Studies of the Electrohydrodynamic Force Produced in a Dielectric Barrier Discharge for Flow Control. Report no. 2, Phase 3
Final rept. 1 Sep 2006-1 Sep 2009
UNIVERSITE PAUL SABATIER TOULOUSE (FRANCE)
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The mechanisms of ion wind generation in surface dielectric barrier discharges SDBDs is identical to the one in corona discharges. The electrohydrodynamic force EHD generated in SDBDs for moderate increase rates of the applied voltage is, as in corona discharges, due to the development of a unipolar region above the dielectric surface, where ion space charge is dominant and ions transfer momentum to the neutral gas. For very fast rise few ns of the applied voltage, ion wind is no longer important and the action of the discharge on the flow is different. SDBDs are more interesting for applications than DC corona because high current breakdown and transition to the arc regime are prevented by the use of a dielectric layer. There is no evidence that SDBDs can generate larger ion wind than DC corona discharges. For a given power dissipated in the discharge, the EHD force decreases when the frequency increases. This trend is also valid for other voltage waveforms. The nanosecond discharge regime has been simulated and its possible aerodynamic effects have been studied by coupling the discharge model with Navier Stokes equations. The results confirm that the EHD force generated in the nanosecond regime is negligible and show that the fast heating of the gas in the vicinity of the exposed electrode can lead to a large temperature increase in a short time, giving rise to the development of micro shockwaves. These pressure waves may be responsible for the observed aerodynamic effects.
- Electricity and Magnetism
- Fluid Mechanics
- Plasma Physics and Magnetohydrodynamics