Experimental investigation on the spray structure of supercritical aviation kerosene in a swirling flow field

In advanced aeroengines with higher inlet temperature, the cooling capacity of kerosene should be fully used, which turns kerosene into supercritical. The spray features of supercritical kerosene make the mixing process of supercritical kerosene with air different from that of subcritical kerosene. In this work, the spray of supercritical kerosene in a swirling flow field is investigated experimentally. The spray characteristics of supercritical kerosene are obtained using the schlieren technique. The instability of the jet morphology is analyzed using proper orthogonal decomposition (POD) method. The results prove that the combustor head structure significantly affects the overall spray morphology. A “packet structure” caused by density stratification is observed in the spray, which suppresses the circumferential diffusion of the jet. The “packet structure” is highly correlated with the airflow speed. The structural parameters of the supercritical kerosene jet are not sensitive to the changes in kerosene injection pressure, which, however, has a positive correlation with injection temperature. The main cause of the instability of the jet morphology in supercritical kerosene jets is the formation and shedding of vortices on the jet surface, which can be intensified by condensation. Density stratification suppresses shear layer instability, stabilizing the “packet structure” during the injection.