Vortex frequency characteristics behind a cylinder in pulsating flow induced by loudspeaker

Abstract

Karman Vortex structure behind a cylinder placed in pulsating air flow induced by loudspeaker investigated experimentally. Horizontality set up wind tunnel used within the range of Reynolds number set from 60 to 600. In the pulsating flow, lock-in phenomenon occurs in which the vortex generated from the cylinder synchronizes with the frequency of the pulsating flow. In the lock-in condition the frequency characteristics corresponds with f / f_K = 1/2, which is the same as the in-line forced oscillating circular cylinder case. The velocity amplitude in the lock-in condition can be indicate the sum of the velocity amplitude of Karman vortex and pulsating flow. The lock-in region increases with increasing the amplitude of the pulsating flow.