Study on Behavior of Methane/Oxygen Gas Detonation Near Propagation Limit in Small Diameter Tube: Effect of Tube Diameter

摘要

The unstable behavior of the detonation is an important issue in predicting detonation limits and safety problems. The present study aims to obtain information of the unstable behavior near the detonation propagating limit in methane/oxygen gas mixture for various initial pressures and tube diameters. The detonation velocity rapidly decreases near alpha = 1.0 and deviates from the theoretical value for alpha < 1.0 conditions (alpha = pi d/lambda; d: tube diameter; lambda: cell width). The onset of the single-head spinning is alpha = 1.0. For alpha < 1.0 conditions, the transition to the single-head spinning from small cells and the failure of cellular patterns were observed. For alpha > 1.0 conditions, the propagation mode was unstable. The unstable phenomenon means that the cellular pattern repeats multi-head and single-head spinning in turn.