顶端振荡激励下柔性立管涡激振动数值研究

Numerical study of vortex-induced vibrations of flexible riser under top oscillation excitation

[目的]采用viv-FOAM-SJTU求解器开展不同顶端振荡激励幅值影响下的柔性立管涡激振动数值模拟。[方法]求解器中立管的流体力学部分基于切片理论和雷诺平均纳维-斯托克斯(RANS)法求解,同时立管的结构动力学部分基于伯努利-欧拉弯曲梁理论和有限元方法求解。[结果]数值分析发现:随着振荡幅值的下降,横流向振动模态由多模态转变为单一模态;同时顺流向振动的主控模态保持不变,但模态振动的幅值减小。[结论]立管在反向运动中冲刷尾涡的行为随着顶端振荡幅值的改变会对立管涡激振动特性产生很大的影响。

[Objective]The viv-FOAM-SJTU solver is used to carry out the numerical simulation of the vortex induced vibrations of a riser under different top oscillation excitation amplitudes. [Methods]The flow field is computed by the strip theory and Reynolds-averaged Navier-Stokes(RANS) method, while the Bernoulli-Euler bending beam theory and finite element method are employed to model the structure of the riser. [Results]The simulation results show that the cross-flow vibrations transform from multi-mode to single mode with the decrease in oscillation amplitude. At the same time, the inline vibrations maintain single mode, but the amplitude of the mode vibration decreases. [Conclusion]With the variation in top oscillation excitation amplitudes, the washing out of the riser by shed vortices affects the characteristics of vortex induced vibrations.