Lift-off and blowoff of a diffusion flame between parallel streams of fuel and air

Fernández Tarrazo, Eduardo and Vera Coello, Marcos and Liñán Martínez, Amable (2006). Lift-off and blowoff of a diffusion flame between parallel streams of fuel and air. "Combustion and Flame", v. 144 (n. 3); pp. 261-276. ISSN 0010-2180.

Description

Title: Lift-off and blowoff of a diffusion flame between parallel streams of fuel and air
Author/s:
  • Fernández Tarrazo, Eduardo
  • Vera Coello, Marcos
  • Liñán Martínez, Amable
Item Type: Article
Título de Revista/Publicación: Combustion and Flame
Date: January 2006
ISSN: 0010-2180
Volume: 144
Subjects:
Freetext Keywords: Diffusion flames; Edge flames; Liftoff; Triple flames; Air; Deep level transient spectroscopy; Fuels; Ignition; Methane; Nitrogen; Stoichiometry; Thermal expansion; Blowoffs; Liftoffs; Parallel streams; Flame research; fuel; flame calculation; diffusion; dilution; dynamics; energy; porosity;
Faculty: E.T.S.I. Aeronáuticos (UPM)
Department: Motopropulsión y Termofluidodinámica [hasta 2014]
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

A numerical analysis is presented to describe the liftoff and blowoff of a diffusion flame in the mixing layer between two parallel streams of fuel (mainly methane diluted with nitrogen) and air emerging from porous walls. The analysis, which takes into account the effects of thermal expansion, assumes a one-step overall Arrhenius reaction, where the activation energy E is allowed to vary to reproduce the variations of the planar flame propagation velocity with the equivalence ratio. First, we describe the steady flame-front structure when stabilized close to the porous wall (attached flame regime). Then, we analyze the case where the flame front is located far away from the porous wall, at a distance xf′ such that, upstream of the flame front, the mixing layer has a self-similar structure (lifted flame regime). For steady lifted flames, the results, given here in the case when the fuel and air streams are injected with the same velocity, relate Uf′/SL, the front velocity (relative to the upstream flow) measured with the planar stoichiometric flame velocity, with the Damköhler number Dm=(δm/δL)2, based on the thickness, δm, of the nonreacting mixing layer at the flame-front position and the laminar flame thickness, δL. For large values of Dm, the results, presented here for a wide range of dilutions of the fuel stream, provide values of the front propagation velocity that are in good agreement with previous experimental results, yielding well-defined conditions for blowoff. The calculated flame-front velocity can also be used to describe the transient flame-front dynamics after ignition by an external energy source.

More information

Item ID: 854
DC Identifier: http://oa.upm.es/854/
OAI Identifier: oai:oa.upm.es:854
Official URL: http://www.sciencedirect.com/science/journal/00102180
Deposited by: Archivo Digital UPM
Deposited on: 11 Feb 2008
Last Modified: 20 Apr 2016 06:33
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