Tension and drag forces of flexible risers undergoing vortex-induced vibration

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• 作者：Lei-jian Song ; Shi-xiao Fu ; Man Li ; Yun Gao ; Lei-xin Ma
• 关键词：Key wordsflexible riser ; drag force ; tension force ; vortex ; induced vibration
• 刊名：China Ocean Engineering
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：31
• 期：1
• 页码：1-10
• 全文大小：
• 刊物类别：Engineering
• 刊物主题：Offshore Engineering; Oceanography; Coastal Sciences; Fluid- and Aerodynamics; Marine & Freshwater Sciences; Numerical and Computational Physics, Simulation;
• 出版者：Chinese Ocean Engineering Society
• ISSN：2191-8945
• 卷排序：31

文摘

This paper presents the results of an experimental investigation on the variation in the tension and the distribution of drag force coefficients along flexible risers under vortex-induced vibration (VIV) in a uniform flow for Reynolds numbers (Re) up to 2.2×105. The results show that the mean tension is proportional to the square of the incoming current speed, and the tension coefficient of a flexible riser undergoing VIV can be up to 12. The mean drag force is uniformly and symmetrically distributed along the axes of the risers undergoing VIV. The corresponding drag coefficient can vary between 1.6 and 2.4 but is not a constant value of 1.2, as it is for a fixed cylinder in the absence of VIV. These experimental results are used to develop a new empirical prediction model to estimate the drag force coefficient for flexible risers undergoing VIV for Reynolds number on the order of 105, which accounts for the effects of the incoming current speed, the VIV dominant modal number and the frequency.