Experimental Investigation on Global Flame Establishment in Wide-Mach-Range Supersonic Inflows

Reliable ignition and flame stabilization over a wide Mach number range remain major challenges for supersonic combustors. This study experimentally investigates kerosene ignition, global flame establishment, and flame stabilization in supersonic combustors with single- and dual-cavity flameholders. Experiments were performed in a direct-connect high-enthalpy wind tunnel at inflow Mach numbers of 1.60 and 2.52. High-speed schlieren imaging, time-resolved [Formula: see text] chemiluminescence, and wall pressure measurements were used to characterize flow structures, flame evolution, and pressure response. Results show that a higher inflow Mach number mainly alters shock structure and increases reaction intensity, whereas the dual-cavity configuration introduces multistage shock interactions and serial recirculation zones that improve fuel mixing. Under high-Mach-number conditions, flame establishment is governed by rapid chemical kinetics and occurs on a sub-millisecond timescale. The dual-cavity configuration further accelerates this process through intercavity combustion coupling. Under low-Mach-number conditions, flame establishment is limited by fuel evaporation and mixing. The single-cavity configuration fails to sustain a global flame, while the dual-cavity configuration extends flame stability through a mixing-favorable flow organization. The dual-cavity configuration also redistributes heat release streamwise, reducing local pressure peaks and broadening the high-pressure region, which suggests an improved margin against localized thermal choking.