Direct Experimental Impulse Measurements for Detonations and Deflagrations

Abstract

Direct impulse measurements were carried out by using a ballistic pendulum arrangement for detonations
\nand deflagrations in a tube closed at one end. Three tubes of different lengths and inner diameters were tested
\nwith stoichiometric propane– and ethylene–oxygen–nitrogen mixtures. Results were obtained as a function of
\ninitial pressure and percent diluent. The experimental results were compared to predictions from an analytical
\nmodel and generally agreed to within 15% (Wintenberger, E., Austin, J., Cooper, M., Jackson, S., and Shepherd,
\nJ. E., “Analytical Model for the Impulse of a Single-Cycle Pulse Detonation Engine, AIAA Paper 2001–3811,
\nJuly 2001). The effect of internal obstacles on the transition from deflagration to detonation was studied. Three
\ndifferent extensions were tested to investigate the effect of exit conditions on the ballistic impulse for stoichiometric
\nethylene–oxygen–nitrogen mixtures as a function of initial pressure and percent diluent.