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Etude expérimentale de la propagation du front de flamme et de la vitesse de combustion d'une explosion de poussières d'aluminium

Abstract : Explosions are one of the most feared events in the industry. Risk of explosions with combustible dusts can occur in a large variety of industry of different fields, because of the large amount of combustible dusts: organic dusts (flour, carbon, sugar…) but also metallic dusts (aluminum, magnesium…). All of these combustible dusts, if they are fine enough, and if they are dispersed in the air, can cause explosions. Companies have to quantify this risk present in their plant. Concerning gas explosions, the current state of knowledge allows an understanding and a precise modelling of the phenomenon. However, the state of knowledge about dust explosions is more limited, especially because of the difficulty to study the explosions experimentally. Some models, based on gas explosions, exist for the case of dust explosion. These models seem coherent in the case of organic dust explosions but less adapted for metallic dust.This PhD work focus on the experimental study of flame propagation during an aluminum dust explosion. To model an eventual propagation of the flame during the explosion, an experimental approach is required. For this experimental study, specific prototypes have been elaborated, and then improved, during the different tests. This work is mainly separated in two parts.In a first part the dispersion of the dust is studied. Indeed, to study the explosion phenomenon, a system has been elaborated to disperse the dust. A first part of study allows checking that the dispersion is well homogeneous in terms of concentration. Then, the turbulence level inside the prototype after the end of the dispersion is studied. Indeed, this parameters influence a lot the flame propagation, increasing the consequences of the explosion.Then, the flame propagation is studied. The dust dispersion, previously studied, is ignited by an electric spark. The phenomenon is studied thanks to visualization of the flame propagation and by the evolution of the pressure inside the prototype. Two main optical techniques, one based on the light emitted by the flame, the other one linked to refractive index variations (due to temperature variations) are used. Thanks to these methods, the propagation velocity in the laboratory referential is studied. However, this velocity depends mainly on the prototype used for his determination. A method is used to determine the burning velocity (consumption rate of the reactants by the flame front). Some potential limits of this method are then exposed, and a new method of determination of this burning velocity is proposed.
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https://tel.archives-ouvertes.fr/tel-02006015
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Submitted on : Monday, February 4, 2019 - 12:43:32 PM
Last modification on : Wednesday, August 5, 2020 - 3:41:53 AM
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  • HAL Id : tel-02006015, version 1

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Clément Chanut. Etude expérimentale de la propagation du front de flamme et de la vitesse de combustion d'une explosion de poussières d'aluminium. Mécanique des fluides [physics.class-ph]. IMT - MINES ALES - IMT - Mines Alès Ecole Mines - Télécom, 2018. Français. ⟨NNT : 2018EMAL0008⟩. ⟨tel-02006015⟩

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