• Title/Summary/Keyword: Critical Flame Radius

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A Study on Transition of Flame Extinction at Low Strain Rate Counterflow Flames (저신장율 대향류화염에서 화염소화에 있어서 천이에 대한 연구)

  • Park, Dae-Geun;Park, Jeong;Kim, Jeong-Soo;Bae, Dae-Suk
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.11a
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    • pp.197-201
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    • 2009
  • Experiments were conducted to study the transition of shrinking flame disk to flame hole in counterflow diffusion flames. The studies of transition are well described by varying burner diameters, global strain rate and velocity ratio. It is experimentally verified that radial conduction heat loss is affected at even high strain rate flames for appropriately small burner diameters. It is also shown that flame extinction modes are grouped into three and particularly, hole or stripe is observed in sufficiently high strain rate flames. There exists critical radius according to burner diameter which divide flame extinction modes into three parts.

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Laminar Burning Velocities and Flame Stability Analysis of Hydrocarbon/Hydrogen/Carbon Monoxide-air Premixed Flames (탄화수소/수소/일산화탄소-공기의 예혼합화염에서 층류화염전파속도와 화염안정성)

  • Vu, Tran Manh;Song, Won-Sik;Park, Jeong;Lee, Kee-Man
    • Journal of the Korean Society of Combustion
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    • v.16 no.2
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    • pp.23-32
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    • 2011
  • To investigate cell formation in hydrocarbon/hydrogen/carbon monoxide-air premixed flames, the outward propagation and cellular instabilities were experimentally studied in a constant pressure combustion chamber at room temperature and elevated pressures. Unstretched laminar burning velocities and Markstein lengths of the mixtures were obtained by analyzing high-speed schlieren images. In this study, hydrodynamic and diffusional- thermal instabilities were evaluated to examine their effects on flame instabilities. The experimentally-measured unstretched laminar burning velocities were compared to numerical predictions using the PREMIX code. Effective Lewis numbers of premixed flames with methane addition decreased for all of the cases; meanwhile, effective Lewis numbers with propane addition increased for lean and stoichiometric conditions and increased for rich and stoichiometric cases for hydrogen-enriched flames. With the addition of propane, the propensity for cell formation significantly was diminished, whereas cellular instabilities for hydrogen-enriched flames were promoted. However, similar behavior of cellularity was obtained with the addition of methane to the reactant mixtures.