An experimental study on flow-induced vibration of three and four side-by-side long flexible cylinders
An experimental study on flow-induced vibration of three and four side-by-side long flexible cylinders
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三、四并列长柔性圆柱体流激振动实验研究
DOI：
10.1016/j.oceaneng.2018.09.038
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发表时间：
2018
影响因子：
5
通讯作者：
Bai Yin
中科院分区：
文献类型：
--
作者：
Xu Wanhai;Zhang Shuhai;Liu Bin;Wang Enhao;Bai Yin
多柔性筒体结构，如海洋平台、电缆等，是海洋工程油气生产和输送的关键设备。到目前为止，关于多个并排柔性圆柱的流致振动（FIV）的研究还很少。虽然多个柔性圆柱的一些FIV特性可以根据两个柔性圆柱经历涡脱落的知识来预测，但仍然有一些其他特性尚未揭示，这需要对两个以上的柔性圆柱进行进一步的实验研究。本文在拖曳水池中对三缸和四缸并列布置、缸距为6.0D时的燃油喷射系数进行了实验研究。采用质量比为1.90、展弦比为350的柔性圆柱体模型，沿贮箱沿着拖曳，模拟均匀流场。拖曳速度范围从0.05到1.0米/秒，相应的雷诺数从800到16000不等。对试验结果进行了详细的分析，包括最大均方根位移幅值、主频率、主振型、测点位移时变、位移反应谱、均方根位移沿展向的演化以及位移时空变化曲线。结果表明，由于柱后复杂尾流的影响，并列布置的三柱系统的多模态响应特性明显不同于四柱系统。这些研究结果对工程应用中一类柔性圆柱体的设计具有重要意义。
Multiple flexible cylinder structures, such as marine risers and cables, are key equipment for the production and transportation of oil and gas in offshore engineering. Till now, little information is available on flow-induced vibration (FIV) of more than two side-by-side flexible cylinders. Though some FIV characteristics of multiple flexible cylinders can be predicted based on the knowledge of two flexible cylinders undergoing vortex shedding, there are still some other characteristics that remain unrevealed, which require further experimental investigations on more than two flexible cylinders. In this paper, the FIV of three- and four-cylinder system in a side-by-side arrangement with a distance of 6.0Dbetween cylinder centerlines was experimentally studied in a towing tank. The flexible cylinder models with mass ratio of 1.90 and aspect ratio of 350 were mounted horizontally and towed along the tank to simulate the uniform flow. The towing velocity ranged from 0.05 to 1.0 m/s and the corresponding Reynolds number varied from 800 to 16000. The experimental results were discussed in detail, including the maximum RMS displacement amplitudes, dominant frequencies, dominant modes, time-varying displacements at the measurement points, displacement response spectra, spanwise evolutions of the RMS displacement and space-time varying displacement contour. It can be found that the multi-mode response characteristics of the three-cylinder system in a side-by-side arrangement are obviously distinct from those of the four-cylinder system due to the effect of complex wake flow behind the cylinders. These findings are very meaningful for the design of a group of flexible cylinders in engineering applications.