Numerical Investigation of Transverse Hydrogen Injection Location Effects on Combustion Performance in a Strut-Cavity Scramjet Combustor

• Examination of combustor performance concerning the injector position. • Influence of cavity upstream injector position in scramjet combustor. • Injectors placed upstream of the cavity improve combustion and fuel-air mixing. • Upstream injectors caused an increase in total pressure loss up to 2.6%, and complete combustion occurs within the shortest span. This study investigates the impact of injector placement on combustion performance in a strut-cavity-based supersonic combustor. Steady-state simulations were conducted to examine the combustion process, focusing on the role of leading-edge shock waves and cavity-driven recirculation zones. The numerical approach was validated with experimental data, confirming its reliability. Results show that injector placement at the cavity's leading edge generates small-scale vortices near the strut injector base due to shock shear layer and fuel injection interactions. A strong compression zone forms in this region, indicating that injector placement significantly influences shock intensity. Total pressure loss increases slightly with CWNI (33.7% to 34.2%) and more substantially with CWI1 (35.9%) and CWI2 (36.4%). Strategic injector placement can enhance mixing and combustion efficiency while minimizing pressure loss.