smoke particle velocity measurements in point to plane corona discharges noureddine zouzou* eric...

Smoke Particle Velocity Measurements in Point to Plane

Corona Discharges

Smoke Particle Velocity Measurements in Point to Plane

Corona Discharges

Noureddine ZOUZOU*Eric MOREAU

Gérard TOUCHARD

Laboratoire d’Etudes Aérodynamiques (LEA)

Poitiers University, FRANCE

22N. Zouzou

I. Introduction

II. Experimental setup

III. Electrical Properties

IV. Flow Visualization and Velocity Profiles

V. System Efficiency

VI. Conclusions

33N. Zouzou

I. Introduction

DC-Corona Discharges and Electrostatic Precipitation

- Negative Corona+ Positive Corona

Ionizationregion

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- ElectronGas moleculeNegative ionPositive ion

Needle

-

e--

e- - -

N+e-

e-

N

N

Corona wind

44N. Zouzou

I. Introduction

Influence of Corona Polarity ….


Current pulses Streamer Trichel

Discharge progress Continuous Non-continuous

Ozone generation Low High

What about: Ionic wind velocity (magnitude and profile) ? System Efficiency (Power output / Power input)?

55N. Zouzou

II. Experimental Setup

r axis

z axis

40 kV 10-50 mm

HV supply

A

2MLasersheet

Camera

acquisition

Glass box: V=252525 cm3

Needle curvature: 100 µmPIV system: LAVISION

66N. Zouzou

III. Results

Electrical Properties


Corona current Air > Air + particles Corona current Negative > Positive Flashover voltage Negative > Positive

0 5 10 15 20 25 30 35 400

100

200

300

400 Air with particles

h=10mm 20mm 30mm 40mm 50mm

Negative Corona

Cor

ona

Cur

rent

(µ

A)

Applied voltage (kV)

Airh=10mm 20mm 30mm 40mm 50mm

0 5 10 15 20 25 30 35 400

20

40

60

80

100 Air with particles


Positive corona

Cor

ona

Cur

rent

(µ

A)

Applied voltage (kV)

Airh=10mm 20mm 30mm 40mm 50mm

77N. Zouzou

IV. Results

Flow Visualization and Velocity Profiles

Needle

Plane

+ Positive Corona (40mm,10kV)

88N. Zouzou

IV. Results


+ Positive Corona (40mm,10kV)

99N. Zouzou

IV. Results


40

35

30

25

20

15

10

5

0

0 1 2 3 4 5 6 7 8

Velocity (m.s-1)

z (m

m)

r=0mm, h=40mm -10kV -15kV -20kV -25kV -30kV -35kV -40kV

40

35

30

25

20

15

10

5

0

0 1 2 3 4

Velocity (m.s-1)

z (m

m)

r=0mm, h=40mm +10kV +15kV +20kV +25kV +30kV +32kV


Velocity profile is asymmetric Velocity 0 m/s near the electrodes Particle acceleration distance is slight ( 3mm)

1010N. Zouzou

IV. Results


-30 -20 -10 0 10 20 301,2

1,0

0,8

0,6

0,4

0,2

0,0

V=+10kVh=40mm

v z (m

.s-1)

r (mm)

z=5mm/point 10mm 15mm 20mm 25mm 30mm 35mm

-30 -20 -10 0 10 20 301,2

1,0

0,8

0,6

0,4

0,2

0,0

V=-10kVh=40mm

v z (m

.s-1)

r (mm)

z=5mm/point 10mm 15mm 20mm 25mm 30mm 35mm


Impacting jet is non-conic Velocity peak magnitude Positive > Negative (mobility) Velocity peak width Negative > Positive (space charge)

1111N. Zouzou

IV. Results


0 100 200 300 4000

1

2

3

4

5

6

7

Negative Corona

Vel

ocity

max

(m

.s-1)

Corona current (µA)


0 20 40 60 80 1000

1

2

3

4

Positive Corona

Vel

ocity

max

(m

.s-1)

Corona current (µA)

h=10mm 20mm 30mm 40mm 50mm 60mm


Velocity can reach 6 m/s Velocity maximum Negative > Positive (current limitation) Velocity square root of the current

1212N. Zouzou

IV. Results


0 10 20 30 40 50 600

1x105

2x105

3x105

4x105

B(m

2 .s-2.A

-1)

h (mm)

Positive Corona Negative Corona

B is proportional to the gap distance B value Positive > Negative (mobility)

IBvmax

1313N. Zouzou

V. Results

System Efficiency

10-3 10-2 10-1 100 10110-1

100

101

Negative coronah=10mm 20mm 30mm 40mm 50mm

Vel

ocity

max

(m

.s-1)

Electric Power (W)

Positive coronah=10mm 20mm 30mm 40mm 50mm 60mm

Power Input maximum Negative > Positive Velocity cube root of input power

1414N. Zouzou

V. Results

System Efficiency

r axis

z axis

S1

S3

S2

)t(D

221

)t(D

221

)D.(Kine dVvvdivdVvt

P

S

221

)D.(Kine dSnvvP

312 S

r2

21

S

z2

21

S

z2

21

)D.(Kine dSvvdSvvdSvvP

Mechanic power associated with a domain (D)

Stationary regime

If (D) is cylindrical in shape

.Elec

)OFF(.Kine)ON(.Kine

P

PP100(%)η

Electro-kinetic conversion efficiency

1515N. Zouzou

-40 -30 -20 -10 0 10 20 30 400,0

0,1

0,2

0,3

(%

)

Applied Voltage (kV)

h=20mm 30mm 40mm

V. Results

System Efficiency

At low voltages Efficiency At high voltages Negative Efficiency

Positive Efficiency

1616N. Zouzou

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

smoke particle velocity measurements in point to plane corona discharges noureddine zouzou* eric...

Documents