A novel strut injector with lateral extruded nozzle for efficient hydrogen mixing in supersonic combustors

Efficient fuel–air mixing is a critical requirement for stable combustion in supersonic combustors, where residence times are extremely short and flow compressibility is significant. In this study, the mixing performance of three hydrogen injection configurations downstream of a strut injector equipped with an extruded rod is numerically investigated. The configurations include discrete multi-port lateral injection, distributed multi-port injection, and a continuous laterally injected slot that is axially distributed along the rod. Three-dimensional Reynolds-averaged Navier–Stokes (RANS) simulations are performed using ANSYS Fluent with the SST k–ω turbulence model, coupled with species transport for an ideal-gas mixture.The results show that discrete injection configurations generate stronger shock–jet interactions and larger recirculation zones, which enhance local turbulence but lead to non-uniform fuel distribution and increased flow disturbance. In contrast, the continuous lateral slot injector produces a smoother shear layer, weaker shock structures, and a more homogeneous hydrogen distribution downstream of the strut. Quantitative analyses of circulation strength, fuel–air mixing efficiency, and total pressure loss indicate that the continuous slot configuration achieves the highest overall mixing efficiency with an acceptable aerodynamic penalty.Overall, the proposed laterally injected, axially distributed slot on an extruded rod provides an effective and robust approach for enhancing hydrogen–air mixing in supersonic combustors, offering valuable guidance for the design of advanced strut-based injectors in scramjet applications.