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Transition to detonation after a 'Volume Explosion' Oppenheim's experiment validation with a numerical calculation

Dzieminska E., Fukuda M., Hayashi A. K., Tsuboi N.

Archivum Combustionis

2011

Vol. 31 nr 3

187-195

Over many years of research Oppenheim's group performed a lot of experimental work concerning detonation. According to his notes the birth of detonation starts as a smooth-surfaced and spheric ally propagating flame which front wrinkles and accelerates. In a short time it produces compression waves that coalesce into a precursor shock which travels with some distance from the flame. Its structure eventually changes to a turbulent flame, while the surface creates so called 'tulip-shape' form. This phenomenon is associated with pressure waves' generation, which becomes slightly more intense in time as the flame becomes highly turbulent. They merge and form shock fronts. This leads to an 'explosion in the explosion' (appearing in the region of the accelerating flame) [1,2], which would be the last stage of the detonation wave birth, just before deflagration-to-detonation transition (DDT). In the first stages of propagation the reflections of the explosion from the back wall help the flame acceleration but later they have no significant meaning.

The Influence of the Structure of the Salts of Azoles upon the Processes of their Thermal and Laser Initiation

Ilyushin M. A., Tselinskii I. V.

Central European Journal of Energetic Materials

2006

Vol. 3, nr 1-2

39-50

It is experimentally shown that for metal salts of azoles there is no universal factor determining the processes of deflagration under thermal and laser initiation. For the series of azoles having a common initial stage of thermal degradation, the step of deflagration-to-detonation transition (DDT) for the same metal cation depends on ΔHf0 value of the salt. At the same time within the range of silver salts of isomeric N-nitroaminotetrazoles ΔHf0 values of the compounds, their structure, reactivity of the products of the initial decomposition and the composition of gaseous products of burning all influence their initiating ability under thermal initiation. But the ionization potential of complex perchlorates of d-metals with 3(5)-hydrazino-4-amino-1,2,4-triazoles as ligands determines the intensity of initial steps of decomposition under laser initiation which, in its turn controls the threshold of ignition. Hence the knowledge of the nature of initial decomposition stages of azole salts, taking into account the mechanism of energetic effects, is necessary for prediction of their behavior under initiation.