Instability of Solid Propellant Combustion Waves with a Subsurface Temperature Maximum

Abstract

Combustion modes with a subsurface maximum temperature may occur in the burning of homogeneous energetic materials, such as solid propellants and explosives. In this paper, we analyzed the stability of a stationary combustion wave with a temperature maximum in the condensed phase. We showed that the boundary of stability corresponds to the merging of a stable and unstable solution while the combustion waves with a subsurface temperature maximum can be unsteady only. A dimensionless criterion of the transition to a pulsating mode, which is equal to the ratio of two times: the time of the adiabatic thermal explosion of the subsurface reactive layer and the time of substance depletion due to the combustion front motion, is given. The possible role of a thermal explosion of hotspots in the heated layer during the transition to a hotspot-pulsating combustion mode is discussed.