Turbulent jet initiation of detonation in hydrogen-air mixtures

Large scale experiments (50 m(3)) have been carried out on the initiation of detonation by means of a jet of hot combustion products. The effects of hydrogen concentration (18 - 30% vol.), jet orifice diameter (100-400 mm), and the mixture composition in constant volume explosion chamber (25-50%) were investigated. Both high enough hydrogen concentration and large enough jet size are necessary for detonation initiation. The minimum values are within the ranges of 20 to 25% vol. H-2, and of 100 to 200 mm correspondingly. A minimum ratio of jet size and mixture cell width 12-13 is required for detonation initiation.