Excitation of Cylindrical Detonation by a Decaying Shock Wave

Abstract

Formal extrapolation of kinetic data obtained in studying the processes of ignition and low-velocity combustion to supersonic detonation processes most often leads to noticeable underestimation of the critical initiation energy, detonation cell size, and other dimensional parameters of detonation as compared to experimental data. Thus, numerical predictions of the combustible system behavior become less reliable. However, because of the instability-induced non-one-dimensional, nonuniform, and oscillating character of the multifront detonation wave, it is next to impossible to perform reliable experimental measurements of the kinetic parameters of combustible mixtures under the detonation conditions. In the present paper, we propose and approve a method that allows one to get over the above-mentioned limitations by using a technique as close to the detonation conditions as possible. The technique is based on using a decaying shock wave for combustible mixture initiation instead of the classical steady shock wave. Such a decaying wave is formed in the case of reaction failure behind a steadily propagating detonation wave due to its propagation in a channel with sudden expansion (so-called detonation wave diffraction). The basic issues of the technique are discussed, required estimates are made, experimental verification is performed, and results obtained are reported.