Investigating the dynamic combustion characteristics of Al-Mg-Li powders in equal cross-section combustion chamber: An experimental study

Given the promising applications of powder ramjet engine technology in hypersonic vehicles, metal powder fuels have garnered significant research interest due to their high energy density. Among these, Al-based metal powder is particularly notable as a potential fuel option with important application prospects. Consequently, investigating the combustion properties of Al-based powder is crucial. In this study, we conducted experimental combustion studies on Al-Mg-Li powders with four different particle size distributions using a cyclone combustion system in an equal cross-section combustion chamber. The results demonstrated a significant effect of particle size distribution on the combustion efficiency of Al-Mg-Li powders. Powders with particle sizes below 75 μm achieve full combustion more rapidly. Additionally, the flame profile at the chamber exit is smoother and more continuous for particles below 45 μm, indicating higher combustion efficiency. The varying sizes of the spoiler cone influence combustion flame intensity by affecting the velocity, heating time, and concentration distribution of the Al-Mg-Li powders. Furthermore, when the cone is positioned closer to the bottom of the combustion chamber (80 mm), both the combustion intensity and efficiency of the Al-Mg-Li powders were improved. Finally, under cold air inflow conditions, self-sustained combustion of Al-Mg-Li powders was observed, with a re-ignition pulse period of 0.7–0.8 s.