Jun Kojima and Quang-Viet Nguyen
Glenn Research Center, Cleveland, Ohio
Development of a High-Pressure Gaseous
Burner for Calibrating Optical
The NASA STI Program Office . . . in Profile
Since its founding, NASA has been dedicated to
the advancement of aeronautics and space
science. The NASA Scientific and Technical
Information (STI) Program Office plays a key part
in helping NASA maintain this important role.
The NASA STI Program Office is operated by
Langley Research Center, the Lead Center for
NASA’s scientific and technical information. The
NASA STI Program Office provides access to the
NASA STI Database, the largest collection of
aeronautical and space science STI in the world.
The Program Office is also NASA’s institutional
mechanism for disseminating the results of its
research and development activities. These results
are published by NASA in the NASA STI Report
Series, which includes the following report types:
TECHNICAL PUBLICATION. Reports of
completed research or a major significant
phase of research that present the results of
NASA programs and include extensive data
or theoretical analysis. Includes compilations
of significant scientific and technical data and
information deemed to be of continuing
reference value. NASA’s counterpart of peer-
reviewed formal professional papers but
has less stringent limitations on manuscript
length and extent of graphic presentations.
TECHNICAL MEMORANDUM. Scientific
and technical findings that are preliminary or
of specialized interest, e.g., quick release
reports, working papers, and bibliographies
that contain minimal annotation. Does not
contain extensive analysis.
CONTRACTOR REPORT. Scientific and
technical findings by NASA-sponsored
contractors and grantees.
CONFERENCE PUBLICATION. Collected
papers from scientific and technical
conferences, symposia, seminars, or other
meetings sponsored or cosponsored by
SPECIAL PUBLICATION. Scientific,
technical, or historical information from
NASA programs, projects, and missions,
often concerned with subjects having
substantial public interest.
TECHNICAL TRANSLATION. English-
language translations of foreign scientific
and technical material pertinent to NASA’s
Specialized services that complement the STI
Program Office’s diverse offerings include
creating custom thesauri, building customized
databases, organizing and publishing research
results . . . even providing videos.
For more information about the NASA STI
Program Office, see the following:
Access the NASA STI Program Home Page
E-mail your question via the Internet to
Fax your question to the NASA Access
Help Desk at 301–621–0134
Telephone the NASA Access Help Desk at
NASA Access Help Desk
NASA Center for AeroSpace Information
7121 Standard Drive
Hanover, MD 21076
Jun Kojima and Quang-Viet Nguyen
Glenn Research Center, Cleveland, Ohio
Development of a High-Pressure Gaseous
Burner for Calibrating Optical
National Aeronautics and
Glenn Research Center
Prepared for the
2003 American Flame Research Committee International Symposium on
Combustion Research and Industrial Practice: Bridging the Gap
cosponsored by the American Flame Research Committee (AFRC) and the
Combustion Research Facility of Sandia National Laboratory
Livermore, California, October 16–17, 2003
NASA Center for Aerospace Information
7121 Standard Drive
Hanover, MD 21076
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22100
This report is a formal draft or working
paper, intended to solicit comments and
ideas from a technical peer group.
Trade names or manufacturers’ names are used in this report for
identification only. This usage does not constitute an official
endorsement, either expressed or implied, by the National
Aeronautics and Space Administration.
This report contains preliminary
findings, subject to revision as
Available electronically at http://gltrs.grc.nasa.gov
The authors acknowledge Mr. Gregg Calhoun, Mr. William Thompson, Mr. Raymond Lotenero, and
Mr. Gary Lorenz for their assistance in the construction and operation of the facilities. We also acknowledge
Mr. Anthony Iannetti for his efforts in providing the NCC simulations for this burner.
Development of a High-Pressure Gaseous Burner
for Calibrating Optical Diagnostic Techniques
Jun Kojima* and Quang-Viet Nguyen†
National Aeronautics and Space Administration
Glenn Research Center
Cleveland, Ohio 44135
In this work-in-progress report, we show the development of a unique high-pressure
burner facility (up to 60 atm) that provides steady, reproducible premixed flames with
high precision, while having the capability to use multiple fuel/oxidizer combinations.
The high-pressure facility has four optical access ports for applying different laser
diagnostic techniques and will provide a standard reference flame for the development of
a spectroscopic database in high-pressure/temperature conditions. Spontaneous Raman
scattering (SRS) was the first diagnostic applied, and was used to successfully probe
premixed hydrogen-air flames generated in the facility using a novel multi-jet micro-
premixed array burner element. The SRS spectral data include contributions from H2, N2,
O2, and H2O and were collected over a wide range of equivalence ratios ranging from
0.16 to 4.9 at an initial pressure of 10-atm via a spatially resolved point SRS
measurement with a high-performance optical system. Temperatures in fuel-lean to
stoichiometric conditions were determined from the ratio of the Stokes to anti-Stokes
scattering of the Q-branch of N2, and those in fuel-rich conditions via the rotational
temperature of H2. The SRS derived temperatures using both techniques were consistent
and indicated that the flame temperature was approximately 500 K below that predicted
by adiabatic equilibrium, indicating a large amount of heat-loss at the measurement zone.
The integrated vibrational SRS signals show that SRS provides quantitative number
density data in high-pressure H2-air flames.
The experimental testing of aircraft engine hardware is becoming prohibitively expensive.
Sometimes more important than the cost of testing, the development time for an engine
can sometimes take upwards of 10 years or more. In order to reduce the costs associated
with engine development and to reduce the time-to-market of new engine concepts,
industry is relying more and more on computational modeling of the engines as an
alternative to testing before actual hardware is built. The quantitative measurement of
species concentration and/or temperature in high-pressure combustion environments is, in
*National Research Council—NASA Resident Research Associate at Glenn Research Center; E-mail:
fact, of prime importance to validate and anchor the current suite of computational
models of gas turbine combustion. Non-intrusive optical diagnostics are becoming more
and more relied upon for code-validation purposes. The application of laser
spectroscopic diagnostics such as laser-induced fluorescence (LIF), SRS, or laser
absorption spectroscopy in high-pressure flames is one of the major challenges in the
code validation process for advanced combustors. We are particularly interested in
measuring the entire Raman spectral response in a variety of high-pressure flames (up to
60 atm) with various fuels (H2, H2-CO, CH4, and jet-A) and oxidizers (Air, O2). In an
effort to develop a SRS spectral database in hydrocarbon flames, we are first examining
simple H2-Air flames in detail before moving on to fuels containing carbon.
High-density gases in high-pressure cells [1-2] are typically used to study
fundamental aspects of laser diagnostics such as the pressure dependence on spectral
shapes or quenching effects. Real combustion experiments, however, are necessary to
look into details about such molecular spectroscopic phenomena over the range of
combustion pressure, temperature, and species composition. Thus, a high-pressure
burner that can serve as a precision calibration standard would be of great use to the
combustion research community. Such a burner should provide a stable and repeatable
source of combustion products over a wide operational range. In the past, water-cooled
sintered-metal porous plate flat-flame burners (so-called McKenna burners) have been
used for studies of high-pressure laminar hydrocarbon flames [3-5]. This type of burner
was reported to work well in providing stabilized high-pressure flames at pressures up to
60 atm for hydrocarbon flames, and is useful for optical calibrations at reduced flame
temperatures . However, this type of burner suffers from a large amount of heat loss
due to the short distance (generally, < 1 mm) between the water-cooled burner surface
and the flat-flame. This type of burner also suffers from flame temperatures that decrease
with increasing pressures due to a reduction in burner surface-to-flame distance caused
by the higher pressures . Furthermore, the low flow velocities through the sintered
plate produce a flame that is susceptible to the increased effects of buoyancy at high
pressures. As for hydrogen flames, sintered bronze-matrix burner have been proposed to
provide a 15-bar H2-air laminar premixed flame for the calibration of CARS diagnostics,
albeit with the risk of thermal meltdown even in fuel-rich (> φ = 3.5) conditions .
Despite these drawbacks, the McKenna burner has been a popular burner for high
pressure studies. However, if higher flame temperatures are required, and they are indeed
necessary for the SRS calibration procedure since the spectral interferences among
different species generally become stronger at higher temperatures, then a different type
of burner must be used.
The alternative is the so-called Hencken burner operated in a non-premixed mode
with multiple fuel tubes is generally used for optical calibration in H2 flames . This
type of burner works well at atmospheric pressure conditions and is able to provide near
adiabatic flames over a wide range of equivalence ratios, however, flow-field uniformity
and the uncertainty in flow rates are still an issue . However, the Hencken burner
cannot survive a high pressure hydrogen-air flame due to thermal meltdown, and cannot
be operated in a premixed mode with hydrogen due to flash-back.
The burner design that we developed as an alternative, is a versatile high-pressure
burner that can operate over a wide range of temperature, pressures, equivalence ratios,
and with different fuels and oxidizers. In this paper, we first describe our burner design
in some detail. We then present the results from a series of SRS measurements applied to
this burner for a 10-atm H2-air premixed flame over the equivalence ratios ranging from
φ = 0.2 to 5.0 to demonstrate a capability of the burner.
The primary goal of our research burner design is to generate a stable and precisely
controllable stream of combustion products for calibrating optical diagnostic techniques.
The ease of manufacturing and testing durability is of prime importance in addition to the
1. Versatile operation: Premixed or Non-premixed
2. Multi-fuel capability (H2, Hydrocarbon, Jet-A, spray fuel)
3. Pressure range up to 60 atm
4. Self-cooling without using water
5. Stable operation over a wide range of equivalence ratios
6. Low cost
Burner Nozzle Design
The design of a burner capable of satisfying the above requirements without flash-back is
indeed challenging. The burner design is based on a premixed concept that also utilizes
back-side impingement cooling and micro-mixing at high velocities to overcome these
Figure 1 shows a schematic of the micro-premixed burner design. Basically, the
burner consists of an array of closely-spaced premixed fuel/oxidizer jets that issue from
the burner face and quickly combine downstream of the face to form a uniform flow
pattern. The fuel/oxidizer premixing occurs via micro-mixing just upstream of the burner
face in a thin cavity just before the flows exit the burner face. An array of 7 x 7 fuel
tubes and 8 x 8 oxidizer tubes approximately 1 mm in diameter in a staggered
arrangement provides the flows to the thin premixing cavity. The oxidizer flow first
impinges on the backside of the burner face and then turn 90 degrees to effect the micro-
mixing with the fuel jets. The mixing is also enhanced by the large shear forces induced
in the sudden directional change of the oxidizer flows. The premixed fuel/oxidizer jets
then exit through an array of 7 x 7 premix holes that are coaxially aligned with the fuel-
tube supply array. These premixed jets have an approximately 1:5 expansion ratio to
slow the jet velocities down from the high velocities through the nozzle throat required to
prevent flash-back. The premixed jet array is approximately 18 x 18 mm in size. These
49 jets then continue to mix and combine to become a single uniform flame downstream
of the burner face. By mixing the fuel and oxidizer just upstream of the burner face in a
region of high gas velocity, flashback into the thin premixing chamber is avoided if the
bulk velocity is kept above the laminar flame speed of the fuel-air mixture (which can be
as high as 10 m/s for high pressure H2-air flames).
By impingement cooling the burner face with the oxidizer flow, the burner can be
operated without any water cooling, and this helps to keep the flame temperatures high.
The burner produces a region of combustion products directly downstream of a premixed
flame with a uniform flow pattern over an approximate 5 x 5 mm zone. The copper
burner face also is cooled to a certain degree by convection to the gases in the mixing
holes as well as the direct conduction to the main burner body. At equivalence ratios
below 0.6 the burner can be operated indefinitely; at higher equivalence ratios, the burner
can be operated for typically 2 minutes before the burner face temperatures (sensed by
thermocouples) get too hot (920 K). However, this is not a problem as only about
30 seconds of run time is needed to acquire the Raman scattering data. Note no preheat
air-fuel mixture was fed to the burner even for a lean flame in this experiment.
Figure 2 shows a schematic of the high-pressure burner rig and gas flow system. The
burner nozzle is mounted inside the air-cooled combustion liner casing of the high-
pressure rig. The pressure inside the casing is the same as for the rig. The following
sections describe the different aspects of the facility.
The rig pressure can range from 1 atm to 60 atm. The rig pressure was automatically
maintained with a stand-alone PID-process controller that regulates a back-pressure valve
to stabilize the pressure fluctuations to better than ± 1 % for each condition.
For rig pressure below 30 atm, ambient-temperature cooling air is supplied from a central
facility compressor and is introduced in two locations: at the bottom of the rig for cooling
the combustion liner (≤ 6.8 kg/min) and downstream of the liner to quench-cool the
combustion by-products (≤ 5.5 kg/min). For rig pressures above 30 atm, the cooling air
is provided by a large trailer-mounted array of high pressure air cylinders. The cooling
airflow was controlled to within 3% accuracy using remotely operated pressure regulators
in conjunction with non-critical flow venturi meters. The mass flow rates of the two
cooling air flows were typically the same. Ten percent or less of the total cooling flow
rate of the facility air was used as a purge-air for the optical windows during experiments
prevent water vapor condensation. A small amount of cooling bleed air was fed into the
casing to avoid building up of combustion products around the burner.
Hydrogen (Fuel) Systems
A remotely controlled flow delivery system is required to accurately meter the flow rates
for the gaseous hydrogen fuel at various operating conditions ranging from fuel-lean to
fuel-rich. Flows ranged from 50 standard liters/min (SLM) to 580 SLM. The H2 flows
were metered using a bank of 3 critical flow venturis fitted with pressure transducers; the
bank of meters allows a wide dynamic range of flow rates to be metered with high
accuracy. An accuracy of better than 1% was achieved for the flow rate measurement
using calibrated (NIST-traceable) critical flow venturi meters. The sonic flow venturis
also serve to limit the maximum flow of the H2 in case of a downstream drop in rig
pressure (as in the case of a burst disc rupture event). The use of critical flow venturi
meters ensures that the mass flow rate stays constant regardless of pressure fluctuations
in the rig. The upstream H2 pressure was controlled with an automatic process control
system which actuates a precision dome-loaded pressure regulator. The H2 gas was
provided by 12-pack cylinder arrays at 150 atm pressure located on a pallet outside of
experimental test cell.
Air (Oxidizer) Systems
The air system is almost identical to the gaseous fuel system except the flows range from
200 SLM to 4600 SLM.
A retractable, high-energy surface-discharge aircraft style igniter system is used to ignite
the burner. The igniter is inserted to a radial location above the burner using a geared
stepper motor, and a 10-spark sequence is then initiated prior to opening the H2 flow
valves to introduce the fuel flow.
Critical facility data was logged using a computer at 1 second intervals (minimum) with
16-bit precision. Data points were stored to computer disk with the choice of averaging
over arbitrary n-points or an instantaneous record mode. Those parameters include all
pressures, temperatures, and flow rates described above.
Remote Control System
The facility and all gas flows were controlled and operated through a computer touch-
screen human-machine-interface (HMI) via a computer controlled interface using the In-
Touch Software Systems’ ‘Wonderware’ package in conjunction with a programmable
logic controller (PLC). Manually set actuators and valves were for facility startup only
and all actuators/valves that need to be controlled during run time were via the HMI
system. The CCD camera for the Raman data collection was also remotely operated via
network-based Windows software.
In a high-pressure, hydrogen-air combustion experiment, safety is as important as the
accuracy of the experiments. A burst disk (64 atm) located between the main pressure
chamber and the exhaust pipe is used to relieve the chamber pressure in case of the
unlikely event of a detonation or explosive event. We also implemented a
comprehensive shutdown system for the facility using the PLC as follows. Firstly,
manual shutdown can be effected by closing fuel and then oxidizer flows gradually.
Secondly, shutdown should be instigated automatically via PLC in the event of:
(1) Flameout detection via low temperature on a flame sensor thermocouple (TC) or via
visual means; (2) Rig over-temperature on a rig TC; (3) Burner hardware over-
temperature on a burner face TC; (4) Gas leak detected for fuel the supply system via
electrochemical leak sensors in both the fuel systems gas cabinet or in the test cell;
(5) Low air cooling flow condition; (6) Low fuel/oxidizer supply pressure; (7) Any
anomalous behavior of burner operation as determined by the qualified operator. A
minimum mass flow rate of total cooling air for the rig was set at 1.36 kg/min in order to
prevent a lower explosion limit (LEL) from being reached in case of a flame-out.
Raman Diagnostics and Experiment
To determine temperature and major species, multiple spontaneous rotational-vibrational
Raman scattering spectra were measured via a spatially-resolved, point laser Raman
system. An injection seeded, Q-switched Nd:YAG laser operating at 532 nm with about
1000 mJ/pulse was used as the excitation laser source. The laser pulse width at FWHM
was measured to be 8.4 ns. The injection seeding feature helps to produce a better pulse-
to-pulse energy stability with less timing-jitter. Each pulse from the laser was temporally
“stretched” to a longer pulse (75 ns halfwidth) by means of the pulse stretching optics 
with 83% energy throughput. The pulse stretcher reduces the peak power to
approximately 10% of the input peak power so that the laser pulse can be focused into the
fine volume without the breakdown of gases as well as without damaging windows. Note
that the breakdown of the air at high-pressure circumstances can be more significant
because breakdown power threshold for the air has negative pressure dependence. Using
a 750 mm focal length lens, the light emerging from pulse stretcher was focused to a
beam waist at the probe volume. The probe volume size is approximately 0.5 mm in
diameter and 1.6 mm in long. The beam, after passing through the probe volume, was
then reflected back into the probe volume using a 400 mm collimating lens and a right-
angle prism; this effectively doubled the laser energy in the probe volume.
The vertically polarized Raman scattering light was collected at a 90-degree angle
with a camera lens (85 mm, f/1.4) and was then focused onto a single silica optical fiber
(400 µm in core diameter) connected to a electro-mechanical high-speed shutter  for
gating the light. The shutter system, which provided 24 µs exposure (FWHM) with
0.4 µs jitter with 12 x 0.762 mm clear aperture to reduce the effects of background light
interferences. The gated light from the shutter was directed to the spectrograph. The
optical throughput of the shutter system was 55% including fiber transmission losses.
The axially transmissive spectrograph (f/1.8) is fitted with a holographic notch filter to
attenuate the Rayleigh scattering component of the signal by over six orders of
magnitude. A volume holographic transmission grating disperses the signal into different
wavelengths which are detected by a non-intensified, liquid nitrogen cooled, backside-
illuminated CCD camera (1340 x 100 pixels). The electronic exposure of the CCD was
5 ms (but the actual time exposure limited by the shutter is 24 µs), and the data was
accumulated for 300 shots (on the chip) to increase the signal-to-noise. The spectral
resolution was 1.2 nm for the 100 µm slit used. The spectral intensity was calibrated by a
NIST-traceable blackbody lamp. Raman scatterings were measured at 25 mm above the
burner nozzle surface on the center axis.
The high-pressure rig was fitted with four 44 mm thick UV grade fused silica
windows with a clear aperture of 85 mm for optical diagnostics. One port was used for a
video camera to record and monitor the burner operation. The other three windows were
used as laser beam inlet ports, and laser scattering detection port. The burner housing
was hydro-tested to 34 atm with burner face blank insert, and was rated for operation up
to 14 atm differential pressure at 920 K with the actual perforated burner face. In this
study, the rig was operated at a nominal pressure of 10 atm.
Results and Discussion
Figure 3 shows photographs of 10-atm H2-air flames at φ = 0.6, 1.0, and 3.2 with an
exposure time of 3 seconds. The luminous zones in the photographs indicate the major
combustion product – water in this case. According to the photographs, the burner
generates multiple small hydrogen premixed flames just above the burner face. The
burned gases combine downstream to deliver a homogeneous zone of combustion
products. The luminous zone appears different in size and shape depending on the
equivalence ratio. The flow rate of the gases was not fixed in the current experiment, so
the mean flow velocity at the burner port was different for each equivalence ratio. The
rich flame (φ = 3.2) has more residual un-burned hydrogen in the post flame gases than
the stoichiometric or lean cases. Thus, the un-burned hydrogen continues to react over a
wider reaction zone downstream of the burner, resulting in a diverging luminous flame
zone as shown in Fig. 3c. Therefore, measurements for the purpose of the optical
calibration are necessary at a point just above the primary flame zone. The current
measurement height, which can be seen in the picture as a background fiber core image,
seems to be still in a homogeneous stream of combustion gases. Further discussion about
flows and distributions of combustion products could be made via flow visualization
and/or planar imaging techniques.
To obtain quantitative information on basic characteristics of the burner we
measured SRS data from H2, H2O, N2, and O2 over a wide range of equivalence ratios.
Figure 4 shows entire Raman spectra of major species in H2-air combustion at 10 atm
(300-shot averaged). The SNR of these spectra is about 10,000:1, sufficient to allow
good-quality analysis of temperature and species concentrations. Because Raman
scattering intensity increases linearly with pressure, Raman spectroscopic techniques
have an advantage in high-pressure or high-density studies. In a lean flame (φ = 0.16), a
higher intensity of O2, and N2 signals are observed than in the other flames, while strong
rotational and vibrational lines of H2 are observed in a highly rich flame (φ = 4.9). In a
stoichiometric flame (φ = 1.03), the anti-Stokes branch of N2 Raman appears, which
indicates a higher temperature.
Temperatures at each equivalence ratio were calculated by either the anti-
Stokes/Stokes ratio of N2 spectra  or rotational spectrum distribution of H2 . The
measurement uncertainty of H2 rotational temperature is 8% maximum for a lean flame
and 1% maximum for a rich flame. The results are shown in Fig. 5. The adiabatic
temperature was calculated using NASA Glenn Chemical Equilibrium (CEA) Code .
Experimentally determined temperatures via the different spectroscopic techniques
agreed well, especially in rich flame cases. Since uncertainty of the rotational H2
temperature increases in stoichiometric or lean flames due to the lower H2 signal intensity,
the mismatches between N2 Raman temperature and H2 temperature between φ = 0.7 to
1.5 do not necessarily mean a non-thermal equilibrium between two molecules. The non-
equilibrium condition, generally, is not likely in high-pressure combustion due to a quite
small collisional time scale [13-14]. Based on the signal-to-noise ratio, N2-based
analyses are more accurate for flames with φ < 2.0, whereas H2-based analyses are more
accurate for flames with φ > 2.0. Overall variation of anti-Stokes/Stokes temperature with
φ was qualitatively the same as the variation of the adiabatic temperature. The
temperature difference between experiment and calculation by more than 500 K indicates
that a large amount of heat loss is occurring in the stoichiometric and rich flames at the
measurement location (25 mm above the burner face). We attribute the large amount of
heat loss to the following causes: (1) near-infrared/infrared radiation emitted by the main
combustion products such as H2O at this temperature; (2) possible cold air entrainment
and dilution in the post flame zone at this axial location; (3) and for the stoichiometric
flame, additional heat losses to the burner face through radiation or conduction, as
evidenced by the brightly glowing central burner face element. One possible solution to
reduce the effects of the heat loss is to move the measurement location closer to the
burner face. Our preliminary analysis of the burner element using a comprehensive CFD
code with finite-rate H2-Air chemistry indicates that the primary flame zone may be
located as low as 1 mm above the burner face .
The variation of measured species concentration (H2, H2O, O2, N2) with equivalence
ratio is shown in Fig. 6 along with calculated chemical equilibrium (at measured
temperature) species concentration. Experimental data were derived from intensity
integrated (pixel integration) contribution of each vibrational Raman spectrum for each
molecule and were not calibrated to absolute number density but based on the
quantitative measurements. Calculated results were shown in the figure to fit to the
experimental data for the comparison. The experimental profile of species number
density agrees reasonably well with the calculated results in the high-pressure flames: the
H2O profile has a peak concentration around stoichiometry (φ = 1.0) which is also
indicated by calculation; O2 concentration decreases with φ then becomes almost zero at
φ > 1.0 as the calculated result shows; N2 also is in good agreement. We, however, found
a difference between experimental and computational result in H2 concentration while
their general trends are the same. The data shows a slightly higher amount of H2 and this
may result from some residual un-burned hydrogen in the post flame zone in the lean
flames, or it may be the result of a spectroscopic interference that needs to be accounted
for using exactly the calibration techniques we are pursuing in this effort.
We developed and tested a novel high-pressure micro-premixed burner design that
utilizes an array of closely-spaced small premixed flames for calibrating optical
diagnostics in high-pressure flames. The new high pressure burner produces steady,
reproducible premixed flames with high precision, and has the ability to use multiple
fuel/oxidizer combinations. Direct observations of flame luminescence at different
equivalence ratios showed that the array of small premixed flames generate a
homogeneous zone of hot combustion products downstream of the burner face. From the
initial test results, this burner appears to be a good candidate for a reference burner to be
used for calibrating optical diagnostic techniques. To demonstrate the performance of the
burner, SRS data from H2, N2, O2, and H2O were measured in a 10-atm H2-air premixed
flame over the wide range of equivalence ratios (φ = 0.16 to 4.9). Temperatures were
determined from Stokes/anti-Stokes N2 spectra as well as from rotational H2 spectra (in
rich flames). Major species concentrations were also determined from each vibrational
Raman spectrum. Experimentally determined temperature and species profiles over the
range of equivalence ratio were compared with computational results via an adiabatic
chemical equilibrium code. The results showed that combustion products produced by
our high-pressure burner behaved in a reasonably predictable manner. However, it
appears that the expectation of a fully-reacted combustion zone was not achieved
according to the residual H2 Raman signals at fuel-lean conditions. Additionally, the
temperature of the combustion products is far below adiabatic equilibrium. Based on
these findings, further experimental efforts to measure temperature and species at
different burner heights are necessary. Additional computational study of the flow field
including mixing conditions and temperature distributions for this burner are also in
 Y. Gu, Y. Zhou, H. Tang, E.W. Rothe, and G.P. Reck, “Pressure Dependence of
Vibrational Raman Scattering of Narrow-Band, 248-nm, Laser Light by H2, N2, O2,
CO2, CH4, C2H6, and C3H8 as High as 97 bar,” Appl. Phys. B 71, 865–871, (2000).
 V. Nagali and R.K. Hanson, “Design of a Diode-laser Sensor to Monitor Water Vapor in
High-Pressure Combustion Gases,” Appl. Opt. 36, 9518–9527, (1997).
 C. Schulz, V. Sick, U.E. Meier, J. Heinze, and W. Stricker, “Quantification of NO A-
X(0,2) Laser-Induced Fluorescence: Investigation of Calibration and Collisional
Influences in High-Pressure Flames,” Appl. Opt. 38, 1434–1443, (1999).
 W.G. Bessler, C. Schulz, T. Lee, J.B. Jeffries, and R.K. Hanson, “Strategies for Laser-
Induced Fluorescence Detection of Nitric Oxide in High-Pressure Flames. I. A-X(0,0)
Excitation,” Appl. Opt. 41, 3547–3557, (2002).
 T.S. Cheng, T. Yuan, C.-C. Lu, and Y.-C. Chao, “The Application of Spontaneous
Vibrational Raman Scattering for Temperature Measurements in High Pressure Laminar
Flames,” Combust. Sci. Technol. 174, 111–128, (2002).
 R.S. Barlow, C.D. Carter, R.W. Pitz, “Chapter 14: Multiscalar Diagnostics in Turbulent
Flames,” Applied Combustion Diagnostics (ed. K. Kohse-Hoinghaus and J. B. Jeffries),
Taylor & Francis, London, 400-401.
 J. Hussong, R. Lückerath, W. Stricker, X. Bruet, P. Joubert, J. Bonammy, and D.
Robert, “Hydrogen CARS Thermometry in High-Pressure H2-Air Flame. Test of H2
Temperature Accuracy and Influence of Line Width by Comparison with N2 CARS as
Reference,” Appl. Phys. B 73, 165–172, (2001).
 J. Kojima, and Q.V. Nguyen, “Laser Pulse-Stretching Using Multiple Optical Ring-
Cavities,” Appl. Opt. 41, 6360–6370, (2002).
 Q.V. Nguyen, “High Speed Electromechanical Shutter for Imaging Spectrographs,”
NASA owned intellectual property, patent pending, (2001).
 S.M. Schoenung, R.E. Mitchell, “Comparison of Raman and Thermocouple
Temperature Measurements in Flames” Combust. Flame 35, 207–211 (1979).
 M.C. Drake, and G.M. Rosenblatt, “Rotational Raman Scattering from Premixed and
Diffusion Flames,” Combust. Flame 33, 179–196, (1978).
 B.J. McBride, and S. Gordon, “Computer Program for Calculation of Complex
Chemical Equilibrium Compositions and Applications – II. Users Manual and Program
Description,” NASA RP–1311, (1996).
 I.S. Dring, R. Devonshire, J. Meads, H.F. Boysan, D.A. Greenhalgh, “Observation of
Non-Equilibrium Effects in Free-Convective Flows Using CARS. Recirculating Flow
Relaxation Spectrometry,” Chem. Phys. Lett. 132, 283–290, (1986).
 C. Eckbreth, Laser Diagnostics for Combustion Temperature and Species: 2nd Ed.,
Gordon and Breach Publishers, The Netherlands, 97–98, (1996).
 Private-communication, A. Iannetti. Combustor simulations were performed using
NASA’s National Combustor Code (NCC), (2003).
Figure 1: A schematic of the burner nozzle design.
Cooling Air (Quench)
Figure 2: High-pressure gaseous burner rig and gas flow system for up to 30-atm
combustion. P: pressure transducer; T: thermocouple; PR: remotely operated regulator; RB:
remotely operated ball valve; V: venturi; SV: sonic venturi; BPV: back-pressure valve;
PID: process controller; BD: burst disk.
φ φ φ φ = 0.16
φ φ φ φ = 1.03
φ φ φ φ = 4.90
Figure 4: Spontaneous Raman spectra in 10-atm H2-air combustion (300-shot averaged). Note the overall
air flow rates for φ = 0.16, 1.03, and 4.90 are 328, 259, and 98 SLM, respectively due to practical operating
reasons. Accordingly, the integrated intensity of N2 Raman decreases asφ increases.
(a) φ = 0.6 (b) φ = 1.0 (c) φ = 3.2
Figure 3: Photographs of H2-air premixed flames at 10 atm. In 3b the burner face glows due to high
surface temperature (~700 K). The images of light-collecting fiber optics appear in photos through
the flame images, which center (fiber core position) indicate the measurement height.
Figure 5: Measured temperature in 10-atm H2-air combustion via Raman spectra. Circle
(white) is anti-Stokes/Stokes temperature; Triangle (black) is rotational H2 temperature. Solid
line is adiabatic temperature via CEA code.
Number density (a.u.)
Figure 6: Quantitative comparison of measured species concentration with calculated results in 10-atm
H2-air combustion. Solid and dashed lines are adiabatic calculation; Dots are experimental data.
Experimental data points are fitted to calculated profiles at the maximum value. Calculated results are
based on CEA calculation with assigned experimental temperature (Stokes/anti-Stokes temperature).
This publication is available from the NASA Center for AeroSpace Information, 301–621–0390.
13. ABSTRACT (Maximum 200 words)
REPORT DOCUMENTATION PAGE
2. REPORT DATE
19. SECURITY CLASSIFICATION
18. SECURITY CLASSIFICATION
OF THIS PAGE
Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources,
gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this
collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson
Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503.
1. AGENCY USE ONLY (Leave blank)
Standard Form 298 (Rev. 2-89)
Prescribed by ANSI Std. Z39-18
OMB No. 0704-0188
12b. DISTRIBUTION CODE
8. PERFORMING ORGANIZATION
5. FUNDING NUMBERS
3. REPORT TYPE AND DATES COVERED
4. TITLE AND SUBTITLE
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
11. SUPPLEMENTARY NOTES
Prepared for the 2003 American Flame Research Committee International Symposium on Combustion Research and Industrial
Practice: Bridging the Gap cosponsored by the American Flame Research Committee (AFRC) and the Combustion Research Facility
of Sandia National Laboratory, Livermore, California, October 16–17, 2003. Jun Kojima, Ohio Aerospace Institute, Brook Park,
Ohio 44142 and National Research Council—NASA Resident Research Associate at Glenn Research Center; and Quang-Viet
Nguyen, NASA Glenn Research Center. Responsible person, Quang-Viet Nguyen, organization code 5830, 216–433–3574.
12a. DISTRIBUTION/AVAILABILITY STATEMENT
14. SUBJECT TERMS
Temperature measurement; Nonintrusive measurement; Hydrogen fuels; Turbulent
combustion; Combustion temperature; Combustion physics; Flame spectroscopy;
Molecular spectroscopy; Raman spectroscopy
17. SECURITY CLASSIFICATION
16. PRICE CODE
15. NUMBER OF PAGES
20. LIMITATION OF ABSTRACT
National Aeronautics and Space Administration
John H. Glenn Research Center at Lewis Field
Cleveland, Ohio 44135–3191
AGENCY REPORT NUMBER
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
National Aeronautics and Space Administration
Washington, DC 20546–0001
Available electronically at http://gltrs.grc.nasa.gov
Development of a High-Pressure Gaseous Burner for Calibrating Optical
Jun Kojima and Quang-Viet Nguyen
Subject Categories: 07, 18, 28, 44 and 77
In this work-in-progress report, we show the development of a unique high-pressure burner facility (up to 60 atm) that provides steady,
reproducible premixed flames with high precision, while having the capability to use multiple fuel/oxidizer combinations. The high-
pressure facility has four optical access ports for applying different laser diagnostic techniques and will provide a standard reference
flame for the development of a spectroscopic database in high-pressure/temperature conditions. Spontaneous Raman scattering (SRS)
was the first diagnostic applied, and was used to successfully probe premixed hydrogen-air flames generated in the facility using a
novel multi-jet micro-premixed array burner element. The SRS spectral data include contributions from H2, N2, O2, and H2O and were
collected over a wide range of equivalence ratios ranging from 0.16 to 4.9 at an initial pressure of 10-atm via a spatially resolved point
SRS measurement with a high-performance optical system. Temperatures in fuel-lean to stoichiometric conditions were determined
from the ratio of the Stokes to anti-Stokes scattering of the Q-branch of N2, and those in fuel-rich conditions via the rotational
temperature of H2. The SRS derived temperatures using both techniques were consistent and indicated that the flame temperature was
approximately 500 K below that predicted by adiabatic equilibrium, indicating a large amount of heat-loss at the measurement zone.
The integrated vibrational SRS signals show that SRS provides quantitative number density data in high-pressure H2-air flames.