Research progress on supercritical kerosene injection mixing and combustion processes

Regenerative cooling technology provides thermal protection for the combustion chamber of scramjet engines through active heat exchange. However, the kerosene, after absorbing high-temperature heat, transits from a liquid to a supercritical state, yielding a physicochemical properties. This transition leads to substantial variations in supersonic combustion processes involving supercritical kerosene injection. This paper systematically reviews research progress on the physicochemical properties of supercritical kerosene and its injection-mixing-combustion processes. First, it introduces the application of supercritical kerosene in scramjets and current challenges. To address these issues, the study analyzes the physicochemical characteristics of China’s domestic RP-3 kerosene under near/supercritical conditions within regenerative cooling channels and nozzles at different temperatures. It further compares the advantages and limitations of methods such as experimental measurements, component surrogate models, modified equations of state, and machine learning for obtaining kerosene thermophysical property parameters. Subsequently, the paper reviews advancements in supercritical kerosene injection and mixing processes under various environmental conditions. Notably, existing studies primarily focus on mixing mechanisms in static environments, coaxial injection configurations, and transverse jet mixing under low-speed crossflow conditions, while research on high-speed crossflow conditions remains limited. Additionally, the impact of mixing enhancement schemes on supercritical kerosene injection-mixing processes has not been explored. Finally, the study summarizes key findings regarding supercritical kerosene combustion characteristics, proposes optimizing injection parameters to mitigate combustion oscillations induced by phase transitions, and suggests future research directions to establish coupled mixing/combustion models applicable across a wide range of velocities.