SiC filament Pyrometry in Near Extinction Diffusion Flame

2002 ◽  
Vol 26 (11) ◽  
pp. 1481-1487
Keyword(s):  
Diffusion Flame ◽  
Near Extinction

Diffusional-thermal instability of diffusion flames

1996 ◽  
Vol 327 ◽  
pp. 273-301 ◽  
Author(s):  
J. S. Kim ◽  
F. A. Williams ◽  
P. D. Ronney
Keyword(s):  
Reaction Zone ◽  
Diffusion Flame ◽  
Thermal Instability ◽  
Eigenvalue Problems ◽  
Numerical Solutions ◽  
Diffusion Flames ◽  
Scalar Fields ◽  
Marginal Stability ◽  
Cube Root ◽  
Near Extinction

The diffusional–thermal instability, which gives rise to striped quenching patterns that have been observed for diffusion flames, is analysed by studying the model of a one-dimensional convective diffusion flame in the diffusion-flame regime of activation-energy asymptotics. Attention is focused principally on near-extinction conditions with Lewis numbers less than unity, in which the reactants with high diffusivity diffuse into the strong segments of the reaction sheet, so that the regions between the strong segments become deficient in reactant and subject to the local quenching that leads to the striped patterns. This analysis differs from other flame stability analyses in that the complete description of the dispersion relation is obtained from a composite expansion of the results of an analysis with the conventional convective-diffusive scaling and one with reaction-zone scaling. The results predict that striped patterns will occur, for flames sufficiently close to quasi-steady extinction, with a finite wavenumber that in convective–diffusive scaling is proportional to the cube root of the Zel'dovich number. The convective–diffusive response contributes to the stabilization of long-wavelength disturbances by through positive excess enthalpies by which the flame becomes more resistant to instability, while the reaction-zone response provides stabilization of short-wavelength disturbances by transverse diffusion, within the reactive inner layer, which relaxes the perturbed scalar fields towards their unperturbed states. As quasi-steady extinction is approached, marginal stability arises first at an intermediate range between these two scalings. Parametric results for this bifurcation point are obtained through numerical solutions of the associated generalized eigenvalue problems. Comparisons with measured pattern dimensions for different sets of reactants and diluents reveal excellent qualitative agreement.

Structure and stabilization mechanism of a microjet methane diffusion flame near extinction

2007 ◽  
Vol 31 (2) ◽  
pp. 3301-3308 ◽  
Author(s):  
C.-P. Chen ◽  
Y.-C. Chao ◽  
T.S. Cheng ◽  
G.-B. Chen ◽  
C.-Y. Wu
Keyword(s):  
Diffusion Flame ◽  
Stabilization Mechanism ◽  
Methane Diffusion ◽  
Near Extinction

New instability modes of a diffusion flame near extinction

1999 ◽  
Vol 11 (10) ◽  
pp. 2818-2820 ◽  
Author(s):  
Paul Papas ◽  
Peter A. Monkewitz ◽  
Ananias G. Tomboulides
Keyword(s):  
Diffusion Flame ◽  
Instability Modes ◽  
Near Extinction

Further analysis of chemical kinetic structure of a standoff microjet methane diffusion flame near extinction

2008 ◽  
Vol 152 (3) ◽  
pp. 461-467 ◽  
Author(s):  
T.S. Cheng ◽  
Y.-C. Chao ◽  
C.-P. Chen ◽  
C.-Y. Wu
Keyword(s):  
Diffusion Flame ◽  
Chemical Kinetic ◽  
Methane Diffusion ◽  
Near Extinction

Experimental characterization of a laminar diffusion flame in micro-gravity

1999 ◽  
Vol 96 (6) ◽  
pp. 1022-1030 ◽  
Author(s):  
T. Vietoris ◽  
P. Joulain ◽  
J. L. Torero
Keyword(s):  
Diffusion Flame ◽  
Experimental Characterization ◽  
Laminar Diffusion Flame ◽  
Laminar Diffusion ◽  
Micro Gravity

Analysis of LPG diffusion flame in tube type burner

2019 ◽  
Vol 13 (3) ◽  
pp. 5278-5293
Author(s):  
Vipul Patel ◽  
Rupesh Shah
Keyword(s):  
Diffusion Flame ◽  
Emission Characteristic ◽  
Flame Stability ◽  
Liquefied Petroleum Gas ◽  
Air Velocity ◽  
Length Fraction ◽  
Low Emission ◽  
Tube Type ◽  
Stability Limits ◽  
Co Emission

The present research aims to analyse diffusion flame in a tube type burner with Liquefied petroleum gas (LPG) as a fuel. An experimental investigation is performed to study flame appearance, flame stability, Soot free length fraction (SFLF) and CO emission of LPG diffusion flame. Effects of varying air and fuel velocities are analysed to understand the physical process involved in combustion. SFLF is measured to estimate the reduction of soot. Stability limits of the diffusion flame are characterized by the blowoff velocity. Emission characteristic in terms of CO level is measured at different equivalence ratios. Experimental results show that the air and fuel velocity strongly influences the appearance of LPG diffusion flame. At a constant fuel velocity, blue zone increases and the luminous zone decreases with the increase in air velocity. It is observed that the SFLF increases with increasing air velocity at a constant fuel velocity. It is observed that the blowoff velocity of the diffusion flame increases as fuel velocity increases. Comparison of emission for flame with and without swirl indicates that swirl results in low emission of CO and higher flame stability. Swirler with 45° vanes achieved the lowest CO emission of 30 ppm at Φ = 1.3.

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