A Study of Active Control of Vortex Shedding and Wake From a Cylinder

The control of vortex shedding and wake from a circular cylinder was studied experimentally at Reynolds numbers, ranging from 160 to 400, using an acoustic active control system. The investigation has been carried by, quantitatively, hot-wire to measure the mean and fluctuating velocities and, qualitatively, by using smoke-wire flow visualization technique to examine the formation of the flow field downstream of the cylinder. The present active control method is able to influence the rate of entrainment from main flow into the wake flow. When the Reynolds number is relatively small, it is the size of the cylinder and the induced sound field velocity rather than Reynolds number which are the significant parameters in determining the controlling reverse and optimum phase lag angels.