A numerical study on preferential diffusion effects in coflowing laminar reacting jets

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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Development of a novel flamelet-based model to include preferential diffusion effects in autoignition of CH 4 /H 2 flames

Combustion and Flame ◽

10.1016/j.combustflame.2015.06.015 ◽

2015 ◽

Vol 162 (11) ◽

pp. 4358-4369 ◽

Cited By ~ 23

Author(s):

Ebrahim Abtahizadeh ◽

Philip de Goey ◽

Jeroen van Oijen

Keyword(s):

Preferential Diffusion ◽

Diffusion Effects

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A Numerical Study on the Effects of Preferential Diffusion in Ethanol Laminar Reactive Flows

10.26678/abcm.encit2016.cit2016-0498 ◽

2016 ◽

Author(s):

Albino Leiroz ◽

Rafael Leitão ◽

Ricardo Soares ◽

Marcelo Colaco

Keyword(s):

Numerical Study ◽

Reactive Flows ◽

Preferential Diffusion

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Numerical Implementation and validation of turbulent premixed combustion model for lean mixtures

MATEC Web of Conferences ◽

10.1051/matecconf/201820900004 ◽

2018 ◽

Vol 209 ◽

pp. 00004 ◽

Cited By ~ 1

Author(s):

Siva Muppala ◽

Vendra C. Madhav Rao

Keyword(s):

Equivalence Ratio ◽

Numerical Study ◽

Premixed Combustion ◽

Reacting Flow ◽

Flame Surface ◽

Parametric Variation ◽

Turbulent Flame Speed ◽

Preferential Diffusion ◽

Good Agreement ◽

Turbulent Premixed

The present paper discusses the numerical investigation of turbulent premixed flames under lean conditions. Lean premixed combustion, a low NOx emission technique but are prone to instabilities, extinction and blow out. Such flames are influenced by preferential diffusion due to different mass diffusivities of reactants and difference between heat and mass diffusivities in the reaction zone. In this numerical study, we estimate non-reacting flow characteristics with implementation of an Algebraic Flame Surface Wrinkling Model (AFSW) in the open source CFD code OpenFOAM. In these flows, the mean velocity fields and recirculation zones were captured reasonably well by the RANS standard k-epsilon turbulence model. The simulated turbulent velocity is in good agreement with experiments in the shear-generated turbulence layer. The reacting flow study was done at three equivalence ratios of 0.43, 0.5 and 0.56 to gauge the ability of numerical model to predict combustion quantities. At equivalence ratios 0.5 and 0.56 the simulations showed numerical oscillations and non-convergence of the turbulent quantities. This leads to a detailed parametric variation study where, the pre-constant of AFSW model is varied with values 0.3, 0.35 and 0.4. However the study revealed the weak dependence of pre-constant value on the equivalence ratio. Hence the pre-constant value is fit for specific equivalence ratio based on the parametric variation study. The tuned AFSW model with fitted pre-constant specific to given equivalence ratio predicted are compared with experiments and discussed. The tuned AFSW model produced turbulent flame speed values which are good agreement with experiments.

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