Experimental analysis of flashback in lean premixed swirling flames: upstream flame propagation

Simultaneous 10-kHz OH-PLIF and 20-kHz two-component PIV were made in conjunction with wide-field 20-kHz flame luminescence imaging of an unconfined, swirling, lean premixed, bluff-body stabilized flame during flashback. Flashback was induced by increasing the stoichiometry or swirl number or reducing the Reynolds number. A detailed stability regime was prepared and compared to predictions. Analysis of the time-correlated flame history inside the exit nozzle during flashback and non-flashback flame events led to a new hypothesis for the flashback mechanism.