Soot studies of laminar diffusion flames with recirculation zones

Dynamic lifted flame in centerbody burner

“…These recirculation zones also influence the sooting characteristics of the burner. Three sooting structures; namely, filled, donut-shaped, and ring-shaped structures, were observed in previous studies [2]. Those different sooting structures were achieved by diluting the fuel and oxidizer jets with nitrogen while maintaining the ethylene + N 2 and air + N 2 flow rates constant, which mean that the average velocities at the exit of the central fuel and annular oxidizer jets (the inlet to the burner) are also held constant.…”

“…2 and is similar to that used for studies of dynamic flames [23]. A schematic diagram of the burner is shown in Fig.…”

“…The Strategic Environmental Research and Development Program (SERDP) office has started a comprehensive fundamental soot research program involving a suite of burners [2]. Complexity of these burners progressed in a way that the effects of chemical kinetics, diffusion, flame stretch, recirculation, and turbulence on the formation of soot can be investigated systematically.…”

“…The centerbody burner [2], one of the few designs selected for studying soot, consists of an annular oxidizer jet and a central fuel jet separated by a bluff body. The formation of recirculation zones in this burner [4] provides a mechanism for decoupling various soot processes and investigating them individually.…”

“…The formation of recirculation zones in this burner [4] provides a mechanism for decoupling various soot processes and investigating them individually. Initial experiments performed by varying the amount of dilution with nitrogen in the fuel and/or annular jets [2] suggested that very different flames with filled, donutshaped, or ring-type soot layers could be obtained. Recent experiments have further revealed that a lifted flame with a column of soot extending into the relatively cold regions between the flame base and the face of the bluff body can also be obtained.…”