Multiple pipes bundled with a certain distance are used for deep ocean development for such as lifting seafloor massive sulfides (SMS), pumping up a large amount of cooling water for onboard natural gas liquefaction, and production of oil/gas. To understand the vortex-induced phenomenon of fluids and the structural mutual interference among pipes in a steady flow, a towing tank test using a model of two vertical elastic pipes in tandem is performed. The parameters of this test are: the distance between the two pipes, the incident angle of crossflow with the inline direction of the pipes, the flow velocity (towing speed), and the boundary conditions of the tops of the pipes. The two horizontal accelerations of the towing direction and perpendicular direction are measured with synchronization. Then, the motion of the two pipes in each direction was measured, and the influence of the distance between the two pipes on the motion from the amplitude and phase information was analyzed. The results are investigated relatively in detail about the tandem arrangements of the two pipes to the incident flow. It is found that the major motion pattern of the two pipes in the tandem case is a rotational motion around the midpoint of two pipes.

中文翻译：

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恒流条件下两个串联立管的弹性行为试验研究

以一定距离捆绑的多根管道用于深海开发，例如提升海底块状硫化物（SMS），抽取大量冷却水用于船上天然气液化，以及石油/天然气的生产。为了了解流体的涡激现象和稳定流动中管道之间的结构相互干扰，使用串联的两个垂直弹性管道模型进行了拖曳水池试验。本次试验的参数为：两管间距离、横流与管内线方向的入射角、流速（拖曳速度）、管顶边界条件。牵引方向和垂直方向两个水平加速度同步测量。然后，测量了两个管道在每个方向上的运动，并从幅度和相位信息分析了两个管道之间的距离对运动的影响。比较详细地研究了两个管道与入射流的串联布置的结果。发现串联情况下两管的主要运动模式是绕两管中点的旋转运动。