Flow Characteristics of Dielectric Barrier Discharge Plasma Actuator Array in Burst Mode

To understand the fundamental physics of dielectric barrier discharge (DBD) actuator array for flow control, the flowfield induced by two successive DBD actuators is investigated under burst-mode actuation. The vortical structures generated by the actuators are revealed using particle image velocimetry (PIV) and high-speed schlieren visualization, allowing their interactions to be explored. Proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) are used to analyze the plasma-induced flow. Both POD and DMD modes indicate staggered vortical structures, whose dynamic features are associated with the burst frequency of the DBD actuation and its harmonics. The POD-DMD coherence indicates that the most relevant dynamic structure is also the most energetic. Spatial DMD analysis reveals an increase in the convection speeds of the flow structures from the upstream DBD actuator to the downstream DBD actuator. The effects of duty cycle and burst frequency on the coherent structures are explored. For different duty cycle cases, the most energetic mode structures evolve in a similar fashion. As the burst frequency increases, the size of the coherent structures decreases, but their number increases. Both POD and DMD analyses reveal that the burst frequency has a greater effect on the coherent structures than the duty cycle.