Role of Fuel Sweeping Injection in Flame Structure of Bluff-Body Flames

A novel self-excited sweeping nozzle (SSN) based on fluidic oscillators is proposed. It is expected to significantly enhance flame stability and combustion efficiency of afterburners as compared to the traditional plain orifice nozzle (PON). Both hydroxyl (OH)/kerosene–planar-laser-induced fluorescence and particle imaging velocimetry are conducted on bluff-body stabilized kerosene spray flames with different nozzles. The fuel distribution, flame structure, and flowfield are obtained at different fuel–air ratios and mixing distances, as well as under identical air velocity and temperature measurements ([Formula: see text] and 600 K). The results demonstrate that the SSN significantly enlarges the flame area and mitigates local extinction. Three distinct fuel–flame interaction modes are identified. Compared to the PON, the flame with a SSN exhibits a lower frequency of local extinction, which is primarily due to its superior initial atomization quality and more dispersed fuel distribution, whereas fuel is concentrated in the central plane for the PON. The local extinction introduced by high-concentration kerosene clusters reduces significantly for the SSN. Furthermore, the closer proximity of the fuel distribution to the shear layer enhances fuel transport to the flame front for reaction. It leads to a larger flame area and a higher combustion intensity of spray flames with the SSN, hence improving their resistance to strong turbulent stretching.