Establishment and stabilization of ethylene-air flames in a strut-fueled supersonic combustor: with and without oxygen supplementation

This study investigates the ignition characteristics and stable combustion behavior of ethylene fuel in a strut-fueled scramjet combustor under supersonic conditions. The role of oxygen supplementation at the strut's trailing edge in enhancing combustion was examined. Through combined experimental and numerical approaches under Mach 2.8 inflow conditions at the isolator inlet, flame dynamics and pressure distributions were characterized using high-speed imaging and pressure measurement techniques. Results demonstrate that flame stabilization without oxygen supplementation relies solely on shear layer combustion at the strut extremities. Oxygen supplementation significantly enhanced mixing efficiency, inducing a dual-mode combustion pattern combining shear layer and strut wake flames while reducing flame establishment time by 78.8%. Further analysis reveals that supplying oxygen extends the ignition boundary of the global fuel-air equivalence ratio from 0.4 to 0.55. Spatiotemporal analysis of flame imaging identifies an attenuation oscillation process in combustion intensity post-oxygen supplementation. These findings provide critical insights for optimizing flame stabilization strategies in scramjet combustor design.