DDT in fuel–air mixtures at elevated temperatures and pressures |
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Authors: | J Card D Rival G Ciccarelli |
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Institution: | (1) Mechanical and Materials Engineering Department, Queen's University, Kingston, Ontario, K7L 3N6, Canada |
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Abstract: | An experimental study was carried out to investigate flame acceleration and deflagration-to-detonation transition (DDT) in
fuel–air mixtures at initial temperatures up to 573 K and pressures up to 2 atm. The fuels investigated include hydrogen,
ethylene, acetylene and JP-10 aviation fuel. The experiments were performed in a 3.1-m long, 10-cm inner-diameter heated detonation
tube equipped with equally spaced orifice plates. Ionization probes were used to measure the flame time-of-arrival from which
the average flame velocity versus propagation distance could be obtained. The DDT composition limits and the distance required
for the flame to transition to detonation were obtained from this flame velocity data. The correlation developed by Veser
et al. (run-up distance to supersonic flames in obstacle-laden tubes. In the proceedings of the 4th International Symposium
on Hazards, Prevention and Mitigation of Industrial Explosions, France (2002)) for the flame choking distance proved to work
very well for correlating the detonation run-up distance measured in the present study. The only exception was for the hydrogen–air
data at elevated initial temperatures which tended to fall outside the scatter of the hydrocarbon mixture data. The DDT limits
obtained at room temperature were found to follow the classical d/λ = 1 correlation, where d is the orifice plate diameter and λ is the detonation cell size. Deviations found for the high-temperature data could be
attributed to the one-dimensional ZND detonation structure model used to predict the detonation cell size for the DDT limit
mixtures. This simple model was used in place of actual experimental data not currently available.
PACS 47.40.-x; 47.70.Fw
This paper was based on work that was presented at the 19th Interna-tional Colloquium on the Dynamics of Explosions and Reactive
Sys-tems, Hakone, Japan, July 27 - August 1, 2003 |
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Keywords: | Deflagration-to-detonation transition Detonation Flame |
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