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Modélisation Eulérienne de l'Atomisation Haute Pression - Influences sur la Vaporisation et la Combustion Induite

Abstract : Nowadays, environmental and economic constraints force the car manufacturers to reduce the consumption and the pollutant emissions of Diesel engines. To improve these engines, it is necessary to precisely understand the physical phenomena that occur in the combustion chamber and more specifically the injection process. A way of analysis and optimization is the numerical simulation and the modeling. After having detailed the physical characteristics of the sprays, the existing models for the atomization process and their limitations, an innovating model is presented: the ELSA model (for Eulerian - Lagrangian Spray Atomization). It takes into account the flow in the dense zone of the spray and deals with the atomization phenomenon from inside the injector to the dilute part of the spray. Two main physical properties are evaluated thanks to transport equations: the mean liquid mass fraction and the mean liquid/gas interface density per unit of mass. In both equations, a turbulent flux term is unclosed. A coupling method between eulerian and lagrangian formalisms is proposed in order to close this term. Moreover, taking into account the physical phenomena that influence the liquid/gas interface density, a transport equation for this quantity is presented. Finally, heat and mass transfers are taken into account and integrated in the ELSA model, thanks to transport equations for the mean vapour mass fraction and the mean liquid enthalpy per unit of mass. Validation cases are presented as comparative studies: in the dense zone of the spray thanks to data obtained via a direct numerical simulation and as a more macroscopic point of view thanks to liquid and vapour penetrations in Diesel conditions or lift-off distances in a case of steady state combustion of a liquid spray.
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https://theses.hal.science/tel-00707588
Contributor : Romain Lebas Connect in order to contact the contributor
Submitted on : Wednesday, June 13, 2012 - 9:18:32 AM
Last modification on : Sunday, June 26, 2022 - 12:26:05 AM
Long-term archiving on: : Friday, September 14, 2012 - 2:21:30 AM

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  • HAL Id : tel-00707588, version 1

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Romain Lebas. Modélisation Eulérienne de l'Atomisation Haute Pression - Influences sur la Vaporisation et la Combustion Induite. Milieux fluides et réactifs. Université de Rouen, 2007. Français. ⟨NNT : ⟩. ⟨tel-00707588⟩

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