Abstract: With the continuous expansion of the flight speed and altitude envelopes of air-breathing hypersonic vehicles, the core technical challenges faced by solid powder scramjets have shifted from simply pursuing improved blending combustion efficiency to deeper wave system regulation and flow control. Based on the Euler-Lagrange framework, this paper establishes a numerical model and method for compressible gas-solid two-phase turbulent flow, investigates the flow control mechanism of powder fuel pre-injection in a wide-speed-range inlet, and analyzes the influence mechanisms of different incoming flow Mach numbers (Ma∞ = 4~7) and powder fuel transport solid-gas ratios (SR = 2~14) on the flow characteristics, performance, and powder fuel mixing process of the inlet. Through a systematic analysis of the interaction mechanism between the inlet wave system structure and the boundary layer under pre-injection, it is found that pre-injection can reconstruct the wave system structures of the internal and external compression sections, which improves the inlet pressurization performance while also reducing the total pressure recovery performance. By establishing the intrinsic correlation between the transport solid-gas ratio and the mixing efficiency of powder fuel, the formation mechanisms of the high vorticity region in the gas-solid two-phase shear layer, the high vorticity region in the wake, and the particle phase stagnation region at the shoulder are revealed, and the particle dispersion characteristics and the evolution laws of the vortex structure in the above regions are clarified.

Key words: Solid powder scramjet, Pre-injection, Transport solid-gas ratio, Vortex structure, Mixing efficiency