Spray and prefilming characteristics of tangentially-injected prefilming injectors

A novel prefilming approach, known as tangentially-injected prefilming (TIP), has recently been employed in airblast injectors in low-emission aero-engine combustors. While TIP offers the advantages of a simplified fueling system and good fuel atomization, its inherent asymmetry associated with fuel injection and prefilming process poses a heightened risk of spray inhomogeneity if not well designed. To address this issue, this study conducted an experimental investigation on tangentially-injected prefilming airblast injectors, focusing on spray homogeneity, fuel circumferential distribution, and internal prefilming dynamics. Techniques such as laser diffraction spectrometry and shadowgraphy were employed to examine the characteristics of the spray and prefilming process. Two critical geometric parameters affecting the prefilming process, i.e., axial prefilming length and fueling hole diameter, were varied to assess their effects on spray homogeneity. The results identified two potential sources of spray inhomogeneities and elucidated their underlying mechanisms. It demonstrated that optimizing the axial prefilming length significantly improves spray uniformity. Furthermore, the complex dynamics of tangentially-injected prefilming were displayed for the first time and depicted through qualitative 3D modelling, providing deeper insights into the prefilming process.