计及内输流作用的立管涡激振动响应特性研究

The Study on VIV Responses of a Flexible Riser Considering Internal Flow

为研究内流对输液立管涡激振动响应的影响,基于计及内流作用的海洋立管运动微分方程,结合涡激振动状态下的立管水动力载荷表征方法,引入相位追赶和频率锁定模型,建立计及内流作用的柔性立管涡激振动时域预报方法。结合有限元法和Newmark-β法,实现对内流作用下的立管涡激振动响应的预报。对比均匀流场下的无内流立管预报结果与试验结果,验证该预报方法的可行性和准确性;同时,对不同外流和内流作用下的输液立管涡激振动响应进行预报。着重观测不同工况下的输液立管时空分布图、RMS幅值、主导响应频率和主导模态。结果表明:内输流的存在会使立管涡激振动呈现出更显著的行波现象;涡激振动响应幅值和主导模态随着内流流速的增大而增大。

To study the internal flow influences on vortex-induced vibration(VIV)response,based on the governing equation considering internal flow and the hydrodynamic load model,a time-domain VIV prediction method for the flexible risers considering internal flow was developed with introducing phase pursuit and frequency locking model.Combining the finite element method(FEM)and Newmark-βmethod,the VIV response of the riser under the internal flow was finally predicted.Comparing the predicted value with the experimental result of the riser without internal flow,the feasibility and accuracy of the proposed method were first verified.Then,the VIV responses of the riser under different external and internal flows were predicted.The space-time distribution,RMS amplitude,dominant response frequency and dominant mode of different conditions were further observed.The results show that the existence of internal flow make the VIV response of the riser show more significant traveling wave behavior.The VIV response amplitude and dominant mode increase with the increase of internal flow velocity.