Direct electrical initiation of freely expanding gaseous detonation waves

Electrical initiation of freely expanding detonation waves has been demonstrated for three gaseous systems. It has been shown that a well-defined minimum stored-energy requirement exists for a given experimental system. Both spark discharges and exploding-wire discharges are discussed as initiation sources, and exploding-wire discharge is shown to produce detonation from smaller stored energies in the systems investigated. In each instance, the existence of a composition, or a range of compositions, requiring discharge of a minimum energy for initiation of freely expanding detonation waves has been established. Typical experimental data have been presented for mixtures of oxygen with the individual fuels ethylene, hydrogen, and propane. The data indicate that initiation of detonation in hydrogen systems requires more energy than in ethylene systems, but less than in propane systems. The pressure dependence of the stored energy required for initiation of detonation is quite complicated; in some instances the pressure sensitivity is large, and in other instances it disappears. Whenever a marked pressure effect exists, increasing the initial pressure decreases the required initiation energy.