Development and Characterization of a Liquid-Fuel-Based Full Annular Ultra-Compact Trapped Vortex Combustor

In this paper, a single cavity trapped vortex annular combustor for a small turbojet was developed and experimentally characterized with varied different airflow conditions. Three different airflows: main, forward cavity, and reverse cavity, were controlled independently to investigate the effects of enhanced vortex trapping from each flow. Liquid fuel spray nozzles were used for fuel atomization, and a glow plug served as the ignition source. Time-averaged OH* chemiluminescence imaging was performed to identify reaction zones inside the combustor. The spatial distribution pattern of the heat release zones varied under different airflow conditions. Also, the lean blowout characteristics of the combustor under different cavity airflow conditions on were investigated. The lean blowout was not dependent on the velocity ratios of the cavity flows but was dependent on the cavity residence time. Furthermore, the combustor’s combustion efficiency was calculated under different flow conditions. At the same fuel flow rate, the efficiency decreased from 60.7 % to 55.7 % as the velocity ratio of the reverse cavity air to the forward cavity air increased. The combustor achieved the best combustion efficiency of 68% at the highest forward cavity air velocity.