Fundamental Mechanisms Predictive Modeling Fundamental Mechanisms, Predictive Modeling, and Novel Aerospace Applications of Plasma

Assisted Combustion

AFOSRMURI Kick off meeting

The Ohio State University

Nov 4, 2009Miles – Shneider Group

PersonnelPersonnel

• Team• Richard Miles (PI)• Mikhail Shneider (Co PI)• Arthur Dogariu (Research Scientist)

S h il Z idi (R h S i ti t)• Sohail Zaidi (Research Scientist)• Chairajeev Kalra (Student- Princeton Plasma Science and Technology Fellow)• James Michael (Student - NDSEG Fellow) • Dimitry Opaits (Student)Dimitry Opaits (Student)• Phil Howard (Technical Support)

• International Collaborators• Sergey Leonov • Christophe Laux• Svetlana Starikovskaya• Boris Potapkin

N k l Al k d• Nickolay Aleksandrov,• (Peter Barker)

Miles – Shneider GroupP FPrimary Foci

• Thrust 1. Experimental studies of nonequilibrium air-fuel plasma kinetics using

advanced non-intrusive diagnostics• Task 2: Laminar Flow Reactor and Nanoparticle Studies at Low to

Intermediate Temperatures (Radar REMPI and Filtered Rayleigh p ( y gScattering in flames)

• Task 7: Fundamental studies on microwave enhanced combustion at atmospheric and higher pressures (Laser designated microwave driven ignition and microwave enhanced flame propagation)

• Thrust 3. Experimental and modeling studies of fundamental nonequilibrium discharge processes

T d d d• Task 10: Characterization and Modeling of Nsec Pulsed Plasma Discharges (Modeling and Radar REMPI of nonequilibrium states)

• Task 11: Experimental and Modeling Study of Plasma properties using Radar REMPI (Radar REMPI measurement of electron loss mechanism

d t d l l l t b d it )and rates and local electron number density)

Preliminary WorkPreliminary Work

• Radar REMPI• Atomic oxygen in a flame• NO mole fractions in laboratory air to <10 ppb

• Limited by natural NO concentration in NJ air (~10 ppb)y J ( pp )• Electron attachment and recombination rate measurements in

nitrogen, air and humid air• Laser designated microwave driven ignitionLaser designated microwave driven ignition

• Point ignition with 180 μJ, 200 fsec laser designator plus 50 mJ, 2 μsec microwave pulse

• Line ignition with 600 μJ 200 fsec laser designator plus 50 mJ 2 μsec• Line ignition with 600 μJ, 200 fsec laser designator plus 50 mJ, 2 μsec microwave pulse

• > 50% ignition kernel growth rate enhancement with triple pulsed microwavec owave

• Multiple point ignition

Radar REMPIRadar REMPI• Microwave scattering from laser-induced carriers

• Microwave illuminates the ionization spot.

• Microwave scattering is collected.

Laser

Microwave Beam

Microwave Echo

Microwave/laser measurement configuration. Thefocused laser creates a small region of ionization andthe microwaves are scattered from that region into themicrowave detector.

Microwave Experimental Setup:Homodyne and Heterodynee e e e

90 GHz

100 GHz10 GHz

Quadraturee

XY

10 GHzpre-amp mixers

mixercirculator

100 GHz horn

Laser

Heterodyne 100 and 90 GHz system. Homodyne 100 GHz system.

100 GHz probes the plasma, the phase shift is measured on the 10 GHz beating signal.

The quadrature mixer provides the X and Y

100 GHz probes the plasma.

The mixer output is proportional with the scattering amplitude hence electron density The quadrature mixer provides the X and Y 

components, hence we also measure the phase. scattering amplitude, hence electron density

Sub-nanosecond temporal resolution!

Atomic oxygen in a flameAtomic oxygen in a flame4

• 2000K Methane Air flame

2

3

Gaussian fit, = 33.5 cm-1 HW1/e2

Cold air

• 2000K Methane – Air flame

• Atomic line of oxygen in flame is narrow (34 cm-1 limited by laser bandwidth)

0

1

88600 88625 88650 88675 88700

laser bandwidth)

• Spectral line in cold air –atomic oxygen via photolysis is 10 times broader: high

1.5

2.0

Gaussian fit, = 3.5 cm-1 HW1/e2

Flame, atomic oxygen line

After subtraction of cold air signalis 10 times broader: high temperature (50,000K) imposed by intense laser pulse.

0.5

1.0

Flame, atomic oxygen linepulse.

• Radar REMPI can distinguish between flame and photolysis atomic oxygen.

0

88600 88625 88650 88675 88700

Energy (cm-1)

atomic oxygen.

Resonant signal from atomic oxygen vs. equivalence ratio

60.0004Atomic Oxygen

Atomic oxygen line signal

5

6

0.0003

0.0004

Atomic Oxygen REMPI signalCalculated O mole fraction

4

0.0002

mpi

sig

nal

2

3

0.0001

Rem

10.60 0.75 0.90 1.05 1.20 1.35

0

Equilibrium model – 1D chemkin

Equivalence ratio

1+1 Radar REMPI in NO1+1 Radar REMPI in NO

1 0

1+1 REMPI in NO, laser at 226nm

2.0

1+1 Radar REMPI in NO

1.0pure NO (50 mTorr)NO (50 mTorr) and N2 (850 Torr)NO (50 mTorr) and dry air (850 mTorr)

sign

al fr

om N

O

1.5 20 Torr NO (80Torr N2)1 Torr NO (4 Torr N2)

0.5

zed

Rad

ar R

EMPI

0 5

1.0

Sign

al

00 50 100 150 200

Nor

mal

iz

0

0.5

40 50 60 70 80 90 00 0 50 100 150 200

Time (ns)

4414

4415

4416

441

4418

4419

4420

Energy (cm-1)

•Pure NO shows longer lifetime due to electron diffusion. In order to measure the recombination rate we suppress diffusion by •In order to measure the recombination rate we suppress diffusion by

adding N2. •In air we can measure attachment rate.

NO trace Detection(limited by background ~ 10 ppb NO in air)

0.03

0.02

air1ppb10ppb100ppb

0.01

100ppb

0

-0.01-20 -10 0 10 20 30

Time (ns)

Direct measurement of electron attachment in atmospheric air

P E Previous Extrapolated estimate for 850 Torr dry air

(78%N2, 21%O2, 1% Ar):

Identifying Electron loss mechanism and rate

0.8

NO at 0.13 Torr in 1atm. buffer (170ppm)

1

NO at 0.13 Torr in 1atm. buffer (170ppm)

0.6

Air buffer, dn/dt = -n2-n = 9.4x107s-1

N2 buffer, dn/dt = -n2 n0 = 14x107s-1 tNNtN

0

0

1)(

In N2:

recombination OT

0.4

mal

ized

Sig

nal

0.1m

aliz

ed S

igna

l

only, NOT an exponential decay

Attachment in air:

0.2

Nor

m

Nor

m

t

a

t

a

a

eNeNtN

0

0 ,11

)(

Attachment in air:

00 20 40 60

Time (ns)

0.010 20 40 60 80

Time (ns)

t

a

aeNNtN

0

0

1)(

close to close to exponential

Testing NO in buffer gasesTesting NO in buffer gases

0.20

1+1 Radar REMPI in NO at 226 nm

• N2 increases

0.10

0.15 NO 0.5Torr + N2 2TorrNO 0.5Torr + N2 2Torr + dry air 100TorrNO 0.5Torr + N2 2Torr + dry air 340TorrNO 0.5Torr + N2 2Torr + dry air 760Torr

Sig

nal

electron loss via recombination by suppressing diffusion

0

0.05

0 40 80 120

diffusion

• Dry air – faster decay due to electron

0.10

0.15

NO 0.5Torr + N2 2Torr

attachment to O2

• Humid air – further increase of losses due to higher

0.05

2NO 0.5Torr + N2 2Torr + humid air 97TorrNO 0.5Torr + N2 2Torr + humid air 752Torr

Sign

al due to higher

attachment rates in water

00 40 80 120

Time (ns)

Laser Designated Microwave IgnitionEExperimental Apparatus

ScreenCamera

Tuner (d)Waveguide

MagnetronSliding Short

Tuner (d)e

Seed Ionization

Laser Pulse

Circulator Collimated Nd:YAG (532 nm)

Laminar Premixed Flow

Microwave Field 3GHz 30kW peak power TE10 Mode

• Dpremixed = 1.9 cm• Uexit = 70 cm/s

14

TE10 Mode λguide = 11.2 cm Efield ~ 0.1Ebreakdown

Ps Laser-MW Evolution in AirPs Laser MW Evolution in AirLaser spot evolution

Laser + MW evolution

MW on

Ignition: Kernel growth comparisonSingle and multiple pulse microwave

0.0 ms 1.0ms 1.1 ms 1.9 ms 2.0ms 2.1 ms 2.9 ms

Laser

Micro-

PULSE 1

Microwave

IGNITION

6 mm

Single pulse

Micro-wave

PULSE 2

PULSE 3

triple pulse

PULSE 1

6 mm

1 msec intervals

Multi-point ignitionMulti point ignition

6mm6 mm

uexit

• Two 7mJ seed laser spots• 75 mJ MW pulse

70 cm/s

• 75 mJ MW pulse• φ = 0.7; Uexit = 70 cm/s• 3 ms after initial seed laser pulse• Flame kernel indicates ignition

200 Femtosecond Seed –180 μJ200 Femtosecond Seed 180 μJ

10 us 100 us 500 us 1000 us

6 mm

200 Femtosecond Seed –600 μJ200 Femtosecond Seed 600 μJ

10 us 100 us 500 us 1000 us

6 mm

Ignition of Methane/Air MixturesIgnition of Methane/Air Mixtures

• Seed ionization pulse7mJ; 200 ps, 780 nm

• MW heating pulse50mJ; 2 μs, 3GHz

λseed [nm] φ f [m] Elaser [mJ] *EMW [mJ]*

Observed Minimum Seed Laser Energies

800 (200 fs) 0.8 0.06 0.2 50

780 0.8 0.06 3 50

780 0.8 0.10 7 50780 0.8 0.10 7 50

780 0.7 0.10 7, 7 75

390 0.8 0.10 1.5 50

Fundamental Mechanisms, Predictive Modeling, d N l A A li ti fand Novel Aerospace Applications of

Plasma Assisted Combustion

Yiguang Ju

AFOSR MURI Ki k ff tiAFOSR MURI Kick off meeting

The Ohio State UniversityThe Ohio State UniversityNov 4, 2009

Team members:

Collaborators:

Team members: Wenting Sun, Sanghee Won, Mruthunjaya Uddi

Interactional: Fei Qi, University of Science and Tech. ChinaAFRL collaborators: Campbell Carter, Timothy Ombrello, Skip Williams

Collaborators:

Ju’s Group Primary Research Focus

Thrust 1. The effects of kinetic and transport of plasma assisted ignition– Task 1: Experimental measurements of minimum ignition energies

using a spherical bomb with different electrode geometriesTask 2: Experimental measurements of ignition/extinction limits by– Task 2: Experimental measurements of ignition/extinction limits by using counterflow flames

Thrust 2. Intermediate Species Measurements at Elevated Pressures pby Using a Plasma Assisted Jet Stirred Reactor with Molecular Beam Sampling

– Task 1: Development of plasma assisted a jet stirred reactorTask 2: Measurements of intermediate species of fuel oxidation– Task 2: Measurements of intermediate species of fuel oxidation

Thrust 3. Mechanism Reduction and Dynamic Multi-time Scale Modeling of Detailed Plasma-Flame Chemistryy– Task 1: Development of dynamic multi-timescale modeling– Task 2: Simulations of unsteady ignition and extinction of plasma

discharge with detailed kinetic mechanisms

Research Task Description,Methods and Preliminary ResultsMethods, and Preliminary Results

Thrust 1. The effects of kinetic and transport of plasma assisted ignition– Task 1: Experimental measurements of minimum ignition energies

using a spherical bomb with different electrode geometriesusing a spherical bomb with different electrode geometries

2.5

Qm

in

2Q

min

2

2.0

2.3

2.4on

pow

er,Q 1.5

onpo

wer

,Q 1.51.9

Le = 2.1

2.2

mun

igni

tio 1

mun

igni

tio 1

1.7

1.8 = Le2.0

1.9

1.8

Q ?

Min

im

0.5 Z = 10

Min

im

0.5Z = 13

1.4

1.6

1.51.4

1.71.6

1.5

Q ?

Cube of critical flame radius, RC3

0 500 1000 1500 2000 25000

Cube of critical flame radius, RC3

0 500 1000 1500 2000 25000

Experimental methods

(a) (b) (c)(a) (b) (c)Igniter configurations

Thrust 1. The effects of kinetic and transport of plasma assisted ignition– Task 2: Experimental measurements of ignition/extinction limits by

using counterflow flame w/wo non-equilibrium plasma dischargeusing counterflow flame w/wo non-equilibrium plasma discharge

2200

2000 Plasma+CH4/air

1600

1800

x, K

Th l i iti

1200

1400T max

1400 K1300 K

1200 K

Thermal ignition

1000

1200

850 K

1100 K1050 K

900 K

1025 K

950 K 1000 K

Kinetic ignition

8001 10 100 1000 10000

Strain, s-1

850 K 900 K

Thrust 1. The effects of kinetic and transport of plasma assisted ignition– Task 2: Experimental measurements of ignition/extinction limits by

using counterflow flame w/wo non-equilibrium plasma dischargeusing counterflow flame w/wo non-equilibrium plasma discharge

Nanosecond pulser: CarterLIF: OH, NO, CH2OTALIF: O, H

Laser beamLaser beamLaser beam

Thrust 2: High pressure JSR and MBMS experimental methods of intermediate species measurements

High pressure, high temperature chamberHigh pressure, high temperature chamberHigh pressure, high temperature chamber

MBMS analysisFuel

Preheated air

Mixing

MBMS analysisFuel

Preheated air

Mixing

MBMS analysisFuel

Preheated air

Mixing

1st T b 2nd Turbo1st T b 2nd Turbo

DBD dischargeJet stirred reactor

DBD dischargeDBD dischargeJet stirred reactor

Rea

ctor

exit

1st Turbopump

2 Turbopump

Mass analyzer

Rea

ctor

exit

1st Turbopump

2 Turbopump

Mass analyzer

Molecular beam

Rea

ctio

npr

oduc

ts

Skimmer

Charged

analyzer

Molecular beam

Rea

ctio

npr

oduc

ts

Skimmer

Charged

analyzer

0.1-5 atm

Quartznozzle

Chargedion separation

10-4

Torr10-6

Torr0.1-5 atm

Quartznozzle

Chargedion separation

10-4

Torr10-6

Torr

Three stage molecular beaming sample for high pressure

Equipment installation (EFRC program)

Comstock Time of flight (TOF) MB system: RTOF210: Mass resolution up to 5000g ( ) y p

Li and Qi, ACR, 2009m/Z

Thrust 3. Mechanism Reduction and Dynamic Multi-time Scale Modeling of Detailed Plasma-Flame Chemistry

– Task 1: Development of dynamic multi-timescale modeling approachapproach

– Task 2: Simulations of unsteady ignition and extinction of plasma discharge with detailed kinetic mechanisms

tt

KtimencomputatioTotal

%80

3

totalChem tt %80

C. K. Law and T. Lu, Energy and Combustion,2009

Multi Time Scale Method (MTS)

40

The Basic Idea of Multi-Time Scale Method: timescale changes!

25

30

35

40

ecie

s

t = 0.1 ms t = 0.2 ms t = 0.3 ms

FastestG

ΔtF

k

t

KY

10

15

20

Num

ber o

f speGroup

Medial Groups

ΔtM

kkk eKY

-1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -130

5

Log10

(characteristic time / s)

SlowestGroup

ΔtS

Diagram of multi time scale scheme

Δt i th ti t f th f t t Δt i th ti t f th di l

0Time

Δt1 2

ΔtF is the time step of the fastest group, ΔtM is the time step of the medial group, and ΔtS is the time step of the slowest group

Validation by homogeneous ignition Ignition in

n-decane/Air 121 species (M. Chaos, IJCK,2007)

ghomogeneous

mixture

105

2 42.62.8

CO2

K)

temperature

1.5

2.0

(ms)

VODE MTSHMTS

1atm

10

10-5

100

1 82.02.22.4

OH

s fra

ctio

n

ODEMTS atur

e (1

000K

0.5

1.0

20 tdela

y tim

e ( HMTS

10-20

10-15

10-10

1 21.41.61.8

C10H22

Mas

s MTS HMTS

Tem

pera

0 5 0 6 0 7 0 8 0 9-0.5

0.0

20atm

Igni

tion

0 1 2 3 4 51020 1.2

Time (0.1 ms)

0.5 0.6 0.7 0.8 0.91000/Initial temperature (1/K)

Temperature and species profiles Ignition delay time for n-decane-air

Computation efficiency vs. Mechanism size

CPU Time(s)No. Mechanism

Base Time

Initial Pressure

Initial Temperature RTOL ATOL

CPU TimeNo. Mechanism Time

Step(s) Pressure

(atm) Temperature

(K) RTOL ATOL

VODE MTSTime

Saving a1 H2 1.0E-6 1 1200 1.0E-4 1.0E-13 0.28 0.13 53.6% a2 H 1 0E 7 1 1200 1 0E 4 1 0E 13 2 58 1 31 49 2%a2 H2 1.0E-7 1 1200 1.0E-4 1.0E-13 2.58 1.31 49.2% a3 H2 1.0E-8 1 1200 1.0E-4 1.0E-13 24.9 7.56 69.6% a4 H2 1.0E-9 1 1200 1.0E-4 1.0E-13 260 18.4 92.9% b1 CH 1 0E 6 1 1400 1 0E 4 1 0E 13 123 25 79 7%b1 CH4 1.0E-6 1 1400 1.0E-4 1.0E-13 123 25 79.7% b2 CH4 1.0E-7 1 1400 1.0E-4 1.0E-13 1269 181 85.7% b3 CH4 1.0E-8 1 1400 1.0E-4 1.0E-13 14639 1029 93.0% c1 C10H22 1.0E-6 1 1400 1.0E-4 1.0E-13 86 14 83.7% c2 C10H22 1.0E-7 1 1400 1.0E-4 1.0E-13 773 125 83.8% c3 C10H22 1.0E-8 1 1400 1.0E-4 1.0E-13 7609 1049 86.2%

A path flux analysis method for model reduction

0.01detail

T0=1200 K ig

(s)

detail DRG PFA

50 60 70 80 90

1E-3 1 atm

1E-3

ig (s

)

50 60 70 80 901E-4

20 atm

N b f i i k l l h i

15

Number of species in skeletal mechnism

Modeling of flame front trajectories of spherical propagating flames using MTSp p p g g g