Regimes of the filtration combustion of structured heterogeneous systems

摘要

An analysis of the characteristics of the combustion front in a multilayer porous system with radiative heat transfer and filtration mass transfer of gaseous reactants into the exothermic conversion zone is presented. At moderate pressures, the mass of the gas in the porous layer is smaller than that required by stoichiometry, and, therefore, filtration transport without diffusion from the ambient medium occurs. It was taken into account that the bulk heat release in the porous media can be limited by both the kinetics of the exothermic chemical reaction and the filtration transport of a gaseous reactant from the ambient medium. The effect of filtration on the characteristics of relay-race combustion was examined. The characteristics of the front and the dynamics of the conversion of the elements of the discrete system were determined. The characteristics of the relay-race filtration combustion front under conditions of heat losses into the ambient medium were examined, and the possibility of existence of two steady regimes, with a low- and a high-temperature relay-race combustion front, was demonstrated. At heat losses above a critical level, relay-race combustion extinguishes. A numerical analysis of relay-race combustion regimes under nonadiabatic conditions showed that the low-temperature front is absolutely unstable and made it possible to study the dynamics of the onset of high-temperature relay-race filtration combustion.