Ignition and combustion of nano-sized aluminum particles: A reactive molecular dynamics study

Combustion mechanism of nano Al particles remains controversies for years. In this paper, we use ReaxFF molecular dynamics simulations to study thermodynamic and structure properties of Al particles from ignition to combustion. Two typical core-shell nano Al models with different oxide shell thickness are studied. Effect of radiative heat transfer is also considered in the combustion stage. Our results show that no shell cracks are observed during both heating and burning periods. The oxide shell hinders the thermal diffusion of core Al atoms and causes the abnormal melting rule. The stress variations at the core-shell interface are the most dramatic during the heating period. The combustion processes are controlled by diffusion behaviors of components in particles and external oxygen molecules. Detailed structural evolution processes are studied by displacement magnitude analysis. Particle with thinner shell has a shorter ignition delay and a higher combustion temperature which directly affect the radiative heat transfer rate during the combustion period. (C) 2019 The Combustion Institute. Published by Elsevier Inc. All rights reserved.