Thermodynamic and experimental investigation of critical factors influencing the combustion characteristics of aluminum particles

Although aluminum (Al) particles have been widely applied in aerospace and missile technologies, the critical factors influencing their combustion remain insufficiently studied. To address this, this work investigates the effects of multiple factors on Al particle combustion through thermodynamic theoretical calculations and experimental approaches. Thermodynamic results indicate that various oxidizing gases can chemically react with Al and release heat. Among them, the reaction between Al and oxygen exhibits the largest enthalpy change and Gibbs free energy change. In both Al/O and Al/O/C/H systems, increasing temperature reduces enthalpy change but enhances Gibbs free energy change. Pressure shows negligible effects on the system, while the influence of Al molar quantity depends on oxygen atom availability. Thermal analysis reveals that smaller particle sizes significantly increase oxidation rates. Moreover, Al particles with different particle sizes can continue to react until complete oxidation at a constant temperature of 1400 °C in air, suggesting that the alumina shell at high temperatures may be loose and porous with a non-dense structure. Combustion tests demonstrate that reducing particle size from 25 μm to 0.1 μm decreases ignition delay time by 86 % and increases combustion temperature by 30 %. Similarly, elevating oxygen concentration or pressure reduces ignition delay, enhances combustion temperature, and improves combustion efficiency. This study provides fundamental data support for constructing Al particle combustion models under complex variable environments.