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中文核心期刊

深海多立柱浮式平台涡激运动特性研究

INVESTIGATION ON THE CHARACTERISITICS OF VORTEX INDUCED MOTION OF A DEEP SEA MUTI-COLUMN FLOATING PLATFORM

  • 摘要: 基于不可压缩纳维-斯托克斯(Navier-Stokes)方程和改进的延迟脱体涡模拟方法(improved delayed detached edd ysimulation method,IDDES),数值研究了深海多立柱浮式平台在海流作用下的涡激运动响应特性.以张力腿平台为对象,计算了该平台在0°,22.5°和45°流向角下的横向和艏摇涡激运动响应,分析了涡激运动响应幅度、频率比随约化速度的变化规律,研究了涡激运动响应能量的分布趋势.数值预报结果与模型实验数据吻合良好,证实了数值模型的有效性;研究发现,当约化速度介于7.0和14.0之间时,横向运动发生锁频,运动幅值稳定在0.2D~0.4D(D为立柱宽)之间,而艏摇涡激运动和约化速度呈线性递增关系;在横向运动锁频区间内,由于艏摇激振力矩主要受升力主导,艏摇频率与横向运动频率相同;相对于0°来流,22.5°和45°流向下的涡激运动频率更高,但艏摇运动能量仅为0°流向角下的10%.基于计算结果,进一步分析了多立柱平台涡激运动中的三维流场结构.

     

    Abstract: Based on the impressible Navier-Stokes equation, the characteristics of the vortex induced motion (VIM) for a multi-column floating platform are investigated by employing an improved delayed detached eddy simulation method (IDDES). Mesh parameters and boundary condition developed in the numerical method are extensively studied. The transverse and yaw motion responses of a Tension Leg Platform (TLP) with four columns are computed in three current headings including 0°, 22.5°and 45°, for di erent reduced velocities. In addition, the behavior of vortex induced motion response, the frequency ratio and the displacement power spectral density are computed and systematically analyzed. The numerical results show that the present predictions of VIM agree well with those from experiments. The lock-in frequency occurs in the transverse reduced velocities ranging from 7.0 to 14.0 and the transverse motion amplitudes vary between 0.2D and 0.4D (where D denotes the width of the column). The yaw motion amplitudes increase with the reduced velocities, which may be related with galloping. It is also found that the transverse motion frequency is the same as the yaw response frequency as the excited yaw moment is governed by the lift force acting on the vertical columns. The frequencies of motion in 22.5° and 45° incidences are higher than that in 0° . However, the yaw motion energy in 22.5° and 45° are around 10% of that in 0 incidences. Further, the three-dimensional fluid pattern is analyzed in the process of VIM for a multi-column floating platform.

     

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