Date of Award


Document Type


Degree Name

Master of Science in Aeronautical Engineering


Department of Aeronautics and Astronautics

First Advisor

Richard D. Branam, PhD


The Ultra-Compact Combustor (UCC) is currently under investigation at the Air Force Institute of Technology (AFIT) and Air Force Research Laboratory’s Propulsion Directorate. The combustor is a small-scale, axi-symmetric, atmospheric pressure, laboratory combustor with an outer circumferential cavity in which the flame is stabilized by a highly accelerated swirled flow. UCCs will enable aero gas turbine reheat cycle engines and significantly shorten conventional aero gas turbine engines. The experiments of this work utilized the AFIT small-scale combustion diagnostics facility, investigating a sector model of the UCC. The research objectives were to perform an addition to the COAL lab laser diagnostic system, validation of this system, and characterization of a small-scale UCC sector model using hydrogen, propane and traditional as well as synthetic jet fuel. Two-line planar laser induced fluorescence (PLIF) of a laminar premixed hydrogen-air flame validated the laser system. OH species concentrations were measured. Flame temperatures between 1650 and 2400 K were measured with a two-line fluorescence technique using different transitions in the (1,0) band of the OH (A-X) electronic transition system with 5-8% error achievable. Comparisons to existing research prove accuracy. Instantaneous temperature measurements were determined with lower confidence in results. Flame location studies revealed swirl within the UCC main channel increasing mixing. UCC and Hencken burner operational procedures were updated and improved where necessary. A UCC sectional model re-design is needed to equalize cavity exit areas for curved and straight sections. An initial comparison of synthetic jet fuel and traditional jet fuel emissions data shows higher combustion efficiency with synthetic fuel. Future work will involve using PLIF to further study the cavity-vane interactions of the UCC.

AFIT Designator


DTIC Accession Number