Influence of physical processes in preflame region on aluminum particles combustion in oxygen-containing media
The processes in preflame region while combustion of aluminum particles in media «79% Ar + 21% O 2» и «79% Не + 21% O 2» were analyzed. The necessity of oxygen dissociation taking into account for explanation of effect of physical processes on particles rate of combustion is proved. The calculations are implemented for particles of diameter 220 mm and ambient pressure p =0,1 MPa provided that quasistationarity and symmetry of processes. Values of concentration of dissociating oxidizer on the flame boundary are established to be lower than those calculated without dissociation taking into account (in 2,5 times lower for combustion in helium and by 30% lower for combustion in argon). Distributions of medium temperature and concentrations of oxidizing components are obtained depending on relation of coordinates R of inner points of region to current particle radius R 0. The preflame region is revealed to be in the range of 2,4£ R / R 0£5,1 for burning in helium and to be in the range of 15£ R / R 0£6,9 for burning in argon. The results of analysis show necessity of molecular oxygen dissociation taking into account in the region under consideration. The results explain differencies of burning rates obtained in experiments from calculated values. Also results of this work explain particles combustion rates ratio in media posessing essentially different transport coefficients.