Structure of a Flat Flame Stabilized by an Air Swirl

By injecting fuel into the duct of a co-axial burner and imparting a strong swirl on the outer air, two modes of flame, turbulent flame and flat flame, appear on the burner under some conditions. The conditions under which a flat flame mode, which features a commpact and a high-density combustion, was formed were studied by measuring temperature, fuel mass concentration, and gas velocity at the burner exit. The flat flame mode was found to be formed when the centripetal force of the high-temperature combustion gases toward the burner rim exceeded that toward the burner axis.