Formation of a detonation-like condensation wave

Abstract

Amplification of a shock wave and its transition to a detonation-like regime due to the energy release in the course of condensation of a strongly supersaturated carbon vapor are observed experimentally. The carbon vapor behind the shock front is formed as a result of the thermal dissociation, C₃O₂ → C + 2CO, of the unstable carbon suboxide in a mixture of 10% C₃O₂ and 90% Ar. The rapid condensation of the vapor into nanoparticles gives rise to a temperature increase by over 500 K from 1600–2200 to 2200–2800 K, a pressure increase from 4 to 6 bar, and the resulting shock-velocity increase by 130–170 m/s. An analysis of the kinetics of the heat release in these mixtures shows that the temperature increase due to the particle formation is observed during a few microseconds if the initial temperature exceeds 1800 K. Calculations of the Hugoniot relations for the initial and final mixtures indicate that the supercompressed detonation is observed in the studied flow regimes. It is shown that the conditions for self-sustained detonation can be realized by increasing the C₃O₂ content in the mixture.