Ignition and combustion characteristics of micron-sized Al-Mg alloy particles in water vapour atmosphere

Abstract

This paper addresses ignition start-up challenges and low combustion efficiency in aluminum-water reactions by proposing the use of Al-Mg alloy particles to enhance ignition and combustion through microexplosion phenomena. Experiments were conducted in a high-temperature furnace with adjustable temperature and pressure in a water vapor environment, varying magnesium content, particle size, ambient conditions to study their impact on ignition delay time ($t_{\text{ig}}$), microexplosion generation time ($t_{\text{expl}}$), combustion time ($t_{\text{com}}$), and ignition temperature ($T_{\text{ig}}$). Key findings include: $t_{\text{ig}}$ for Al-Mg particles fluctuates between 50 ms to 200 ms, secondary particles from microexplosion reduce combustion particle size significantly, and $t_{\text{com}}$ ranges from 3 ms to 10 ms. The study shows consistency with theoretical expectations in the pre-microexplosion stage, while post-microexplosion reveals opposing effects of ambient temperature and pressure on $t_{\text{com}}$. Empirical equations for Al-Mg particle ignition and combustion characteristics in a water vapor atmosphere were derived, aiding in predicting effects by adjusting variable parameters. These results support the development of an (Al-Mg)/H₂O microexplosion model and engine combustion design.