Numerical Investigation of Alternate Fuel Injection Strategies in a Scramjet Combustor

Supersonic combustion in scramjet engines is a vital phenomenon where effective air-fuel mixing is essential for stable performance, which is highly influenced by injection methodologies. This study analyzes a hybrid parallel-transverse injection in a strut-based scramjet via 3D CFD, showing deeper penetration, swirl generation, recirculation, and significantly enhanced air-fuel mixing. Results demonstrate that the angled injection alone amplifies whirling strength by eight times, while the hybrid configuration (upward–parallel–downward–parallel, U–P–D–P) attains a tenfold improvement relative to the DLR reference model. As a result, the U–P–D–P model demonstrates a threefold increase in turbulent kinetic energy, twice the H2O mass percentage, and a 32% increase in temperature. Moreover, optimal mixing and combustion transpire 13% and 40% earlier along the combustor length, respectively, underscoring the efficacy of the proposed hybrid injection technique.