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Atmospheric-pressure dielectric barrier discharges for aerodynamic flow control are investigated. The properties of the plasma discharge during positive and negative half-cycles of the driving voltage are studied experimentally and numerically. The simulations are performed in nitrogen. It is shown that during the positive half-cycle the plasma operates in the streamer mode, whereas the negative half-cycle is characterized by a glow-type discharge. The computational results are compared with experimental optical measurements and found to be in good agreement.

Recent studies have investigated the use of plasma actuators for the active control of the boundary layer on turbine blades. Although the overall effects have been quantified through experiments, the exact nature of the plasma and its momentum-transfer mechanisms have not been well characterized. In this study, particle-in-cell and Monte Carlo methods are used to computationally explore the plasma discharge and its interaction with the flow. The plasma composition, its methods of momentum addition, and the physics of its generation are quantified. Comparisons with experiments are made in order to support the findings. Simulations indicate that the plasma is generated through an electron avalanche in a dielectric harrier discharge. The plasma is created as the electrons stream to the dielectric on the first half of the electrode bias cycle and stream back on the second half. Momentum is imparted to the flow on both half-cycles, but the ionization is not equal during both half-cycles. This results in the plasma actuator producing a net force in one direction.