Christensen, J
1992
CARS Temperature Measurements in the Brigham Young University Controlled Profile Reactor in Natural Gas and Natural Gas-Assisted Coal Flames
Pyper, D.K.; Blackham, S.; Warren, D.; Hansen, L.; Christensen, J.; Haslam, J.; Germane, G.J. and Hedman, P.O.
Fall Meeting of the Western States Section/Combustion Institute, Berkeley, CA, October 1992. Funded by ACERC.
Coherent anti-Stokes Raman spectroscopy (CARS) is a laser diagnostic technique that can be used to determine temperature and major species concentrations in harsh combustion environments without the disturbing influence of a sample probe. CARS can be applied to dirty, luminous systems because it has a large signal to interference ratio due to high signal conversion efficiency and the coherent nature of the CARS spectral emission. CARS has been shown to be an effective means of determining the temperature and species concentrations in clean gas flames (Boyack, 1990). CARS measurements are more difficult to make in particle-laden flames due to the increased luminosity and enhanced background caused by particle and gas breakdown. The increased luminosity and breakdown alter the shape and intensity of the CARS signal, thus making analysis with unmodified versions of standard CARS fitting codes more complex.
The objectives of this study were to extend the capability at Brigham Young University (BYU) of making temperature measurements in the BYU-ACERC Controlled Profile Reactor (CPR) with gaseous and pulverized coal fuels, to demonstrate the ability of making reliable CARS temperature measurements in both clean and dirty flame, and to collect representative sets of data in a natural gas and in natural gas assisted coal flames. CARS temperatures were produced with a natural gas flame and with a mixture of natural gas and Utah Blind Canyon bituminous coal. The CARS signal in the natural gas-assisted coal flame showed the same resonant spectra from particle-induced gas breakdown as has been seen previously (Hancock, 1991 and 1992). The techniques of Hancock were used to account for the background spectra in analyzing the data from the coal flame. The coal concentration in the flame was limited by the CARS signal strength and the particle-induced gas breakdown signal strength at the detector.
CARS measurements were obtained at 4 cm intervals from -20 to +40 cm across the diameter of the 80 cm combustor. These radial data sets were collected at 10 different axial locations along the 2.5 m height of the reactor, giving a total of 160 separate locations. Two hundred single laser pulses were used at each location within the reactor to collect "single shot" temperature data, which allowed the calculation of local mean temperatures as well as probability density functions. These 200 single shots were repeated at least twice during the same test and several tests were duplicated. It was found that the temperature measurements were in good agreement during a single test, but the accuracy was in the order of ±100 K from test to test.
Investigation of the Combustion Characteristics of a Swirled Injector in a Confined Coannular System with a Sudden Expansion
Warren, D.; Pyper, D.K.; Blackham, S.; Christensen, J.; Hedman, P.O.; Goss, L.P.; Trump, D.; Sarka, B.; Hsu, K.Y. and Roquemore, W.M.
Fall Meeting of the Western States Section/The Combustion Institute, Berkeley, CA, October 1992. Funded by Wright-Patterson Air Force Base and Air Force Office of Scientific Research.
This paper presents preliminary results of an Air Force Office of Scientific Research (AFOSR) program being conducted at Brigham Young University (BYU), Provo, Utah and at Wright-Patterson Air Force Base (WPAFB) under Summer Faculty and Research Initiation Programs. This study is part of an extensive research effort being carried out by the Fuels Combustion Group of the Aero Propulsion and Power Laboratory at Wright Patterson Air Force Base (APPL, WPAFB), Dayton, Ohio, in which simple and complex diffusion flames are being studied to better understand the fundamentals of gas turbine combustion. The program's long-term goal is to improve the design methodology of gas turbine combustors.
The work at BYU is being accomplished by the systematic study of a geometrically simple burner "designed and developed to specifically reproduce recirculation patterns and lean blow out (LBO) processes that occur in a real gas turbine combustor" (Sturgess, et al., 1990). There are two configurations used in the burner. The Task 100 burner uses a central fuel tube surrounded by a concentric air jet with a step expansion at the plane of discharge. The Task 150 burner has replaced the central fuel and air tubes with a double swirler injector from an actual Pratt-Whitney jet engine. Both configurations have been designed to be nearly axisymmetric and incorporate quartz windows to allow laser diagnostics. The burner is currently fueled by propane.
This paper contains a brief summary of work done at BYU and at Wright-Patterson Air Force base during the AFOSR summer faculty research programs. Intriguing flame structures have been visually characterized and captured in both still and video images with both the Task 100 and Task 150 configurations. Additional images of the flame and flow structures have been taken with laser sheet lighting, including Mie scattering and OH- florescence. These two-dimensional laser images have frozen structures missed with the visual observations due to the integrating nature of the eye and camera. LDA velocity maps have been collected over a variety of conditions, ranging from the relatively simple flow of the Task 150. This information not only yields velocity and turbulence data but will be used to obtain streamline functions as well. Both isothermal flow and combusting hot flow data have been collected. Limited CARS temperature data is compared in the paper LDA velocity maps and LIF image of OH-. Additional CARS temperature data are currently being collected at the test conditions of the LDA measurements and OH- images.
Christensen, J
1992
CARS Temperature Measurements in the Brigham Young University Controlled Profile Reactor in Natural Gas and Natural Gas-Assisted Coal Flames
Pyper, D.K.; Blackham, S.; Warren, D.; Hansen, L.; Christensen, J.; Haslam, J.; Germane, G.J. and Hedman, P.O.
Fall Meeting of the Western States Section/Combustion Institute, Berkeley, CA, October 1992. Funded by ACERC.
Coherent anti-Stokes Raman spectroscopy (CARS) is a laser diagnostic technique that can be used to determine temperature and major species concentrations in harsh combustion environments without the disturbing influence of a sample probe. CARS can be applied to dirty, luminous systems because it has a large signal to interference ratio due to high signal conversion efficiency and the coherent nature of the CARS spectral emission. CARS has been shown to be an effective means of determining the temperature and species concentrations in clean gas flames (Boyack, 1990). CARS measurements are more difficult to make in particle-laden flames due to the increased luminosity and enhanced background caused by particle and gas breakdown. The increased luminosity and breakdown alter the shape and intensity of the CARS signal, thus making analysis with unmodified versions of standard CARS fitting codes more complex.
The objectives of this study were to extend the capability at Brigham Young University (BYU) of making temperature measurements in the BYU-ACERC Controlled Profile Reactor (CPR) with gaseous and pulverized coal fuels, to demonstrate the ability of making reliable CARS temperature measurements in both clean and dirty flame, and to collect representative sets of data in a natural gas and in natural gas assisted coal flames. CARS temperatures were produced with a natural gas flame and with a mixture of natural gas and Utah Blind Canyon bituminous coal. The CARS signal in the natural gas-assisted coal flame showed the same resonant spectra from particle-induced gas breakdown as has been seen previously (Hancock, 1991 and 1992). The techniques of Hancock were used to account for the background spectra in analyzing the data from the coal flame. The coal concentration in the flame was limited by the CARS signal strength and the particle-induced gas breakdown signal strength at the detector.
CARS measurements were obtained at 4 cm intervals from -20 to +40 cm across the diameter of the 80 cm combustor. These radial data sets were collected at 10 different axial locations along the 2.5 m height of the reactor, giving a total of 160 separate locations. Two hundred single laser pulses were used at each location within the reactor to collect "single shot" temperature data, which allowed the calculation of local mean temperatures as well as probability density functions. These 200 single shots were repeated at least twice during the same test and several tests were duplicated. It was found that the temperature measurements were in good agreement during a single test, but the accuracy was in the order of ±100 K from test to test.
Investigation of the Combustion Characteristics of a Swirled Injector in a Confined Coannular System with a Sudden Expansion
Warren, D.; Pyper, D.K.; Blackham, S.; Christensen, J.; Hedman, P.O.; Goss, L.P.; Trump, D.; Sarka, B.; Hsu, K.Y. and Roquemore, W.M.
Fall Meeting of the Western States Section/The Combustion Institute, Berkeley, CA, October 1992. Funded by Wright-Patterson Air Force Base and Air Force Office of Scientific Research.
This paper presents preliminary results of an Air Force Office of Scientific Research (AFOSR) program being conducted at Brigham Young University (BYU), Provo, Utah and at Wright-Patterson Air Force Base (WPAFB) under Summer Faculty and Research Initiation Programs. This study is part of an extensive research effort being carried out by the Fuels Combustion Group of the Aero Propulsion and Power Laboratory at Wright Patterson Air Force Base (APPL, WPAFB), Dayton, Ohio, in which simple and complex diffusion flames are being studied to better understand the fundamentals of gas turbine combustion. The program's long-term goal is to improve the design methodology of gas turbine combustors.
The work at BYU is being accomplished by the systematic study of a geometrically simple burner "designed and developed to specifically reproduce recirculation patterns and lean blow out (LBO) processes that occur in a real gas turbine combustor" (Sturgess, et al., 1990). There are two configurations used in the burner. The Task 100 burner uses a central fuel tube surrounded by a concentric air jet with a step expansion at the plane of discharge. The Task 150 burner has replaced the central fuel and air tubes with a double swirler injector from an actual Pratt-Whitney jet engine. Both configurations have been designed to be nearly axisymmetric and incorporate quartz windows to allow laser diagnostics. The burner is currently fueled by propane.
This paper contains a brief summary of work done at BYU and at Wright-Patterson Air Force base during the AFOSR summer faculty research programs. Intriguing flame structures have been visually characterized and captured in both still and video images with both the Task 100 and Task 150 configurations. Additional images of the flame and flow structures have been taken with laser sheet lighting, including Mie scattering and OH- florescence. These two-dimensional laser images have frozen structures missed with the visual observations due to the integrating nature of the eye and camera. LDA velocity maps have been collected over a variety of conditions, ranging from the relatively simple flow of the Task 150. This information not only yields velocity and turbulence data but will be used to obtain streamline functions as well. Both isothermal flow and combusting hot flow data have been collected. Limited CARS temperature data is compared in the paper LDA velocity maps and LIF image of OH-. Additional CARS temperature data are currently being collected at the test conditions of the LDA measurements and OH- images.