Studies on combustion of aluminum-magnesium alloy hydro-reactive metal fuel

In order to explore the steady-state combustion of high-metal Al-Mg alloy hydro-reactive metal fuels for water ramjet engines, experiments were conducted to study the primary combustion and the secondary combustion of propellant with the Al-Mg alloy content 80%. Oxygen bomb calorimeter was used to collect the solid products of primary combustion. The secondary combustion was simulated in the high temperature tube furnace by using the solid products of primary combustion and water vapor. Thermal performance of Al, Mg and Al-Mg alloy was analyzed by thermogravimetric analysis (TGA). The solid products were characterized by using scanning electron microscopy (SEM), x-ray diffraction (XRD), chemical analysis method. TGA traces in air indicate that the oxidation onset temperature (530℃) of Al-Mg alloy powders is lower than that (600℃) of Mg and the oxidation performance of Al-Mg alloy powders is better than that of Al in case II. There were MgO, MgAl, Mg₂Al₃, MgAl₂ produced by Mg₁₇Al₁₂ in the primary combustion. There were MgO, Al and Al₂MgO₄ in the products of secondary combustion. The content of residual aluminum increases with the increasing of temperature of the tube furnace, and then decreases. It is thought that the combustion of magnesium in Al-Mg alloy occurs first and the combustion of aluminum happens later.