Combustion of aluminum particles in a high-temperature furnace under various O2/CO2/H2O atmospheres

Abstract

The study focusing on the combustion of flowing aluminum particles and the properties of condensed phase products has important guiding significance for the practical application of aluminum-based propellants. Based upon an in-house built dynamic combustion experimental system, the dynamic combustion process of aluminum particles and the properties of condensed phase products under different atmospheres were studied in detail. The microstructure, size distribution and active aluminum content of samples were analyzed by field emission scanning electron microscopy, laser particle analyzer and inductively coupled plasma atomic emission spectroscopy. By monitoring the temperature distribution at different points in the furnace, the heat release of the samples at different positions is approximated, and the combustion efficiency is calculated. In the atmosphere containing CO2, the maximum combustion efficiency can reach the value of 94.41%, followed by that in H2O atmosphere, which had the value of 81.19%. Finally, under the N2 containing atmosphere, the combustion is the weakest, and has the value of only 53.91%, confirming that the combustion followed the following descending order: CO2 > H2O > N2. The condensed phase products were mainly composed of agglomerates formed by the aggregation of particles and alumina smoke. It is well known that the reaction of the sample in the furnace not only follows the melt-dispersion mechanism, but also the diffusion mechanism. The high-speed camera captured four typical combustion forms of aluminum particles during flow, which are stable combustion, release of alumina smoke, crushing and extinction. The average burning time of four stages were studied. The two reaction mechanisms occurring under the same reaction conditions are determined by the nature of aluminum particles themselves.