Shock Waves for Enhanced Mixing in Scramjet Combustors
Shock Waves for Enhanced Mixing in Scramjet
Flow Research, Inc.
21414 68th Avenue South
Kent, WA 98032
Suresh Menon (206-872-8500)
LeRC -- NAS3-25332
For an efficient supersonic combustion ramjet (scramjet), mixing enhancement between
the incoming supersonic air and the injected fuel is essential. However, at hypersonic
flight speeds, the short residence time and decreased mixing rate cause deterioration
in the combustion efficiency as compared with lower speeds. A configuration recently
developed to promote rapid mixing in a supersonic flow is a single-step flame holder
with a wedge on the opposite supersonic passage wall to induce a weak shock. The
objective of this project is to evaluate the configuration as a means for rapid and
thorough mixing of the fuel with the supersonic air stream through interactions between
the shock wave and shear layer.
During Phase I, the interaction between a shock wave generated by a wedge and a
supersonic (Mach 2.5) mixing layer was investigated by observing the mixing between
two species (nitrogen and helium) downstream of a scramjet flame holder (i.e., rearward-facing
step). Schlieren flow visualization and Rayleigh scattering concentration measurements
indicate that significant spreading of the mixing layer may be occurring downstream
of the shock impingement region. It appears that the shock wave/shear layer interaction
allows the helium to diffuse more rapidly across the supersonic nitrogen flow.
Potential Commercial Application:
Potential Commercial Application: The flame holder design, the experimental data,
and the diagnostic instrumentation developed in this project will be provided to
NASA for practical evaluation in the scramjet engine.