Structure of Flat Flame Stabilized by an Air-Swirl

Abstract

When fuel is injected into the duct of a co-axial burner and a strong swirl is given to the outer air, two modes of flame, turbulent flame and flat flame, appear on the burner under some conditions If the exit is divergent, a stable flat flame may be realized, which features a compact and a high-density combustion. In the present study, the condition of forming such a flat flame mode was studied by measuring temperature, fuel mass concentration, and gas velocity at the burner exit. As a result, it has been suggested that the flat flame mode is formed if the centripetal force of the high-temperature combustion gases toward the burner rim exceeds that toward the burner axis.