A novel mixer design for gas-particle two-phase mixing and combustion in a wide Mach range

Wide-range flight capability represents a pivotal development trajectory in advanced propulsion technologies. Efficient gas-particle two-phase mixing and combustion in a wide Mach range is essential for maintaining the performance of the wide-range solid-fuel ramjet engine. To address the challenge, this study proposes a novel mixer design capable of effectively enhancing gas-particle mixing and combustion processes under variable flight conditions. Based on the numerical simulation validated by the experimental data, the performance enhancement mechanism of the mixer and the influence of key structural parameters (including rotation angle, length, and peak-to-valley distance) are investigated. The key findings include: (1) The increased rotation angle, reduced length, and enlarged peak-to-valley distance enhance mixing efficiency, achieving peak improvements of 115.4 % at Mach 3, and 68.8 % at Mach 6. However, excessive particle migration to the recirculation zone inhibits combustion under the Mach 3 flight condition due to the low ambient temperature. (2) Under the Mach 3 flight condition, combustion efficiency and specific impulse initially increase and then decrease with the increasing rotation angle, peaking at 15°. Performance in the Mach 6 flight condition remains stable beyond 15°. Reduced length produces similar effects to increased rotation angle. In the peak-to-valley distance range of 0.57R–0.77R, particles maintain favorable distribution. Increasing the distance enhances combustion under both flight conditions. (3) Structural optimization demonstrates the potential for combustion enhancement in a wide Mach range, achieving performance improvements up to 18.2 % and 15.6 % at Mach 3 and Mach 6, respectively.