Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Department of Aeronautics and Astronautics

First Advisor

Douglas D. Decker, PhD.


The scramjet isolator is a duct in which pressure increases from the inlet to the combustor via a shock train. The shock train leading edge (LE) location must be controlled in an operational scramjet. A LE location measurement algorithm, dynamic model, and control algorithm were developed and validated with 500 frame per second (FPS) shadowgraph images in this research. The test apparatus consisted of a direct connect cold-flow high-speed wind tunnel with an adjustable ramp mounted in the tunnel floor. Ramp adjustments changed the tunnel cross-sectional area which changed the tunnel back pressure and LE location. Wall-mounted pressure transducers and a high-speed camera were used for data collection. The LE location measurement algorithm is the first with results validated using 500 FPS shadowgraph images to measure the LE location with root mean square (RMS) errors less than 20% of a duct height, D, although the transducers were separated by 50% of D. The developed and validated dynamic model is the first with error RMS values less than 24% of D. Finally, the first control algorithm capable of controlling the LE location within 50% of D was developed and validated.

AFIT Designator


DTIC Accession Number