考虑辐射和流固耦合的Spar平台多自由度涡激运动非线性分析方法研究

Spar平台的涡激运动(VIM)发生在超或跨临界雷诺数范围，对立管以及锚泊系统的疲劳寿命有严重影响。由于其大直径圆柱体的辐射作用不能忽略，传统的涡激振动理论不适用于Spar平台VIM分析，模型试验因雷诺数不相似而无法准确预测原型的VIM。本课题考虑结构自身速度和加速度对流体的反作用力，将结构阻尼和流体阻尼分开进行计算，通过数值模拟和模型试验论证辐射对涡激升力和脉动拖曳力的影响，建立考虑辐射的圆柱体涡激升力和脉动拖曳力模型；基于辐射对Spar平台VIM的作用机制，建立考虑辐射的Spar平台两自由度VIM模型；研究横摇和纵摇及螺旋侧板对涡激升力和脉动拖曳力及Spar平台VIM的影响，提出考虑辐射的Spar平台多自由度VIM非线性流固耦合分析方法。本课题的开展可以优化涡激升力和脉动拖曳力模型，认识Spar平台VIM多自由度耦合的机制，对Spar平台VIM的水动力研究具有重要的科学意义和应用价值。

The vortex-induced motion of a Spar platform occurs at the supercritical or the transcritical areas of Reynolds number, which is bad for the fatigue life of risers and mooring system. On account of the radiation due to the large diameter of circular cylinder, the vortex-induced motion of a Spar can't be analysed by using the traditional method based on current vortex-induced vibration theory. In addition, the VIM response of a Spar platform can't be predicted by scaled model test based on current similarity. The reactive force deduced by velocity and acceleration of the structure itself will be considered in this project. Moreover, the damping coefficient in most research is an integration of structural damping and radiation damping, but in this project, the structural damping and radiation damping are calculated separately. Through numerical simulation and model test, firstly, the effects of the radiation of a Spar platform on the lift and drag, acted on the Spar platform, induced by vortex shedding are studied and the mathematical models of the lift and drag considering the radiation are established. Secondly, the effects of the radiation on Spar platform vortex-induced motion are studied and the mathematical model of a Spar platform vortex-induced motion in two-degree of freedom considering its radiation is established. Thirdly, the effects of the roll and pitch of a Spar platform as well as the strakes on its hull on vortex-induced motion are investigated and the lift and drag model of a Spar platform considering the roll and pitch of the Spar are established. Finally, a non-linear method for a Spar platform VIM analysis considering its radiation, fluid–structure interaction and multi-degree of freedom is proposed. Through this project, the lift and drag model are optimized, and the mechanism of Spar VIM in multi-degree of freedom is realized. It is of important scientific significance and application value to investigate hydrodynamics of Spar VIM.