Modeling of unsteady filtration gas combustion

Abstract

Unsteady filtration gas combustion with various gas flow parameters is studied by mathematical modeling. Transition processes due to a sudden change in the calorific value of the gas mixture, gas flow velocity, and flow direction are considered. Trends and mechanisms of change in the structure of the filtration gas combustion wave and its propagation velocity are analyzed for various types of transition processes. It is found that with a sudden change in gas flow parameters, the flame can abruptly move large distances in the porous medium. Subsequently, at the new flame localization, a wave of filtration gas combustion forms which corresponds to the changed parameters of the gas flow. If in the porous medium, the amount of heat is insufficient, the transition process ends with quenching. As the gas flow direction changes, the combustion wave continues to propagate in the former direction for some time, which can lead to the spread of the high-temperature zone in devices based on the reverse process with a homogeneous gas-phase reaction.

Dynamics of gas combustion in a channel with combustion product flow through a porous wall

“…Note that the characteristic size of the space between the elements of the porous medium is much smaller than the critical diameter and the heating of the porous walls by the combustion products is negligible because of the high heat capacity of the porous walls. Under these conditions, filtration gas combustion is impossible [6,7]. Such conditions occur in the case where the porous layer consists, for example, of natural soils.…”

Counterflow infiltration combustion in conditions of fluid-dynamic instability: Fingering in low gas flow

“…Earlier, various aspects of the problem were treated [2][3][4][5][6] under the assumption of the same gas permeability of starting reactants and combustion products. The influence of changing gas permeability of burning medium on counterflow combustion in conditions of fluid dynamic instability was studied by us previously [7].…”