Numerical investigation of effect on three-dimensional dual cavity in a scramjet combustor

This research explores the combustion process in supersonic combustors using steady-state numerical simulations, with a particular emphasis on strut- and cavity-based mixing techniques. The study reveals that shock waves emanating from the leading edge and recirculation zones generated by cavities significantly influence flame structure and stability, underscoring their importance in achieving stable combustion. Numerical simulations were conducted to examine the effects of dual cavity positioning on a Mach 2.0 airflow, with a baseline setup for comparison. The results were verified against experimental data, demonstrating the reliability of the simulation method. The study used a combination of steady-state RANS simulations, the SST k–[Formula: see text] turbulence model, species transport equations and the ideal gas assumption. The Finite Rate Eddy Dissipation model effectively captured the intricate dynamics of turbulence-chemistry interactions in the reacting flow. The strategic placement of dual cavities allows for investigation into the complex interactions of waves and shear layer mixing. Compared to the baseline model, the dual cavity configuration facilitates more complete combustion. When the dual cavities cause the shock train to move downstream of the strut injector, the combustion zone expands laterally due to intense interactions between shocks and shear layers. The presence of cavities alters the dominant frequencies and impacts the strength of coherent flow structures in the diverging section. The pressure loss for configurations C45 and C55 is approximately 33%, about 8% higher than the baseline case. Configuration C35, however, incurs a greater penalty, with a pressure loss of around 36%, or 17% above the baseline. Despite these losses, C45 and C55 show notable improvements in combustion efficiency and mixing length, making them promising design options. Optimal cavity positioning can enhance mixing and combustion efficiency while reducing total pressure loss.