An Experimental Study of the Effects That Change the Vibration Mode of Riser VIV
An Experimental Study of the Effects That Change the Vibration Mode of Riser VIV
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DOI：
10.1115/omae2011-49677
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发表时间：
2011-10
期刊：
影响因子：
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通讯作者：
Tomo Fujiwara;S. Uto;S. Kanada
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文献类型：
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作者：
Tomo Fujiwara;S. Uto;S. Kanada
近年来，世界范围内正在进行一些深水开发项目。随着水深的增加，隔水管的安全性和可靠性成为一个关键问题。其中最重要的问题之一是涡激振动（VIV）。在墨西哥湾等深水强流区，由于水动力条件的变化，立管的涡激振动运动会不断发生变化。为了评估深水隔水管的安全性和可靠性，研究隔水管涡激振动的动态变化是非常重要的。本文研究顶张式立管。为了阐明立管振动模式的动态变化现象，在日本国立海洋研究所深海盆地进行了一项使用28.5 m长模型的大规模实验。在这个实验中，模型的底端是固定的，而顶端连接到一个张紧器。安装了发电系统，使水流从水面流到约5m深。通过改变模型的顶部张力，从自重平衡状态改变到自重的4倍，对水流条件下隔水管的涡激振动进行了测量。振型由最高15阶的高振型向最低5阶的低振型变化很大。为了研究立管振动模态的变化对立管涡激振动的影响，在顶部张力周期性变化的情况下进行了一系列实验。结果表明，在振动模态发生变化的瞬间，行波从顶端向底端发生。Copyright © 2011 by ASME
In recent years, a number of deepwater development projects are running worldwide. As the water depth increases, safety and reliability of the riser is a critical issue. One of the most important matters is vortex-induced vibration (VIV). In the deepwater area with strong current, for example in the Gulf of Mexico, a riser pipe’s VIV motion changes continually due to the change of hydrodynamic conditions. In order to assess safety and reliability of deepwater riser, investigation of the dynamic variation of riser VIV is important. This paper deals with top tensioned riser. To clarify the phenomena of dynamic variation of the riser’s vibration mode, a large-scale experiment using a 28.5 m long model was carried out at the Deep Sea Basin of the National Maritime Research Institute in Japan. In this experiment, the model’s bottom end was fixed, while top end was connected to a tensioner. The current generating system was installed to make flow from water surface to about 5m in depth. A measurement of riser VIV motion in current condition was carried out by changing the model’s top tension from self-weight balanced condition to four times of the self-weight. Vibration mode widely changed from high mode of up to 15th to low mode of 5th. In order to investigate an influence of the change of vibration mode on the riser VIV motion, a series of experiments were conducted with the periodic variation of top tension. It was found that the traveling wave occurred from top to bottom end in a moment of vibration mode changed.Copyright © 2011 by ASME