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朱红钧, 刘文丽, 高岳. 平台运动对柔性立管涡激振动影响的实验研究. 力学学报, 2024, 56(3): 1-12. DOI: 10.6052/0459-1879-23-415
引用本文: 朱红钧, 刘文丽, 高岳. 平台运动对柔性立管涡激振动影响的实验研究. 力学学报, 2024, 56(3): 1-12. DOI: 10.6052/0459-1879-23-415
Zhu Hongjun, Liu Wenli, Gao Yue. Experimental study of the influence of platform motion on the vortex-induced vibration of a flexible riser. Chinese Journal of Theoretical and Applied Mechanics, 2024, 56(3): 1-12. DOI: 10.6052/0459-1879-23-415
Citation: Zhu Hongjun, Liu Wenli, Gao Yue. Experimental study of the influence of platform motion on the vortex-induced vibration of a flexible riser. Chinese Journal of Theoretical and Applied Mechanics, 2024, 56(3): 1-12. DOI: 10.6052/0459-1879-23-415

平台运动对柔性立管涡激振动影响的实验研究

EXPERIMENTAL STUDY OF THE INFLUENCE OF PLATFORM MOTION ON THE VORTEX-INDUCED VIBRATION OF A FLEXIBLE RISER

  • 摘要: 基于自循环实验水槽开展了存在平台纵荡和横荡运动时的悬链线型柔性立管涡激振动响应测试, 模型立管的长径比为125, 测试的平均约化速度范围为4.40 ~ 39.33. 利用激光位移传感器和高速摄像机分别监测了平台运动和立管振动位移, 从响应频率、振幅和振动形态等方面分析了平台运动对立管振动的影响. 根据立管振动的主导频率与平台运动的主导频率是否相同, 区分了强耦联和弱耦联现象, 定义了强耦联的立管长度, 其在立管振动的模态过渡组次相对较短. 立管振动与平台运动存在两个方向均耦联、仅单一方向耦联和不耦联3种情形. 其中, 立管平面外振动受平台运动的影响较平面内振动小. 以立管瞬时形态的波腹个数变化量化了模态竞争和平台运动对振动形态的影响. 通过对比过滤平台固有频率前后的立管振幅、振形与主导频率的时空分布, 用强耦合的时间权重和空间长度量化了平台对立管振动耦合的影响, 发现高约化速度时, 平台运动抑制了立管空间的频率竞争, 也抑制了立管平面内与平面外振动的耦合响应.

     

    Abstract: The effects of surge and sway motion of top platform on the vortex-induced vibration (VIV) of a catenary flexible riser were experimentally investigated based on a circulating water flume. The VIV of the flexible riser possessing an aspect ratio of 125 was tested in an averaged reduced velocity range of 4.40–39.33. The motion of the platform and the vibration displacement of the riser were monitored by the laser sensor and high-speed cameras, respectively. The effects of platform motion on the riser response are examined in terms of the response frequency, amplitude and instantaneous shapes. According to the coincidence of the dominant frequency, the strong and weak coupling between the platform motion and riser vibration are identified. A strong coupling length is proposed to quantify the interaction between them, which is relatively short in the mode transition cases of riser response. According to the in-plane and out-of-plane responses of the flexible riser, there are three coupling patterns with the platform motion, including the bidirectional coupling, unidirectional coupling and uncoupling. Compared to the in-plane response, the out-of-plane response of the riser is less affected by the platform motion. The influences of mode competition and platform motion on the instantaneous vibration shapes of riser are quantified with respect to the number of peaks. The spatial-temporal distribution of response amplitude, vibration shape and dominant frequency before and after the filtering of the natural frequency of platform are compared to figure out the influence. Furthermore, the time weight of strong coupling and the coupling length are proposed to quantify the influence of platform motion on the coupling between the in-pane and out-of-plane responses of the flexible riser. It is found that the platform motion suppresses the spatial mode competition as well as the coupling between the in-plane and out-of-plane responses at high reduced velocity cases.

     

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