Laboratory Measurements of Vortex- and Wake-Induced Vibrations of A Tandem Arrangement of Two Flexible Risers  

作　　者：刘怀增 王飞 蒋国盛 郭海燕 李效民 

机构地区：[1]Faculty of Engineering, China University of Geosciences, Wuhan 430074, China [2]College of Engineering, Ocean University of China, Qingdao 266100, China

出　　处：《China Ocean Engineering》2016年第1期47-56,共10页中国海洋工程（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Grant Nos.51279187 and 41174157);the Fundamental Research Funds for the Central Universities(Grant No.201262005)

摘　　要：The dynamic response of two flexible model risers in tandem arrangement immersed in a stepped current was analyzed. The risers, with an external diameter of 20 mm and a total length of 6200 mm, had an aspect ratio of 310. They were hinged to the support structure at the center-to-center distances away 3-12 times the external diameter. The top 1200 mm was exposed to a uniform current at a speed which was up to 0.9 m/s（the Reynolds number was 18000） and the rest in still water. The dynamic responses, which were obtained through the Fiber Bragg Grating strain gauges mounted on the surface, were analyzed by studying the cross-flow amplitudes and modal weights. The cross-flow vibration were observed up to the third mode, and the modal transformation from the second mode to the third mode was clearly observed. The experiment confirmed that the typical vortex-induced vibration（VIV） had occurred on the up-stream riser. But for the down-stream riser, the main excitation mechanism was wake-induced vibration（WIV）. The modal transformation of WIV was more complex than that of VIV, which might be helpful for other researchers to study the interference effect.The dynamic response of two flexible model risers in tandem arrangement immersed in a stepped current was analyzed. The risers, with an external diameter of 20 mm and a total length of 6200 mm, had an aspect ratio of 310. They were hinged to the support structure at the center-to-center distances away 3-12 times the external diameter. The top 1200 mm was exposed to a uniform current at a speed which was up to 0.9 m/s（the Reynolds number was 18000） and the rest in still water. The dynamic responses, which were obtained through the Fiber Bragg Grating strain gauges mounted on the surface, were analyzed by studying the cross-flow amplitudes and modal weights. The cross-flow vibration were observed up to the third mode, and the modal transformation from the second mode to the third mode was clearly observed. The experiment confirmed that the typical vortex-induced vibration（VIV） had occurred on the up-stream riser. But for the down-stream riser, the main excitation mechanism was wake-induced vibration（WIV）. The modal transformation of WIV was more complex than that of VIV, which might be helpful for other researchers to study the interference effect.

关 键 词：marine riser vortex-induced vibration tandem arrangement 

分 类 号：P742[天文地球—海洋科学]