计及不同尺度流固耦合影响的船舶局部结构砰击响应计算方法研究

With respect to the urgency of the rational analysis method of local structure response under slamming loads in the structural safety design and the importance of fluid-structure interaction in slamming response analysis, the fluid-structure interaction between ship vibration and wave during the ship slamming is investigated and the calculation method of slamming response of ship local structure that considers the effect of fluid-structure interaction in different scales is established. There are two different scale coupling problems between ship structure and flow field. One is the coupling between ship structure global vibration and the fluid ("Global coupling" for short in this article) and the other one is the coupling between the local grillage and the fluid ("local coupling" for short in this article). Both of them would affect the slamming response of local structures (such as bottom and flare structures of bows) suffering wave impact. Firstly, the dynamic deformation of the local structure boundary and method for solving the slamming pressure during the global coupling are researched. Secondly, the coupling mechanism between the local vibration and the fluid is studied and solution methods for the analysis of dynamic response of ship local slamming are established; Finally, based on the analysis of fluid-structure interaction in different scales, the calculation method of slamming response of ship local structures with the influence of "Global coupling" and "Local coupling" is established by the submodel technique.

考虑到船舶局部结构砰击响应的合理分析在船舶结构安全设计中的迫切性以及流固耦合现象在砰击响应分析中的重要性，本项目以船舶振动与波浪间的流固耦合问题为着眼点，研究建立计及不同尺度流固耦合影响的船舶局部结构砰击响应计算方法。船舶砰击时，船舶结构与流场间存在两种尺度的耦合，一种为船舶总体振动与流场间的耦合（本文简称为“总体耦合”），一种为局部板架振动与流场间的耦合（本文简称为“局部耦合”），二者均会影响遭受波浪砰击的局部结构（如船首底部、外飘结构等）响应。首先，研究伴随“总体耦合”的局部结构边界的动态变形和砰击压力场的求解方法；其次，研究“局部耦合”的作用机理，建立面向船舶局部结构砰击动力响应分析的求解方法；最后，基于对不同尺度流固耦合作用的分析，采用子模型技术建立计及“总体耦合”和“局部耦合”影响的船舶局部结构砰击响应计算方法。

船舶在恶劣海况中航行时，船舶与波浪之间经常会发生剧烈的冲击作用，导致船体瞬间承受较大的载荷，这一现象通常被称为“砰击”。过大的砰击载荷十分有可能造成船体局部结构，甚至总体结构的的损伤，从而威胁整船的生存。本项目围绕船舶局部结构砰击响应问题，采用数值仿真和模型试验相结合的技术手段，开展局部结构边界位置的动态变形求解、波浪冲击区域的高频压力场求解、局部振动与流体之间的耦合机理、船舶局部结构的砰击响应分析几方面研究。在船舶局部结构边界位置动态变形方面，耦合势流框架下的三维边界元方法和结构有限元方法，建立了伴随总体颤振响应的船舶局部结构边界动态变形的计算方法；在砰击压力场求解方面，结合落体砰击载荷试验和CFD技术，建立了船首外飘砰击载荷的数值预报方法；在局部流固耦合作用分析方面，建立了弹性板架入水砰击的流固耦合分析模型，并实现了局部流固耦合影响的量化分析；在船舶局部结构的砰击响应方面，开发用于求解子模型边界动态变形和外板砰击压力场的插值程序，进而采用结构动力学技术，建立计及流固耦合影响的船舶局部结构砰击动力响应分析方法。总体而言，本项目系统地揭示了船舶砰击过程中的流固耦合机理，从理论和方法上为航空母舰、两栖攻击舰、集装箱船、滚装船等大型军用或民用船舶的局部砰击加强设计提供技术支撑。