随机波中船舶参数激励横摇发生的波群作用机理与分析方法研究

The ship parametric rolling is a nonlinear resonant roll motions due to the time varied restoring rolling moment in waves. It is noted that the ship parametric rolling in random seas is quite dangerous due to the random inception with difficult prediction in advance. The accurate estimation of parametric rolling is crucial for the safety design and operation of ships in waves. For the statistical estimation of ship parametric rolling in waves, one of the evident feature is its practical non-ergodicity characteristics. It means that the ship parametric rolling is quite sensitive to the incident wave time history, there is a quite large statistical uncertainty for the typical statistical value of the ship parametric rolling. Belenky et al. (2011) mentioned that the parametric roll is excited by a consecutive action of a series of waves. Therefore, it is logical to evaluate probability for the encounter of a wave group rather than for a single wave. The relation between the parametric rolling and ocean waves can be established using the wave group, which provides the guidance for understanding the mechanism of ship parametric rolling and for improving the numerical simulation method in random seas. . With regard to the ship parametric rolling statistical analysis using wave group method, it needs further improvement in the following respects: the wave group characteristics leading to the inception of ship parametric rolling, the modelling of the wave group signal based on the probablility of the successive wave in the wave group, the hydrodynamic interactions between the wave group and ship. With the purpose of solving the above mentioned problems, this proposal performs the research using the nonlinear wave theory, potential flow based and viscous flow based hydrodynamic theory. Via the above research, the mechanism of random wave group induced parametric rolling can be analyzed, the numerical analysis method of ship parametric rolling in random waves can also be improved.

船舶参数激励横摇是由于船舶海浪中航行时横摇复原力周期性变化引起的一种参数共振横摇运动，随机波中参数激励横摇具有突发性，准确模拟对于保障船舶安全具有重要意义。而随机波中船舶参数激励横摇统计分析由于具有很强的非各态历经性，对波浪时历样本敏感，直接数值模拟结果不确定性很大。Belenky等(2011)指出参数激励横摇由一连续的波列作用而引起，较为合理的方法是评估船舶遭遇波群的概率而不是单个波的概率。基于波群分析船舶参数激励横摇可建立起其与海浪特性的联系，为理解随机波中船舶参数激励横摇机理，完善分析方法提供了方向。针对随机波群中参数激励横摇分析，当前对引起参数激励横摇的波群特征，基于波群出现概率的波群建模，波群与船舶参数激励分析建模问题还很不完善，本课题针对上述问题结合非线性波浪理论、势流和粘流水动力学开展研究，以研究随机波中参数横摇分析的波群作用机理，完善随机波中参数横摇统计分析方法。

船舶参数激励横摇是由于船舶海浪中航行时横摇复原力周期性变化引起的一种参数共振横摇运动，随机波中参数激励横摇具有突发性，准确模拟对于保障船舶安全具有重要意义。而随机波中船舶参数激励横摇统计分析由于具有很强的非各态历经性，对波浪时历样本敏感，直接数值模拟结果不确定性很大。Belenky等(2011)指出参数激励横摇由一连续的波列作用而引起，较为合理的方法是评估船舶遭遇波群的概率而不是单个波的概率。基于波群分析船舶参数激励横摇可建立起其与海浪特性的联系，为理解随机波中船舶参数激励横摇机理，完善分析方法提供了方向。针对随机波群中参数激励横摇分析，对引起参数激励横摇的波群特征，基于波群出现概率的波群建模，波群与船舶参数激励分析建模问题还很不完善，本课题开展了引起参数激励横摇的波群造波以及物理模型试验研究，通过模型试验再现了随机波群作用的船舶参数激励横摇现象。然后基于非线性波浪理论研究了波群的模拟方法，以非线性波群为输入，研究了船舶的参数激励横摇运动模拟方法，分析了初始激励，波群个数，连长等因素对参数激励横摇的影响。本项目研究揭示了随机波群引起参数激励横摇的内在机理，发展了随机波群作用下船舶参数激励横摇评估方法，对于后续开展的船舶随机中参数激励横摇评估方法和实船航行危险海况预警具有一定的参考价值。