深海悬垂取水管振动特性研究

深海悬垂取水管的设计趋向于大直径、高内流流速，内流对取水管振动特性的影响不可忽略，分析内部流动引起的管道动态失稳行为以及评估失稳临界流速具有重要工程意义。基于小尺度模型试验，研究内流对深海悬垂取水管道振动特性的影响规律，结果表明：随着内流流速增加，取水管模型会发生动态失稳行为，表现为一种间歇性的近周期运动，该运动主要由管道一阶弯曲模态引起的不稳定性诱导。管道材料、顶端连接方式及底部配重块均影响其动态稳定性，顶端固定连接时质量比小的管道更易发生动态失稳；顶端变为铰接时，质量比大的管道失稳临界流速变小，质量比小的管道失稳临界流速变大。相比顶端边界条件，底部配重块对管道失稳临界流速影响不显著但可以减小其振动幅值。

Research on the vibration characteristics of deep-sea free-hanging water intake riser

The design of deep-sea free-hanging water intake riser (WIR) tends towards large diameter and high internal flow velocity. The influence of internal flow on the vibration characteristics of WIR cannot be ignored. Analyzing the dynamic instability behavior caused by internal flow and evaluating the critical flow velocity for instability is of great engineering significance. Based on small-scale model experiments of WIR are performed to investigate, the impact of internal flow on the vibration characteristics of deep-sea free-hanging water intake riser is studied. The results show that as the internal flow velocity increases, WIR model undergoes dynamic instability behavior, manifested as intermittent nearly periodic motion, mainly induced by the instability of the first bending mode of the pipe. The material of the pipe, the top connection method, and the bottom counterweight block all affect its dynamic stability. Pipes with lower mass ratios are more prone to dynamic instability when fixedly connected at the top. When the top is changed to a pinned connection, the critical flow velocity for instability decreases for pipes with higher mass ratios and increases for pipes with lower mass ratios. Compared to the top boundary condition, the bottom counterweight block has a less significant effect on the critical flow velocity for pipe instability but can reduce its vibration amplitude.