INITIATION OF SPHERICAL DETONATION IN HYDROCARBON-AIR MIXTURES

Spherical detonations have been initiated by solid explosive (Tetryl) charges in well-mixed stoichiometric air mixtures with each of the hydrocarbons, ethane, propane, n-butane, isobutane, and ethylene at atmospheric pressure. In a few experiments close to the limits of detonability, velocity and blast pressure/time records indicated that the propagating wave system is sometimes irregular. The irregularity that occurs just after initiation is characterized by a reaction front velocity very much lower than the constant detonation velocity, but subsequently attaining the latter by an acceleration process. These observations indicate the existence of a dissociated phase in which shock and reaction fronts may no longer be coupled.