A numerical investigation on heterogeneous combustion of aluminum nanoparticle clouds

This study investigated the heterogeneous combustion of nano-sized aluminum dust clouds. A numerical model was developed to capture the combustion properties of aluminum nanoparticle clouds by employing multiphase flow approach and combustion model of nano-aluminum particle. The simulation framework adopts an accurate modeling of heat convection in the transition and free-molecular regimes besides considering inter-particle radiation and surface reaction. The numerical model was validated by comparison against predicted/experimental results. The flame structure of nano-aluminum dust-air mixture has been demonstrated, whose flame thickness is thinner than their micron-sized counterparts. The ignition front propagation speed increases with raising equivalence ratio in the lean mixture and almost maintains a constant under fuel-rich conditions; and it raises with decreasing particle size and increasing oxygen concentration. The oxygen content plays a significant role on flame behaviors than the particle concentration and size. The flame temperature and feedback of heat from reaction zone to preheat zone plays a crucial role in ignition front propagating process.