COMPARISON OF PHYSICAL AND AERODYNAMIC RAMPS AS FUEL INJECTORS IN SUPERSONIC FLAW

An experimental investigation was conducted to compare the supersonic mixing performance of a novel flush-wall aerodynamic ramp injector wit h that of a physical ramp injector, The aerodynamic ramp injector cons ists of nine hush-wall jets arranged to produce fuel-vortex interactio ns for mixing enhancement in a supersonic crossflow. Test conditions i ncluded a Mach 2.0 crossflow of air with a Reynolds number of 3.63 x 1 0(7) per meter and helium injection with jet-to-freestream momentum fl ux ratios of 1.0 and 2.0, Conventional probing techniques, including s pecies composition sampling, were employed to interrogate the flowfiel d at several downstream locations, Results show that with increasing j et momentum the aeroramp exhibited a significant increase in fuel pene tration, whereas the physical ramp showed no discernible change, The n ear-field mixing of the aeroramp was superior to that of the physical ramp; however, the physical ramp reaches a fully mixed condition at ap proximately half the distance of the aeroramp, As the jet momentum was increased, the far-field mixing performance of the aeroramp approache d that of the physical ramp, In all cases the total pressure loss incu rred with the aeroramp was Less than that caused by the physical ramp, For both injectors the total pressure loss decreased with increasing jet momentum, It was concluded that, although physical ramps may provi de better far-field mixing, properly designed flush-wall injection can provide comparable mixing performance while avoiding the practical pr oblems associated with an intrusive geometry in a scramjet combustor.