Ignition dynamics of nitramine composite propellants under CO2 laserheating

The ignition dynamics of a series of RDX-based nitramine propellants was investigated by using a high-powered C02 laser ignition system. Interactions between infrared laser beam and nitramine composite propellants revealed a number of interesting processes. Information obtained can be used for validation of models developed for radiative ignition of composite propellants. In general, the delay time based upon the Onset of light emission decreases monotonically with the increase of incident laser energy flux. The slope was found to be affected by the oxygen concentration in the ambient gas . This effect is prominent when the sample contains volatile energetic plasticizer. The effects of oxygen concentration are more pronounced in the gas-phase ignition of nitramine propellants than in conventional AP-based composite propellants. The flame Structures of nitramine propellants depend strongly upon the ambient gas conditions. As ambient oxygen concentration is increased, the flame moves closer to the sample surface; this implies that gas-phase reaction with ambient oxygen plays an important role in the initial phase of laser ignition of nitrarnine propellants. -