Hot-Spot Ignition of Solid Propellants by a Hot Surface

The combustion of homogeneous energetic materials such as ballistic powders and explosives usually begins with the formation of a hot spot. This paper studies the conditions for an occurrence of a hot spot in case of heating by a hot surface with constant temperature. It is shown that the hot spot is formed at a certain depth under the surface, and the specific location of the hot spot depends on the geometry of the surface. Dimensionless criteria are reported for the estimation of this depth and prediction of the precise location of the hot spot. Some limit cases are studied and the function of the ignition time of a rough surface with protrusion of different heights and angles are found for several geometries of the surface.