An experimental study on the detonation transmission behaviours in acetylene-oxygen-argon mixtures

Abstract Accidental explosions/detonations preventions and control are practical as well as scientific issues. Although numerous research have been carried out to examine the combustion characteristics in acetylene mixtures, very limited studies focused on detonation transmission behaviours in a finite expansion space, which is of vital importance for the explosion safety assessment. This paper reports the detonation transmission behaviours through a confined sudden expansion in stoichiometric acetylene-oxygen mixtures diluted with varying amount of argon. Detonation velocity measurement and soot film visualization were used to characterize the detonation behaviour. The experimental results indicate that the initial over-driven degree of re-initiated detonation decreases with the increase of argon dilution in the expanded tube. Two transmission modes with distinct detonation cellular structures are experimentally observed. For the large expansion ratio, localized explosions followed by fine-scale detonation structures are observed in the expanded tube. As the initial pressure approaches the limiting transmission pressure, the re-initiation distance remarkably increases. For the small expansion, the near-limit detonation waves are observed to transmit to the expanded tube successfully without detonation re-initiation. A dimensionless cell size Λ is introduced to correlate with the re-initiation distance of transmitted detonation in acetylene-oxygen-argon mixtures, and a unified curve can be obtained.