Influence of boron particle diameter on combustion process of gel scramjet

High-energy gel propellants applied to scramjet engines can effectively enhance combustion chamber efficiency and overall performance, which has a favorable application prospect in the hypersonic vehicle field. In this paper, numerical investigations are carried out on the combustion process of the boron-loaded gel fuel scramjet. Turbulent flow is simulated based on the standard k–ω model, and the motion of boron particles is solved using the discrete phase model. A surface reaction model is used to calculate the combustion process of the boron particles and gel. The comparison between numerical results and experimental data confirms the validity of the multiphase-coupled combustion model for a boron-dodecane gel scramjet engine. Based on this comparison, the variation patterns of engine combustion efficiency, temperature rise efficiency, cavity performance, and mass specific impulse under different boron particle diameters are investigated. The study shows that with increase in the boron particle diameter, the combustion chamber and temperature rise efficiencies initially increase and then decrease, whereas the specific impulse and total pressure recovery coefficients generally show a gradually decreasing trend. When the boron particle diameter is 45 μm, the temperature rise efficiency, combustion efficiency, and mass exchange rate reach their maximum values of 70.19%, 67.22%, and 34.60%, respectively. In summary, these research results provide a reference for the design optimization of boron gel scramjet engines.