Experimental Investigation on Dilution of Disk-Shaped Pressure Gain Combustor Exhaust

Abstract

The benefits of detonation over deflagration in a combustion-based thermodynamic cycle engine, despite increased dilution cooling requirements for a fixed turbine inlet temperature, were assessed with a thermodynamic model. The experiments demonstrated that an axially compact disk-shaped pressure gain combustor can sustain detonation operation at dilution ratios of up to 1.5 tested; hence, they are suitable for integration with downstream devices. The range of operable equivalence ratios was generally unaffected by dilution and showed single-wave operation for [Formula: see text]. The paper also presents and adopts an alternative method for estimating total temperatures and combustion efficiencies at the exhaust by using thermocouples in the diluted flows. The combustion efficiencies at the combustor exhaust were estimated to be between 65.4 and 73.8% for single-wave mode operation and increased to about 81.4% at the end of the nozzle due to continued combustion after mixing. The converging combustor geometry was also evaluated to reduce pressure fluctuations more than additional dilution air, demonstrating suitability for integration with conventional turbines.