Effect of suboxides on dynamics of combustion of aluminum nanopowder in water vapor: Numerical estimate

The model of dynamics of combustion of a pre-prepared mixture of aluminum nanoparticles and water vapor under adiabatic conditions is considered and the results of numerical calculations are presented. The formation dynamics of the condensed phase of aluminum oxide (c-phase) in the form of aerosol particles is modeled with allowance for the homogeneous nucleation of Al2O3 molecules, and the processes of condensation, evaporation and coagulation. The condensation process is considered with participation of unstable Al2O3 gas molecules, and heterogeneous processes involving gaseous and adsorbed suboxides of aluminum: AlO, AlO2 Al2O2, and atomic oxygen. The participation of aluminum suboxides has been found to accelerate the combustion of aluminum. Besides, it increases the depth of aluminum burning and rises the final temperature of the process. The changes of temperature, phase composition, and concentrations of gaseous and adsorbed components during the combustion are reported. The mechanism of combustion and c-phase formation is detailed, and the mutual influence of reactions in the gas phase, heterogeneous reactions and the process of aerosol particle formation during combustion are analyzed.