Laboratoire de Physique des Plasmas
Nanosecond discharges: high power density for distributed in space ignition
Svetlana Starikovskaia
Laboratory for Plasma Physics, Ecole Polytechnique, Paris
2
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
3
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
• 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
1998 2001 2004 2007 2010 2013Years
OH
CH
History of plasma assisted combustion
6
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)
7
Close of faraway from the combustion threshold: what is the difference?
I: wall recombination
II: volume recombination
III: heat dissipation
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
9
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
Pressure: 10-15 bar
10
High pressures, low temperatures
Temperature: 600-1000 K
11
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).
12
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
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
14
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
15
ICCD image (camera gate is 0.5 ns) of discharge in 1 atm air: “combined” SDBD
16
All the experiments are performed in SINGLE-SHOT regime
±(25-50) kV pulses, 15-25 ns duration, 0.5-3 ns rise time 17
Electrode system and applied pulses
18
Machine at PC2A laboratory, Lille University
19
Combustion chamber for RCM with discharge
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
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
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
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
(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
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
26
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)
27
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
28
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
29
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
30
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
31
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
32
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)
33
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
34
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
35
High speed flame propagation imaging. LaVision Phantom v9 camera
CH4/O2/Ar, Φ = 1, 76% Ar, TC = 911 K, PTDC = 15.4 bar
36
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
37
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
38
- 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
39
+ 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
Quasi-uniform (“diffusive”) and filamentous modes
40
ICCD imaging: air, gate=2 ns. Emission of the 2+ system of molecular nitrogen
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
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
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
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
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
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
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
(**)
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
- 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
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
- 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
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
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
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
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
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
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.
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)
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?
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;
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)
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
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
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).
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)
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)
67
Ignition by surface DBD at 1 atm, C2H6:O2
Plasma Sources Sci. Technol. 21 (2012) 045012 (15pp)
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
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
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