Pyrotechnic generator of low temperature gases

In the paper the construction and principle of operation of a two-stage pyrotechnic gas generator is presented. The generator produces gases with comparatively low temperature. It exploits an over adiabatic combustion process of a granular pyrotechnic charge that is ignited and sustained by the heat flux from the gaseous products moving in the same direction as the combustion wave. The heat exchange between already liberated gaseous products and the initial mixture enables the combustion wave to propagate even in low energy mixtures because in this way the amount of energy sustaining their combustion is maximised but the energy losses to the surroundings are minimised. Finally a majority of the heat released in the combustion process remains in the condensed combustion products and thanks to this the gaseous products can have the desired low temperatures. The thermochemical characteristics of the combustion process of various pyrotechnic mixtures that could be potentially applied as a filling of the generator were determined. The adiabatic flame temperatures, the heats of reaction and the composition of combustion products were calculated with CHEETAH code. The correctness of the calculations was verified by comparison of the calculated values with measured heats of reaction and temperature profiles in the combustion wave and it the combustion products leaving the generator.