6-DOF numerical model for the simulation of surf-riding and broaching in irregular waves is developed based on the unified theory. Then, relationships between surf-riding and wave characteristics are revealed from numerical simulation results. The non-Gaussian distributions of the identical variables are constructed using the improved time-frequency method based on Hilbert transform to overcome the practical non-ergodicity. Finally, the pioneering method for the statistical analysis of surf-riding and broaching is developed. It is expected to lay theoretical and technical foundations for the criteria and rule check of surf-riding and broaching.

骑浪横甩是尾浪下船舶失稳的主因，也是基于概率的新一代稳性规范的五大重要失效模式之一。然而，骑浪横甩的强非线性造成其概率统计研究面临数值模型准确性不足和表征参量（航速、艏向和横摇）非高斯统计分布不确定等问题。本项目发展基于扩展状态空间模型的改进数值延拓方法，克服传统解析方法在自由度和耦合因素上的限制，实现对骑浪横甩多自由度系统时变动力特性的分析，揭示其强非线性下的多自由度耦合和多因素叠加作用机制，并结合约束模实验阐明其定量变化规律，进而基于统一理论建立准确的不规则波下骑浪横甩操纵耐波耦合六自由度数值模型；借此阐释骑浪发生与波浪特征参数间的内在联系，提出基于改进希尔伯特变换的时频分析方法克服骑浪横甩表征参量的不完全各态历经性，构建其非高斯概率分布模型并形成一套特有的骑浪横甩统计分析方法，为骑浪横甩的规范研究与校核提供理论与技术支撑。

骑浪横甩是尾浪下船舶失稳的主因，也是基于概率的新一代稳性规范的五大重要失效模式之一。然而，骑浪横甩的强非线性造成其概率统计研究面临数值模型准确性不足和表征参量（航速、艏向和横摇）非高斯统计分布不确定等问题。本项目首先采用非线性力学方法，克服传统解析方法在自由度和耦合因素上的限制，实现对骑浪横甩多自由度系统时变动力特性的分析，界定了多自由度耦合和船体力等影响因素对骑浪横甩的影响程度；然后，基于粘流CFD方法建立定常波下约束模实验数值水池，在横甩运动模型中首次准确定量的计入了粘性船体力的影响，在此基础上基于统一理论建立了准确的不规则波下骑浪横甩操纵耐波耦合六自由度数值模型，形成了一套满足IMO新一代完整稳性直接计算衡准指导性建议的骑浪横甩数值预报理论方法；进而，采用此数值模型对不同不规则波工况下的船舶骑浪横甩运动进行了大量长时数值模拟，并通过直接计数法对“增速”、“增速”后横甩、显著艏摇和横摇等骑浪横甩表征参量的发生概率进行了定量分析，揭示了不规则波中骑浪横甩表征参量统计特性，为构建骑浪横甩非高斯概率分布模型以及建立基于概率衡准思想的骑浪横甩统计分析方法奠定了坚实的基础。.项目实施期间，共发表第一标注论文8篇，其中SCI论文3篇，授权发明和实用新型专利各1项，培养硕士研究生4人，骑浪横甩数值模型方面的相关论文被国际拖曳水池大会（ITTC）报告多次引用介绍，受中船集团702所委托开发骑浪横甩数值预报软件，支撑了我国骑浪横甩IMO规范提案工作，获教育部科技进步二等奖1项（第七完成人），参与申报中国海洋学会科学技术奖和中国造船工程学会科学技术奖各1项，研究成果为骑浪横甩的规范研究与校核提供理论与技术支撑。