Observed Structure of Spray Detonations

The propagation of a detonation wave in a tube containing a single stream of 2600-μ-diam diethylcyclohexane droplets dispersed in gaseous oxygen has been studied with streak and space resolved photography, special pressure transducers, and thin-film heat-transfer gauges. The detonation wave, which reached a velocity of 4100 ft/sec, consisted of a planar shock front followed by secondary shocks and a gradual decrease in pressure as heat is added. A detailed history of an individual drop within the reaction zone is presented. Under the observed conditions a 2600-μ-drop disintegrates continuously over a period of 500 μsec. Combustion is initiated in the wake of the drops at 65 μsec after the passage of the shock with the reaction zone considered completed in 670 μsec. One-dimensional equations for a two-phase Chapman-Jouguet detonation wave with mass and heat addition within the reaction zone, and momentum and heat transfer out of the reaction zone are derived. Comparison of the experiments with the theoretical prediction yields a reasonable agreement.