| Summary: | Millimetric and sub-millimetric DBD plasma actuators have been investigated for flow control applications using a 4-species plasma-fluid model. The discharge structures for a number of cases were studied and an understanding of the mechanics of these plasma actuators was developed.
The model was initially used to investigate the mechanism behind the unexplained flow reversal observed in annular DBD actuators. It was found that at reduced diameters, the increased curvature of the electric field was responsible for suppressing the discharge during the positive part of the cycle, and thereby inducing an inward axial flow.
Secondly, the model was used to investigate the effect of geometry and ambient gas-fraction on the performance of annular DBD actuators at different scales. It was found that by increasing the local production of ions, both increasing
the oxygen gas-fraction and reducing the exposed electrode thickness increased the discharge intensity during the positive part of the cycle. Finally, a sub-millimetric parallel actuator was also examined. The applied voltage frequency was varied to induce different magnitude streaks in a boundary layer flow over a flat plate. Such a design could be used to control individual streaks via antagonistic superposition.
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