Detonation propagation over a wedge with two channels in a duct

Abstract

An experimental study was performed in a rectangular duct to investigate the detonation diffraction process in stoichiometric methane-oxygen mixtures. A wedge was placed in the duct to form two channels between the wedge and the channel walls, i.e., an upper channel and a divergence channel. The upper channel heights were 27mm, 47mm and 67mm, and the deviation angles (α) were 60 ° and 30 °. On the bottom wall and side wall, soot foils were placed to record the cellular structure evolution. For the larger deviation angle (α =60 °), the re-initiation mechanisms can be varied, which are affected by the upper channel height. Two overdriven detonation regions are generated behind the wedge on the bottom wall as well as the side wall for more sensitive mixtures (characterized by smaller detonation cell sizes). However, for insensitive mixtures, the re-initiation process seems to be more complicated. More regions containing finer cells can be observed on the foils. In case of α =30 °, the detonation re-initiates at the divergence wall and propagates toward the side wall. Universally, the re-initiation is facilitated as the upper channel height increases, and equivalently, the re-initiation distance is reduced.