Models for Metal Particle Combustion with Extended Flame Zones

Abstract

A class of models is proposed to describe the vapor-phase combustion of metal particles. Optional features of the models include surface condensation of the oxide vapor and the existence of an extended flame zone, formed by condensing part or all of the outwardly-diffusing oxide vapor. Two types of extended flames, an isothermal flame and a non-isothermal flame with the inner edge hotter than the outer edge, are found to exist. It is shown that by including the additional gas-phase condensation process, the mass burning rate increases slightly whereas the outer edge of the flame can attain substantial size. Sample solutions are obtained for magnesium reacting with oxygen. Fair agreements exist between theoretical predictions and experimental results.