5. laser induced fluorescence - princeton university lecture notes/alden/lecture-5...lif thermometry...
TRANSCRIPT
![Page 1: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/1.jpg)
5. Laser Induced Fluorescence
GeneralGeneral• Introduction to LIF; Theory• Species concentrations• Temperature measurementsTemperature measurements• Multi-dimensional imaging
Applications– Engines– GasturbinesGasturbines– Furnaces/boilers-Biomass applications
![Page 2: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/2.jpg)
Laser-induced fluorescence
LIF: Measures e.g, NO, OH,LIF: Measures e.g, NO, OH, CH, CN, C2, O2, fuel-tracer
General features:- High sensitivityHigh sensitivity- 2D imaging capabilities- Spontaneous techniquep q- Measures temp. and konc.- Quantification problem
![Page 3: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/3.jpg)
Different LIF approachesExcitation scanFluorescence spectrum
pp
v’
B
J’ = 0J’ = 1J’ = 2
B
J’ = 0J’ = 1J’ = 2
v’ J 0J 0
Xv’’ = 1
Xv’’ = 1
v’’ = 0J’’ = 0J’’ = 1J’’ = 2
v’’ = 0J’’ = 0J’’ = 1J’’ = 2
Joakim Bood
Laser tuned to a specific absorptionline and the spectrometer is scanned
Laser is tuned across the various absorptionlines and the total fluorescence is monitored
![Page 4: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/4.jpg)
Excitation and fluorescence spectra
Excitation spectrum of OH Fluorescence spectrum of CN
![Page 5: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/5.jpg)
I t t l l d t t d b LIFImportant molecules detected by LIF
Table I
Molecule Abs. wavelength (nm)OH ~306C 516C2 ~516CH ~431CN ~388NH ~336NO ~226CH2O ~320-360NO2 450-470
![Page 6: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/6.jpg)
LIF Theory
S ~ N2 , How is N2 related to Ntot ?21A
N2 2
B Bc
B L1221A
cB L21 21Q
N11
![Page 7: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/7.jpg)
Rate equation analysisRate equation analysis
BBtN
cBQAtN
cBtN
ttN LL 21
2121212
11
BQAtNBtNtN LL 21122
c
QAtNc
tNt 212121
21 NNNtot and assume steady state; dN/dt=0
bij=Bij/c
A /B = h/3A21/B21=h/
![Page 8: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/8.jpg)
Results
Ltot
bbQAbNN
)(12
2
LbbQA )( 12212121
Ltot
bbQAbNAS
)(12
21
LbbQA )( 21122121
LLptot bbQA
AbVFNS
)( 21122121
2112
LbbQA )( 21122121
Stern-Vollmer factor = Y
![Page 9: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/9.jpg)
Evaluate Lptot bbQA
AbVFNS
)(
2112
L l li it (b b ) (A Q )
LbbQA )( 21122121
Low laser limit: (b12+b21)L<<(A21+Q21)
21AbVFNS 2121
2112 QA
bVFNS Lptot
![Page 10: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/10.jpg)
LIF in the linear regime
21AbVFNS Fluorescence
efficiency
Th fl i li l ti l t th i t l i di
212112 QA
bVFNS Lptot y
• The fluorescence is linearly proportional to the input laser irradiance
• Since most often A21 << Q21, the fluorescence efficiency is generally <<1,which diminishes the sensitivitywhich diminishes the sensitivity
• For quantitative measurements usually Q21 has to be evaluated
• Q21(p,T,composition) difficult to obtain quantitative data
For quantitative measurements it is critical to measure/estimate Q !!
Joakim Bood
critical to measure/estimate Q !!
![Page 11: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/11.jpg)
Make Q small: High laser intensityMake Q small: High laser intensity
ijLjiijij
ij
QbbAA
Y
)(
(b +b ) >>(A +Q )
ijLjiijij Q)(
(b12+b21)L>>(A21+Q21)
1221 bb
bVNAS tot2112
21 bbtot
Saturation
![Page 12: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/12.jpg)
Fluorescence power versus laser irradianceSaturated regime
1.0
Saturated regime
0.8
pow
er At saturation
0.6
esce
nce
p
0.20
Linear regime •S is independent of both and Q21
• S is maximized sensitivity maximized0.4
Fluo
re
0.05
0.10
0.15
S is maximized sensitivity maximized
0 0
0.20.0 0.5 1.0 1.5 2.0
0.00
0 100 200 300 4000.0
Laser irradiance (arb. unit)
Joakim Bood
Power dependence
![Page 13: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/13.jpg)
SaturationSaturation
• Saturation depends on Q
• Saturation depends on pspatial, temporal and frequency laser wing High Qq y geffects
g
KvvKzF
zRrExp
TtExpvrzt
LL
2
22,,,
![Page 14: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/14.jpg)
Two-photon LIF
Differences between one- and two-photon LIF:
Diff t l ti l- Different selection rules- Doppler-free measurements
possible- Temporal behaviour of laser pulse
important- LIF signal proportional to the laser-g p p
intensity squared
Species Exc (nm) Em (nm)Species Exc. (nm) Em. (nm)H 2x205 656O 2x226 845 (777)N 2x211 870 (822,744)( , )C 2x280 910CO 2x230 400-725H2 2x193 830H2O 2x248 400-500NH3 2x305 550-575 (720)
![Page 15: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/15.jpg)
Difference between one and two-photon LIF
• Ione-photon ~ I/A x A = I , independent on focusing
• Itwo-photon ~ (I/A)2 x A = I2 /A
![Page 16: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/16.jpg)
LIF thermometry
A th d th t fl t th di t ib ti f l ti t• Any method that reflects the distribution of population over two or moreindividual vibrational rotational states can in principle be used fortemperature measurement. LIF is such a method.
• LIF thermometry restricted to high temperatures if molecular radicalsare employed. For OH temperatures above ~1500 K are needed.p y p
• If atomic species, such as metal atoms, are used, these have to be seededinto the flame or flowinto the flame or flow.
• If LIF was used for concentration measurements it is definitelyconvenient to apply it for thermometry tooconvenient to apply it for thermometry too.
Joakim Bood
![Page 17: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/17.jpg)
Temperature masurementsTemperature masurements
jtot kT
EExpNJ
n)(12
rotvib
j QQn
0.010
]
0.005
300 K 1500 K 3000 K
popu
latio
n [a
u]Fr
actio
nal p
0 5 10 15 200.000
Rotational level [J]
![Page 18: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/18.jpg)
Various techniquesq
Excitation Scans Thermally-Assisted
Collisions
Two-Line
2
Electronicallyexcited
CollisionsVibrational
Levels 02
12
2stateLaser variable
with scans from i to j
Laser fixed
RotationalGroundEl i
F21
1F
i j
RotationalLevelsElectronic
State 0F20
![Page 19: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/19.jpg)
Excitation spectraExcitation spectra
NO roomNO room
T~ 300 K
NO flame
T~ 2000 K
![Page 20: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/20.jpg)
Excitation scans of OH A-X (0,0)
T = 500 K
T = 500 K
T = 1500 K
arb.
uni
t)
T 2000 Ktens
ity (a
T = 2000 K Int
T = 2500 K
Joakim Bood
3040 3060 3080 3100 3120 3140 3160
Wavelength (Å)
![Page 21: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/21.jpg)
Plotting approach for yielding TPlotting approach for yielding T
ln (ni ) ~ - Ei /kT
R2(3)
R2(2)
P1(2)
5Temperature 1794 K; =185 K
R2(10)R2(11)
P1(1)
Q1(5)
3
4
Boltz
man
n - f
acto
rR1(12)
R2(13)
R1(14)
0 1000 2000 3000 40001
2
B
Energy (cm-1)
![Page 22: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/22.jpg)
Single shot 2D LIF flame thermometry strategies: Two-line excitationg
T li l l fl OH NOTwo-line molecular fluorescence: e.g OH, NO, ketones
Problems: • Applicable only in areas where the species is located; high T (OH) ,
low T (ketones) E it ti i UV b k d i i t i t• Excitation in UV, may cause background emission, trapping etc,
• Require relatively high laser intensities P bl i f l i h i t• Problems in fuel rich environments
• Complex set up (NO)
![Page 23: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/23.jpg)
Two-Line Atomic Fluorescence (TLAF)
• Atoms usually possesses much higher transitionprobabilities than molecules Very low laser power can be used for excitation
• Excitation can be made in the visible region
• Measurements in sooty flames can be made
• Usually metal atoms are seeded into the flame
The tracer species should be selected based on:• The tracer species should be selected based on:• temperature sensitivity• complexity of the emission spectrum
Joakim Bood
complexity of the emission spectrum• minimum intrusion on the combustion process
![Page 24: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/24.jpg)
Two-line LIF thermometryy
2Basic idea:
12F21
Basic idea:
To measure the relative populationf t t t T f B lt
02
12F21
F20
of two states T from Boltzmannexpression
1Excitation to the same upper state F21 and F20 are equally affected byquenching and energy transfer processes
0
quenching and energy transfer processes
kEE C
II
FF
kEETlnln4lnln 211221
01
C non-dimensional system
dependent calibration constant
Joakim Bood
IF 200220
![Page 25: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/25.jpg)
Two-line fluorescenceTwo-line fluorescence
Species 1(nm) 2(nm) E(eV)
Gallium 403.4 417.3 0.109Indium 410.3 451.3 0.274Thallium 377 6 535 0 0 966Thallium 377.6 535.0 0.966Lead 339.4 461.9 1.320
![Page 26: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/26.jpg)
Temperature sensitivitiesTemperature sensitivities
T sensitivites of different atomic seeder species
0.8
arb.
u.)
In Ga TlPb
0 4
0.6
T-se
nsiti
vity
(a
0.2
0.4
rela
tive
T
0 1000 2000 3000 4000
0.0
0 1000 2000 3000 4000Temperature (K)
![Page 27: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/27.jpg)
LIF set up: 0DLIF set-up: 0D
![Page 28: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/28.jpg)
Multi-point visualization: 1DMulti-point visualization: 1D
![Page 29: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/29.jpg)
Multi-point visualization: 1DMulti-point visualization: 1D
![Page 30: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/30.jpg)
Two-dimensional visualization: 2D
![Page 31: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/31.jpg)
Two-dimensional measurements
FlameLaser beam
Cylindrical lensLensLens
2D-detector
![Page 32: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/32.jpg)
![Page 33: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/33.jpg)
CH visualization
Motivation: Intermediate in NOx formationFlame front markerFlame front marker
Approach: Excitation X-B at ~ 387 nmEmission B-X, A-X; ~430 nmBroadband excitation
~ two orders of magnitudeincreased detectability
Kiefer et al, 31st Comb. Symp
![Page 34: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/34.jpg)
CH visualization in a turbulent flameCH visualization in a turbulent flame
Kiefer et al, 31st Comb. Symp
![Page 35: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/35.jpg)
Multi species pvisualization CH, OH
Kiefer et al, Comb.Flame 2008
![Page 36: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/36.jpg)
Simultaneously multi-species visualization CH, CH2O
Courtesy: Z-S. Li et al.Li et al. ECM 2009, poster 259
![Page 37: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/37.jpg)
Exp set-up for 2D temperature measurements i TLAFusing TLAF
YAG 1
YAG 2
355
532 667
451mixing
410
451dye 1
dye 2
1064
451crystal 410
/2 platedelay line
polarizerCCD 1( )F20
CCD 2( )F21
cylindricaltelescope
( )21
signal beamsplitter
photodiode
filters
engine
CCDcontrol
CCDcontrol
boxcarint.
PC1 PC2boxcar
int.
![Page 38: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/38.jpg)
2D TLAF
![Page 39: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/39.jpg)
Temperature field in a Bunsen burnerTemperature field in a Bunsen burner
![Page 40: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/40.jpg)
High speed visualization I: Turbulent non premixed CH /air flame Re=5500
AirCH4CH4
Turbulent non-premixed CH4/air flame, Re=5500
![Page 41: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/41.jpg)
High speed visualization II.Flame extinction – simultaneous scalar/flow measurements
Simultaneous PIV and OH PLIF
• Turbulent opposed jet flames as model-systems for aerodynamically Simultaneous PIV and OH PLIF
at 5 kHz repetition ratemodel systems for aerodynamically induced extinction
Oxidant
• White area: Instantaneous flame position from OH PLIF
• Arrows: Velocity vectors from PIV• Color-code: Out-of-plane vorticity
(blue: clockwise rotation, red: counter-clockwise rotation)Fuel
Courtesy: Andreas Dreizler (Böhm, Heeger, Boxx, Meier and Dreizler. Proc. of the Comb Inst 32 (2009) 1647)
Fuel
![Page 42: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/42.jpg)
3D measurements
![Page 43: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/43.jpg)
Formaldehyde visualization
![Page 44: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/44.jpg)
Multi-Species Measurements
![Page 45: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/45.jpg)
Multi-Species Measurements
Jet speed 120m/sJet speed 60m/s
OH CH O CH OOH CH O CH O OH CH2O CH2OCH CH Toluen
OH CH2O CH2OCH CH Toluen
![Page 46: 5. Laser Induced Fluorescence - Princeton University Lecture Notes/Alden/Lecture-5...LIF thermometry • A th d th t fl t th di t ib ti f l ti tAny method that reflects the distribution](https://reader034.vdocuments.site/reader034/viewer/2022042022/5e795d882b014431e43c475d/html5/thumbnails/46.jpg)
Summary: LIF• Can measure 2D temperatures and species distributions• Measure preferably atoms (O, H, N, C) and diatomic molecules (NO, OH,
CH CN C O CO H ) S l t i i (NH H O HCO CH O)CH, CN, C2, O2, CO, H2). Some polyatomic species (NH3, H2O, HCO, CH2O)• High sensitivity (ppm)• Mainly used for one species detection• Accuracy; concentration: ~10% (stationary flame, all quenching
parameters known)~30% (turbulent flame, no quenching
corrections)corrections)temperature: ~2% (point measurement)
~8 % (2D measurement)
• Resonant excitation Tunable laser needed• Incoherent non-elastic scattering Signal emitted in all directions
S ff f hi i lli i l d it ti tit ti i• Suffers from quenching, i.e. collisional deexitation quantitative speciesconcentration measurements not trivial
• Problem with separation of multi-atomic species, e.g. PAH’s• Outlook: Further 3D visualization high speed imaging (>kHz) velocity• Outlook: Further 3D visualization, high speed imaging (>kHz), velocity
visualization without molecule seeding