Gas-heating phenomenon in a nanosecond pulse discharge in atmospheric-pressure air and its application for high-speed flow control

The interaction between the gas-heating phenomenon in a pulsed discharge in atmospheric-pressure air and the separated shear layer in the flow around the airfoil is discussed. The first half of the paper details the development of the modeling for gas heating in a pulsed discharge in atmospheric-pressure air and reviews recent research results. Particular attention is paid to the processes of fast and slow gas heating. In the latter half of the paper, the experimental results of the high-speed Schlieren visualization are presented and the interaction between the nanosecond-pulse-driven dielectric-barrier-discharge plasma actuator (ns-DBDPA) actuation and the density field is discussed, based on the periodic and time-averaged components of the Schlieren signal intensity. The time-averaged intensity of the contrast of the Schlieren signal that originates in the separated shear layer changes according to the normalized actuation frequency of ns-DBDPA, F ⁺. As F ⁺ increases from 0.1 to 2, the periodic component of the Schlieren signal intensity increases, resulting in a decrease in the time-averaged contrast of the Schlieren signal. When F ⁺ > 2, the heated air caused by ns-DBDPA actuation is accumulated along the separated shear layer, resulting in an increase in the time-averaged contrast of the Schlieren signal.