Experimental Study on Kerosene Combustion Under Ambient, Near-Critical, and Supercritical Conditions for Aero-Engine Applications Based on CCA Technology

The present work adopts a cooled cooling air (CCA) technology based on the integrated aircraft/engine thermal management concept, by coupling an air-kerosene heat exchanger with a high-temperature combustor. Using the heat exchanger, kerosene is preheated to near-critical and supercritical conditions, and the combustion characteristics of kerosene at ambient, near-critical, and supercritical states were investigated. The combustion performance tests were carried out in a model combustor under varying fuel-to-air ratios (FARs) and different kerosene injection conditions. The experimental results show that when the combustor’s FAR is increased to 0.055, the supercritical kerosene exhibits significant advantages over kerosene of the ambient state. The comparison of the combustion performance parameters shows that the combustor outlet temperature distribution factor (OTDF) and radial temperature distribution factor (RTDF) decrease by 52.26% and 51.07%, respectively; in terms of the pollutant emissions, the CO emission index (EI_CO) and unburned hydrocarbon emission index (EI_UHC) are reduced by 66.63% and 68.33%, respectively, while the NOx emission index (EI_NOx) increases by 76.26%, and the combustion efficiency improves by 2.0%. It is noteworthy that once the kerosene reaches the supercritical state, the threshold for the optimal FAR in the combustor rises to 0.055, which carries the significant engineering value for enhancing an aero-engine combustor’s operability across variable conditions and its low-emission combustion performance.