Detonation Transmission with an Abrupt Area Change

Abstract

Detonation initiation is a crucial step in a pulse detonation system Further in the concept of pre-detonator detonation transmission between two mixtures through an abrupt area change is a critical aspect In this study detonation transmission between propane/oxygen and propane/air with and without an abrupt area change was investigated In the donor there are two types of incident detonation waves: a self-sustained Chapman–Jouguet (CJ) detonation wave and an overdriven detonation wave generated by the difference in initial donor pressure ratios In a straight tube with an incident CJ detonation wave a high initial pressure level is required in the donor for successful detonation transmission When the incident wave is an overdriven detonation wave shock wave amplification appears to be the dominant mechanism of detonation re-initiation The bi-dimensional effect was also examined In an expansion tube the piston work is used to characterize the strength of the incident detonation wave For an incident CJ detonation wave the re-initiation of a detonation wave in the acceptor depends on the initial pressure in the donor and the expansion ratio Additionally a numerical simulation was performed under cold flow conditions for understanding the effect of wall confinement on the reflection of the diffracted shock wave The regimes of detonation transmission across a mixture include a transmitted shock wave detonation re-initiation and smooth detonation transmission all of which depend on the amplitude of piston work Axisymmetric and non-axisymmetric soot patterns correspond to direct detonation and detonation re-initiation respectively Nevertheless a delay regime was also observed and it was thought to result from the effect of wall confinement on the reflected shock wave structure

Date of Award	2016 Jun 27
Original language	English
Supervisor	Yei-Chin Chao (Supervisor)