Results 221 to 230 of about 2,639 (256)
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Experiments on imploding spherical flames: Effects of curvature
Proceedings of the Combustion Institute, 2002An experimental study of imploding combustion is carried out by creating spherical pockets of unburned methane/air or propane/air mixtures for several equivalence ratios. The aim is to quantify the influence of the isotherm contour upon the determination of the flame displacement speed as a function only of the curvature effects of the stretch.
Françoise Baillot +2 more
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High-curvature outwardly propagating flames
International Communications in Heat and Mass Transfer, 2001Abstract A model describing the evolution of laminar, high-curvature outwardly propagating flames is presented. The model, valid in the limit of large chemical activation energies, can be useful for simulations of the evolution of flame kernels shortly after ignition when flame curvature is high and significantly modifies the local normal burning ...
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Curvature Effects in Non-Premixed Tubular Flames
44th AIAA Aerospace Sciences Meeting and Exhibit, 2006Non-premixed tubular flames are formed by the opposed tubular burner. A detailed structural investigation using the spontaneous Raman scattering technique is conducted on flames with constant curvature using 15% H2 diluted by N2 against air at various stretch rates. The measured temperature and major species concentrations agree well with the numerical
Shengteng Hu +3 more
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Analysis of the contribution of curvature to premixed flame propagation
Combustion and Flame, 1999In this analysis, the authors attempt to identify the contributions of curvature to the displacement speed by using the governing transport equation for the deficient reactant. They show that the displacement speed is a balance of three components: reaction, normal diffusion, and curvature.
Tarek Echekki, Jacqueline H Chen
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Wrinkling and curvature of laminar and turbulent premixed flames
Combustion and Flame, 2002Abstract Premixed iso-octane and methane-air flames have been ignited in a fan stirred bomb in laminar conditions and turbulent flow fields at 1 and 5 bar. Sheet images of the flames were captured using LIF of OH. In spherically expanding laminar flames, the shape of cusps in the flame surface was shown to change from a dent for flames with positive ...
M.Z Haq +4 more
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The interaction of flame curvature and stretch, part 2: The convex premixed flame
Combustion and Flame, 1984Abstract Premixed flames with radii of curvature of the order of the preheat zone thickness are studied with activation energy asymptotics. The flames studied are convex to the fresh mixture and the flame stretch is negative as in Bunsen burner flame tips.
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Studies on the Flame Curvature Effect on Burning Velocity
44th AIAA Aerospace Sciences Meeting and Exhibit, 2006The curvature effect on the burning velocity of highly curved flames has been investigated numerically and theoretically. The cylindrical flame was used and compared with the counterflow flame to extract the curvature effect. The numerical simulation with detailed chemistry for hydrogen/air, methane/air, and propane/air flames showed that the burning ...
Takeshi Yokomori, Zheng Chen, Yiguang Ju
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The interaction of flame curvature and stretch, part 1: The concave premixed flame
Combustion and Flame, 1984Premixed flames with radii of curvature on the order of the preheat zone thickness are studied with activation energy asymptotics. The changes in flame speed caused by varying the flame stretch as the flame radius is held fixed are calculated. The result of this calculation is that the decrease in flame speed due to flame stretch is amplified by more ...
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A quantitative evaluation method of 3D flame curvature from reconstructed flame structure
Experiments in Fluids, 2020Three-dimensional (3D) imaging techniques, such as computed tomography of chemiluminescence and volumetric laser-induced fluorescence, are advanced combustion diagnostic tools that can provide rich insights on the spatial distribution of combustion intermediates.
Tao Yu +6 more
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Studies on strained non-premixed flames affected by flame curvature and preferential diffusion
Symposium (International) on Combustion, 1996Experimental and numerical studies are made of H 2 -N 2 -air laminar counterflow diffusion flames strained by steadily impinging micro fuel jet or air jet from the fuel side or the air side. Direct observation and two-dimensional temperature measurements by laser Rayleigh scattering method show that the flame strained by the micro fuel jet from the ...
Toshimi Takagi +4 more
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