Gas flame acceleration in long ducts

Abstract : In many practical situations, a flame may propagate along a pipe, accelerate and perhaps transform into a devastating detonation. This phenomenology has been known, more or less qualitatively, for a long time and mitigation techniques were proposed to try and avoid this occurrence (flame arresters, vents,...). A number of parameters need to be known and in particular the “distance to detonation” and more generally the flame acceleration characteristic scales. Very often, the ratio between the detonation run-up distance and the pipe diameter is used without any strong justification other that using a non-dimensional parameter (L/D). In this paper, novel experimental evidence is presented on the basis of relatively large scale experiments using 10 cm and 25 cm inner diameter duct with a length between 7 and 40 m. Homogeneous C2H4-air, CH4-air, C3H8-air and H2-air mixtures were used and different ignition sources. The interpretation suggests that the self-acceleration mechanism of the flame may be much better represented by flame instabilities than by turbulence build-up. One consequence would be that the maximum flame velocity and, following, the maximum explosion overpressure, would be rather linked with the run-up distance than with the L/D ratio.
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Submitted on : Tuesday, August 7, 2018 - 1:41:02 PM
Last modification on : Wednesday, August 8, 2018 - 1:08:10 AM

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Christophe Proust. Gas flame acceleration in long ducts. Journal of Loss Prevention in the Process Industries, Elsevier, 2015, 36, pp.387-393. ⟨10.1016/j.jlp.2015.04.001⟩. ⟨ineris-01855065⟩

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