1. Smoke Particle Velocity Measurements in Point to Plane Corona Discharges Noureddine ZOUZOU* Eric MOREAU Gérard TOUCHARD Laboratoire d’Etudes Aérodynamiques (LEA) Poitiers University, FRANCE

2. N. Zouzou 2 I.Introduction II.Experimental setup III.Electrical Properties IV.Flow Visualization and Velocity Profiles V.System Efficiency VI.Conclusions

3. N. Zouzou 3 I. Introduction DC-Corona Discharges and Electrostatic Precipitation - Negative Corona + Positive Corona Ionization region Drift region Needle Grounded Electrode + + e- + Particles (dusts) + N Positive ions are directly created in the ionisation region (ions act like an extension of the active electrode) Negative ions are created in ionisation and drift regions N - + e- Electron Gas molecule Negative ion Positive ion Needle - e- - - - N + N N Corona wind

4. N. Zouzou 4 I. Introduction Influence of Corona Polarity …. - Negative Corona+ Positive Corona Current pulsesStreamerTrichel Discharge progressContinuousNon-continuous Ozone generationLowHigh What about: Ionic wind velocity (magnitude and profile) ? System Efficiency (Power output / Power input)?

5. N. Zouzou 5 II. Experimental Setup r axis z axis  40 kV 10-50 mm HV supply A 2M  Laser sheet Camera acquisition Glass box: V=25  25  25 cm 3 Needle curvature:   100 µm PIV system: LAVISION 

6. N. Zouzou 6 III. Results Electrical Properties - Negative Corona + Positive Corona Corona current  Air > Air + particles Corona current  Negative > Positive Flashover voltage  Negative > Positive

7. N. Zouzou 7 IV. Results Flow Visualization and Velocity Profiles Needle Plane + Positive Corona (40mm,10kV)

8. N. Zouzou 8 IV. Results Flow Visualization and Velocity Profiles + Positive Corona (40mm,10kV)

9. N. Zouzou 9 IV. Results Flow Visualization and Velocity Profiles - Negative Corona + Positive Corona Velocity profile is asymmetric Velocity  0 m/s near the electrodes Particle acceleration distance is slight (  3mm)

10. N. Zouzou 10 IV. Results Flow Visualization and Velocity Profiles - Negative Corona + Positive Corona Impacting jet is non-conic Velocity peak magnitude  Positive > Negative (mobility) Velocity peak width  Negative > Positive (space charge)

11. N. Zouzou 11 IV. Results Flow Visualization and Velocity Profiles - Negative Corona + Positive Corona Velocity can reach 6 m/s Velocity maximum  Negative > Positive (current limitation) Velocity  square root of the current

12. N. Zouzou 12 IV. Results Flow Visualization and Velocity Profiles B is proportional to the gap distance B value  Positive > Negative (mobility)

13. N. Zouzou 13 V. Results System Efficiency Power Input maximum  Negative > Positive Velocity  cube root of input power

14. N. Zouzou 14 V. Results System Efficiency r axis z axis S1S1 S3S3 S2S2 Mechanic power associated with a domain (D) Stationary regime If (D) is cylindrical in shape Electro-kinetic conversion efficiency

15. N. Zouzou 15 V. Results System Efficiency At low voltages  Efficiency  At high voltages  Negative Efficiency   Positive Efficiency 

16. N. Zouzou 16 IV. Conclusion Corona current  with voltage, however it  with the presence of incense particles The axial and radial profiles of the velocity show some differences associated with the discharge polarity (Velocity  6 m/sec) Velocity  (current) 1/2, and Velocity  (Input Power) 1/3 Electro-kinetic conversion efficiency  0.2 %, it  with Negative applied voltage