The experimentally known phenomenon of an abrupt transition from slow conductive to fast convective (penetrative) burning in a confined gas-permeable explosive is discussed. A simple model, involving only the most essential physical ingredients, is formulated and analyzed. A good qualitative agreement between theoretical and experimental dependencies is obtained. The transition is triggered by a localized autoignition in the extended resistance-induced preheat zone formed ahead of the advancing deflagration, provided the pressure difference between hot gas products and gases deep inside the pores of the unburned solid exceeds a certain critical level. In line with observations the critical overpressure increases with diminishing permeability.
- Conductive to convective burning transition
- Convective burning
- Gas-penetrative burning