考虑顺流向和横流向耦合作用的海洋立管涡激振动响应特性

海洋立管的涡激振动是导致海洋油气井事故的主要因素。笔者采用Hamilton变分原理考虑海洋立管内部流体和管外海洋环境载荷的联合作用下,建立了立管横流向和顺流向耦合振动模型,采用尾流振子模型模拟流体对大长径比立管横向和顺流向的涡激力。借助Newmark-β和4阶Runge-Kutta耦合迭代法,求解立管振动和涡激力计算模型,与现有文献实验数据结果对比验证了模型的有效性。在此基础上,系统地分析了不同均匀流和顶张力情况下立管横流向和顺流向涡激振动响应的特性。结果表明,横流向振动在剪切流和均匀流中都具有频率锁定效应,顺流向振动表现为均匀流中的频率锁定效应和剪切流中的多频效应;在高流速下,需同时重视顺流向和横流向的涡激振动影响。

Vortex induced vibration response characteristics of marine riser considering the in-line and cross-flow coupling effect

Vortex induced vibration(VIV)of marine riser is the main factor leading to accidents in offshore oil and gas wells. Based on Hamilton's variation principle, considering the combined effect of the internal fluid of marine riser and the marine environment load outside of pipe, this study establishes the coupled cross-flow and in-line vibration model of the riser. Then the wake oscillator model is used to simulate the cross-flow and in-line vortex-induced force of the riser with large length-diameter ratio. The New mark-β and 4-order Runge-Kutta coupled iteration method is used to solve the calculation model of riser vibration and vortex-induced force. The comparison with experimental data from the existing literature has proved the validity of the model. On this basis, the characteristics of cross-flow and in-line vortex-induced vibration response of the riser in case of different uniform flow sand top tensions are systematically analyzed. The results show that the cross-flow vibration has a frequency locking effect in both shear flow and uniform flow; the in-line vibration is characterized by the frequency locking effect in uniform flow and the multi-frequency locking effect in the shear flow. At the high flow rates, attention should be paid to the effects of in-line and cross-flow vortex-induced vibration.