Frequency Effects on the Efficiency of the Aerodynamic Plasma Actuator

Abstract

We present the results of temporally- and spatially-resolved neutral density measurements and direct measurements of force produced by the aerodynamic plasma actuator (a dielectric barrier discharge plasma in which an asymmetric arrangement of electrodes leads to momentum coupling into neutral air). Specifically, we make measurements of low-duty-cycle plasma discharges that, although not practical for operational use of the device, yield insight into the mechanism of the actuator's operation and the relationship between the charged/neutral particle interactions and the overall inertia of the neutral fluid. Our measurements indicate that the momentum coupling between the charged particles in the plasma and the neutral particles in the air occurs on timescales much shorter than that for the bulk fluid motion. As a consequence, we conclude that in terms of modeling the fluid flow, it is sufficient to treat the actuator as a heat and momentum input into a small control volume, or even as an input on a boundary, depending on the scale size of the model in question. Nonetheless, our measurements of force production on different waveforms indicate that the amount of momentum coupled to the fluid is a strong function of the details of the plasma discharge.