Self-Induced Combustion Instability of Laminar Premixed Flames on a Slot Burner(<Special Issue>Advanced Fluid Information)

Combustion dynamics of laminar-premixed flames is experimentally studied using a slot burner. Sound levels and CH chemiluminescence intensity are measured for various mixture flow velocities and equivalence ratios of propane/air mixtures. Combustion instability is observed only for fuel lean conditions. The instability frequency increases with the mixture velocity and the measured sound level increases with the equivalence ratio as well as the mixture velocity. The nature of combustion oscillation is also investigated using a high-speed CCD camera and a periodic sudden extinction at the tip of flame caused by the interaction between flame and vortex-shedding process is identified as the source of noise emission.