Flow control around the NACA 4415 airfoil by steady and unsteady actuations of Dielectric Barrier Discharge (DBD) plasma actuator

Spectral study was conducted to investigate the outcome of steady and unsteady actuations of dielectric barrier discharge (DBD) plasma as an active flow control for vortex shedding in the wake of the NACA 4415 airfoil with a 10° angle of attack and Reynolds number of 12,800. The spectra of both streamwise and normal fluctuating velocity components ($\text{u}^{\prime}$ and $\text{v}^{\prime}$ respectively) show that their power spectral densities are greatly diminished. This active flow control helps the low momentum fluid in the boundary layer to overcome the unfavorable effect of the adverse pressure gradient and control flow separation on the suction surface of the airfoil. The spectral study results reveal that the vortex shedding is controlled by the duty cycle frequency $(f_{\text{d}\text{c}})$ used. This result demonstrates a potential application of unsteady actuation of DBD plasma as an active flow control.