A global reaction model for oh* chemiluminescence applied to a laminar flat-flame burner

Haber, Ludwig C.; Vandsburger, Uri

doi:10.1080/713713115

Cited by 53 publications

(37 citation statements)

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“…The reaction of CH with molecular oxygen (R2) has been initially proposed by Krishnamachari and Broida [25] who studied the emission spectra of oxygen-acetylene flames at low pressures. The lesser known reaction of HCO + O is suggested by Haber and Vandsburger [13].…”

Section: Chemiluminescence Mechanismmentioning

confidence: 98%

Experimental and numerical study of chemiluminescent species in low-pressure flames

et al. 2012

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Chemiluminescence has been observed since the beginning of spectroscopy, nevertheless, important facts still remain unknown. Especially, reaction pathways leading to chemiluminescent species such as OH * , CH * , C * 2 , and CO * 2 are still under debate and cannot be modeled with standard codes for flame simulation. In several cases, even the source species of spectral features observed in flames are unknown. In recent years, there has been renewed interest in chemiluminescence, since it has been shown that this radiation can be used to determine flame parameters such as stoichiometry and heat release under some conditions. In this work, we present a reaction mechanism which predicts the OH * , CH * (in A-and B-state), and C * 2 emission strength in lean to fuel-rich stoichiometries. Measurements have been performed in a set of low-pressure flames which have already been well characterized by other methods. The flame front is resolved in these measurements, which allows a comparison of shape and position of the observed chemiluminescence with the respective simulated concentrations. To study the effects of varying fuels, methane flame diluted in hydrogen are measured as well. The 14 investigated premixed methane-oxygen-argon and methanehydrogen-oxygen-argon flames span a wide parameter field of fuel stoichiometry (φ = 0.5 to 1.6) and hydrogen content (H 2 vol% = 0 to 50).The relative comparison of measured and simulated excited species concentrations shows good agreement. The detailed and reliable modeling for several chemiluminescent species permits correlating heat release with all of these emissions under a large set of flame conditions. It appears from the present study that the normally used product of formaldehyde and OH concentration may be less well suited for such a prediction in the flames under investigation.

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Section: Chemiluminescence Mechanismmentioning

confidence: 98%

Experimental and numerical study of chemiluminescent species in low-pressure flames

et al. 2012

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“…Smith et al [23] proposed a rate constant for OH* formation three times greater than that of Porter et al [18] by measuring absolute excited concentrations of OH* at a flat premixed low-pressure methane-air flame. Haber and Vandsburger [35] have proposed the reaction of HCO with O as a formation path for OH* chemiluminescence. This formation path has been rejected in the literature because of the lack of energy release to produce the excited OH* radical and also because that path shows very little variation with stoichiometry, in contrast to the observations of Smith et al [23].…”

Section: Geometry and Excited Species Mechanismsmentioning

confidence: 99%

Numerical evaluation of equivalence ratio measurement using OH∗ and CH∗ chemiluminescence in premixed and non-premixed methane–air flames

Panoutsos

Hardalupas

Taylor

2009

Combustion and Flame

231

104

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This work presents results from detailed chemical kinetics calculations of electronically excited OH (A 2 Ȉ, denoted as OH*) and CH (A 2 ǻ, denoted as CH*) chemiluminescent species in laminar premixed and non-premixed counterflow methane-air flames, at atmospheric pressure. Eight different detailed chemistry mechanisms, with added elementary reactions that account for the formation and destruction of the chemiluminescent species OH* and CH*, are studied. The effects of flow strain rate and equivalence ratio on the chemiluminescent intensities of OH*, CH* and their ratio are studied and the results are compared to chemiluminescent intensity ratio measurements from premixed laminar counterflow natural gas-air flames. This is done in order to numerically evaluate the measurement of equivalence ratio using OH* and CH* chemiluminescence, an experimental practice that is used in the literature. The calculations reproduced the experimental observation that there is no effect of strain rate on the chemiluminescent intensity ratio of OH* to CH*, and that the ratio is a monotonic function of equivalence ratio. In contrast, the strain rate was found to have an effect on both the OH* and CH* intensities, in agreement with experiment. The calculated OH*/CH* values showed that only five out of the eight mechanisms studied were within the same order of magnitude with the experimental data. A new mechanism, proposed in this work, gave results that agreed with experiment within 30%. It was found that the location of maximum emitted intensity from the excited species OH* and CH* was displaced by less than 65 and 115 ȝm, respectively, away from the maximum of the heat release rate, in agreement with experiments, which is small relative to the spatial resolution of experimental methods applied to combustion applications, and, therefore, it is expected that intensity from the OH* and CH* excited radicals can be used to identify the location of the reaction zone.Calculations of the OH*/CH* intensity ratio for strained non-premixed counterflow methane-3 air flames showed that the intensity ratio takes different values from those for premixed flames, and therefore has the potential to be used as a criterion to distinguish between premixed and non-premixed reaction in turbulent flames.

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“…OH* chemiluminescence intensities from lean premixed flames are regarded as an indicator for the heat release rate [Haber 2003, Hardalupas 2010, but the correlation between OH* chemiluminescence and heat release rate may be influenced by several effects like e.g. turbulence level [Ayoola 2006] or signal trapping [Brockhinke 2012, Sadanandan 2011.…”

Section: Chemiluminescence Measurementsmentioning

confidence: 99%

Experimental analysis of thermo-acoustic instabilities in a generic gas turbine combustor by phase-correlated PIV, chemiluminescence, and laser Raman scattering measurements

et al. 2015

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A global reaction model for oh* chemiluminescence applied to a laminar flat-flame burner

Cited by 53 publications

References 0 publications

Experimental and numerical study of chemiluminescent species in low-pressure flames

Experimental and numerical study of chemiluminescent species in low-pressure flames

Numerical evaluation of equivalence ratio measurement using OH∗ and CH∗ chemiluminescence in premixed and non-premixed methane–air flames

Experimental analysis of thermo-acoustic instabilities in a generic gas turbine combustor by phase-correlated PIV, chemiluminescence, and laser Raman scattering measurements

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