短峰波中船舶大幅运动及砰击上浪载荷的时域水弹性方法研究

With the development of ships towards large-scale, high speed and light weighted, ship hydroelastic responses, including springing and whipping loads, and slamming strength issues are becoming increasingly evident. The existing hydroelasticity theories are mainly focus on investigating motion and load responses of ship in regular waves with zero or low forward speed. The realistic ocean waves are however short-crested irregular waves, and associated with strong nonlinearity, randomicity and directional spreading characteristics. The bending-torsional coupled vibrations, slamming and green water loads acting on ships with flare bow operating in rough seas is also a reason of concern..A scheme of three-dimensional time-domain nonlinear hydroelasticity theoretical and experimental methodology is aimed to be proposed in this project. First, a bending-torsional coupling hydroelastic motion governing equation is established with instantaneous wetted body surface nonlinearity, slamming and green water loads and auto-pilot control effects considered. Then the flow field velocity potential around the elastic hull is solved by Rankine panel method to consider ship forward speed effects. The wave forces for ship advancing in short-crested waves are then obtained by time-domain convolution integral and retardation function methods. The fourth-order Runge-Kutta algorithm is used to solve the nonlinear governing equation in time-domain. Finally, large-scale model experiments are conducted in sea waves to obtain the realistic and reliable motion and load responses and slamming load characteristics of ship in short-crested waves, which are also used for numerical approach validation.

随着船舶向大型化、高速化及轻量化发展，船体结构的弹振与颤振等水弹性响应及砰击载荷强度问题日益突出。现有的水弹性理论大多是针对中低速船舶在规则波中的响应进行预报，然而实际海浪是短峰不规则波，具有非线性、随机性和方向分布性，且高速航行于恶劣海况下外飘型船的弯扭耦合振动及砰击上浪载荷等强非线性效应不可忽视。.本课题拟提出短峰不规则波中航行船舶的三维时域非线性水弹性理论与试验研究方案。首先，综合考虑瞬时物面非线性、砰击上浪、自动舵操纵等因素，建立船舶在三维海浪中航行的弯扭耦合时域水弹性运动方程。然后，基于Rankine源法求解有航速弹性船体周围流场速度势及波浪扰动力，通过时域卷积和延迟函数法扩展至短峰波中波浪扰动力计算，并基于Runge-Kutta法求解时域非线性微分方程。最后，基于实海况下大尺度模型试验技术，获取船舶在短峰波中航行时运动与载荷响应及砰击上浪特性的真实可靠试验数据并验证理论算法。

实际海浪是三维短峰不规则波，具有非线性强、随机性强、方向分布广等特征。长期以来，船舶耐波性、波浪载荷和水弹性理论大多是针对无航速浮体或中低速船舶在规则波中的响应进行预报，而关于短峰不规则波中船舶与海洋结构物的运动与载荷响应的研究十分缺乏，相关方法对于准确预报船舶与海洋结构物在真实海况中的水动力性能与结构载荷是十分必要的。本课题建立了三维短峰不规则波的模拟与测量分析方法，提出了短峰不规则波中航行船舶的运动、波浪载荷、砰击载荷、甲板上浪、水弹性响应等的理论与试验研究方案，分析了复杂海况下船舶的大幅运动、砰击颤振、波激振动、弯扭耦合等复杂现象。所采用的研究方法包括三维时域势流理论、基于势流理论和模态叠加法的水弹性理论、CFD模拟技术、CFD-FEM双向耦合方法、水池模型试验、大尺度模型海上试验等。基于上述研究内容，在Marine Structures、Journal of Fluids and Structures、Applied Ocean Research、Ocean Engineering、《船舶力学》、《中国造船》等期刊发表了SCI/EI论文18篇（其中SCI论文11篇、EI论文7篇），申请国家发明专利21件（其中已授权7件），登记软件著作权2件，参加国内外学术交流会议10次（包括ISOPE、MARTECH、ISSC-ITTC联合会议、全国水动力学会议等），指导完成了本科生毕业设计论文15篇，培养了研究生5名（包括2名博士生和3名硕士生）。