nanosecond discharges: high power density for …...high pressures, low temperatures temperature:...
TRANSCRIPT
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Laboratoire de Physique des Plasmas
Nanosecond discharges: high power density for distributed in space ignition
Svetlana Starikovskaia
Laboratory for Plasma Physics, Ecole Polytechnique, Paris
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Our scientific team:
Laboratory for Plasma Physics, Ecole Polytechnique, Paris: Sergey Stepanyan, Sergey Shcherbanev Moscow State University, Skobeltsyn Institute of Nuclear Physics: Nikolay Popov PC2A, Lille University of Science and Technology: Mohamed Boumehdi, Guillaume Vanhove, Pascale Desgroux Moscow Institute of Physics and Technology: Ilya Kosarev, Vladimir Khorunzhenko, Victor Soloviev
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Outline of talk
Introduction. High pressures (7-15 bar), low T (600-1000 K). Do we need very high [O] densities for plasma assisted ignition (PAI)? Rapid compression machine (RCM): ignition by nanosecond discharge. Analysis of experimental results and perspectives Surface dielectric barrier discharge (SDBD): quasi-uniform and filamentary mode Surface dielectric barrier discharge (SDBD): what can we get from E-field measurements by emission? Conclusions
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• 150 ms x 2.5 m/ms (M=8) = 375 m
• TGV Eurostar: TransManche Super Train, 393.72 m (20 cars)
A typical ignition length for uniform flow
4
F+O
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1998 2001 2004 2007 2010 2013Years
OH
CH
History of plasma assisted combustion
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Available reviews
Starikovskaia (J. Phys. D 2006) Popov (High Temp. 2007) Adamovich (PSST, 2009) Starikovskaia and Starikovskiy (In: Handbook of Combustion, 2010) Starikovskiy and Aleksandrov (Aeronautics & Astronautics 2011) Popov (43rd AIAA Plasma Dyn. Lasers Conf. 2012) Starikovskiy and Aleksandrov (Progr. Energy Comb. Sci. 2013)
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Close of faraway from the combustion threshold: what is the difference?
I: wall recombination
II: volume recombination
III: heat dissipation
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Parameters of Shock Tube PAI experiments: temperature, pressure, ignition delay time
1 2 3 4 5
1200
1400
1600
1800
2000
PAI
Autoignition
T 5, K
Number of C atoms
1 2 3 4 50
2
4
6
8 Autoignition
PAI
n 5, 10
18 c
m-3
Number of C atoms
1 2 3 4 5
100
101
102
103
10-30 mJ/cm3
PAI
Autoignition
Igni
tion
dela
y tim
e, µs
Number of C atoms
NeQ MIPT Lab, Moscow, 1998-2008
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Active species produced by plasmas and their role in kinetics
- Rotationally excited molecules (RT-relaxation)
- Vibrationally excited molecules (VT-relaxation+ acceleration of chain branching/prolongation)
- Electronic states (dissociation, chemistry, ∆T)
- Atoms and radicals (chemistry, ∆T)
- Charged particles (chemistry, heating)
“reaction path”: AB+C = A + BC
Ea
k=Aexp(-E /R )a T
Q
(ABC)*
pote
ntia
l ene
rgy
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Pressure: 10-15 bar
10
High pressures, low temperatures
Temperature: 600-1000 K
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Induction time as a function of “atomic oxygen density” (difference:
discharge & cool flame)
1E-3 0.01 0.1 1 10
1E-9
1E-8
1E-7
1E-6
1E-5
1E-4 Butane stoichiometric mixture diluted by 76 % of Ar
T0=800 KP0=8.6 bar
OH fr
actio
n
Time, ms
Ignition
Cool flame initiation
1E-3 0.01 0.1 1 108.68.89.09.29.49.69.8
10.010.210.410.6
0 % 0.05 % 0.1 % 0.2 % 0.3 % 0.4 % 0.5 % 0.6 % 0.7 % 0.8 % 0.9 % 1 %
1 %0.9 %
0.8 %0.7 %
0.6 %0.5 %
0.4 %
0.2 %
0.3 %
0 %
0.1 %
T0=800 KP0=8.6 bar
Butane stoichiometric mixture diluted by 76 % of Ar
Pres
sure
, bar
Time, ms
0.05 %Cool flame initiation
Artificial action: O2 -> O + O
(C4H10:O2, ER=1):Ar, P=8.6 bar, T=800 K
D. HEALY, H.J. CURRAN, J.M. SIMMIE et al, Combustion and Flame 155(3): 441-448 (2008).
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Remark: why discharge is NOT a cool flame
1E-3 0.01 0.1 1 10
1E-9
1E-8
1E-7
1E-6
1E-5
1E-4
0.5% of O
0.05% of O
Butane stoichiometric mixture diluted by 76 % of Ar
T0=800 KP0=8.6 bar
OH fr
actio
n
Time, ms
Ignition
Cool flame
Relaxation of W leads to ∆T and initiates chemistry
Equilibrium: chemistry leads to ∆T
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Ignition delay at additions of O-atoms: weak dependence at [O]>0.5%
13
0.0 0.2 0.4 0.6 0.8 1.0
0
10
20
30
40
50 Tc=800 KPTDC=8.6 bar
Butane stoichiometric mixture diluted by 76 % of Ar
Indu
ctio
n de
lay
time,
ms
Percent of initially dissociated O2
0.0 0.2 0.4 0.6 0.8 1.01
10
Tc=800 KPTDC=8.6 bar
Butane stoichiometric mixture diluted by 76 % of Ar
Indu
ctio
n de
lay
time,
ms
Percent of initially dissociated O2
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Energy cost for active species in C2H6:O2 mixture: too much dissociation?
0 200 400 600 800 1000
10H
CH3
O(3P)
O2(a1∆g)
Ener
gy c
ost,
eV /
part
icle
E/N, Td
10-30 ns
PSST, 21(2012) 045012
Energy W=50 mJ; volume V=5 mm3: [O] is about 1019 cm-3
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ICCD image (camera gate is 0.5 ns) of discharge in 1 atm air: “combined” SDBD
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All the experiments are performed in SINGLE-SHOT regime
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±(25-50) kV pulses, 15-25 ns duration, 0.5-3 ns rise time 17
Electrode system and applied pulses
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Machine at PC2A laboratory, Lille University
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Combustion chamber for RCM with discharge
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Temperature and pressure
High-voltage pulse
RCM core temperature: TC=640-980 K
Pulse duration: 25 ns, front rise time: 0.5 ns
Pulse amplitude on the electrode: ± (24-54) kV
Pressure at Top Dead Center: PTDC=7.5-16 atm
20
Initial parameters of the experiments
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3) C4H10/O2/Ar, φ=1, 76 % of Ar
4) C4H10/O2/N2, φ=1, 76 % of N2
1) CH4/O2/Ar, φ=1, 0.5, 0.3, 76 % of Ar
2) C4H10/O2/Ar/N2, φ=1, 38 % of N2, 38 % of Ar
21
Mixtures used in the high pressure (RCM) experiments
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Methane is not the easiest fuel to burn
22
0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85100
101
102
103
104
105
CH4-C5H12, PAI, 0.2-0.7 atm
C2H6-C5H12, auto, 0.2-0.7 atm
CH4, auto, 0.4-0.7 atm
CH4, auto, 2 atm
Igni
tion
dela
y tim
e, µ
s
1000/T, K-1
Auto Exp, C2H6 Auto Calc, C2H6 PAI Exp, C2H6 PAI Calc, C2H6, , , C3H8, , , C4H10, , , C5H12
Comb. & Flame, 2008, 2009
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Aldehydes and chain branching: RO2 → R’ + R’’CHO R’’CHO + O2 →R’’CO + HO2
aldehyde
D. Healy, N.S. DONATO, C.J. AUL et al, Combustion and Flame 157: 1526-1539 (2010).
Negative temperature coefficient
23
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(P,T) - field of RCM ignition experiments
24
n=2 natm
n=4.3 natm
600 650 700 750 800 850 900 950 10006
8
10
12
14
16
Region of calculations
(CH4:O2, φ=0.5) + 75% Ar
(CH4:O2, φ=0.3) + 75% Ar
(C4H10:O2, φ=1) + 38% Ar + 38% N2 (C4H10:O2, φ=1) + 76% N2 (C4H10:O2, φ=1) + 76% Ar
(CH4:O2, φ=1) + 76% Ar
No autoignition
Pres
sure
Pd,
atm
Temperature Tc, K
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Induction time decreases significantly 25
0 50 100 150 2000
10
20
30
40
Plasma assisted ignition, U=-24 kVPTDC=14.7 atmTC=972 K
discharge initiation
(blue step)
Pres
sure
, atm
Time, ms0 50 100 150 200
0
10
20
30
40PTDC=14.7 atmTC=972 K
Pres
sure
, atm
Time, ms
Autoignition
Auto- and plasma assisted ignition. CH4:O2:Ar, ER=1, 71% of Ar
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Confirmed statistically (30 experiments)
58 59 60
20
22
24
26
C4H10/O2/Ar/N2, φ = 1, 38 % of Ar, 38 % of N2
Pres
sure
, atm
Time, ms
Atoignition with knocking
58 59 60
20
22
24
26
C4H10/O2/Ar/N2, φ = 1, 38 % of Ar, 38 % of N2
Pres
sure
, atm
Time, ms
PAI, U=-50 kV
Possible knocking suppression (CH4:O2:N2:Ar, T=730 K)
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Intermediate modification of pressure profile occurs in experiments with cool flames
0 50 100 150 2000
5
10
15
20
25
Pres
sure
, atm
Time, ms
discharge initiation
(blue step)
PAI, U=-37 kV
20 ms
0 50 100 150 2000
5
10
15
20
25
Pres
sure
, atm
Time, ms
30 ms
Autoignition
0 50 100 150 2000
5
10
15
20
25PAI, U=-35 kV
Pres
sure
, atm
Time, ms
discharge initiation
(blue step)
Cool flame regime modification under the discharge action
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25 30 35 400
5
10
15
20
P
Pres
sure
, atm
Time, ms
P/2
τ
Discharge initiation
Definition of the ignition delay time
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Ignition delay time vs voltage/deposited energy. CH4:O2:Ar, ER=0.3 and 0.5, 76% of Ar
0 10 20 30 40 500
50
100
150
200
250
300
350
CH4/O2/Ar, φ = 0.3, 76 % of Ar PTDC=15.5 atmTc=962 K
Indu
ctio
n tim
e, m
s
Voltage on HV electrode, kV0 10 20 30 40 50
0
50
100
150
200
250
300
350
CH4/O2/Ar, φ = 0.5, 76 % of ArPTDC=15.1 atm
Tc=943 K
Indu
ctio
n tim
e, m
s
Voltage on HV electrode, kV
ER=0.3 ER=0.5
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Ignition delay time vs deposited energy. CH4:O2:Ar, ER=0.3, 76% of Ar
0 5 10 15 20 25 3020
40
60
80
100
120
140
160
180Ig
nitio
n de
lay
time,
ms
Deposited energy, mJ
PTDC=15.1 atm Tc=943 K
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MIE: minimal ignition energy, CH4:O2:Ar
2 4 6 8 10 12 14 16
0.1
1
10
MIE, 1 bar, 300 K PAI-total, 15 bar, 960 K PAI/channel (qu), 15 bar, 960 K PAI/channel (fil), 15 bar, 960 K
MIE
, mJ
% of CH4 in the mixture
MIE: 1 bar/300 K ns PAI: 15 bar/960 K
<ms
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820 840 860 880 9000,0
0,5
1,0
40
50
60
70
C4H10/O2/Ar, φ = 1De
lay
time,
ms
Core gas temperatureTc, K
Autoignition PAI, U=-55 kV
Suppression of NTC phenomena by nanosecond discharge (10-20 mJ)
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NTC region calculation: P=8.6 bar, T=800 K
0 10 20 30 40 50 60
9
10
11
12
13
14 P0=8.6 bar, T0=840 K P0=8.6 bar, T0=800 K
Pres
sure
, bar
Time, ms
cool flame
ignition
600 700 800 900 10000
100
200
300
400 P=8.6 bar P=7.6 bar
Indu
ctio
n de
lay
time,
ms
Temperature, K
Buthane stoichiometric mixture diluted by 76 % of Ar
T=843 K, P=(8.6-7.7) bar, τ=68 msT=844 K, P=(8.6-7.7) bar, τ=68 msT=822 K, P=(8.7-7.8) bar, τ=65 ms
Experimental results:
Experiments are in this region
NTC
65 and 68 ms
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Calculated (smooth) change of ignition delay time
1E-3 0.01 0.1 1 10
1E-9
1E-8
1E-7
1E-6
1E-5
1E-4
0.5% of O
0.05% of O
Butane stoichiometric mixture diluted by 76 % of Ar
T0=800 KP0=8.6 bar
OH fr
actio
n
Time, ms
Ignition
Cool flame
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High speed flame propagation imaging. LaVision Phantom v9 camera
CH4/O2/Ar, Φ = 1, 76% Ar, TC = 911 K, PTDC = 15.4 bar
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Induction time as a function of deposited energy (Popov’s mechanism)
0.02 0.04 0.06 0.08
0.01
0.1
1
10
275 K4%
207 K3%173 K
2.5%
138 K2%104 K
1.5%
83 K1.2%
70 K1%
Indu
ctio
n tim
e, m
s
Deposited energy, eV/mol
Methane/oxygen mixture diluted by 76 % of ArPgas=960 KPgas=15 bar
Heating and production of O-atoms are taken into account
343 K5%
14 mm
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Preliminary modeling: coupling of afterglow-combustion kinetics?
1 10 100
1016
1017
1018
0.05 eV/mol
CH2O
H2OOH
CH3
H
O(1D)
O(3P)
Dens
ity, c
m-3
Time, ns
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- 24 kV discharge; O2: Ar; T=300 K; P=3.2 bar
0.5 ns 2 ns 13 ns
21 ns 27 ns 35 ns
-10 0 10 20 30 40
-25
-20
-15
-10
-5
0
Volta
ge, k
V
Time, ns
U = + 24 kV on the electrode
2 ns ICCD gate
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+ 24 kV discharge; O2: Ar; T=300 K; P=3.2 bar
0.5 ns 2 ns 4 ns
12 ns 17 ns 40 ns
U = + 24 kV on the electrode
-10 0 10 20 30 40
0
5
10
15
20
25
Volta
ge, k
V
Time, ns
2 ns ICCD gate
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Quasi-uniform (“diffusive”) and filamentous modes
40
ICCD imaging: air, gate=2 ns. Emission of the 2+ system of molecular nitrogen
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41
0 30 60 90 120 150 180 210 240-30
-20
-10
0
10
20
305 atm, -55 kV
Volta
ge in
cab
le, k
V
Time, ns0 30 60 90 120 150 180 210 240
-30
-20
-10
0
10
20
303 atm, -35 kV
Volta
ge in
cab
le, k
V
Time, ns
Oscillograms corresponding to different high pressure discharge modes
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42
Uniform-filamentary transition: 337 nm spectra
335.0 335.5 336.0 336.5 337.0
0.01
0.1
1
Inte
nsity
, a.u
.
Wavelength, nm
region 0-2 mm from HV electrode region 3-5 mm from HV electrode theoretical fit, T=360 K
P=1 atm, U=-24 kVt=5 ns
335.0 335.5 336.0 336.5 337.00.01
0.1
1
t=40 nsIn
tens
ity, a
.u.
Wavelength, nm
Filamentous Theoretical fit, T=420
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Transition between quasi-uniform and filamentous modes, synthetic air
1 2 3 4 5 638
40
42
44
46
48
50
52Vo
ltage
am
plitu
de o
n HV
ele
ctro
de, k
V
Pressure, bar
Negative polarity pulses
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P= 3 bar, U=-47 kV on the HV electrode
Diffusive beginning (first 6 ns)
Transition to filaments
Filamentous
Transition between quasi-uniform and filamentous modes, synthetic air
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45
Uniform-filamentary transition, P=3 atm in synthetic air: deposited energy
20 25 30 35 40 45 50 55
0
20
40
1 atm, synthetic air
Depo
site
d en
ergy
, mJ
Voltage, kV
3 atm, synthetic air
transition filamentousquasi-uniform
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46
Uniform-filamentary transition, P=3 atm, air: currents and emission
0 5 10 15 20 25 30 35 40
-60
-40
-20
0
20
40
60
80
1.6 A/ch
1.8 A/ch
Curr
ent,
A
Time, ns
Mode: quasi-uniform transtion filamentous
0.1 A/ch
0 5 10 15 20 25 30 350.0
0.2
0.4
0.6
0.8
1.0
1.2
Inte
nsity
, a.u
.
Time, ns
Mode: quasi-uniform transition filamentous
Transition point
Electrical current 337 nm emission
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47
Electric field in SDBD: emission measurements, 391/337 ratio
][1
][1
) ]([) ]([
)(
0
)(
0
2
2
2
2
Mk
Mk
CNBN
kk
CNq
C
BNq
B
C
B
Σ+
Σ+×=
+
+
τ
τ
''''''
0
..* ][
vvvv
l u m
Ah vIN τ
= KII
kk
C
B
C
B ×= Measured
εεεεεσ dfm
ke
e x c )(.2) .(∫=
=
NEf
kk
C
B
Calculated
(**)
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48
Emission measurements, 391/337 ratio: experimental calibration
P Paris, M Aints, F Valk, T Plank, A Haljaste, K V Kozlov and H-EWagner J. Phys. D: Appl. Phys. 38 (2005) 3894–3899
R391/337=0.07 E/N = 600 Td
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- assumption about the plasma uniformity: not true 49
0 1 2 3 4 50
1
2
3
4
Dry air, edge of HV electrode, P=4 atm, U=+24 kV
Inte
nsity
, a.u
.
Time, ns
337.1 nm
391.4 nm
0 1 2 3 4 50
200
400
600
800
1000 Dry air, edge of HV electrode, P=4 atm, U=+24 kV
E/N,
Td
Time, ns
Intensity of 391.4 and 337.1 nm emission; Electric field in air at 4 atm and +24 kV
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Electric field is higher in case of positive polarity pulses
High values of the E-field right after peak 50
0 1 2 3 4 50
200
400
600
800
1000
1200 Dry air, edge of HV electrode, P=1 atm, U=+24 kV
E/N,
Td
Time, ns0 1 2 3 4 5
0
200
400
600
800
1000
1200 Dry air, edge of HV electrode, P=1 atm, U=-24 kV
E/N,
Td
Time, ns
Comparison of “E-field” in positive and negative polarity pulses
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- higher values of the electric field for positive polarity
- higher P → lower Emax 51
Discharge: T=300 K; P=5 atm
RCM: T=900 K; P=15 atm
W=10-30 mJ 1 2 3 4 5
300
400
500
600
700
800
900
1000
Max
imal
E/N
, Td
Pressure, atm
Positive polarity Negative polarity
Dry air, edge of HV electrode, ±24 kV
Comparison of “E-field” in positive and negative polarity pulses vs pressure
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V R Soloviev and V M Krivtsov, J. Phys. D: Appl. Phys. 42 (2009)
measured ch gapI I I= +
The same order of Ich and Igap is possible 52
Principal explanation of observed results
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53
Results of numerical modeling (Soloviev)
0 0.2 0.4 0.6 0.8 1 1.2 1.40
0.1
0.2
y,
E/N =f(x,y,t) I(N2(C))=f(x,y,t)
I(N2+(B))=f(x,y,t)
I(N2(C)) I(N2
+(B))=f(x,y,t) integrated over Y
Ratio of integrals
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54
Electric field in the discharge: analysis of numerical modelling
0.00 0.05 0.10 0.15 0.20 0.25
0.00
0.02
0.04
0.06
0.08
U=+24 kV: <200 TdRatio
of I
nteg
rals
391
/337
ove
r Y
Y,mm
391/337; 0.002 mm, -24kV 391/337; 1 mm, -24kV 391/337; 2 mm, -24kV 391/337; 3.35 mm, -24kV 391/337; 0.002 mm, +24kV 391/337; 0.004 mm, +24kV 391/337; 3 mm, +24kV 391/337; 5 mm, +24kV 391/337; 7 mm, +24kV 391/337; 8 mm, +24kV 391/337; 8.1 mm, +24kV
U=-24 kV: 400-430 Td
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55
Electric field in the discharge: analysis of numerical modelling
1 2 3 4 5 6 7 8 90.00
0.05
0.10
0.15
0.20
0.25
0.30
Ratio
of i
nteg
rals
of e
miss
ion
391.
4/33
7.1
alon
g O
Y
X, mm
-24 kV, t=2.15 ns +24 kV, t=4.85 ns +24 kV, t=0.75 ns
Calculations
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56
Electric field in the discharge: analysis of numerical modelling
100 100010-4
10-3
10-2
10-1
100
+24 kV, calculations
-24 kV, calculations
-24 kV, measurements
Ratio
of i
nteg
rals
, A, a
nd b
ase
curv
e, R
(391
/337
)
E/N, Td
+24 kV, measurements
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57
Conclusions
Low T, high P: The ignition delay time decreases significantly under the action of nanosecond SDBD, from tens and hundreds milliseconds to units of milliseconds at deposited energy within a range 10-30 mJ. It is possible to describe qualitatively the results taking into account O-atoms production and ∆T. Starting from some O-density, ignition delay time remains close to a fixed value determined by gas mixture composition. NTC region and cool flame kinetics are significantly influenced by addition of radicals. Detailed discharge-combustion mechanism for heavy hydrocarbons is a challenge. Uniform discharge is a challenge. Discharge study is necessary for each range of conditions. Multipoint ignition is efficient.
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58
Acknowledgements
-EOARD AFOSR
- Russian Foundation for Basic Research
-ANR, French National Agency for Research, Project PLASMAFLAME (2011-2015)
- PUF Collaborative Grant (Ecole Polytechnique-Princeton University)
- French Academy of Science (CNRS) / Russian Academy of Science (RAS) collaborative grant No 23994 2010-2012) and PICS-RFBR grant (5745-11.02.91063-a/5745)
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59
Thank you for your attention… …You are invited
4th Aerospace Thematic Workshop “Fundamentals of aerodynamic-flow and combustion control by plasmas” CNRS Conference Centre Paul Langevin, Aussois, France 7-12 April, 2013; the next is in 2015 Questions: Restrictions for March 2013? Program?
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60
PAI/PAC task formulation: assumptions
- Initial mixture parameters are the following: (F+O+D) mixture of known composition; - Initial gas pressure is P; - Initial gas temperature is T
- Plasma is nonequilibrium (Te>>Tg, shorter than needed to arc transition) and can be modeled by E/N(t), [70-200 Td], and ne(t)
- The PAI/PAC problem can be considered in 0D;
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61
Plasma action (tens-hundreds of ns)
Drawbacks: For fuels, no self-consistent data set is available for higher hydrocarbons
Advantages: for majority of oxidizers and diluters, the discharge action is well-known: the sets of cross-sections measured by using electron beams technology (60th-70th) are self-consistent and verified on the basis of the experimentally measured swarm parameters (ionization coefficient, drift velocity, electron mobility)
{E/N(t), ne(t)} EEDF(t) M+, M*, A*, M(v)
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62
Afterglow (hundreds of ns - ms)
Drawbacks: the main classes of reactions are well-known, but a lack of data is observed when trying to describe the details of minor species behavior in chemically active mixtures
Advantages: ”plasma” and “combustion” kinetics are separated in time; “plasma” kinetics with participation of electronically and vibrationally excited species is well known at room temperatures for N2, O2, Ar…
{ne, M+, M*, A*, M(v), E/N->0 } kinetics, T
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63
Ignition: µs – ms, f(P, T, composition)
Drawbacks: There is no ready mechanism for the low-temperature ignition: it must be built as an intersection of available “pure” oxidation mechanism, “common” combustion mechanism and “plasma” action.
Advantages: main classes of plasma-gas interaction are well-known, there is no risk to miss a whole class of chemical transformation; although special attention and detailed literature analysis is needed to know the limits of used kinetic schemes.
{M*, A*, M(v), T} “combustion” kinetics
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64
Peculiarities and universal (C1-C3) and extended (low T) mechanisms
GRI C3 -- GRI C30
500
1000
1500
2000Number of reactions
Number of species
CH4/C2H6/C3H8 oxidation at high P and high, intermediate and low T (2008)
289 species 1580 reactions
D. HEALY, H.J. CURRAN, J.M. SIMMIE et al, Combustion and Flame 155(3): 441-448 (2008).
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65
ICCD imaging: air, gate=0.5 ns, P=1 atm, U=-22 kV (time in ns)
I N Kosarev, V.I. Khorunzhenko, E. I. Mintoussov, P.N. Sagulenko, N.A. Popov, S.M. Starikovskaia, Plasma Sources Sci. Technol. 21 (2012) 045012 (15pp)
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Ignition by spark discharge: 1 atm of C2H6:O2=2:7, Tin=300 K
Single pulse spark discharge ignition of C2H6:O2=2:7 at 1 bar and ambient temperature.
Plasma Sources Sci. Technol. 21 (2012) 045012 (15pp)
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67
Ignition by surface DBD at 1 atm, C2H6:O2
Plasma Sources Sci. Technol. 21 (2012) 045012 (15pp)
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68
Preliminary numerical modelling: CH4:O2:Ar. P=20 bar; T=950 K
Autoignition Ignition initiated by 0.05% of O 45 ms 9 ms
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69
Preliminary numerical modelling: n-C4H10:O2:Ar. P=8 bar; T=700 K
Autoignition
Ignition initiated by 0.05% of O 43 ms 6 ms
Cool flame: 37 ms Cool flame: 2 ms
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70
Comparison of experiments and numerical modeling: all (CH4-C5H12) mixtures
0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85100
101
102
103
104
105
CH4-C5H12, PAI, 0.2-0.7 atm
C2H6-C5H12, auto, 0.2-0.7 atm
CH4, auto, 0.4-0.7 atm
CH4, auto, 2 atm
Igni
tion
dela
y tim
e, µ
s
1000/T, K-1
Auto Exp, C2H6 Auto Calc, C2H6 PAI Exp, C2H6 PAI Calc, C2H6, , , C3H8, , , C4H10, , , C5H12
I N Kosarev, N L Aleksandrov, S V Kindysheva, S M Starikovskaia, A Yu Starikovskii, Combustion and Flame, 156 (2009) 221-233