High Mach Number Operation of Accelerator Scramjet Engine

Accelerating scramjet engines could efficiently propel the second stage of an access to space system. A scramjet engine designed to accelerate from Mach 5 to 10 requires geometric features to assist performance at either end of the trajectory, which negatively affects the performance at the opposite end. This work discusses the necessity of these features and their implications on performance. A fueling configuration for the high Mach number operation of an accelerator scramjet is introduced. This injection scheme was designed for a ground test model, at small scale. The high Mach number performance of the engine is categorized at on- and off-design conditions. Its extension to a full-scale engine was also investigated. The full-scale engine generates thrust at Mach 10, despite a reduced area-ratio nozzle. Across all conditions simulated, the engine and fueling scheme has robust performance, although it required a reduction of inlet fueling at scale.