Experimental and numerical study on the development process and flow characteristics of powder fuel jet in the powder fuel scramjet

The injection process of powder fuel directly affects the scramjet operating performance. This study analyzes gas-particle two-phase flow during powder fuel injection. The macroscopic behavior of powder fuel jets under different injection pressure conditions is characterized using the high-speed shadow imaging technology. Simultaneously, the coupled model of computational fluid dynamics-discrete element method is employed to determine the experimental conditions, and the flow field structure and gas-particle interactions are analyzed. The results show that the development of powder fuel jets mainly occurs in three stages: the low-speed development stage, the high-speed development stage, and the stable stages. A long transition period exists between different stages, and the transition time decreases with increasing injection pressure. In the low-speed development stage, the powder fuel jet initially develops slowly and then develops rapidly. In the high-speed development stage, the jet initially develops rapidly and then develops slowly. The jet in the stable stage is classified into the powder particle, fluidized gas, and free flow regions. The distribution range of the particles decreases with increasing injection pressure. The fluidized gas velocity and drag force curve on the axis experience many fluctuations, and the particle velocity is almost always accelerated. Fluidized gas velocity, drag force, particle velocity, and particle acceleration distance increase with the injection pressure.