Experimental Investigation of the Influence of Highly Argon Dilution on the Critical Initiation Energy for Direct Initiation of C2H2-2.5O2 Mixtures

Direct initiation is achieved via a high voltage capacitor spark discharge, and the critical energy is accurately estimated from the analysis of the current output. A good agreement is found by comparing the critical initiation energy from experimental measurement and Lee's surface energy model. The influences of highly argon dilution on the critical energy of direct initiation are investigated experimentally for C2H2-2.5O2 and 70% argon diluted C2H2-2.5O2 mixtures. The results show that the critical energy is inversely exponential to the initial pressure for C2H2-2.5O2 mixtures with and without highly argon. Both the experimental and theoretical results indicate that dilution of highly argon in C2H2-2.5O2 enhances the critical initiation energy for direct initiation at the same initial condition. Since the critical initiation energy is proportional to the cube of ZND induction zone length, the dilution of highly argon increases the ZND induction zone length of C2H2-2.5O2 mixture under the same initial pressure, and accordingly the critical initiation energy is raised remarkably.