Numerical investigation on the combustion characteristics of boron powder fuel under H2/Air flame in a supersonic cavity-based combustor

To explore the combustion organization rules of powder-fueled scramjets, this study conducted numerical simulations to investigate the combustion characteristics of boron particles in the supersonic combustion chamber, while varying the injection scheme, cavity structure, and hydrogen flow rate. The results demonstrate that the addition of a small flow of hydrogen assists in the ignition and combustion of boron particles when combined with incoming air in a supersonic combustor. Compared to the injection scheme at the wall of the combustor upstream of the cavity, the proposed intra-cavity injection scheme significantly improves the combustion efficiency of boron particles. Moreover, the combustion efficiency of boron particles improves further as the cavity depth increases. Successful ignition and combustion of boron particles occur when the solid-to-gas ratio (SB/GH) of boron powder fuel to hydrogen is below 20 at a constant boron powder fuel mass flow rate. The highest combustion efficiency of boron particles is observed at an SB/GH ratio of approximately 12.5. Further decreasing SB/GH no longer improves the combustion efficiency of boron particles. The findings of this research can provide valuable insights for the engineering application of combustion organization schemes in powder-fueled scramjets utilizing boron powder as fuel.