On the Blockage Effects of the Diffusion Burner Flame Stabilized by a Rim Type Flameholder

Abstract

Concerning a diffusion flame stabilized by the rim type flameholder in the two-dimensional duct in which air flows, the effects on a few blockage ratios ("BR"s) for the flame configuration, the ratio of air flowing into the reaction zone through the flame boundary, and the blow-off velocity were studied experimentally. The main conclusions obtained are as follows : (1) It is clear that the flow pattern close to the flameholder is considerably similar to that of the premixed gas flame stabilized by a bluff body when the velocity of the fuel jet is smaller than that of the free stream as in the present experiment. (2) A part of fuel flows into the recirculation zone (RZ) immediately. But the greater part of fuel flows from the nozzle to both sides of the flameholder and mixes with a part of the free air stream at the shear layer. RZ plays an important role for flame stabilization. (3) The ratio of air flowing into the reaction zone through the flame boundary for the total air flow entering the duct is about 20% at BR=0.5 and is 0% at BR→0. The percentage variation between the above "BR" s is linear.