Focus on Combustion
Optical Measurement Solutions

Focussing onCombustion

Energy Challengesof TodayDeveloping industries and quickly increasing markets worldwide are continuously demanding an increased primary energy supply, reliable domestic production and flexible public transportation. Even
though alternative technologies are a growing market and will gain relevance, conventional power generation from combustion will continue to hold a strong share of the energy mix for the next decades(see „world energy outlook“ below).
The diversity of fuels for power and heat generation with the stronger impact of renewable sources has been massively extended. Furthermore, requirements for energy efficiency and legislationon combustion generated pollutants have tightened. With a detailed understanding of the complex
processes in combustion advances in combined measurement technologies are helping to meet thechallenges of today and to develop the technology for the future.

18 000World Energy
Outlook

Otherrenewables

16 000Hydro

million tonnes of oil equivalent

14 000

Nuclear

12 000
10 000

Biomass

8 000

Gas

6 000

Coal

4 000

Oil

2 000
01980

1990

2000

2010

2020

2030

Prediction of future energy supply sources© OECD/ IEA 2008

2Optical Measurement
Solutions

Advanced Combustion
Diagnostics

Due to their non-intrusive nature, optical diagnostics offer unique capabilities for in-situ multi-parameter reactive flow field measurements even in the harsh environment of practical combustion
systems. These can not be achieved using conventional, i.e. non-optical probe techniques. Optical
diagnostics contribute significantly to the reduction of combustion generated pollution, particularly
the greenhouse gases CO2, CH4 and H2O.

LaVision‘s Expertise

LaVision has over 25 years of expertise and experience in the field of combustion diagnostics.
Our competence is in offering the knowledge and the most modern technology of optical diagnostic
tools. Our strength is the flexibility and the motivation to satisfy our customer’s needs by providing
the best measurement solution.

4IC engines

4flame-flow

4gas turbinesinteraction

4spray flames

4flame stability

4technical flames
4reaction chemistry
4combustor
performance4soot formation
4burner vibration

Advantages of LaVision’s Laser-based
Measurement Instruments

34validation ofcomputational models

4in-situ
4nonintrusive
4instantaneous with high spatial and temporal resolution
41D, 2D or 3D imaging
4highly integrated (laser) imaging systems
4modular and flexible system setups for multi-parameter measurements

FlameCharacterization

Imaging andAbsorption Techniques

The realization of efficient and optimal combustion systems requires in-situ measurements and detailed understanding of complex gas dynamical processes. Laser imaging techniques such as Laser
Induced Fluorescence (LIF), Laser Induced Incandescence (LII), Particle Image Velocimetry (PIV),
Mie- and Rayleigh Scattering (RS), Spontaneous Raman Scattering (SRS) as well as Emission andAbsorption Spectroscopy are well suited for this purpose allowing multi-parameter measurementswith high spatial and temporal resolution in technical combustion systems.

Laser Imaging

Flame Imaging

Characteristics

Laser Imaging
on Light Sheets(Multi-Phase) Flow Field

PIV

Absorption

Flame Imaging
Line-of-Sight

Mixture Preparation

Fuel & Tracer PLIF

Flame Radicals

PLIF (OH, CH, NO ..)Flame Emission

Flame Temperature

Rayleigh, Raman,
PLIF

IR-Thermography

Soot & Particulates

LII, Mie

Pyrometry

Exhaust Gas (H2O, CO2)

Raman

IR-Imaging

Absorption
Path Integrated
IR-Absorption
IR-Absorption

IR-Absorption

LIF imaging= Planar LIF= PLIF

4

FlameCharacterization

OH-PLIFOH*

CH-PLIF
Soot Formation

Rayleigh
Thermometry

CO2

Flow Field

5

Resolving
Mixing Processes

Liquid and Gaseous
Fuel Distribution

FeaturesDriven by the continuous demand for increased fuel efficiency and improved performance the designof combustion devices requires detailed knowledge about the fuel preparation and mixing processes.
A thorough analysis necessitates the use of advanced diagnostic tools which have to be capable ofresolving the liquid and gaseous fuel distribution in a harsh environment sustaining highly transient
flow and transport phenomena. Researchers and industries rely on the imaging systems from LaVision that enable versatile diagnostic applications: fuel distribution, mixture fraction, temperature andflow fields of liquid and gaseous fluids.

4quantitative air-fuel mixing
4fuel injector patternation
4heat transfer in thermal flows
4fuel spray imaging and evaporation
4flow field in multi-phase flows

Kerosene-PLIF

fuel vapor
PLIF

Courtesy of R. Fink et al.,Technical University Munich, TUM

liquid fuel
Mie

Fuel distribution inside a lean premixed prevaporized gas turbine combustor at 4 bar6Insight into
Reaction Chemistry

EnergyTransformationFeatures

LaVision offers diagnostic solutions for the detection of reactive species. These systems can characterize the conditions inside the reaction zone of laminar and turbulent flames. The location of initial
flame kernels and precursor species is identified via species selective detection of the chemiluminescence. Advanced diagnostics such as LIF enable instantaneous 2D imaging of important intermediate species in reaction kinetics like H2CO, CH and OH.
LaVision’s diagnostic tools furthermore utilize processes like spontaneous Raman scattering andRayleigh scattering for simultaneous and quantitative measurement of temperature and all major
species inside and outside the flame structure.

4species selectivity and sensitivity in the lower ppm range
4instantaneous temperature fields
4identification of hot spots and reaction zone
4characterization of flame structure and stability

LIF Principle

Tunable-LIF Setup

courtesy of R. Bombach (PSI)

CHCH

CNOH

H2CO

H2CO

CHO

PLIF imaging of flame species in a Wolfard-Parker-Burner
Courtesy of Rolf Bombach,Paul Scherrer Institut, Switzerland,Appl. Phys. B 68, 1999

7

Analysis ofPollutant Formation

In-situ Imaging ofPollutants

FeaturesCombustion research must face the challenges of future legislation. A thorough understanding of reaction chemistry for the related post-combustion processes and the mechanisms of flame quenchingis essential to reduce pollutant emissions.
LaVision offers laser based techniques that are able to resolve the distribution of prominent pollutants
like NO, CO or SO2 as well as particulate matter. Self-emission of a sooting flame is utilized to determine particle temperatures applying pyrometry. Advanced diagnostics like Laser Induced Incandescence are capable to quantify the size and volume fraction distribution of soot particles in both, thehot flame front and in the cold exhaust gas.

4details on NO formation4soot distribution (soot volume fraction) and primary particle size
4soot temperature

Soot-LII

courtesy of K. Geigle (DLR)

300
200
1000

Soot volume fraction/ ppm

400

Distribution of soot volume fraction in a laminar diffusion flame8A Global View
on Combustion

IR Imaging

Features

3D Imaging

OH*

3D Flame Imaging

Besides the insight into the details of reaction kinetics in combustion it is the integral view that contributes to the understanding on important features like ignition, flame structure and stability. LaVision
is offering this global view on combustion via infrared (IR) imaging of the major relevant species,
such as CO2, H20 and hydrocarbon based fuels. Furthermore, IR imaging introduces the capabilitiesof thermal imaging and active IR absorption.
By providing IR technology to the scientific community and industrial partners, LaVision maintains
the same system integration and performance as for standard imaging systems.

4detection of major combustion species
4thermal imaging of gases, particulate matter and combustor surfaces
4dynamic and flexible image synchronization on external events

IR Imaging

Fuel + H2O

IR Imaging

Volumetric flame imaging based on tomographic reconstruction gives insights into the complex 3Ddistribution of flame species. While multi-cameras are used in parallel to reconstruct the instantaneous 3D flame structure, time-averaged 3D flame imaging is possible with only one camera collecting
consecutively the flame emission from multiple views.

Courtesy of Weinkauf et al., TU-Darmstadt,
17th Int. Symp. on Applications of Laser
Techniques, Lisbon, 2014
movie and moreFeatures

9CO24 3D-flame structure in all details
4 volumetric distribution of the flame radicals OH*, CH*, …

Laser Imaging in Flames
FlameMaster Systems

Modular and Upgradable
Laser Imaging Solutions forCombustion Research

LaVision’s FlameMaster laser imaging systems are designed for multi-parameter measurements withhigh spatial and temporal resolution in flames. The systems provide in-situ and online flame imaging
as well as quantitative information about species (particle) concentration, gas composition and flametemperature.

FlameMaster Multifunctionalsystem supporting the following flame imaging applications:CH4-air flame

FlameMasterApplication Matrix

CH4 with Tracer-LIF

OH-LIF with T-YAGTM

Temperature withRayleighSoot with LII

The FlameMaster application matrix shows the imaged combustion parameter in combination withthe applied laser imaging technique and FlameMaster system setup. For each application a dedicatedset of hardware and software modules is provided allowing straightforward imaging upgrades fordifferent flame imaging applications.
The intelligence of the FlameMaster laser imaging systems is concentrated in LaVision’s powerfultiming and synchronization unit PTU X and the versatile software platform DaVis.

Tunable LIFRaman

Multifunctional

Flame Species: OH, NO, CH...............with LIF
Flame Composition
Flame Temperature
Fuel (Tracer) LIF
Formaldehyde LIF
OH-PLIF with T-YAG
Rayleigh Thermometry
Soot with LII

10

Laser Imaging in Flames
FlameMaster Systems

FlameMaster Raman

LaVision’s FlameMaster Raman system measures simultaneously all major species concentrations
together with flame temperature along a line focus (1D). Scanning the line focus through the flamegenerates 2D or even 3D views of the flame composition.
%%%

CO2Raman imaging setup%

FlameMaster Tunable LIF

Ksystem setup for flame species and radicals.

OH-PLIFNO-PLIF

11CH-PLIF

For the detection of all LIF-active diatomic flame species such as
OH, NO, CH, CN, CO a dye laser is added to the multifunctional
FlameMaster system. The precise dye-laser wavelength tuning forthe selected diatomic molecule is under DaVis control. For concentration calibration of the LIF signals a calibration burner is used.

High-Speed
Combustion Imaging

Time-resolved(Laser) ImagingFeatures

Most mixing and combustion phenomena are highly turbulent processes where diagnostic tools require high spatial and temporal resolution. Truly time-resolved laser imaging requires repetition rates
in the kHz-range to visualize the development of unsteady or statistical phenomena such as flame
vibrations. These diagnostic tools have become available with the development of powerful laser
sources and sensitive detection units, like intensified CMOS cameras.

4modular image intensifiers: The modular design adds UV-sensitivity and short exposure times(fast gating) to the CMOS camera. Weak signals of LIF processes are substantially enhanced
4state-of-the-art tunable dye laser for highest repetition rates

High repetition rate (kHz) laser imaging allows the investigation of transient combustion phenomena
like flame ignition or local flame extinction.

1.5 ms

1.6 ms

1.7 ms

1.8 ms

1.9 msHigh-speed (10 kHz) OH-LIF imaging

0 µs

83 µs

Courtesy of V. Sick et al., University of Michigan

166 µs249 µs332 µsHigh-speed (12 kHz) fuel LIF imaging at spark plug

12Sensors forCombustion Diagnostics

LaVision’s OpticalSensor Systems

LaVision offers three types of optical sensor systems for combustion diagnostics. They are capableof time resolved (real-time) point measurements for mixture characterization in internal combustion(IC-) engines, flame temperature and sensitive soot detection:

4The ICOS and TDLAS sensors are keyhole detection devices based on IR-absorption allowing
in-situ measurement of concentration and temperature at high data rates.

4The LII soot sensor measures soot volume fraction and primary particle size in-situ as wellas in the exhaust line for continuous emission control.

Internal Combustion Optical Sensor (ICOS)
systems for ultra fast crank angle resolved
measurements of fuel and exhaust gas
concentration or gas temperature
together with engine pressure indication atkilohertz data rates.

Flame temperature sensor based on tunable
diode laser absorption spectroscopy (TDLAS)
of water. Flame temperatures up to 2200°C are
measured in-situ at a sampling rate of 200 Hz.

Most advanced Laser Induced Incandescence
instrument (LII-300/ 200) for particulate mattermeasurements. Specifically designed for
accurate, non-intrusive, and temporally resolved
in-situ measurements of soot concentration,
specific surface area, and primary particle
diameter in the exhaust gas stream.

13Multi-Parameter
Laser Imaging

Time-resolved laser imaging of fuel-air mixing, reaction zone visualization and flow field
in a turbulent swirl flame inside a gas turbine model combustor
Simultaneous high-speed (10 kHz) laser imaging:
OH-PLIF
Acetone-PLIF
PIV

t=0 msReaction zone
Fuel transport
Flow structure

85 mm
t=0.8 ms

110 mmt=0.8 mswell-mixed
unmixedt=1.9 ms

FuelSwirler
movie and moreAirx [mm] -2 0-1 00

102030Courtesy of M. Stöhr et al., German Aerospace Center (DLR),
Proc. Combust. Inst. (2014)

Simultaneous imaging of fuel and reaction zone using FlameMaster multifunctional system
A standard Nd:YAG laser upgraded with an intra-cavity tuning
device (T-YAGTM-module) allows the simultaneous detection offuel (acetone) LIF and OH-LIF. One intensified camera allows theimaging of both LIF signals at different locations in the flame.

Single-shot distribution of OH-radicals and acetone in a turbulent Bunsenburner flame.
Picture a shows the combined OH and acetone LIF signals, while in picture b
the laser was tuned away from the OH-line and thus only the acetone signals
are produced.

ab

Courtesy of V. Sick et al, University of Michigan,Appl. Phys. B 79, 2004

14

Multi-Parameter
Laser Imaging

OH concentration and flame temperature in a rich methane-air flame

OH

2800

T

2400
2000

2.0

1600
1200

OH

1.5

T

1800
1600
1400
1200

Temperature/ K

3200

Concentration/ ppmvm/s

OH concentration (left side) and flame temperature
T (right side) for different stoichiometries and flow
velocities of a methane-air diffusion flame.

A tunable Nd:YAG laser (T-YAGTM) was used for UV
Rayleigh thermometry and OH-PLIF imaging.

1000
80060080040040020000OH

T

1.00.4		0.5		0.6			λCourtesy of S. Marengo et al., SSC, Italy

Multi-parameter laser imaging inside a gas turbine combustor

OH-PLIF

2 bar

Courtesy of R. Fink et al.,Technical University Munich, TUM

15NO-PLIFPIVRelated Product Information

LaVisionUK Ltd

Downsview House / Grove Technology Park
Grove / Oxon / OX12 9FF / United Kingdom
E-Mail: sales@lavisionuk.com
www.lavisionUK.com
Phone: +44-(0)-870-997-6532
Fax: +44-(0)-870-762-6252

LaVision GmbHAnna-Vandenhoeck-Ring 19D-37081 Goettingen / Germany
E-Mail: info@lavision.com
www.lavision.com
Tel.: +49-(0)5 51-9004-0
Fax: +49-(0)551-9004-100

LaVision Inc.

211W. Michigan Ave. / Suite 100
Ypsilanti, MI 48197 / USA
E-Mail: sales@lavisioninc.com
www.lavision.com
Phone: (734) 485 - 0913
Fax: (240) 465 - 4306

05/15