Fundamental Mechanisms, Predictive Modeling,
and Novel Aerospace Applications of Plasma Assisted Combustion
AFOSRMURI Kick off meeting
The Ohio State UniversityNov 4, 2009
Drexel Group: Main TasksThrust 1. Experimental studies of nonequilibrium air-fuel plasma kinetics using advanced non-intrusive diagnostics
Task 1: Low-to-Moderate (T=300-800 K) temperature, spatial and time-dependent radical species concentration and temperature measurements in nanosecond pulse plasmas in a variety of fuel-air mixtures pressures (P=0.5-5 atm), and equivalence ratiosTask 4: Moderate-to-high (T=800 – 1800 K) temperature PAC oxidation kinetics in Discharge Shock Tube Facility at pressures up to 10 barTask 5: PAC oxidation and combustion initiation at high pressure, high temperature conditions
Thrust 2. Kinetic model development and validationTask 8: Development and validation of a predictive kinetic model of non-equilibrium plasma fuel oxidation and ignitionTask 9: Mechanism Reduction and Dynamic Multi-time Scale Modeling of Detailed Plasma-Flame Chemistry
Thrust 3. Experimental and modeling studies of fundamental nonequilibriumdischarge processesTask 10: Characterization and Modeling of Nsec Pulsed Plasma Discharges
Thrust 4. Studies of diffusion and transport of active species in representative two-dimensional reacting flow geometries Task 13: Ignition and flameholding in high-speed non-premixed flowsTask 14: High Fidelity Modeling of Plasma Assisted Combustion in Complex Flow Environments
Drexel Group: International Collaboration
International Collaborators
Svetlana Starikovskaya (Ecole Pol) – Thrust 1 Alexander Rakitin (NEQLab) – Thrust 1Boris Potapkin (KIAE) – Thrust 2Alexander Konnov (VUB) – Thrust 2Nickolay Aleksandrov (MIPT) – Thrust 3Sergey Pancheshnyi (Univ Toulouse) – Thrust 3Sergey Leonov (IVTAN) – Thrust 4
Physics of Nonequilibrium Systems Laboratory
Range of Parameters – Combustion Kinetics
P, atm
0.02 1 40
T, K
250 K
2500 K
S/I
φ
0.1
3.0
1
Problems of Plasma-Chemical Models
Availability and accuracy of data on electron collision cross sections
+ H2 CH4 C2H6 C3H8? C4H10 C5H12 …
Availability and accuracy of chemical models below self-ignition point
+ H2? CH4 C2H6 C3H8 C4H10 C5H12 …
Availability and accuracy of physical and chemical models for non-equilibrium conditions
+ Radical’s mechanism ? Ionic chain mechanism? Energy chain mechanism
Physics of Nonequilibrium Systems Laboratory
Models for Low-Temperature Plasma Assisted Combustion
Starikovskii et al.,
Plasma Physics Reports, 2000 (26) 701
O2 + e- + M → O2- + M
H2 + O2- → OH- + OH
OH + H2 → H2O + HOH- + H → H2O + e-
H + O2 + M → HO2 + MOH- + HO2 → H2O + O2 + e-
Starikovskii,Chemical Physics Reports, 2003 (11) 1
N2O* + H → N2* + OHCO + OH → CO2* + HCO2* + N2O → N2O* + CO2N2* + N2O → N2O* + N2
Physics of Nonequilibrium Systems Laboratory
PAC: Where we are
P, atm
0.02 1 40
T, K
250 K
2500 K
S/I
φ
0.1
3.0
E/n, Td
1000
B/S
1
1
300
Mechanisms of Plasma Influence
1. Heating
2. Turbulization
3. Momentum Transfer
4. Electrons/Ions Diffusion/Drift
5. Dissociation, Ionization
Physics of Nonequilibrium Systems Laboratory
Shock Wave - Nonequilibrium Plasma Interaction
Physics of Nonequilibrium Systems Laboratory
Relaxation of Nonequilibrium Plasma. Air. P1 ~ 20 Torr
0 50 100 150 200 250 300 350 400 450 5000.96
0.98
1.00
1.02
1.04
1.06
1.08
1.10
1.12
1.14V/
V 0
Pre-trigger Time, μs
V, Base 3-4 Ms=3.0 Ms=2.3 Ms=2.2 Ms=2.2 Ms=1.8 Ms=1.56
τE
Physics of Nonequilibrium Systems Laboratory
Relaxation of Nonequilibrium Plasma. Air. P1 ~ 20 Torr
Mechanism of fast heating in discharge plasmas (low E/N)
Low (< 20 Td) E/N:
e + N2 , O2
- elastic scattering
- rotational excitation
100 101 102 1030
50
100
O2(ion)O2(rot)
O2(el)
N2(ion)
N2(el)
O2(vib)
N2(rot)
N2(vib)
Frac
tiona
l ene
rgy
depo
sitio
n, %
E/n, Td
Air
Mechanism of fast heating in discharges (moderate E/N)
Moderate (20 - 200 Td) E/N:
Popov (2001) heating → 28 % of power spent on N2* + O2
*
e + O2 → e + 2O + ΔE
e + N2 → e + N2*(A, B, C, a’, ...)
N2*(A, B, C, a’, ...) + O2 → N2 + 2O + ΔE
O(1D) + N2 → O + N2 + ΔE k ~ 10-10 cm3/s
Mechanism of fast heating in discharge plasmas (high E/N)
High (> 200 Td) E/N:
electron-ion and ion-ion recombinationkinetics
100 1000
10
20
30
40
50
28% of energy spent on N2(el) + O2(el)(Popov (2001))
Hea
ting
perc
enta
ge, %
E/N, Td
ne0=1014 cm-3; dry air ne0=1015 cm-3; dry air ne0=1014 cm-3; 1 % H2O ne0=1015 cm-3; 1 % H2O
e + O2+ → O + O* + ΔE
O2- + O2
+ + M→ 2O2 + M + ΔE
Aleksandrov et al. (2009)
Physics of Nonequilibrium Systems Laboratory
Heat Release and Shock Waves Formation by “Nonequilibrium” Plasma
50 ns, ΔT = 420 K
7 ns, ΔT = 240 K
Energy Distribution in Gas Discharge
100 101 102 1030
50
100
O2(ion)O2(rot)
O2(el)
N2(ion)
N2(el)
O2(vib)
N2(rot)
N2(vib)
Frac
tiona
l ene
rgy
depo
sitio
n, %
E/n, Td
Air
Molecular Oxygen ExcitationTo directly observe the influence of SDO on the combustion of H2-O2 mixture
Delivering sufficient amount of SDOMinimizing the effect of O atomLower the inlet temperature
V V Smirnov, O M Stelmakh, V I Fabelinsky, D N Kozlov, A M Starik and N S Titova,J. Phys. D: Appl. Phys. 41 (2008)
SDO kinetic analysis
The ignition time as a function of SDO mole fraction in oxygen.T=775 K and P=10 Torr in the H2:O2=5:2 mixture
0% 1.2% 4% 6%
-2,0
-1,5
Experiment Calculations Calculations with
laminar boundary layerlg(t,s)
SDO mole fraction
SDO kinetic analysis
Auto-ignition
6% SDO
The evolution in time of the mole fractions of the main component for autoignition (a) and ignition with 6% singlet delta oxygen. The gas temperature
evolution is represented by the thick red line.
1E-6 1E-5 1E-4 1E-3 0.01 0.11E-8
1E-7
1E-6
1E-5
1E-4
1E-3
0.01
0.1
1
H2 O2 SDO O H OH HO2 H2O H2O2 O(1D) O2(1S) O3 Temp
800
1200
1600
2000
2400
Temeprature, K
1E-6 1E-5 1E-4 1E-3 0.01 0.11E-8
1E-7
1E-6
1E-5
1E-4
1E-3
0.01
0.1
1
H2 O2 SDO H O OH HO2 H2O H2O2 O(1D) O2(1S) O3 Temp
Time s
800
1200
1600
2000
2400
Temperature, K
Possible reasons
Radical generation efficiency
Auto SDOO2+M=O+O+M (slow)
H2+O=OH+HO2+H=OH+O
OH+OH=H2O+O……
O2(a1 Δg)+H2=OH+OH (fast)OH+H2=H2O+H
O2(a1 Δg)+H=OH+OO2+H=OH+O
OH+OH=H2O+O…
O2(a1 Δg)+H2=OH+OH O2(a1 Δg)+H=OH+O
200% 100%~80 μs
SDO kinetic analysis
Energy Distribution in O2-Ar (15%:85%) Mixture
74% energy in excitation of singlet oxygen at E/n= 5 TdApproximately 53% in singlet delta state
About 21% in singlet sigma state
1 10 100 10000
10
20
30
40
50
60
70
80
Ene
rgy
depo
sitio
n, %
Reduced Electric Field, Td
Ar(elastic) Ar(11.6eV) Ar(11.3eV) Ar(Ionization) O2(v=1) O2(v=2) O2(v=3) O2(1Δ) O2(1Σ) O2(4.5eV) O2(6.0eV) O2(8.4eV) O2(Ionization)
H + O2(1Δ) = OH + O
0,8 1 2 4 6 8 10 20 400,0
0,5
1,0
1,5
2,0
2,5
SDO
Exc
itatio
n Ef
ficie
ncy,
%
E/n, Td
E/n = 6 Td (=10−17 Vcm2)
N2 Elastique 1.8 % N2(ROT) 4 %
N2 (V=1) 49 % N2 (V=2) 7.3 % N2 (V=3) 1.4 % N2 (V=4) 0.2 %
O2 Elastique 0.3 % O2 (ROT) 0.2 % O2 (V=1) 17 % O2 (V=2) 11 %O2 (V=3) 4.1 %O2 (V=4) 1.4 %O2 (a1Δg) 2.2 %O2 (b1Σ) 0.1%
SDO Excitation efficiency in air plasma
Air Plasma
Physics of Nonequilibrium Systems Laboratory
Shock Tube with Discharge Section.U ≤ 0.3 MV, M ≤ 3
Test Section of the Shock Tube
Starikovskaya et al
Physics of Nonequilibrium Systems Laboratory
Main Processes During Discharge Phase
0 20 40 60 80 100
20000
40000
60000
80000
2
76
48
13 5
4
Rea
ctio
n R
ate
Time, ns
1 Ar + e- ⇒ Ar+ + e- + e-
2 O2 + e- ⇒ O + O + e-
3 CH4 + e- ⇒ CH3 + H + e-
4 Ar + e- ⇒ Ar* + e-
5 Ar* + O2 ⇒ Ar + O + O
6 Ar* + CH4 ⇒ Ar + CH2 + H + H
7 O2 + e- ⇒ O2* + e-
8 O2* + CH4 ⇒ O2 + CH3 + H
1
Physics of Nonequilibrium Systems Laboratory
Radicals Production in DischargeCH4-containing mixture
Physics of Nonequilibrium Systems Laboratory
Ignition Delay Time: Methane-Containing Mixture
0.5 0.6 0.7 0.8
100
101
102
103
104
105
I
II
III
autoignition
autoignition, experimentautoignition, calculations
PAI, calculationsPAI, calculations
PAI, experimentsPAI, experiments
PAIPAI
Igni
tion
dela
y tim
e, μ
s
1000/T5, K
CH4
Physics of Nonequilibrium Systems Laboratory
90 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.901
10
100
1000In
duc
tion
tim
e, μs
1000/T, K-1
Auto Exp Auto Calc FIW Exp FIW Calc
(C5H12:O2) + 90% Ar
b)
C H5 12
RAMEC (for C1) + Westbrook (C2-C7) + High Pressure Adjustment
Physics of Nonequilibrium Systems Laboratory
Experiment and Calculations in H2-Air Mixture
Physics of Nonequilibrium Systems Laboratory
Modeling of Radicals Formation vs E/n (W=14 mJ/cm3)
10 1000.0
5.0x10-4
1.0x10-3
1.5x10-3
2.0x10-3
2.5x10-3
3.0x10-3
3.5x10-3
4.0x10-3
4.5x10-3
5.0x10-3
Den
sity
, cm
-3
E/N, Td
O H Sum
100 10000.0
5.0x10-4
1.0x10-3
1.5x10-3
2.0x10-3
2.5x10-3
3.0x10-3
3.5x10-3
4.0x10-3
Den
sity
, cm
-3E/N, Td
O H SumH2:O2:Ar=29.5:14.75:55.75
H2:O2:N2=29.5:14.75:55.75
Delay time for autoignition and plasma assisted ignition in CH4-containing mixture
CH4:O2:N2:Ar = 1:4:15:80
0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90101
102
103
104
PAI with E(t)/N
PAIauto
auto0.5 atm
~0.5 atm
~2 atm
Igni
tion
dela
y tim
e, μ
s
1000/T, K-1
Aleksandrov et al. (2009)
Physics of Nonequilibrium Systems Laboratory
Plasma Recombination at High Pressures and Temperatures
0 5 10 15 20 25 30 35 40 45 50
1012
p=2.56atm,T=2036Kp=2.2atm,T=2036Kp=1.96atm,T=2065Kp=1.9atm,T=2276K
p=1.5atm,T=2598Kp=1.07atm,T=2770K
n e, c
m-3
Время, мкс
p=1.68atm,T=2384K
N2
0.1 1 10
1010
1011
1012
p=2.1атм.,T=1989Kp=2атм.,T=2150Kp=2атм.,T=2100Kp=1.9атм.,T=2270Kp=1.8атм.,T=2558Kp=1.5атм.,T=2680Kp=1.1атм.,T=2990K
N2:O2:CO2=76:19:5
n e, c
m-3
Время, мкс
0.1 1 10
1012
p=2.3атм.,T=2316Кp=2атм.,T=2411Кp=1.7атм.,T=2442Кp=1.3атм.,T=2517Кp=1.1атм.,T=2845К
N2:H2:O2:CO2=67:15:11:7
n e, c
m-3
Время, мкс
N2:H2O:O2:OH:CO:CO2:H:O:H2=67:10:5:4:3.5:3:3:3:2
N2:H2:O2:CO2=67:15:11:7
After 10 μs, at 1atm., 2800К
Physics of Nonequilibrium Systems Laboratory
Evolution in Time of Electron Density During Plasma Decay
500 1000 1500 2000 250010-8
10-7
10-6
p=0.4 atm
0.2
T, K
Effe
ctiv
e re
com
bina
tion
coef
ficie
nt, c
m3 s-1
)
500 1000 1500 2000 250010-8
10-7
10-6
p=0.4 atm0.2
T, K
Effe
ctiv
e re
com
bina
tion
coef
ficie
nt, c
m3 s-1
air
O2:N2:CO2=1:4:5 O2:N2:CO2=5:86:9
Dissociative electron-ion recombinatione + O2
+ → O + O
Electron attachment and detachmente + O2 + M → O2
- + MO2
- + O → e + O3
500 1000 1500 2000 250010-8
10-7
10-6
p=0.4 atm0.2
T, K
Effe
ctiv
e re
com
bina
tion
coef
ficie
nt, c
m3 s-1
)
Physics of Nonequilibrium Systems Laboratory
Discharge Development at Different Overvoltage and Plasma Generation
10 100 1 0001E11
1E12
1E13
1E14
1E15
1E16
Elec
t ron
Den c
ity,c
m-3
Reduced El ectr ic Fi eld, Td
T = 8000 KT = 350 K
T = 400 K
T = 300 K
Arc Discharge: equilibrium plasmaApplications: melting & welding
MW Discharge: partial equilibriumApplications: plasma chemical conversion, chemical vapor deposition (CVD)
Glow Discharge: E/n close to the breakdown thresholdApplications: light sources, surface treatment, CVD
Streamer Discharge: overvoltage up to 200%Applications: surface treatment, flue gases treatment, electrical breakdown, power switches
Nanosecond Pulsed Discharge: overvoltage up to 10 timesApplications:• Plasma supported combustion• Plasma supported aerodynamics• Chemical conversion• CVD
Types of Gas Discharges and Their Applications
T = 4000 K
Types of Gas Discharges and Their Applications
Physics of Nonequilibrium Systems Laboratory
Setup for OH Dynamic Measurements in Streamer Channel Afterglow
Pancheshnyi et al
Physics of Nonequilibrium Systems Laboratory
LIF Diagnostics Setup: OH Profile Control
NdYAG laserDye laserDoublingsystem
Spectrometer
ICCD - camera
burner
LIF OHOH (X-A):
Excitation: Q1(6) 282.92 nm;Emission:
315nm, δλ=1.8 нм; Registration –
PicoStar LaVision ICCD камера
LIF OH
LIF Emission of OH at 300 K
1 10 100
0
50
100
150
200
250
Methane lean Ethane lean Propane lean Butane lean
Methane St Ethane St Propane St
Methane Rich
OH
LIF
, 300
K, 1
atm
Time, μs
0.1 1 10 100
1
10
100
Methane lean Ethane lean Propane lean Butane lean
Methane St Ethane St Propane St
Methane Rich
OH
LIF
, 300
K, 1
atm
Time, μs
LIF Emission of OH at 500 K
Methane
Ethane
300 K Versus 500 K LIF of OH
Physics of Nonequilibrium Systems Laboratory
High-pressure Conditions:Always Non-Uniform
9 ns
11 ns
Pancheshnyi et al
Physics of Nonequilibrium Systems Laboratory
Rapid Compression Machine:High-Pressure, Low-Temperature
Physics of Nonequilibrium Systems Laboratory
PAC at High Pressure: ER = 1 (Rakitin et al)
T2 = 713 KP2 = 26.5 bar
Propane,Surface DBD,
< 50mJ
Physics of Nonequilibrium Systems Laboratory
PAC at High Pressure: ER = 0.4 (Rakitin et al)
T2 = 794 KP2 = 32 bar
Propane,Surface DBD,
< 50mJ
Physics of Nonequilibrium Systems Laboratory
Propane-Butane-Air Lean Mixtures. φ = 0.5 (C3:C4=85:15)
0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00 1,05 1,10 1,15
10
100
Igni
tion
Del
ay, µ
s
1000/T, K-1
P=500 atm P=210 atm P=66 atm P=20 atm P=4.7 atm Cadman et. al
P=10 atm
Physics of Nonequilibrium Systems Laboratory
Propane-Butane-Air Mixture Ignition. φ = 0.5 (C3:C4=85:15). Calculations
Physics of Nonequilibrium Systems Laboratory
Propane-Butane-Air Mixture Ignition. Experiment vs Calculations.
0,6 0,7 0,8 0,9 1,0 1,1 1,210
20
40
6080
100
200
400Ig
nitio
n De
lay,
µs
1000/T, K-1
, P=500 atm, P=210 atm, P=66 atm, P=20 atm, P=4.7 atm
Physics of Nonequilibrium Systems Laboratory
Channels of Kinetic Scheme Optimization
Reaction T k
C3H8 + HO2 = C`H2C2H5 + H2O2 1200 2.5
C3H8 + HO2 = CH3C`HCH3 + H2O2 1200 2.5
O2C3H7 = HOOCH2C`HCH3 800-1000 0.2
CH3CHO2CH3 = CH3CH(OOH)C`H2 800-1000 0.2
OCHCH(OOH)CH3 = CH3CHO + HCO + OH 800 0.2
OCHCH2CH(OOH)2 = CH2O + CH2CHO + OH 800 0.2
CH3COCH2(OOH) = CH2O + CH3CO + OH 800 0.2
0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00 1,05 1,10 1,15 1,20 1,25
10
100
H2O
2 and HO
2Formation and Decomposition
Fueldecomposition
AlkylHydroperoxidesformation and decomposition
H2O2+M -> OH+OH+M
CH3+CH
3O
2 = CH
3O+CH
3O
Igni
tion
Dela
y (µ
s)
1000/T (K-1)
n-Hexane P = 220 atm n-Pentane P = 250 atm C
3H
8+C
4H
10 P=210 atm
Methane P = 150 atm
Konnov,Potapkin
Physics of Nonequilibrium Systems Laboratory
Mixture C3H8:C4H10:Air = 1.8:0.3:97.9
0,7 0,8 0,9 1,0 1,1 1,2
10
100
C3H8:C4H10:Air=1.8:0.3:97.9Ig
nitio
n De
lay,
µs
1000/T, K-1
, P = 4.7 atm, P = 20 atm, P = 66 atm, P = 210 atm, P = 500 atm
Physics of Nonequilibrium Systems Laboratory
Discharge Formation and Flame Stabilization in High Speed Flow
IVTAN (Sergey Leonov):M = 2Maximal stagnation pressure 1.8 BarStagnation temperature 670 KDischarge Power ~ 1 kW
DPI Shock Tunnel:M = 2-5Static pressure 0.1 - 1 BarStatic temperature 700-1000 KDischarge Power ~ 1 kW
Physics of Nonequilibrium Systems Laboratory
Summary
Range of ParametersP = 0.1 – 70 atmT = 300 – 2000 KM = 0 - 5φ = 0.01 – 1E/n = 200-500 Td (Air)Fuels: H2, C1 – C4Acetones, Alcohols, CO
Experiment:Shock TubeShock TunnelRapid Compression MachinePremixed Flow Nozzle
Theory:Discharge ModelsPlasma Models Chemical Kinetic Models