Effect of Heat Losses on Boron Particle Combustion in Air.

This paper presents an analytical analysis of the effect of heat losses on the possibility of occurrence of the most effective gas-phase combustion of a single boron particle in air at different initial temperatures and pressures of the oxidizing medium. The analysis is performed with account for the possibility that the particle enters into an air medium (its temperature is lower than the melting point of boron) after its ignition and the establishment of a steady gas-phase combustion. A method for calculating the maximum initial air temperature below which a burning boron particle cools down and extinguishes is developed. The boundaries of the regions of its gas-phase combustion and extinguishing are determined. It has been established that when a single boron particle in a state of gas-phase combustion enters air with a temperature below the melting point, the main factor determining the its combustion mechanism is the air temperature. Depending on the air temperature, either the gas-phase combustion of the particle continues or the particle cools down and the gas-phase combustion changes to heterogeneous combustion. [ABSTRACT FROM AUTHOR]