[Stabilisation des flammes non prémélangées dans les écoulements supersoniques réactifs]
Une approche Lagrangienne est introduite pour décrire les flammes turbulentes non prémélangées dans des jets co-courants supersoniques. L'objectif final est de disposer d'un modèle numérique robuste pour la simulation de la torche sous-détendue GH2/GO2 utilisée comme système d'allumage dans un moteur fusée. L'approche retenue repose sur les travaux de Borghi et de ses collaborateurs. Elle permet de décrire les effets de chimie finie et sa récente extension aux écoulements à grandes vitesses permet de prendre en compte l'influence des phénomènes liés à la dissipation visqueuse. En effet, les termes sources chimiques étant fortement sensibles à la température, l'influence des phénomènes visqueux sur l'emballement thermique devient d'autant plus importante que le nombre de Mach est grand. La validation du modèle étendu a été récemment effectuée en considérant deux cas expérimentaux de référence. Cette étape préliminaire de validation est brièvement résumée mais le but essentiel de la présente étude est de procéder maintenant à la simulation numérique de configurations regroupant les particularités de la torche sous-détendue GH2/GO2. Le comportement des flammes jet supersoniques correspondant aux différentes conditions est discuté à la lumière des résultats des simulations numériques.
A Lagrangian framework is set out to describe turbulent non-premixed combustion in high speed coflowing jet flows. The final aim is to provide a robust computational methodology to simulate, in various conditions, the underexpanded GH2/GO2 torch jet that is used to initiate combustion in an expander cycle engine. The proposed approach relies on an early modelling proposal of Borghi and his coworkers. The model is well suited to describe finite rate chemistry effects and its recent extension to high speed flows allows one to take the influence of viscous dissipation phenomena into account. Indeed, since the chemical source terms are highly temperature sensitive, the influence of viscous phenomena on the thermal runaway is likely to be all the more pronounced since the Mach number values are high. The validation of the extended model has been recently performed through the numerical simulation of two distinct well-documented experimental databases. Only a brief summary of this preliminary validation step is provided here. The main purpose of the present work is to proceed with the numerical simulation of geometries that bring together the essential peculiarities of the underexpanded GH2/GO2 torch. The behavior of the corresponding supersonic coflowing jet flames for various conditions is discussed in the light of computational results.
Mot clés : Combustion, Modèle Lagrangien, Combustion supersonique, Effets visqueux, Jets sous-détendus
@article{CRMECA_2009__337_6-7_362_0,
author = {Jean-Francois Izard and Arnaud Mura},
title = {Stabilization of non-premixed flames in supersonic reactive flows},
journal = {Comptes Rendus. M\'ecanique},
pages = {362--372},
publisher = {Elsevier},
volume = {337},
number = {6-7},
year = {2009},
doi = {10.1016/j.crme.2009.06.006},
language = {en},
}
Jean-Francois Izard; Arnaud Mura. Stabilization of non-premixed flames in supersonic reactive flows. Comptes Rendus. Mécanique, Volume 337 (2009) no. 6-7, pp. 362-372. doi : 10.1016/j.crme.2009.06.006. https://comptes-rendus.academie-sciences.fr/mecanique/articles/10.1016/j.crme.2009.06.006/
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