Basic aspects of OH(A), CH(A), and C2(d) chemiluminescence in the reaction zone of laminar methane–air premixed flames

Kojima, Jun; Ikeda, Yuji; Nakajima, Tatsuo

doi:10.1016/j.combustflame.2004.10.002

Cited by 193 publications

(100 citation statements)

References 28 publications

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“…The sequence of the location of the calculated maximum intensities for the OH* and CH* excited radicals, is OH* followed by CH*, as one scans the flame from the reactants to the products. The calculated distance between them agrees well with the experimental results found in the literature [2,24,58].…”

Section: Discussionsupporting

confidence: 89%

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

240

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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Section: Discussionsupporting

confidence: 89%

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

240

104

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“…The GB ratio variation at different equivalence ratios between 0.9 and 1.5 of premixed methane flames have been obtained by Migliorini et. al [14], which shows a good match with the spectral measurements, as shown in Fig.7b. It can be seen that the GB ratio is increasing with the equivalence ratio on the whole, only with a slight decreasing when the equivalence ratio is increased from 1.4 to 1.5.…”

Section: Resultssupporting

confidence: 79%

Time-resolved 3D investigation of the ignition process of a methane diffusion impinging flame

Wang

Zhao

Zhang

2015

Experimental Thermal and Fluid Science

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The ignition process of a methane diffusion impinging flame was investigated experimentally, using high speed schlieren/stereo imaging and image processing techniques. Two types of flame can be identified during the ignition process: premixed like flame with weak blue colour and diffusion flame with yellow-reddish colour. The 3D structure of blue flame after enhancement and yellow flame has been reconstructed and analysed seperately. The ratio between green and blue colour intensity is used to provide indications of the global fuel/air mixture state of the blue flame, which is found to correlate well with the flow conditions and flame propagation characteristics.

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“…Chemiluminescence signal is also difficult to quantity and its applicable range has been extensively investigated in terms of temperature, pressure, equivalence ratio, and strain rate [3,5,[11][12][13]. Out of all the limitations, the lack of spatial resolution perhaps represents the most important limitation of chemiluminescence-based techniques.…”

Section: Introductionmentioning

confidence: 99%

Numerical and experimental validation of a three-dimensional combustion diagnostic based on tomographic chemiluminescence

Cai¹,

Li²,

Li³

et al. 2013

Opt. Express

130

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Three-dimensional (3D) measurements are highly desirable both for fundamental combustion research and practical monitoring and control of combustion systems. This work discusses a 3D diagnostic based on tomographic chemiluminescence (TC) to address this measurement need. The major contributions of this work are threefold. First, a hybrid algorithm is developed to solve the 3D TC problem. The algorithm was demonstrated in extensive tests, both numerical and experimental, to yield 3D reconstruction with high fidelity. Second, an experimental approach was designed to enable quantifiable metrics for examining key aspects of the 3D TC technique, including its spatial resolution and reconstruction accuracy. Third, based on the reconstruction algorithm and experimental results, we investigated the effects of the view orientations. The results suggested that for an unknown flame, it is better to use projections measured from random orientations than restricted orientations (e.g., coplanar orientations). These findings are expected to provide insights to the fundamental capabilities of the TC technique, and also to facilitate its practical application.

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Basic aspects of OH(A), CH(A), and C2(d) chemiluminescence in the reaction zone of laminar methane–air premixed flames

Cited by 193 publications

References 28 publications

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

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

Time-resolved 3D investigation of the ignition process of a methane diffusion impinging flame

Numerical and experimental validation of a three-dimensional combustion diagnostic based on tomographic chemiluminescence

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