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

Abstract

Novel low swirl concepts provide a promising approach to ensure stable flame anchoring over an extensive operation condition range, necessary for optimising compact designs for liquid fuel combustors as used in hybrid aero-engine or micro gas turbines in terms of scalability and flexibility. The current study utilises 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 zero to 45° for co- and counter-direction against the orientation of the liquid sheet ejected from the pre-filming pressure swirl injector. The spray atomization in swirl afflicted air jet is demonstrated by phase Doppler interferometry and shadowgraphy. The combustion process is analysed using OH* -chemiluminescence 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, non-monotonic decomposed mode energy with considerable NOx reduction is observed.