Quantitative technique for imaging mixture fraction, temperature, and the hydroxyl radical in turbulent diffusion flames

Kelman, James; Masri, Assaad R.

doi:10.1364/ao.36.003506

Cited by 32 publications

(10 citation statements)

References 11 publications

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“…Any experimental technique that registers one or two components of $n (and temperature, needed in the calculation of D n ) is measuring a surrogate of v. Past research has concentrated on measurements of one-dimensional (1D) surrogates in hydrogen [2,3] and methane flames [4]. Other works have examined the feasibility of 2D surrogate measurements [5][6][7][8] and even 3D ones [9]. The present work reports results for full scalar dissipation, v, as well as flame orientation, in turbulent methane flames.…”

Section: Introductionmentioning

confidence: 99%

Measurements of flame orientation and scalar dissipation in turbulent partially premixed methane flames

Karpetis

Barlow

2005

Proceedings of the Combustion Institute

103

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Section: Introductionmentioning

confidence: 99%

Measurements of flame orientation and scalar dissipation in turbulent partially premixed methane flames

Karpetis

Barlow

2005

Proceedings of the Combustion Institute

103

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“…The mixture fraction is defined as Z ‫ס‬ (b ‫מ‬ b ox )/(b fu ‫מ‬ b ox ), where fu and ox denote fuel and oxidizer nozzle, respectively, and b is a conserved scalar. Z and b have been measured extensively with single-shot, two-dimensional Raman and Rayleigh imaging in turbulent flows [16][17][18][19][20]. The only factor determining the choice of the particular formulation of b for two-dimensional, single-shot measurements is S/N.…”

Section: Resultsmentioning

confidence: 99%

Quantitative scalar dissipation rate measurements in vortex-perturbed counterflow diffusion flames

Kyritsis

Santoro

Gomez

2002

Proceedings of the Combustion Institute

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Even though the scalar dissipation rate at the stoichiometric surface, v stoich , is recognized to be the most fundamental fluid time scale in laminar diffusion flames, their structure and extinction behavior are often characterized simply in terms of strain rate, a much more easily measurable observable. Yet, the two variables are different, especially in unsteady flamelets. An experimental technique based on line Raman imaging of major species is presented for the quantitative measurement of v stoich in vortex-perturbed counterflow diffusion flames. Three formulations are evaluated, and it is shown that a formulation based on N 2 -mass fraction is the most appropriate, provided that N 2 is experimentally accessible and that there is no significant preferential diffusion. The technique is used to compare vortex-perturbed and quasi-steady extinction. The thesis that for a given composition of the counterflowing streams, extinction occurs at a given value of v stoich , irrespective of the mode of perturbation, steady or unsteady, is verified experimentally and is contrasted with the observation that vortex-perturbed flames can sustain an almost double strain rate at extinction compared to steadily strained ones. The effect of two-dimensional phenomena on the results is discussed. Finally, a promising approximation of v stoich using estimates of the thickness of mixing layer from temperature profiles, with significant simplifications in the required measurements, is investigated.

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“…Extending the technique to 2-D measurements of all major scalars, and coupling to PLIF images of minor species is highly desirable. Several attempts have been reported [4][5][6][7][8], but are limited to imaging of one or two major scalars. A notable example is a study by Kelman and Masri [6] where mixture fraction, temperature, and OH mole fraction were measured using Raman/Rayleigh/LIF imaging.…”

Section: Introductionmentioning

confidence: 99%

“…Several attempts have been reported [4][5][6][7][8], but are limited to imaging of one or two major scalars. A notable example is a study by Kelman and Masri [6] where mixture fraction, temperature, and OH mole fraction were measured using Raman/Rayleigh/LIF imaging.…”

Section: Introductionmentioning

confidence: 99%

Single-shot imaging of major species and OH mole fractions and temperature in non-premixed H2/N2 flames at elevated pressure

Guiberti

Krishna

Boyette

et al. 2021

Proceedings of the Combustion Institute

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Simultaneous, single-shot imaging of all major species (N2, O2, H2, and H2O), OH, temperature, and mixture fraction is demonstrated for the first time in H2-N2 non-premixed jet flames at 12 bar. The spatial distribution of mole fraction is obtained for the four major species by recording images of Raman scattering on four separate back-illuminated CCD cameras. The available field-of-view is 25(H)8(V) mm2. Temperature and mixture fraction are derived from Raman scattering images.Images of OH fluorescence intensity are recorded using OH-PLIF and are converted into OH mole fraction by calculating the Boltzmann population distribution and the quenching rate accurately for each pixel. Precision and accuracy are assessed by comparing 2-D Raman/OH-PLIF measurements in laminar flames to 1-D flame computations accounting for differential diffusion. Single-shot precision on N2, O2, H2, and temperature is better than 5%. It is better than 6% and 10% for H2O and OH, respectively. Accuracy lies within these values, except for H2O with 10%. Such good performance of Raman imaging is attributed to (a) the use of non-intensified CCD cameras, (b) wavelet adaptive thresholding (WATR) image denoising, (c) rejection of flame luminosity by a Pockels cell electrooptical shutter with 500 ns gating, and (d) elevated pressure that boosts the Raman signal intensity.Measurements in a turbulent flame (3.6N2:H2 by vol. and Re = 29,000) show that most of the flame's thermochemical structure is accurately captured by unity Lewis number computations, suggesting that effects of differential diffusion are less important above some Reynolds number. This is consistent with expectations and it engenders confidence in the Raman imaging technique. Because images of both mixture fraction and OH mole fraction are available, it is also possible to reconstruct a more accurate scalar dissipation rate by projection onto the 2-D flame front normal.

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Quantitative technique for imaging mixture fraction, temperature, and the hydroxyl radical in turbulent diffusion flames

Cited by 32 publications

References 11 publications

Measurements of flame orientation and scalar dissipation in turbulent partially premixed methane flames

Measurements of flame orientation and scalar dissipation in turbulent partially premixed methane flames

Quantitative scalar dissipation rate measurements in vortex-perturbed counterflow diffusion flames

Single-shot imaging of major species and OH mole fractions and temperature in non-premixed H2/N2 flames at elevated pressure

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