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Title: Experimental study of the stabilization process of a non-premixed flame via the destabilization analysis of the blue ring flame

Abstract

The flame stabilization phenomenon remains a crucial issue. The experimental study of flame stabilization behind a tulip-shaped flame-holder is addressed in this paper. The process leading to the transition between specific modes - the blue ring flame and the instable ring - of a non-premixed flame stabilized on a tulip-shaped bluff-body is detailed. The aim of this study is to provide an accurate description of the destabilization of specific combustion modes, which enables a further understanding of the entire stabilization mechanism. The aerodynamic and mixing fields are described by laser Doppler anemometry and concentration measurements by sampling probe respectively. The behaviour of shear layers developing at the wake and jet boundaries are characterized by means of a spectral analysis of the fluctuating radial velocity. Results show that the destabilization process is related to the intensification of hot gas recirculation, inducing an upheaval of the dynamical condition of stabilization and a transition of mixing phenomena. (author)

Authors:
;  [1]
  1. Centre de Thermique de Lyon (CETHIL) UMR 5008 CNRS-INSA-UCBL, INSA de Lyon, 20 av. A. Einstein, 69621 Villeurbanne cedex (France)
Publication Date:
OSTI Identifier:
20864949
Resource Type:
Journal Article
Resource Relation:
Journal Name: Experimental Thermal and Fluid Science; Journal Volume: 31; Journal Issue: 5; Conference: MCS-4: 4. Mediterranean combustion symposium, Lisbon (Portugal), 6-10 Oct 2005; Other Information: Elsevier Ltd. All rights reserved
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; COMBUSTION KINETICS; FLAMES; STABILIZATION; RINGS; RADIAL VELOCITY; MIXING; LAYERS; SHEAR; JETS

Citation Formats

Pinguet, Guillaume, and Escudie, Dany. Experimental study of the stabilization process of a non-premixed flame via the destabilization analysis of the blue ring flame. United States: N. p., 2007. Web. doi:10.1016/J.EXPTHERMFLUSCI.2006.04.014.
Pinguet, Guillaume, & Escudie, Dany. Experimental study of the stabilization process of a non-premixed flame via the destabilization analysis of the blue ring flame. United States. doi:10.1016/J.EXPTHERMFLUSCI.2006.04.014.
Pinguet, Guillaume, and Escudie, Dany. Sun . "Experimental study of the stabilization process of a non-premixed flame via the destabilization analysis of the blue ring flame". United States. doi:10.1016/J.EXPTHERMFLUSCI.2006.04.014.
@article{osti_20864949,
title = {Experimental study of the stabilization process of a non-premixed flame via the destabilization analysis of the blue ring flame},
author = {Pinguet, Guillaume and Escudie, Dany},
abstractNote = {The flame stabilization phenomenon remains a crucial issue. The experimental study of flame stabilization behind a tulip-shaped flame-holder is addressed in this paper. The process leading to the transition between specific modes - the blue ring flame and the instable ring - of a non-premixed flame stabilized on a tulip-shaped bluff-body is detailed. The aim of this study is to provide an accurate description of the destabilization of specific combustion modes, which enables a further understanding of the entire stabilization mechanism. The aerodynamic and mixing fields are described by laser Doppler anemometry and concentration measurements by sampling probe respectively. The behaviour of shear layers developing at the wake and jet boundaries are characterized by means of a spectral analysis of the fluctuating radial velocity. Results show that the destabilization process is related to the intensification of hot gas recirculation, inducing an upheaval of the dynamical condition of stabilization and a transition of mixing phenomena. (author)},
doi = {10.1016/J.EXPTHERMFLUSCI.2006.04.014},
journal = {Experimental Thermal and Fluid Science},
number = 5,
volume = 31,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
  • In the present work, a direct numerical simulation (DNS) of an experimental high Karlovitz number (Ka) CH 4/air piloted premixed flame was analyzed to study the inner structure and the stabilization mechanism of the turbulent flame. A reduced chemical mechanism for premixed CH 4/air combustion with NO x based on GRI-Mech3.0 was used, including 268 elementary reactions and 28 transported species. The evolution of the stretch factor, I0, indicates that the burning rate per unit flame surface area is considerably reduced in the near field and exhibits a minimum at x/D = 8. Downstream, the burning rate gradually increases. Themore » stretch factor is different between different species, suggesting the quenching of some reactions but not others. Comparison between the turbulent flame and strained laminar flames indicates that certain aspects of the mean flame structure can be represented surprisingly well by flamelets if changes in boundary conditions are accounted for and the strain rate of the mean flow is employed; however, the thickening of the flame due to turbulence is not captured. The spatial development of displacement speeds is studied at higher Ka than previous DNS. In contrast to almost all previous studies, the mean displacement speed conditioned on the flame front is negative in the near field, and the dominant contribution to the displacement speed is normal diffusion with the reaction contribution being secondary. Further downstream, reaction overtakes normal diffusion, contributing to a positive displacement speed. The negative displacement speed in the near field implies that the flame front situates itself in the pilot region where the inner structure of the turbulent flame is affected significantly, and the flame stabilizes in balance with the inward flow. Notably, in the upstream region of the turbulent flame, the main reaction contributing to the production of OH, H+O 2⇌O+OH (R35), is weak. Moreover, oxidation reactions, H 2+OH⇌H+H 2O (R79) and CO+OH⇌CO 2+H (R94), are influenced by H 2O and CO 2 from the pilot and are completely quenched. Hence, the entire radical pool of OH, H and O is affected. Furthermore, the fuel consumption layer remains comparably active and generates heat, mainly via the reaction CH 4+OH⇌CH 3+H 2O (R93).« less
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