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Contribution à l'étude numérique des écoulements turbulents inertes et réactifs stabilisés en aval d'un élargissement brusque symétrique

Abstract : Abstract: This work is aimed at simulating the inert and reactive flows stabilized by a symmetrical sudden expansion and fed by two fully developed turbulent channel flows of air or air+propane. The objectives are, on one hand, to validate on a “simple” geometry, a rather standard modelling of turbulent premixed combustion and, on the other hand, to estimate the level of accuracy obtained in order to be able to quantify the potential improvement that could be brought by the use of more sophisticated models. The models used for our simulations were a standard k-epsilon turbulence model with the law of the wall, and the CLE model (presumed PDF approach) of turbulent combustion. A preliminary study of KPP type enabled us to deduce the basic propagation properties of the mean reaction zones calculated on the basis of the retained turbulent combustion model.
Three inert flows and three reactive flows with constant equivalence ratio and Reynolds numbers equal to 25,000, 50,000 and 75,000 are simulated along with two reactive flows with variable equivalence ratio and a Reynolds number equal to 25,000.
Concerning the inert flows, the dissymmetry observed in the experiments between the two average zones of recirculation is well represented. For the reactive flows with constant equivalence ratio, the symmetry of the mean flow observed experimentally is also correctly predicted by the simulations. In return, the length of the two mean recirculation zones is strongly underestimated by the calculations. A self-similar behavior of the flows (wake and shear layers) close to the expansion is also evidenced. The loss of symmetry of the mean flow observed experimentally when an equivalence ratio difference is present between the two feeding streams is qualitatively recovered numerically, but the length of the mean recirculation zones are still underestimated by the calculations. Quantitative indicators of the difference between the numerical and experimental results are provided for the inert and reactive flows, giving the opportunity to assess, in the future, the improvement brought by the recourse to a more elaborated modelling of this kind of flows.
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https://tel.archives-ouvertes.fr/tel-00012093
Contributor : Bernardo Martinez-Ramirez <>
Submitted on : Friday, April 7, 2006 - 11:20:03 AM
Last modification on : Thursday, March 7, 2019 - 3:08:06 PM
Long-term archiving on: : Saturday, April 3, 2010 - 9:27:43 PM

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  • HAL Id : tel-00012093, version 1

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Bernardo Martinez-Ramirez. Contribution à l'étude numérique des écoulements turbulents inertes et réactifs stabilisés en aval d'un élargissement brusque symétrique. Sciences de la Terre. Université de Poitiers, 2005. Français. ⟨tel-00012093⟩

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