Abstract: To evaluate the feasibility of enhancing thrust performance in hydrocarbon-fueled scramjet engines through sec-ondary combustion by injecting magnesium powder to fully combusted exhaust gases, a powder-enhanced direct-connect scramjet experimental system was developed. Experiments were conducted under simulated flight condi-tions of Mach 6.0 at an altitude of 30 km. An improved thrust measurement method was employed to obtain the thrust and combustion performance parameters of the powder-based scramjet combustor. The study focused on the feasibility of the powder enhanced scramjet, the effects of the powder-gas ratio, and the powder residence distance on thrust performance. Results demonstrated the viability of the proposed scheme, with magnesium powder primari-ly reacting with water vapor and carbon dioxide in the exhaust gases, where water vapor was the dominant reactant. When 13% magnesium powder was injected, the engine achieved a specific thrust gain of 86.6% and a combustion efficiency of 65.1%. Considering both engine size and performance, it is recommended to design the powder resi-dence distance-to-combustor length ratio around 0.62.

Key words: metal fuel, hydrocarbon fuel, powder scramjet, magnesium powder, thrust performance