Test on combustion and deposition characteristics of aluminum-based powder-fueled ramjet

The deposition of combustion products in powder-fueled ramjet will aggravate the ablation of thermal protection materials, change the internal structure and size of the engine, and seriously affect the engine performance. Therefore, the combustion and deposition characteristics of aluminum-based powder-fueled ramjet are investigated by ground direct connection test, and the micro-morphology and composition of deposition at different positions are analyzed. The results show that the deposition in the combustion chamber is mainly distributed in the nozzle contraction section and the secondary air inlet. With the increase of air-fuel ratio, the pressure fluctuation of combustion chamber decreases gradually, and the combustion efficiency of engine increases continuously, up to 95%. Increasing air-fuel ratio has little effect on the deposition distribution, but it can effectively reduce the deposition rate in the combustion chamber and improve the specific impulse efficiency. At the head of the combustion chamber, the deposit is granular, mainly composed of aluminum, and the deposit downstream of the secondary air inlet is block or strip, mainly composed of alumina, and there are two different crystal forms. There are several different deposition behaviors after the particles collide with the wall, such as keeping spherical, developing into liquid film, splashing, sliding along the wall, etc. In addition, due to the existence of oxide film, the collision between aluminum particles and the wall may cause the oxide film to rupture.