Date of Award


Document Type


Degree Name

Master of Science


Department of Aeronautics and Astronautics

First Advisor

Ralph A. Anthenien Jr., PhD


A numerical analysis and design optimization of the Ultra Compact Combustor (UCC) has been conducted. The UCC is a combustor designed to incorporate high-g loadings to increase flame propagation speed while reducing flame length, thereby helping to significantly reduce the size of a combustor. A commercial CFD package with a k-Ⲉ turbulence model has been used to develop design rules for the construction of future UCCs. There have been several versions of UCC that have been designed, built and tested by AFRL/PRTC. Since real experimental tests are expensive and construction time is prohibitive to test many different design configurations, CFD modeling of the UCC is used to speed up the design optimization process while reducing the overall costs. The CFD models have been validated by comparison to data from recent experimental tests. The use of periodic sections and grid independence were validated as well. Modifications to the physical configuration were then modeled using CFD. Shortening the cavity to 38.1 mm and then to 25.4 mm was investigated. On the shortest cavity configuration the air inlets were canted to higher angles, from initially 37° to 45° and then 55°. Next, the radial vane was aerodynamically improved with a rounded aft corner in addition to air inlets introduced into the leading edge of the vane. The final configuration included increasing the vane height from the baseline dimensions. The modified combustors were all compared using exhaust samples, combustion efficiency, pattern and profile factors, as well as flow visualization. The shortening of the cavity was found to reduce the harmful emissions in the exhaust. Increasing the angle of the air inlets further improved the emissions by increasing the residence time of the fuel particles in the cavity. Aerodynamically improving the vane reduced the pressure loss of the combustor by up to 25%. The increased vane height was an initial step in scaling up the UCC to operational configurations. Of the models in this research, the most improved configuration was found to be the 45° air inlet on the shortest cavity.

AFIT Designator


DTIC Accession Number