Abstract.
Diffraction phenomena of gaseous detonation waves behind a backward-facing step in a tube are observed by using high-speed schlieren photography and soot-track records as well as by pressure measurements on the sidewall. Mixtures are stoichiometric oxyhydrogen and those diluted by argon at sub-atmospheric pressures. Three types of phenomena are observed, that is, continuous propagation of detonation, re-initiation after a temporal extinction of detonation and complete extinction of detonation. The continuous propagation means that the diffracted wave does not affect the main propagation although reflected shock waves from the bottom surface of the tube may affect it. The re-initiation occurs at a wall surface of the tube behind a reflected shock wave after the main detonation wave has been extinguished. Positions and conditions of the re-initiation are discussed. The complete extinction is defined as disappearance of detonation cells behind the step within a certain length of the tube. Cases exist where an ignition occurs after several reflections off the bottom and top surface of the tube.
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Received 30 October 2001 / Accepted 5 May 2002 Published online 12 August 2002
Correspondence to: S. Ohyagi (e-mail: ooyagi@mech.saitama-u.ac.jp)
An abridged version of this paper was presented at the 18th Int. Colloquium on the Dynamics of Explosions and Reactive Systems at Seattle, USA, from July 29 to August 3, 2001.
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Ohyagi, S., Obara, T., Hoshi, S. et al. Diffraction and re-initiation of detonations behind a backward-facing step. Shock Waves 12, 221–226 (2002). https://doi.org/10.1007/s00193-002-0156-z
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DOI: https://doi.org/10.1007/s00193-002-0156-z