Comparison of Physical and Aerodynamic Ramps as Fuel Injectors in Supersonic Flow

TLDR

The study compares the supersonic mixing performance of a novel e‑ush‑wall aerodynamic ramp injector with that of a conventional physical ramp injector. The experiment used a Mach 2.0 cross‑flow with nine e‑ush‑wall jets at jet‑to‑freestream momentum ratios of 1.0 and 2.0, helium injection, and species‑composition sampling to probe downstream mixing. Results show that higher jet momentum increases fuel penetration and reduces pressure loss for the aerodynamic ramp, which achieves superior near‑field mixing but requires longer distance for full mixing, while the physical ramp mixes faster but incurs higher pressure loss; overall, properly designed e‑ush‑wall injection can match or exceed the physical ramp’s performance without intrusive geometry.

Abstract

An experimental investigation was conducted to compare the supersonic mixing performance of a novel e ush-wall aerodynamic ramp injector with that of a physical ramp injector. The aerodynamic ramp injector consists of nine e ush-wall jets arranged to produce fuel‐ vortex interactions for mixing enhancement in a supersonic crosse ow. Test conditions included a Mach 2.0 crosse ow of air with a Reynolds number of 3.63 10 7 per meter and helium injection with jet-to-freestream momentum e ux ratios of 1.0 and 2.0. Conventional probing techniques, including species composition sampling, were employed to interrogate the e owe eld at several downstream locations. Results show that with increasing jet momentum the aeroramp exhibited a signie cant increase in fuel penetration, whereas the physical ramp showed no discernible change. The near-e eld mixing of the aeroramp was superior to that of the physical ramp; however, the physical ramp reaches a fully mixed condition at approximately half the distance of the aeroramp. As the jet momentum was increased, the far-e eld mixing performance of the aeroramp approached that of the physical ramp. In all cases the total pressure loss incurred 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 provide better far-e eld mixing, properly designed e ush-wall injection can provide comparable mixing performance while avoiding the practical problems associated with an intrusive geometry in a scramjet combustor.