Evaluation on motions of downstream cylinder in tandem arrays of two flexible circular cylinders which are towed in still water has been conducted.Partially submerged cylinders was installed as hanging-offvertical cantileversf rom a towing carriage.Each cylinder has length-to-diameter ratio of 34.4 with low mass ratio 1.24.Based on cylinders diameter and free-stream flow velocitiesthe Reynolds number varied from 10800 up to 37800within the range of subcritical regime. F or examining wake interference effects on the motion of the downstream cylinder some different gaps between the two cylinders were employed. Contrary to the single case as the Ur the transverse amplitudes of the downstream cylinder gradually getting larger as p ower function of the Ur rather than the inline one for all Zup. For lud 12D at largest Ur the xlD and ylD decreased from the single case values by approximately 93 and 75 respectively. Combination between own shedding frequency from VIV of the downstream cylinder and interference from the vortices shed from the upstream cylinder iupprlssed the motion of the downstream cylinder in both inline and transverse directionseven a i the largestg ap Luo- l2D . Basically the traJectoryp attemso fthe responsed isplacementsin the tandemc onfigurationsc learly changedw ith the parameters Ur andL ua. At approximately Ur 3.47relatively clearv ertical figure-of-eight patterns appeared for all Lup values.
At ZuD 3.97 the response amplitude became smaller and the trajectory patterns gradually broken from the basic pattern ofvertical figure-of-eight at smallest LuD value.
hanging-off flexible cylinders, inline and transverse amplitudes, upstream and downstream cylinders,
tandema arrangement, wake interference,motion trajectories.
: 532.5 Pra m
Source Article of Proceedings
Coverage ITS Community
Rights TEAM 2008, Oct. 6-9, 2008, Istanbul, Turkey