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中文核心期刊

基于能量传递规律的海洋立管涡激振动抑制研究

STUDY ON VORTEX-INDUCED VIBRATION SUPPRESSION OF MARINE RISER BASED ON ENERGY TRANSFER

  • 摘要: 涡激振动是造成海洋立管疲劳损伤的重要因素, 抑制振动能够保障结构安全, 延长使用寿命. 多数涡激振动抑制方法基于干扰流场的方式, 但在复杂环境条件下, 仅通过干扰流场对振动的抑制效果有限. 因此, 从结构层面考虑开展了海洋立管涡激振动抑制研究. 基于能量传递的理论, 阐述了立管涡激振动过程中的能量传递规律. 振动能量以行波形式由能量输入区传播至能量耗散区, 主要在能量耗散区被消耗. 通过局部增大能量耗散区的阻尼, 增加振动能量在传播过程中的消耗, 实现涡激振动抑制. 为了求解立管涡激振动响应, 构建了尾流振子预报模型, 并根据实验结果验证了理论模型的可靠性. 基于理论计算得到的能量系数, 判定立管涡激振动的能量输入区和能量耗散区. 通过对比立管增大阻尼前后的响应, 分析了涡激振动抑制效果. 研究结果表明: 在能量输入区增大阻尼对涡激振动的抑制效果并不显著; 在能量耗散区增大阻尼使能量衰减系数达到临界值之后, 能够显著降低立管上部和底部的涡激振动位移; 当能量衰减系数超过临界值后, 继续增大耗散区阻尼对涡激振动抑制效果的提升不明显.

     

    Abstract: Vortex-induced vibration is an important factor which may cause serious fatigue damage of marine risers. The suppression of vortex-induced vibrations can ensure structural safety and prolong service life of marine risers. Most of the suppression methods of vortex-induced vibrations are based on disturbing the flow fields. In some complex environmental conditions, only disturbing the flow fields behind marine risers may have limited effect on the suppression of vortex-induced vibration. Therefore, the vortex-induced vibration suppression of marine risers was studied from the perspective of structure. Based on the theory of energy transfer, the law of energy transfer during vortex-induced vibrations of marine riser was described. The vibration energy propagates from the energy input region to the energy dissipation region in the form of traveling wave and is mainly consumed in the energy dissipation region. By locally increasing the damping in the energy dissipation region, the consumption of vibration energy in the propagation process can be increased to achieve the suppression of vortex-induced vibrations. In order to solve the vortex-induced vibration response of the marine riser, a theoretical model was established based on the wake oscillator model, and the reliability of the theoretical model was verified by the experimental results. The energy input region and energy dissipation region of the vortex-induced vibrations were determined by the energy coefficients calculated from the theoretical method. The suppression effect of the vortex-induced vibrations was studied by comparing the response of the marine riser before and after increasing the damping. If the damping in the energy input region is increased, the suppression effect of vortex-induced vibrations is not obvious. The vibration displacements in the upper and bottom locations of the marine riser significantly decrease when the energy attenuation coefficient reaches the critical value by increasing the damping in the energy dissipation region. When the energy attenuation coefficient exceeds the critical value, the suppression effect of vortex-induced vibrations is not improved by increasing damping in the energy dissipation region.

     

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