Comparative Analysis of Oxygen- and Air-Assisted Atomization in Supersonic Combustion

This study presents an experimental investigation of oxygen-assisted atomization as a novel strategy for supersonic combustion control, benchmarked against air-assisted atomization. Experiments were conducted in a Mach 2.5 flow with liquid kerosene injection with a 1580 K total temperature and 0.93 MPa total pressure at an equivalence ratio of 0.6, varying gas-to-liquid mass flow rate ratios (GLRs). CH* chemiluminescence was employed to identify combustion zones. Increasing GLR enhances combustion performance and regulates flame stabilization modes. At low-to-moderate GLRs (10–14%), cavity-shear-layer-driven combustion manifests as flame oscillations (265–278 Hz) between cavity and jet wake regions. Transitioning to high GLR (20%) stabilizes combustion in jet wakes, suppressing low-frequency oscillations but inducing broadband fluctuations. Furthermore, oxygen-assisted atomization demonstrates synergistic physicochemical enhancement at [Formula: see text]: improved atomization quality strengthens fuel–air mixing (physical effect), while localized oxygen enrichment accelerates reaction kinetics (chemical effect). This dual mechanism shifts the flame upstream and expands the reaction zone, yielding a peak static pressure increase exceeding 10% and a 23.7% improvement in thrust augmentation compared to air-assisted cases. However, in the local low-temperature region, oxygen tends to combine with H and OH radicals to form [Formula: see text], inhibiting the reactivity of the chain reaction.