A comparison of the critical energies for direct initiation of spherical detonations in acetyleneoxygen mixtures

Abstract

The present paper describes some new results for the critical energy for direct initiation of detonations in acetyleneoxygen mixtures using electrical sparks. The present spark energies represent the true effective initiation energies, independent of discharge characteristics and electrode configurations and gap spacings. Comparisons with existing data from exploding wire, laser and electrical sparks, as well as initiation by firing a planar detonation in a larger volume, indicate no qualitative differences in the dependence of the critical energy on mixture composition. As far as pressure dependence is concerned, the present results agree with the previous data on laser sparks and electrical sparks. However, for exploding wire and initiation by a planar detonation, much stronger pressure dependence is obtained. A simple model is proposed for direct initiation of spherical detonation by firing a planar detonation into a larger volume. The model enables critical tube diameter data to be reduced to equivalent energies, and good agreement between the critical diameter data of Matsui and the present critical spark energies is obtained on the basis of this model.