Laminar premixed flame extinction limits. I. Combined effects of stretch and upstream heat loss in the twin-flame unburnt-to-unburnt opposed flow configuration

In this paper, we provide a numerical study of the stability analysis of a planar premixed flame. The interaction of preferential diffusion and heat loss for a planar premixed flame is investigated using a thermodiffusive (constant density) model. The flame is studied as a function of three nondimensional parameters, namely, Damköhler number (ratio of diffusion time to chemical time), Lewis number (ratio of thermal to species diffusivity), and heat loss. A maximum of four solutions are identified in some cases, two of which are stable. The behavior of the eigenvalues of the linearized system of stabilty is also discussed. For low Lewis number, the heat loss plays a major role in stabilizing the flame for some moderately high values of Damköhler number. The results show the effect of increasing or decreasing Lewis number on adiabatic and nonadiabatic flames temperature and reaction rate as well as the range of heat loss at which flames can survive.

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The effects of self-absorption of radiation on an opposed flow partially premixed flame

Combustion and Flame ◽

10.1016/s0010-2180(02)00341-3 ◽

2002 ◽

Vol 129 (3) ◽

pp. 342-345 ◽

Cited By ~ 29

Author(s):

X Zhu

Keyword(s):

Premixed Flame ◽

Opposed Flow ◽

Partially Premixed ◽

Partially Premixed Flame

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The Combined Effects of Heat Loss and Reversibility on the Propagation of Planar Premixed Counterflow Flames

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4040657 ◽

2018 ◽

Vol 10 (6) ◽

Author(s):

Faisal Al-Malki

Keyword(s):

Activation Energy ◽

Finite Elements ◽

Strain Rate ◽

Heat Loss ◽

Constant Density ◽

Combined Effects ◽

Stability Of Solutions ◽

Counterflow Flames ◽

The Stability ◽

The Impact

Abstract We study in this paper the combined effect of heat loss and reversibility on the propagation of planar flames formed within the counterflow configuration. The problem has been formulated first using the thermodiffusive model with constant density and then solved numerically using finite elements. The impact of four main parameters, namely the reversibility r, the heat loss κ, the strain rate ε, and the activation energy β, on the propagation of planar flames has been discussed in details. The study has shown that planar flames under reversible conditions behave qualitatively similar to those observed for irreversible reactions, which agree with the asymptotic findings. In the presence of heat loss, the problem exhibits multiplicity of solutions whose number and stability were found to vary according to the strain rate ε. In addition, the study has predicted the existence of a certain value of the reversibility parameter r beyond which the impact of reversibility becomes negligible. Finally, we have examined the stability of the solutions and determined the domain of stability of solutions and their multiplicity for this problem.

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