Modeling of combustion wave propagation in a carbon dust/gas mixture

Abstract

Combustion wave propagation in a carbon dust/gas mixture isstudied, taking into account both radiative and conductive heat transfer. A two-temperature mathematical model is suggested for the analysis of the nonstationary processes occurring in exothermic reactions during propagation of the wave front in a carbon dust/gas mixture. Temperatures of the particles and gas are assumed to be different and radiative heat transfer is described by a diffusion approximation. Particle size is varied in the range of 10 to 200 μm. In the absence of heat losses, transition from the slow conductive combustion to the fast radiative one is explosive in nature. In such a case, both the combustion wave velocity and the width of the reaction zone are enhanced by 2–3 orders of magnitude. In the presence of heat losses, the behavior of the flame front propagation is changed drastically. Conductive heat losses may result in nonuniqueness of combustion. Depending on the initiation conditions, either a slow, or fast combustion wave may be expected to be generated in the system. Radiative heat losses lead to diminished combustion wave velocities, and marginally, to the transition from fast to slow combustion. Some aspects of pulsating combustion have also been considered, such as the oscillations of combustion wave velocity and particle and gas temperatures. Instability development is studied with the suggested model.