基于参激-波激-涡激深海Spar平台垂荡-纵摇-横摇耦合随机运动特性研究

本申请是对已完成的基金项目的进一步深入研究。本申请主要针对我国深海桁架式Spar平台，考虑深海平台的张紧式系泊系统，研究随机波浪力及涡激升力共同作用下，深海Spar平台垂荡-纵摇-横摇耦合动力运动及稳定性。考虑平台初稳性高和排水体积的随机时变特性，提出参数激励项表达式和计算方法；考虑系泊缆恢复刚度与浮体运动之间的非线性关系、平台系统多种水动力阻尼因素，以及平台运动模态之间的内共振关系，建立垂荡-纵摇-横摇三自由度耦合运动方程，研究系泊系统回复刚度、吃水、涡激等对于不同运动模态耦合运动的影响，确定平台不同运动模态失稳的参数域，以及平台运动模态之间内共振运动的动力学行为，揭示Spar平台垂荡运动模态对其它运动模态的影响和平台运动失稳机理，分别给出规则波和随机波作用下三个运动模态的大幅运动和失稳的动力学条件。这将为恶劣海况下深海Spar平台动力优化设计和生存能力评估奠定重要的理论基础。

This application is a further study on the accomplished fund projects. Considering the tensioned mooring system, the dynamic response and stability of the coupling heave-pitch-roll motion for the deep-sea Spar platform under the combined effects of random wave forces and the vortex-induced lift are studied in this application. The calculation methods and the expressions of parametric excitation items are proposed considering the stochastic time-varying metacentric height and the displacement volume. The nonlinear coupled heave-pitch-roll motions are established, taking the different factors into consideration. Such as, the nonlinear relationship between the restoring stiffness of mooring system and the floating-body motion, the various hydrodynamic damping factors of platform system, and the internal resonance relations between the platform movement modes. The influences of restoring stiffness, draft, and vortex-induced on the coupled motion between different movement modes will be studied, and the instability domain for different movement modes, as well as the Spar platform dynamic behavior with internal resonance between different movement modes will be determined. Both the effects of heave motion modes on other motion modes and the instability mechanism for the motion of Spar platform will be revealed.The instability dynamic conditions of the three movement modes under regular waves and stochastic waves are given, respectively.This research can lay an important theoretical foundation for the dynamic optimization design and survivability evaluation for the Spar platform under severe sea state.