Premixed Flame Stabilization in an Axisymmetric Curved-Wall Jet

Abstract

The flame stabilization and flow field characteristics of premixed flames in an axisymmetric curved-wall jet utilising the Coanda effect are investigated experimentally. The advantages of this flow field include the formation of a recirculation zone near the burner tip and the enhancement of turbulence by the radially inward velocity component of the jet. Results show that the blow-off velocity is much higher and the flame height is reduced significantly as compared to a tube jet burner. The condition of maximum blow-off velocity occurs when the mixture is rich and the equivalence ratio increases as the nozzle exit area decreases. Velocity fields measured by laser Doppler velocimetry confirm the existence of a recirculation zone and flame stabilization in this zone. Flashback is effectively prevented by adjusting the slit width in the axisymmetric curved-wall jet burner. The combined effects of flame height reduction, extended blow-off condition, prevention of flashback, and easy controllability of the flame height through the adjustment of slit width provide promising characteristics for applications in practical burner design.