参数激励下深海立管动力特性研究

Vibration analysis of deep-sea risers under parametric excitations

针对参数激励下深海立管的水平动力响应及参量不稳定性进行研究。随着海洋油气资源勘探开采往深海进发,立管结构与以往相比起到更为关键的作用,并面临着众多的挑战。特别是当立管系统参数处于不稳定区域时,立管结构易发生参量共振,导致立管破坏,造成环境污染及经济损失。深海立管结构动力特性较为复杂,首先建立了深海立管的结构动力学方程,然后采用富洛开理论分析了立管含阻尼与不含非线性阻尼的参量稳定性,计算了立管结构四个典型工况下的水平动力响应。系统方程的求解考虑了模态之间的耦合作用,探讨了参数激励频率与平台振动幅度之间的关系,最后,着重分析了阻尼变化对系统参量稳定区域的影响,研究表明系统阻尼能够有效缩减参量不稳定性的区域,并对深海立管结构设计提出有益的建议。

Lateral response and parametric instability of deep-sea risers due to parametric excitation were studied. As offshore hydrocarbon resources exploration and exploitation moving to much deeper waters,risers play more important roles than before,and face to many technological challenges. Especially,parametric resonance will appear when riser system parameters lie within an unstable region. The riser resonance can create serious damages which cause environment pollution and economical loss. Unquestionably,the risers under ultra-deep water have complex dynamic characteristics. Firstly,the governing motion equation of a marine riser was formulated. Then,the stability behavior of the riser with and without nonlinear damping was investigated by employing the Floquet theory. The numerical simulations for the lateral response of the riser were validated for four typical cases. In the numerical solving of the governing equation,the coupling between the modes was considered. Finally,special attention was paid to the effect of damping on the parametric unstable region. The results showed that damping could effectively reduce unstable regions. Several useful suggestions were proposed for the design of deep-sea riser structures.