Supersonic Mixing Enhancement Using Fin-Guided Fuel Injection

The mixing flowfields of transverse walled fuel injection with and without the guidance of a fin in a Mach 2.2 flow were experimentally characterized and compared. This study evaluated the ability of fin-guided injection to enhance fuel-air mixing while reducing shock-induced stagnation pressure losses. The nonreacting gaseous injection experiments used helium as a hydrogen surrogate and simulated four mass flow rate conditions to investigate the performance of the proposed injection scheme with variable jet momentum. The analysis of schlieren visualizations demonstrated a 100-200% increase in jet penetration for the fin-guided cases over the baseline 12 diameters downstream of the injection point. Wall pressure measurements were correlated to the schlieren results which showed that the strength of the jet-induced shock in the baseline was reduced by 33-47% by using the fin. A planar-Mie scattering method used to obtain cross-sectional views of the injection flowfields revealed that the fin was not only responsible for raising the fuel jet away from the wall but also enabled its vertical spreading. The present results demonstrate that this fin geometry can enhance mixing via increased penetration and spreading, reduce the strength of jet-induced shocks, and potentially displace the reaction zone away from the combustor wall.