Date of Award


Document Type


Degree Name

Master of Science


Department of Aeronautics and Astronautics

First Advisor

Paul I. King, PhD


Cavity-based fuel injection and flame holding found in hydrocarbon-fueled scramjet applications are of interest. The Air Force Research Lab (AFRL) and the Air Force Institute of Technology (AFIT) at Wright-Patterson Air Force Base in Ohio are investigating the enhancement of fuel-air mixing with small pylons that project into the supersonic flow upstream of a flame holder cavity. This follows previous qualitative (Mie scattering and NO-PLIF visualizations) results which suggested that injection behind pylons, may improve fuel-air mixing. Three pylons geometries (medium, tall, and wide) shaped as thin triangular wedges with a 30o inclination angle were tested and compared to baseline transverse injection without pylons at two injection pressures. The AFRL provided facility, was a supersonic (Mach 2) continuous flow wind tunnel with existing cavity and pylon setup. The goal was to measure mixing efficiency and shock loss of each pylon setup for comparison to the baseline condition of transverse injection without pylons. Non-reacting flow was measured using conventional probing and spontaneous Raman spectroscopy to obtain pitot pressure, total temperature, cone-static pressure and species concentration over the cavity downstream of the injection. Results demonstrated that pylons increase fuel penetration, while not adding significantly to shock losses or overall mixing compared to baseline.

AFIT Designator


DTIC Accession Number