Low Swirl Effect on Compact Spray and Combustion Systems Using Additive Manufactured Dual Airblast Injectors

Novel low swirl concepts provide a promising approach to ensure stable flame anchoring over an extensive operation condition range, necessary for optimizing compact designs for liquid fuel combustors as used in hybrid aero-engine or microgas turbines (MGTs) in terms of scalability and flexibility. This study utilizes seven different additive manufactured low swirler integrated into a dual airblast injection concept to delineate the influence of high momentum swirling air jet on spray atomization and combustion performance. The developed injector is designed for vane angles from 0° to 45° for co- and counterdirection against the orientation of the liquid sheet ejected from the prefilming pressure swirl (PS) injector. The spray atomization in swirl afflicted air jet is demonstrated by phase Doppler interferometry and shadowgraphy. The combustion process is analyzed using OH∗-chemiluminescence (CL) imaging and emission measurements. The results show that a circumferential gaseous flow acting on the wall-film amplifies the radial fuel penetration and atomization. The latter produces robust spray dispersion in response to variations of operational conditions. The effect of low swirl injection on combustion process of kerosene flames leads to a noticeably more compact and intensified heat release zone. In addition, nonmonotonic decomposed mode of energy with considerable NO_x reduction is observed.