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We study a flame propagating in the gaseous combustible mixture withsuspended inert particles. The gas is assumed to be transparent for theradiation emitted by the combustion products, while particles absorb andre-emit the radiation. Thermal radiation heats the particles, which in turntransfer the heat to the surrounding gaseous mixture by means of heatconduction, so that the gas temperature lags that of the particles. We considerdifferent scenarios depending on the spatial distribution of the particles,their size and the number density. In the case of uniform distribution of theparticles the radiation causes a modest increase of the temperature ahead ofthe flame and the corresponding increase of the flame velocity. The effects ofradiation preheating is stronger for a flame with smaller normal velocity. Inthe case of non-uniform distribution of the particles, such that the particlesnumber density is smaller just ahead of the flame and increases in the distantregion ahead of the flame, the preheating caused by the thermal radiation maytrigger additional independent source of ignition. This scenario requires theformation of a temperature gradient with the maximum temperature sufficient forignition in the region of denser particles cloud ahead of the advancing flame.Depending on the steepness of the temperature gradient formed in the unburnedmixture, either deflagration or detonation can be initiated via the Zeldovich'sgradient mechanism. The ignition and the resulting combustion regimes depend onthe temperature profile which is formed in effect of radiation absorption andgas-dynamic expansion. In the case of coal dust flames propagating through alayered dust cloud the effect of radiation heat transfer can result in thepropagation of combustion wave with velocity up to 1000m/s and can be aplausible explanation of the origin of dust explosion in coal mines.

Ignition of Deflagration and Detonation Ahead of the Flame due to Radiative Preheating of Suspended Micro Particles