流れ方向軸に非対称な断面を有する流れ方向強制振動柱体からの渦放出

抄録

In this study, in order to understand the vortex shedding characteristics from an asymmetrical bluff cylinder, the flow features of vortex shedding from a square cylinder oscillating along the direction of the flow were observed by visualizing water flow experiment at the ranges of the frequency ratio f/fK=1~6, amplitude ratio 2a/d=0.67 and 1.00, and main flow velocity U=0.0654m/s. Experimental apparatus consists of the closed circuit water channel apparatus, an oscillating apparatus, a visualization apparatus, and a video recording apparatus. Use those equipment, the variations of mean vortex shedding frequency were investigated and the existence range of the lock-in was shown. As a result of the experiments, Even if it used the cylinder of asymmetrical cross-sectional shape for the flow axis, producing the lock-in phenomenon was observed. It was shown that the lock-in range is in the tendency which will narrow if oscillating half amplitude becomes large. It was found that distribution of the flow pattern of the lock-in region and changes process change with degrees of angle of attack.