1. 1 NUMERICAL ANALYSES OF A VISCID COMPRESSIBLE IONIC FLOW C. Tulita, S.Raghunathan, E. Benard 1

2. 2 1 PLASMA FLOW CONTROL OBJECTIVES Prevent Separation Reduce Drag PLASMA TECHNIQUES Corona Discharge Glow Discharge By creating an important electric charge distribution in a particular region of the flow. It occurs near sharp points, where it creates a localized electric field greater than the breakdown electric field of the medium surrounding it. It operates at the Stoletow point, at which the energy cost of an ion-electron pair is the minimum theoretically possible.

3. 3 2 Case: M  =0.147, Re=2.8  10 6,  =0° CORONA DISCHARGE EFFECT ON AN AEROFOIL IN SUBSONIC FLOW Local electric field Electric potential Plasma on Plasma off

4. 4 3 Aerofoil wall Wake cut NUMERICAL STRATEGY C-Grid Transformation CFD mesh Electro-dynamic grid

5. 5 4 ELECTRODYNAMIC PROBLEM Poisson equation Conservation of the electric charge Patankar control-volume method Leger-Moreau-Touchard 2001

6. 6 5 CORONA EXPERIMENTAL CORRELATION AT ANODE. Peek (1929) & Cobine(1958) The initiating voltage for corona The empirical surface roughness factor The relative atmospheric density factor d a r Plasma Active Volume

7. 7 6 ELECTRODYNAMIC RESULTATS Electric potential Electric field

8. 8 7 FLUIDE PROBLEM Inflow:given andextrapolated Outflow: given and

9. 9 MASS-AVERAGED NAVIER-STOKES EQUATIONS IN TWO DIMENSIONAL CONSERVATION FORM 8

10. 10 Tow dimensional thin-layer, mass-averaged Navier-Stokes code NUMERICAL METHOD Upwind implicit MacCormack predictor/corrector cell-centered finite-volume method Flux Splitting method of Van Leer Mulder’s continuous differentiable flux limiter Gauss-Seidel line relaxation iterative procedure 9 Modified version of the Baldwin-Lomax turbulence model, using a non-linear formulation of the wall region anisotropy

11. 11 10 AERODYNAMIC RESULTATS Case: M  =0.147, Re=2.8  10 6,  =0° Plasma offPlasma on

12. 12 11 SKIN FRICTION COEFFICIENT Plasma on Plasma off

13. 13 12 PRESSURE COEFFICIENT DISTRIBUTIONS Plasma onPlasma off

14. 14 CONCLUDING REMARKS Reduces drag Enhance the mass and heat transfer between the aerofoil and surrounding flow 13 SUBSONIC REGIME CORONA DISCHARGE TECHNIQUE Prevents separation The ionic charge distribution depends strongly on: The anode electrode radius The empirical surface roughness factor The relative atmospheric density factor The potential difference between anode and cathode PLASMA CHEMISTRY FROM THE ACTIVE VOLUME

15. 15 Electric field Electric potential Possible Electric Results 14