The effect of stretch on cellular formation in non-premixed opposed-flow tubular flames

Shopoff, S.W.; Wang, P.; Pitz, Robert W.

doi:10.1016/j.combustflame.2011.01.016

Cited by 11 publications

(6 citation statements)

References 19 publications

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“…The N 2 diluted cases shown in Figures 5 and 6 are very similar despite doubling the stretch rate from 100 to 200 s −1 . The main observable difference for the profiles through the reaction cell is that the cell width narrows with increasing stretch, agreeing with previous observations of chemiluminescence [8]. The character of the extinction zone varies considerably; the temperature is over predicted and O 2 is consumed at longer radii for the low stretch simulation, while the opposite is true for the high stretch case.…”

supporting

confidence: 87%

“…The camera was focused at the center of the burner with a 35 mirror oriented at 45 • , to provide an axial image with the camera safely mounted out of the flame exhaust stream. The mirror has a slot cutout to accommodate the inner nozzle, similar to previous investigations of non-premixed tubular flames [8,11].…”

Section: Experimental Methodsmentioning

confidence: 99%

“…However, the axial jet flow field is 3D and time dependent, greatly complicating numerical and experimental characterizations. A lower dimensionality flow field alleviates this difficulty: cellular flames in the opposed tubular burner [6] exhibit structure that is time independent, spatially 2D, and planar [6, 7,8]. 10 Reported here are 2D spatially resolved quantitative measurements and detailed simulation results for the major species and temperatures found in select non-premixed cellular tubular flame cases.…”

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confidence: 99%

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Experimental and numerical study of H2-air non-premixed cellular tubular flames

Hall

Pitz

2017

Proceedings of the Combustion Institute

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Experimental and numerical simulation results are presented for the first time of H 2 fueled non-premixed cellular tubular flames. Non-intrusive measurements of temperature and major species were obtained with Raman scattering. Numerical simulations were performed with a 2D fully-implicit primitive variable finite difference code that includes multicomponent transport and detailed chemical kinetics. Good agreement is found for all flame cases. The experimental cell temperatures and the shapes of the flame cells are well predicted. Less significant discrepancies are observed in the character of the extinction zones and are discussed. Overall, non-premixed cellular tubular flames are found to be valuable experimental and numerical targets for fundamental combustion research.

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confidence: 87%

Section: Experimental Methodsmentioning

confidence: 99%

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confidence: 99%

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Experimental and numerical study of H2-air non-premixed cellular tubular flames

Hall

Pitz

2017

Proceedings of the Combustion Institute

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“…Suenaga et al (2011) have also studied the extinction behavior of the tubular diffusion flame experimentally. Hu et al (2009b) and Shopoff et al (2011aShopoff et al ( , 2011b have studied the cellular instability of the tubular diffusion flame experimentally. Xuan et al (2014) have developed the flamelet modeling method considering curvature effect for diffusion flame simulation.…”

Section: Stretch and Curvature Effects On No Flame Emission 1521mentioning

confidence: 99%

Stretch and Curvature Effects on NO Emission of H₂/Air Diffusion Flames

Fernandez

Zhang

et al. 2015

Combustion Science and Technology

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Opposed jet H 2 diffusion flames are simulated with different H 2 /O 2 and NOx chemical kinetic mechanisms. The simulations with University of California, San Diego (UCSD) NOx and H 2 /O 2 mechanisms are identified to have the best agreement with the experimental data. With these mechanisms, the pressure effect on NO emission of the opposed jet flame is studied and it is shown that higher pressure enhances combustion increasing the flame temperature and NO emissions. The curved opposed tubular H 2 diffusion flames are simulated and compared with the opposed jet flames. It is shown that positive curvature enhances the preferential diffusion effect and increases flame temperature and NO emission; and vice versa for negative curvature. Flame curvature can change the NO emission as much as 5.4 times for the tested cases. A detailed flame structure comparison among curved flames and planar flames demonstrates that tubular flames are slightly narrower and their maximum stretch rates are slightly higher.

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“…Laminar tubular flames are highly stretched and curved similar to turbulent flames and thus allow for isolating and studying stretch and curvature effects in flames [1]. In the past, tubular flames have been studied at 1 bar to understand the effect of stretch and curvature on preferential diffusion in hydrogen [2][3][4][5][6][7][8][9][10][11][12] and hydrocarbon flames [13] in premixed [2][3][4][5], non-premixed [6][7][8][9][10][11][13][14][15][16], and partially premixed configurations [12]. However, at high pressures, which are also characteristic of real-life combustors, minimal literature exists in the field of premixed tubular flames [17] and nothing in the field of non-premixed tubular diffusion flames.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of the Structure and NO Emission Characteristics of N2- and CO2-Diluted Tubular Diffusion Flames

2019

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The structure of methane/air tubular diffusion flames with 65 % fuel dilution by either CO2 or N2 is numerically investigated as a function of pressure. As pressure is increased, the reaction zone thickness reduces due to decrease in diffusivities with pressure. The flame with CO2-diluted fuel exhibits much lower nitrogen radicals (N, NH, HCN, NCO) and lower temperature than its N2-diluted counterpart. In addition to flame structure, NO emission characteristics are studied using analysis of reaction rates and quantitative reaction pathway diagrams (QRPDs). Four different routes, namely the thermal route, Fenimore prompt route, N2O route, and NNH route, are examined and it is observed that the Fenimore prompt route is the most dominant for both CO2- and N2-diuted cases at all values of pressure followed by NNH route, thermal route, and N2O route. This is due to low temperatures (below 1900 K) found in these highly diluted, stretched, and curved flames. Further, due to lower availability of N2 and nitrogen bearing radicals for the CO2-diluted cases, the reaction rates are orders of magnitude lower than their N2-diluted counterparts. This results in lower NO production for the CO2-diluted flame cases.

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The effect of stretch on cellular formation in non-premixed opposed-flow tubular flames

Cited by 11 publications

References 19 publications

Experimental and numerical study of H2-air non-premixed cellular tubular flames

Experimental and numerical study of H2-air non-premixed cellular tubular flames

Stretch and Curvature Effects on NO Emission of H₂/Air Diffusion Flames

Numerical Study of the Structure and NO Emission Characteristics of N2- and CO2-Diluted Tubular Diffusion Flames

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The effect of stretch on cellular formation in non-premixed opposed-flow tubular flames

Cited by 11 publications

References 19 publications

Experimental and numerical study of H2-air non-premixed cellular tubular flames

Experimental and numerical study of H2-air non-premixed cellular tubular flames

Stretch and Curvature Effects on NO Emission of H2/Air Diffusion Flames

Numerical Study of the Structure and NO Emission Characteristics of N2- and CO2-Diluted Tubular Diffusion Flames

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Stretch and Curvature Effects on NO Emission of H₂/Air Diffusion Flames