Visualization and Measurement of the Deflagration of Metal-Foil Bounded JA2

Abstract : The US Army Research Laboratory conducted experiments to broaden its knowledge of the mechanisms underlying the deflagration of nitrate ester-based propellants embedded with thermally conductive components. JA2 was employed for the experiments. Strands were bonded on 1 side with 0.001-inch-thick aluminum foil, and their deflagration was videographically recorded. The data yielded measured values for 1) the JA2 stock's normal linear burning rate, 2) test article burning rates relative to an axis parallel to their side wall, and 3) the angle between the burning surface and the side wall. The condensedphase to gas-phase mass conversion rates for foil-bounded sections were 1.5-2.5 times higher than those for foil-less sections. The increases appear to be almost entirely due to increases in the area of the burning surface rather than an increase in the normal linear burning rate. It was also found that the pressure dependence of the gas generation rates for foil-bounded sections was slightly less than that for foil-less sections. Finally, the videographs clearly showed that the gas-phase flame has cellular structure. Because the test articles have relatively simple geometry, the results produced provide a good basis with which to validate computational fluid dynamics models for simulating the deflagration of wire-embedded propellants.