振荡来流下柔性立管涡激振动响应特性试验研究

摘要

Under the top vessel motions, dynamic responses of the catenary risers would generate relative-ly oscillatory flow around themselves. Such oscillatory flow would easily trigger the ‘intermittent VIV’ at sag-bend part of the riser. This paper mainly focuses on the experimental investigations on the behaviors of a flexible cylinder in oscillatory flow with different combinations of both maximum reduced velocity URmax and KC number. Fiber Brag Grating (FBG) strain sensors were used to measure the VIV response of the model cylinder. Then, modal analysis and wavelet analysis were utilized to study the experimental data, VIV responses in oscillatory flow and the effects from both reduced velocity and KC number were discussed and summarized. Furthermore, novel features such as higher harmonics and hysteresis were observed.%在顶部浮体的带动下，悬链线立管的动力响应会诱发其周围产生相对来流，而这种振荡来流将激励立管悬垂段产生“间歇性”的涡激振动。文章在海洋工程水池中对不同最大约化速度URmax、KC数组合下的振荡来流作用下的柔性立管开展模型试验研究，利用光纤应变片测量模型的涡激振动响应。结合模态分析与小波变换对试验数据进行分析，讨论并总结了最大约化速度URmax以及KC数对涡激振动位移幅值响应特性的影响规律。文中进一步分析发现振荡来流下的涡激振动响应还存在“迟滞”及“高阶谐频”现象。