Development and application of laser diagnostic techniques for combustion studies
Marcus Aldén
Division of Combustion Physics
Lund University, Sweden
Annual meeting of Finnish National Committee of IFRF
January 14th, 2010

• Introduction
• Laser-induced fluorescence
– 2D imaging, multiple species visualization
– High speed (3D) visualization
– Applications; Engines, gasturbines, furnaces
• Thermographic phosphors
• Future diagnostic challenges
• Conclusions
Acknowledgements

Why lasers in combustion diagnostics ?
Photo: P.-E. Bengtsson
•Non-intrusive
•High spatial resolution (<0.001 mm 3 )
•High temporal resolution (<10 ns)
•High spectral resolution (~MHz)
•Multiplex (multi-species, multi-point)
•Can measure non-thermal equilibrium
Undisturbed premixed flame
Premixed flame disturbed by a thermocouple

Laser diagnostics in combustion
What can be measured ?
• Temperatures (rotational/vibrational/electron)
• Species concentrations (molecules, radicals, atoms )
• Velocities
• Particle number densities/diameters
• Surface characteristics
• Two-phase characterization

Incoherent techniques:
•
Mie/Rayleigh scattering
•
Laser-induced fluorescence (LIF)
•
Laser-induced incandescence (LII)
•
Laser-induced phosphorescence (LIP)
•
Raman scattering

Coherent techniques:
•
CARS
•
Polarisation spectroscopy
•
DFWM

LIF:
General features:
- Mesures, e.g. NO, OH, CH, CN, C
2
, O
2
, CH
2
O, fuel-tracer using onephoton LIF; e.g. O, H, C, N, CO, H
2
O, NH
3
, using two-photon LIF
- High sensitivity
- 2D imaging capabilities
- Spontaneous technique
- Measures temp. and konc.

Two dimensional measurements
Laser beam
Flame
Cylindrical lens
Lens
2D-detector

Kiefer et al, 31 st Comb. Symp

Simultaneous single shot fuel & OH visualization in a gasturbine at SIEMENS
Green: Fuel
(acetone LIF)
Red: Flame
(OH LIF)
• The example images are obtained from a production gas turbuine burner
• Natural gas fuel distribution is visualized using acetone as tracer

Formaldehyde and OH distributions for SOI 80 CAD BTDC
Digitalized data Formaldehyde
OH

Challenges, e.g. in large scale applications
Furnaces, boilers, fires;
• Very limited optical access

Furnace applications - LIF

Furnace temperature measurements using CARS

Practical diagnostics CARS
Suction Pyrometer constant thermal load 72 MW
1380
1370
1360
1350
1340
1330
1320
1310
1300
1290
1280
4 m from focusing lens time (h,m)

High speed LIF system
Ordinary Nd:YAG laser
Nd:YAG laser cluster t t
M irro r
Beam splitter optics
M irr or
Iris

Kaminski et al. Appl Phys B 1999
Turbulent non-premixed
CH
4
/air flame, Re=5500
CH
4
Air
CH
4

Fuel Tracer PLIF in an SI-engine
(single-cycle-resolved )
7 ATDC
7.75 ATDC 8.5 ATDC 9.25 ATDC 10 ATDC 10.75ATDC 11.5ATDC 12,25 ATDC
• Fuel: iso-octane
• Tracer: 6% 3-pentanone
Hult et al. Appl Opt 2002
13 juni

• Information on “flame” topology
• Rapid slicing of the measurement volume
• 3D data reconstructed from the eight resulting 2D-measurements

+6 CAD 3-D fuel tracer PLIF in an engine
1 2 3 4
5 6 7 8
Sheet spacing: 0.5 mm
Iso-concentration surface
Isolated fuel islands
Nygren et al . 29 th Comb Symp.

Thermographic phosphors for temperature measurements
• Host inorganic material (ceramic) doped with an activator (rare earth metal)~1 %. Normally used in lamps,
CRT, field emission displays (FED).
• Through complex interactions in the electronic configuration of the activator and the host, temperature will influence the spectral and temporal behaviour of the emission
• Powder(1-10µm), sensitivity from cryogenic to 2000K
• Industrial and scientific applications
• Excitation: UV (light), laser, e-beam.

Spectral (left) and temporal (right) method

Temperature dependent phosphors
Summary of some phosphors
Särner et al. Meas. Sci Techn. 2008,
Lindén et al. ECM 2009, poster 329

2D measurements: Spectral method

•Excitation 266 or 355 nm
•Fuel: Alcohol and Heptane.
•Detection: Framing Camera.
•Material: LDF and PMMA.
Omrane et al. , 29 st Comb Symp.

Omrane et al. , 29 st Comb Symp.

intake valves exhaust valves
Application:
IC engines
Omrane et al. SAE 2004

2D temperature measurements in a burning droplet using ZnO:Ga
Särner et al. Opt Lett 2008

Future laser diagnostic challenges
• Limited optical access
• Characterization of optical dense media, e.g dense sprays
• Multiple-parameter visualization (

, T, v, soot)
• 4D visualization (3D + t)
• Accurate species concentration measurements
• 2D velocity measurements without seeding
• Quantitative fuel visualization without seeder
• Accurate 2D temperature measurements
• On/near surface measurements (LIP, FRS, picosec.)
• Spatially resolved identification of different HC’s
• Measurements of EGR (CO
2
)

Future laser diagnostic challenges
• Limited optical access
• Characterization of optical dense media, e.g dense sprays
• Multiple-parameter visualization (

, T, v, soot)
• 4D visualization (3D + t)
• Accurate species concentration measurements
• 2D velocity measurements without seeding
• Quantitative fuel visualization without seeder
• Accurate 2D temperature measurements
• On/near surface measurements (LIP, FRS, picosec.)
• Spatially resolved identification of different HC’s
• Measurements of EGR (CO
2
)

Future laser diagnostic challenges
• Limited optical access
• Characterization of optical dense media, e.g dense sprays
• Multiple-parameter visualization (

, T, v, soot)
• 4D visualization (3D + t)
• Accurate species concentration measurements
• 2D velocity measurements without seeding
• Quantitative fuel visualization without seeder
• Accurate 2D temperature measurements
• On/near surface measurements (LIP, FRS, picosec.)
• Spatially resolved identification of different HC’s
• Measurements of EGR (CO
2
)

Future laser diagnostic challenges
• Limited optical access
• Characterization of optical dense media, e.g dense sprays
• Multiple-parameter visualization (

, T, v, soot)
• 4D visualization (3D + t)
• Accurate species concentration measurements
• 2D velocity measurements without seeding
• Quantitative fuel visualization without seeder
• Accurate 2D temperature measurements
• On/near surface measurements (LIP, FRS, picosec.)
• Spatially resolved identification of different HC’s
• Measurements of EGR (CO
2
)

Future laser diagnostic challenges
• Limited optical access
• Characterization of optical dense media, e.g dense sprays
• Multiple-parameter visualization (

, T, v, soot)
• 4D visualization (3D + t)
• Accurate species concentration measurements
• 2D velocity measurements without seeding
• Quantitative fuel visualization without seeder
• Accurate 2D temperature measurements
• On/near surface measurements (LIP, FRS, picosec.)
• Spatially resolved identification of different HC’s
• Measurements of EGR (CO
2
)

Future laser diagnostic challenges
• Limited optical access
• Characterization of optical dense media, e.g dense sprays
• Multiple-parameter visualization (

, T, v, soot)
• 4D visualization (3D + t)
• Accurate species concentration measurements
• 2D velocity measurements without seeding
• Quantitative fuel visualization without seeder
• Accurate 2D temperature measurements
• On/near surface measurements (LIP, FRS, picosec.)
• Spatially resolved identification of different HC’s
• Measurements of EGR (CO
2
)

Future laser diagnostic challenges
• Limited optical access
• Characterization of optical dense media, e.g dense sprays
• Multiple-parameter visualization (

, T, v, soot)
• 4D visualization (3D + t)
• Accurate species concentration measurements
• 2D velocity measurements without seeding
• Quantitative fuel visualization without seeder
• Accurate 2D temperature measurements
• On/near surface measurements (LIP, FRS, picosec.)
• Spatially resolved identification of different HC’s
• Measurements of EGR (CO
2
)

Future laser diagnostic challenges
• Limited optical access
• Characterization of optical dense media, e.g dense sprays
• Multiple-parameter visualization (

, T, v, soot)
• 4D visualization (3D + t)
• Accurate species concentration measurements
• 2D velocity measurements without seeding
• Quantitative fuel visualization without seeder
• Accurate 2D temperature measurements
• On/near surface measurements (LIP, FRS, picosec.)
• Spatially resolved identification of different HC’s
• Measurements of EGR (CO
2
)

Future laser diagnostic challenges
• Limited optical access
• Characterization of optical dense media, e.g dense sprays
• Multiple-parameter visualization (

, T, v, soot)
• 4D visualization (3D + t)
• Accurate species concentration measurements
• 2D velocity measurements without seeding
• Quantitative fuel visualization without seeder
• Accurate 2D temperature measurements
• On/near surface measurements (LIP, FRS, picosec.)
• Spatially resolved identification of different HC’s
• Measurements of EGR (CO
2
)

Future laser diagnostic challenges
• Limited optical access
• Characterization of optical dense media, e.g dense sprays
• Multiple-parameter visualization (

, T, v, soot)
• 4D visualization (3D + t)
• Accurate species concentration measurements
• 2D velocity measurements without seeding
• Quantitative fuel visualization without seeder
• Accurate 2D temperature measurements
• On/near surface measurements (LIP, FRS, picosec.)
• Spatially resolved identification of different HC’s
• Measurements of EGR (CO
2
)

Future laser diagnostic challenges
• Limited optical access
• Characterization of optical dense media, e.g dense sprays
• Multiple-parameter visualization (

, T, v, soot)
• 4D visualization (3D + t)
• Accurate species concentration measurements
• 2D velocity measurements without seeding
• Quantitative fuel visualization without seeder
• Accurate 2D temperature measurements
• On/near surface measurements (LIP, FRS, picosec.)
• Spatially resolved identification of different HC’s
• Measurements of EGR (CO
2
)


Laser diagnostic techniques are of essential importance for combustion characterization

Further fundamental activities for accurate quantitative measurements are important

Close coupling between modelling/validation and experiments necessary for phenomenological studies

Present och past members of the Division of
Combustion Physics, in specific:
Zhongshan Li, Mattias Richter, Gustaf Särner, Johan Hult, Clemens
Kaminski, Joakim Bood, Alaa Omrane, Billy Kaldvee, Johannes Lindén,
Jenny Nygren, Johan Zetterberg, Martin Levin, Bo Li, Shewei Sun,
Jimmy Olofsson, Hans Seyfried, Andreas Ehn, Elias Kristensson,
Edouard Berrocal,,,,,, and colleagues in the Divisions of Combustion Engines, Fluid Mechanics,
Fire and Safety Eng. in Lund and TU/e Eindhoven,,,,,,, and many more,,,,,,,,,(Johannes Kiefer, Zeyad Alwahabi,,,,)
Financially support from Swedish Energy Administration, Swedish
Foundation for Strategic Research and the Swedish Research
Council, LSF (EU)