PLIF species and ratiometric temperature measurements of aluminum particle combustion in O 2, CO 2 and N 2O oxidizers, and comparison with model calculations

Abstract

Planar laser-induced fluorescence (PLIF) was used to probe the flame structure about single, isolated aluminum particles burning in pure gases of CO 2 and N 2 O and gas mixtures of O 2 , N 2 , and Ar at near atmospheric pressures. Temporally resolved temperature measurements were obtained by a two-camera two-excitation-line PLIF technique. To aid the interpretation of the experimental results, a detailed, diffusionally controlled local equilibrium model of aluminum particle combustion was developed. AlO was found to be a gas-phase intermediate in all combustion environments studied. The measurements confirm the concept of a “limit temperature” in metal combustion and support the local equilibrium model. The model predicts the pressure dependence of the mass burning rate found in the literature. Contrary to previous explanations, this pressure sensitivity was found to originate from the pressure dependence of the gasification temperature of Al and decomposition temperature of Al 2 O 3 (1). Both experiment and model indicate the importance of nitrogen as a reactant.