Acceleration of laminar hydrogen/oxygen flames in a tube and the possible onset of detonation

Abstract

The possibility is analysed of a laminar flame accelerating along a cylindrical tube, closed at one end, and inducing a deflagration to detonation transition in a stoichiometric H2/O2 mixture. The pressure and temperature ratios at the ensuing shock wave increase, as do laminar burning velocities, while autoignition delay times decrease. Combined with appreciable elongation of the flame, these enhance the strength of the shock. The conditions necessary for delay times of 0.05, 0.1, 1.0 and 5.0 ms, at an unburned mixture critical Reynolds number of 2300, are computed for different tube diameters. Probable consequences of the different delay times and hot spot reactivity gradients, including detonation, are all considered. The probability of a purely laminar propagation leading to a detonation is marginal. Only when the initial temperature is raised to 375 K, do purely laminar detonations become possible in tubes of between about 0.5 and 1.35 mm diameter.

Hydrogen generation, and its venting from nuclear reactors

“…Hydrogen and O2 can also be formed in light water cooled nuclear reactors by the radiolytic decomposition of water [7]. If significant amounts of H2 and O2 were to be created by radiolysis in stoichiometric proportions, this would be very serious because of the very high reactivity, and the potential for detonation, of such a mixture [8]. However, Gordon et al [9] found this not to be so, with no more than 0.7% H2 being created by radiolysis, which could be removed by recombination.…”