Coupling effect of time-varying axial tension and combined unsteady flow on vortex-induced vibration of flexible risers
Coupling effect of time-varying axial tension and combined unsteady flow on vortex-induced vibration of flexible risers
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DOI：
10.1016/j.oceaneng.2023.115358
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发表时间：
2023-10
影响因子：
5
通讯作者：
Xinghui Li;Yuchao Yuan;Zhongdi Duan;Hong-xiang Xue;Wenyong Tang
中科院分区：
文献类型：
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作者：
Xinghui Li;Yuchao Yuan;Zhongdi Duan;Hong-xiang Xue;Wenyong Tang
浮式平台的纵荡和垂荡运动对海洋平台的涡激振动（VIV）有着不可忽视的影响，VIV会产生随时间变化的轴向拉力，参数激励和非定常流动，并使涡激振动的预测复杂化。本文改进了半经验模型，模拟了组合非定常流场中参数激励下的柔性涡激振动。流速和刚度矩阵都随时间更新。对55个工况进行了数值模拟，研究了参数激励和非定常混合流对涡激振动的单独和耦合作用。观察到和频、差频、马修型共振、间歇振动和频率起伏等现象。详细讨论了激振振幅T、激振频率fp、组合比和振荡周期P等参数对涡激振动的影响。得出了一些有趣的结论：瞬态低频参数激励和短周期非定常流联合作用可以显著抑制涡激振动。r越大，组合非定常流的影响越显著。当fp为立管主振型固有频率的2倍时，涡激振动主要由参数激励控制。
The surge and heave motions of the floating platform have a non-negligible effect on vortex-induced vibration (VIV) of marine risers, which generates time-varying axial tension of risers, i.e., parametric excitation, and unsteady flow and complicates the prediction of VIV. A semi-empirical model is improved to simulate the VIV of flexible risers with parametric excitation under combined unsteady flow. Both the flow velocity and the stiffness matrix are updated with time. Fifty-five cases are simulated to investigate the separate and coupling effects of parametric excitation and combined unsteady flow on VIV. The phenomena such as sum and difference frequencies, Mathieu-type resonance, intermittent vibration and frequency fluctuation are observed. The effects of parameters such as excitation amplitudedT, excitation frequencyfp, combined ratiorand oscillation periodPon VIV are discussed in detail. Some interesting conclusions are drawn: VIV may be significantly suppressed when transition-low-frequency parametric excitation and short-period combined unsteady flow act together. Largerrmakes the effect of combined unsteady flow more significant. VIV is mainly dominated by the parametric excitation whenfpis twice the natural frequency of the riser corresponding to the dominant mode.