This study analyzes the flow around a circular cylinder when a dielectric barrier discharge (DBD) plasma actuator is mounted on the cylinder surface. The experiments are mainly performed at Re = 26500. Flow visualization, surface pressures, and wake velocity measurements are performed for the on and off modes of the plasma (pulse modulated drive). The results indicate that the wake expansion and the length of the cavity region significantly change depending on the actuator location, duty ratio and modulation frequency. When the actuator is located close to the separation point and is driven at the Karman vortex shedding frequency (St = 0.19) with the symmetric actuation mode or at St = 0.38 with the asymmetric actuation mode, the vortex shedding is amplified and the surface pressure behind the cylinder decreases; consequently, the pressure drag increases. On the other hand, at a higher modulation frequency (St ≧1), the vortex shedding process is weakened and the wake turbulence is suppressed; consequently, the drag is reduced to 80% of the non-excited case.

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