دانلود Physical mechanisms involved into the flame propagation process through aluminum dust-air clouds: A review

Abstract

In this paper, the combustion mechanisms of aluminum particles suspended in air and dust flame propagation mechanisms in dust-air mixtures, more specifically, in aluminum dust-air mixture are reviewed. Experimental data about individual aluminum particles combustion are collected and explained with details. It is shown from previous studies that despite the well understanding of the individual particles combustion process, the ignition and the inter-particles interaction need moreinvestigation seen that potential differences exist between the combustion regimes of isolated particles and a group of particles. The combustion regime may affect the ignition temperature resulting in the difference in the burning velocity. Additional experimental data and theoretical/numerical studies are needed. It is afterwards shown that, at these temperatures level, the thermal radiation contribution could be significant. Therefore, optical properties of aluminum burning particles and alumina particles are determined based on Mie scattering solutions showing that both aluminum and alumina are poor emitters but excellent scatterers. Then, several flame propagation models which take into account the thermal radiation exchanges are reviewed. The review of existing models reveals that the knowledge of the nature of radiative exchanges remains piecewise and basics need to be founded in order to be able to test modeling routes and plan experiments. The interaction of the different heat exchange modes and combustion regimes within the flame propagation process should be studied with a minimum of simplifying assumptions and the nature and characteristics of thermal radiation exchanges should be the key.