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Title: Dual-pump CARS temperature and major species concentration measurements in counter-flow methane flames using narrowband pump and broadband Stokes lasers

Abstract

Dual-pump coherent anti-Stokes Raman scattering (CARS) is used to measure temperature and species profiles in representative non-premixed and partially-premixed CH{sub 4}/O{sub 2}/N{sub 2} flames. A new laser system has been developed to generate a tunable single-frequency beam for the second pump beam in the dual-pump N{sub 2}-CO{sub 2} CARS process. The second harmonic output ({proportional_to}532 nm) from an injection-seeded Nd:YAG laser is used as one of the narrowband pump beams. The second single-longitudinal-mode pump beam centered near 561 nm is generated using an injection-seeded optical parametric oscillator, consisting of two non-linear {beta}-BBO crystals, pumped using the third harmonic output ({proportional_to}355 nm) of the same Nd:YAG laser. A broadband dye laser (BBDL), pumped using the second harmonic output of an unseeded Nd:YAG laser, is employed to produce the Stokes beam centered near 607 nm with full-width-at-half-maximum of {proportional_to}250 cm{sup -1}. The three beams are focused between two opposing nozzles of a counter-flow burner facility to measure temperature and major species concentrations in a variety of CH{sub 4}/O{sub 2}/N{sub 2} non-premixed and partially-premixed flames stabilized at a global strain rate of 20 s{sup -1} at atmospheric-pressure. For the non-premixed flames, excellent agreement is observed between the measured profiles of temperature and CO{submore » 2}/N{sub 2} concentration ratios with those calculated using an opposed-flow flame code with detailed chemistry and molecular transport submodels. For partially-premixed flames, with the rich side premixing level beyond the stable premixed flame limit, the calculations overestimate the distance between the premixed and the non-premixed flamefronts. Consequently, the calculated temperatures near the rich, premixed flame are higher than those measured. Accurate prediction of the distance between the premixed and the non-premixed flames provides an interesting challenge for future computations. (author)« less

Authors:
; ; ; ; ;  [1]
  1. School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907 (United States)
Publication Date:
OSTI Identifier:
21328639
Resource Type:
Journal Article
Resource Relation:
Journal Name: Combustion and Flame; Journal Volume: 157; Journal Issue: 7; Other Information: Elsevier Ltd. All rights reserved
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; METHANE; CARBON DIOXIDE; LAMINAR FLAMES; COUNTERFLOW SYSTEMS; CONCENTRATION RATIO; DISTANCE; ATMOSPHERIC PRESSURE; CALCULATION METHODS; NONLINEAR PROBLEMS; RAMAN EFFECT; CHEMICAL COMPOSITION; FORECASTING; TEMPERATURE DISTRIBUTION; OXYGEN; NITROGEN; TEMPERATURE RANGE 0400-1000 K; TEMPERATURE RANGE 1000-4000 K; Dual-pump CARS; Non-premixed flames; Partially-premixed flames; Laminar counter-flow flames; Laser diagnostics

Citation Formats

Thariyan, Mathew P., Ananthanarayanan, Vijaykumar, Bhuiyan, Aizaz H., Naik, Sameer V., Gore, Jay P., and Lucht, Robert P. Dual-pump CARS temperature and major species concentration measurements in counter-flow methane flames using narrowband pump and broadband Stokes lasers. United States: N. p., 2010. Web. doi:10.1016/J.COMBUSTFLAME.2010.03.002.
Thariyan, Mathew P., Ananthanarayanan, Vijaykumar, Bhuiyan, Aizaz H., Naik, Sameer V., Gore, Jay P., & Lucht, Robert P. Dual-pump CARS temperature and major species concentration measurements in counter-flow methane flames using narrowband pump and broadband Stokes lasers. United States. doi:10.1016/J.COMBUSTFLAME.2010.03.002.
Thariyan, Mathew P., Ananthanarayanan, Vijaykumar, Bhuiyan, Aizaz H., Naik, Sameer V., Gore, Jay P., and Lucht, Robert P. 2010. "Dual-pump CARS temperature and major species concentration measurements in counter-flow methane flames using narrowband pump and broadband Stokes lasers". United States. doi:10.1016/J.COMBUSTFLAME.2010.03.002.
@article{osti_21328639,
title = {Dual-pump CARS temperature and major species concentration measurements in counter-flow methane flames using narrowband pump and broadband Stokes lasers},
author = {Thariyan, Mathew P. and Ananthanarayanan, Vijaykumar and Bhuiyan, Aizaz H. and Naik, Sameer V. and Gore, Jay P. and Lucht, Robert P.},
abstractNote = {Dual-pump coherent anti-Stokes Raman scattering (CARS) is used to measure temperature and species profiles in representative non-premixed and partially-premixed CH{sub 4}/O{sub 2}/N{sub 2} flames. A new laser system has been developed to generate a tunable single-frequency beam for the second pump beam in the dual-pump N{sub 2}-CO{sub 2} CARS process. The second harmonic output ({proportional_to}532 nm) from an injection-seeded Nd:YAG laser is used as one of the narrowband pump beams. The second single-longitudinal-mode pump beam centered near 561 nm is generated using an injection-seeded optical parametric oscillator, consisting of two non-linear {beta}-BBO crystals, pumped using the third harmonic output ({proportional_to}355 nm) of the same Nd:YAG laser. A broadband dye laser (BBDL), pumped using the second harmonic output of an unseeded Nd:YAG laser, is employed to produce the Stokes beam centered near 607 nm with full-width-at-half-maximum of {proportional_to}250 cm{sup -1}. The three beams are focused between two opposing nozzles of a counter-flow burner facility to measure temperature and major species concentrations in a variety of CH{sub 4}/O{sub 2}/N{sub 2} non-premixed and partially-premixed flames stabilized at a global strain rate of 20 s{sup -1} at atmospheric-pressure. For the non-premixed flames, excellent agreement is observed between the measured profiles of temperature and CO{sub 2}/N{sub 2} concentration ratios with those calculated using an opposed-flow flame code with detailed chemistry and molecular transport submodels. For partially-premixed flames, with the rich side premixing level beyond the stable premixed flame limit, the calculations overestimate the distance between the premixed and the non-premixed flamefronts. Consequently, the calculated temperatures near the rich, premixed flame are higher than those measured. Accurate prediction of the distance between the premixed and the non-premixed flames provides an interesting challenge for future computations. (author)},
doi = {10.1016/J.COMBUSTFLAME.2010.03.002},
journal = {Combustion and Flame},
number = 7,
volume = 157,
place = {United States},
year = 2010,
month = 7
}
  • Simultaneous temperature and N/sub 2/-concentration data have been obtained employing a 10-Hz coherent anti-stokes Raman spectroscopy system on two propane-air turbulent-jet diffusion flames with Reynolds numbers of 2000 and 6000. Average values, probability density functions, and correlation plots show reasonable trends for both centerline and radial profiles of the turbulent flames.
  • Measurements of visible flame heights, global radiative heat loss fractions, distributions of mole fractions of stable gas species, and pollutant emission indices in laminar partially premixed flames burning various fuel-rich mixtures of CH{sub 4} and air in an overventilating co-flow of air are reported. Mole fractions of CO{sub 2}, CO, H{sub 2}, O{sub 2}, N{sub 2} CH{sub 4}, C{sub 2}H{sub 4} and C{sub 2}H{sub 2} were measured, using sampling and gas chromatography, at several radial locations at three different heights above the fuel tube for a fixed fuel flow rate and six different fuel tube equivalence ratios. Mole fractions ofmore » H{sub 2}O were inferred from the dry based measurements. With increasing levels of partial premixing following effects are observed: (1) the visible flame height decreases and the overall flame color changes from yellow to blue; (2) the radiative heat loss fraction first decreases and then reaches a constant value; (3) the mole fractions of CO decrease and those of CO{sub 2} and H{sub 2}O increase in the lean parts of the flame; (4) mole fractions of C{sub 2}H{sub 2} decrease and those of C{sub 2}H{sub 4} first increase and then decrease in the rick parts of the flame; (5) mole fractions of CO and H{sub 2} first decrease slightly and then increase in the rich parts of the flame; and (6) the O{sub 2} mole fractions at the point of negligible CH{sub 4} mole fraction decrease. Measurements of emission indices for NO, NO{sub x}, CO and HC show that, for a fixed fuel flow rate and overall equivalence ratio, an optimum level of partial premixing exists.« less
  • An investigation of in situ background normalization for obtaining sensitive and accurate concentration measurements with coherent anti-Stokes Raman spectroscopy (CARS) is reported. Flame species concentrations measured with CARS were in good agreement with IR laser absorption measurements of CO in extracted flame gases and with equilibrium calculations. Time-averaged detectivity for CO at the 1000-ppm level was obtained at 1900 K. Background normalization was also shown to be capable of improving CARS pulse-to-pulse signal reproducibility nearly to the shot-noise limit. We consider factors important for concentration measurements with CARS, including laser-induced Stark effects, accuracy of susceptibility calculations, and effects of differentmore » laser linewidth models.« less
  • Simultaneous temperature and N2-concentration data have been obtained employing a 10-Hz CARS system on two propane-air turbulent-jet diffusion flames with Reynolds numbers of 2000 and 6000. Average values, probability density functions, and correlation plots show reasonable trends for both centerline and radial profiles of the turbulent flames.