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Etude de l'allumage par laser de mélanges en phase liquide dispersée et gazeuse

Abstract : The study of ignition of fuel/oxidizer mixtures is of fundamental and crucial importance for the internal combustion engines and for the gas turbines. A new method of ignition, recently used, consists in creating a spark by focusing of a laser beam. The objective of this work is to carry out a parametric study of this mode of lighting for mixtures in liquid dispersed and gas phases, as well as contributing to the comprehension of the physical phenomena related to optical breakdown, both in the air and in flammable mixtures. Plasmas met are characterized in terms of concentrations and electronic temperatures, before presenting the parametric study of breakdown in the air and the lighting of the gas and two phase mixtures. The importance of the dynamics induced by the laser spark on the evolution of the structure and the shape of the ignition kernel is considered. The role of the aberrations, and in particular of the spherical aberration, is carefully studied from the theoretical point of view. Important conclusions on the interpretation of the experimental results are then drawn. The determination of the breakdown threshold, as well as the identification of the determining processes are analyzed in the light of a model based on the determination of the evolution of the concentration of free electrons in focal volume. Finally, the feasibility of laser lighting at the outlet of a lean prevaporized premixed injector is proven.
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Contributor : Hazem El-Rabii <>
Submitted on : Saturday, February 26, 2005 - 12:17:01 PM
Last modification on : Thursday, November 5, 2020 - 8:16:02 PM
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Hazem El-Rabii. Etude de l'allumage par laser de mélanges en phase liquide dispersée et gazeuse. Energie électrique. Ecole Centrale Paris, 2004. Français. ⟨tel-00008582⟩

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