Effect of a V-shaped groove on the performance of a circular-cylinder energy harvester

The effect of a V-shaped groove on the performance of a circular-cylinder energy harvester was investigated in this study. The experiments were conducted in a closed-loop wind tunnel at a wind speed ranging from 1 to 7 m s(-1). A standard circular-cylinder bluff body was modified to have the V-shaped groove at the front. The angle theta of the half V-shaped groove was adjusted from 15 degrees to 45 degrees. The experimental results demonstrate that the groove angle between 2 theta = 45 degrees and 68 degrees can sustain energy harvesting when the wind speed increases continuously and provide higher performance on the power output than that in other cases. However, at a wind speed of 7 m s(-1) in the V-shaped groove of 2 theta = 68 degrees, it can provide a maximum root-mean-square power output of 20.33 mW, which is about 140 times that of a standard circular cylinder. Furthermore, particle image velocimetry was used to visualize the flow field around the V-shaped groove bluff body. It showed that the groove angle and wind speed had a direct effect on the bluff body's degree of vibration. The results can be used to improve the energy harvester's efficiency.