The emergency venting of a gaseous deflagration is widely used to prevent severe consequences of a confined explosion. Processes of
vented deflagrations have been studied extensively and a substantial amount of experimental data has been analyzed in Ref. 1. It has
been found that venting, in some cases, can
result in strong explosions. One of the reasons
is flame instabilities, which give rise to flame
area increase and the generation of high peak
overpressures [2-4]. The existence of an external explosion in vented unburned gas has been
shown in Ref. 5. Another important case is the
onset of detonation induced by a sudden venting [6]. Detonations were observed in high
sensitivity mixtures at elevated pressures.
The purpose of the present paper is to report observations of detonation onset in the
course of hydrogen-air deflagration, due to
sudden venting. Although the aim of the tests
was not to investigate the effect of venting on
gaseous explosion, this effect appeared to be
defining the explosion mode.