FLAME PROPAGATION AND EXTINCTION WITHIN MIXTURES INVOLVING HYDROGEN AND DILUENT INERT-GASES IN AIR

The application of an inerting gaseous atmosphere to overlay a combustible mixture of hydrogen and air produces, at any location, stratified mixtures whose composition would vary continuously with time. The behavior of flames propagating in such stratified diluent - hydrogen - air mixtures and the location of flame extinction were established at atmospheric pressure within a long circular tube closed at the top, yet open at the bottom. Helium, nitrogen and carbon dioxide were employed in turn as the diluent gas, atop various initially combustible homogeneous mixtures of hydrogen and air. Differences from the corresponding behavior of entirely homogeneous mixtures were established. The implication of these findings for the efficient quenching of propagating flames of hydrogen-air lean mixtures with the application of diluents is then discussed.