Fundamental study on thevortex bursting phenomena in small diameter tubes

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In this study, effects of the tube diameter as well as thermal and transport properties of mixture on the vortex bursting have been experimentally investigated. At first, it was found that the flame can be propagate through 2.4mm tube for propane/air mixture, which is enough less than the so called, quenching diameter. To investigate effects of the thermal / transport properties of unburned gas, further experiments have been made with various inert mixtures (N2, Ar, He, CO2). Results showed that the fuel rich side “vortex bursting limits” for CH4/Air and CH4/O2/Ar mixtures are enough higher than the conventional “upper flammability limit”. Consequently, it was found that the vortex bursting can be occur even for the conditions beyond the quenching diameter and flammability limits, in the cases of the thin flame can be established and the tip of the flame can be intensified, which correspond to the cases of the burning velocity is low enough and Le <1.