Home – Home – Jornals – Combustion, Explosion and Shock Waves 2020 number 4

Mathematical modeling of combustion of micron-sized and nanometer boron particles in air with allowance for changes in the heat and mass transfer mechanism and a decreasing particle size is carried out. The Knudsen number is taken as an indicator of the transition from one regime to another: a continuous medium assumption is valid for describing the heat and mass transfer mechanisms in the case where Kn < 0.01, the free molecular regime takes place for Kn > 10, and a transition regime is realized for 0.01 < Kn < 10. Particle sizes at which different types of heat and mass transfer occurs with respect to boron combustion in air at pressures of 0.1 ÷ 4 MPa are estimated. The time it takes for boron particles to combust within the framework of the assumption of a continuous medium and in a free molecular mode is determined. It is shown that calculation models for determining the burning time of boron particles with initial sizes close to micron-sized and nanodispersed ones should take into account a change in the heat and mass transfer mechanism with variation in the current particle radius during burnout.