管内流向对深海立管涡激振动的影响与机理研究

In the design of flexible marine risers, the effects of internal flow velocity and flow direction on the dynamic characteristics of flexible marine risers have rarely been taken into account, given the present design standards and rules. Sometimes, the loads due to it have also been neglected. It is inconsistent with the fact we encounter in engineering practice. .By means of numerical simulation and model test, the relevance investigation concerning the vibration mode conversion (travelling and standing wave modes), the energy transfer coefficient and the relative vortex shedding mode of self-excited riser vibration will be carried out. During this process, the ascending and descending internal flows will be regarded as critical dynamic load for flexible marine risers. In addition, various combinations of external sheared flows and several end-support conditions of pipe end have also been taken into account. Based on the preliminary analysis about the effect of additional load centrifugal force, Coriolis force and restoring force on different marine riser zones, the coupled rule about vibration mode conversion along flexible marine riser span may be obtained. Subsequently, the conclusion about the distribution characteristics of instantaneous vibration energy transfer coefficient along riser span, the effect and sensibility of internal flow velocity and direction on vortex-induced vibration relating to flexible marine risers might be drawn. The research work which takes the internal flow into account would be helpful to provide design reference and application guide for flexible marine riser systems in the area of vibration mode and pattern prediction.

在海洋立管设计领域，目前采用的设计标准大多未考虑管内流速和流向对立管动力特性的影响，甚至忽略内流引起的荷载，这与工程实际是不相符的。.本研究拟通过数值仿真与模型试验相结合的手段，将内流速和内流向作为影响弹/柔性海洋立管动力响应的重要因素，同时考虑剪切外流及多种管端约束条件的组合工况，开展弹性立管系统自激振动模式（即行波和驻波模式）、能量传递系数与对应区段泻涡发放形态关联性的分析；阐明不同流向内流诱发的附加荷载离心力、柯氏力、振动回复力与立管振动形态、顺/横流向最大应力出现位置的耦合规律；进而总结海洋立管结构瞬态振动能量传递系数沿立管的分布特征，以及管内流向对深海立管涡激振动形态的影响机理。为内、外流共同作用下，真实细长弹/柔性海洋立管的振动模式和振型预报提供理论依据和工程应用参考。

在海洋立管设计领域，目前采用的设计标准大多未考虑管内流速和流向对立管动力特性的影响，甚至忽略内流引起的荷载，这与工程实际是不相符的。.本研究通过数值仿真与模型试验相结合的手段，将内流速和内流向作为影响弹/柔性海洋立管动力响应的重要因素，同时考虑剪切外流及多种管端约束条件的组合工况，开展弹性立管系统自激振动模式（即行波和驻波模式）、能量传递系数与对应区段泻涡发放形态关联性的分析；阐明不同流向内流诱发的附加荷载离心力、柯氏力、振动回复力与立管振动形态、顺/横流向最大应力出现位置的耦合规律；进而总结海洋立管结构瞬态振动能量传递系数沿立管的分布特征，以及管内流向对深海立管涡激振动形态的影响机理。.该研究相关成果，为内、外流共同作用下，真实细长弹/柔性海洋立管的振动模式和振型预报提供理论依据和工程应用参考。