Performance evaluation of a backward-facing H 2 -fueled supersonic combustion chamber with dual-strut injector: efficiency and shock wave analysis

Abstract While scramjets offer promising advantages such as reduced mechanical complexity and high thrust-to-weight ratios, their performance is severely constrained by extremely short residence times for fuel-air mixing and combustion. Efficient flame stabilization and rapid mixing remain two of the most critical challenges in this domain. One of the most effective methods to address these challenges involves the use of strut-based fuel injectors, which simultaneously deliver fuel and promote turbulence through shock wave interactions and vortex formation. However, the performance of these injectors depends heavily on their geometric configuration. This current study presents a comprehensive computational fluid dynamics (CFD) study aimed at evaluating the impact of backward-facing strut injector design parameters, including tip angle, step height, and spacing, on shock wave structure, mixing efficiency, and combustion characteristics in a scramjet combustor operating at Mach 2.5 with hydrogen fuel. The simulations are conducted using ANSYS Fluent with a density-based solver, incorporating the SST k–ω turbulence model and a Finite-Rate Eddy-Dissipation (FRED) chemical reaction model. High combustion efficiency was observed, increasing from 98.5 % at Mach 2–99.9 % at Mach 3.