Abstract
In this study, the flow features of vortex shedding from a pair of tandem arranged circular cylinders oscillating Jong the direction of the flow were observed by visualizing water flow experiment at the ranges of the frequency ratio YK=0-7 , the amplitude ratio 2a/d=0.25 and 0.5, the distance ratio L/d=1.5, 2.5 and 5.5 and Reynolds number Re=640. the variations of mean vortex shedding frequency were investigated. Although the cylinder oscillation frequency f is ower than the natural Karman vortex's frequency fK, the lock-in phenomenon can be seen even in tandem arrangement ;ase. The lock-in ranges have been shown in each distance ratio L/d. It is found that the lock-in ranges become wide vhen comparing with the single cylinder case. The typical flow patterns of the lock-in or un-lock-in states were shown Nery distance ratio L/d. In distance ratios L/d=2.5 and 5.5, the twin vortex street from the 2nd cylinder (rear set ;ylinder) was not seen.
