Flame evolution and radiative heat transfer during aluminum dust explosions in open environments

Aluminum powder is an important high-energy raw fuel, which has a high explosion risk when fine particles form combustible dust clouds in the air. In the open space environment, the flame propagation and thermal radiation generated by aluminum dust explosions may cause serious secondary disasters. However, there is still a lack of research on the flame evolution and thermal radiation characteristics during aluminum dust cloud explosion under open conditions. In this paper, the effects of dust concentration, particle size and ignition delay time on flame propagation speed and heat flux were systematically analyzed by experimental and numerical simulation methods. The results show that the peak flame propagation velocity (27 m/s) occurs at a concentration of 400 g/m³, an ignition delay time of 300 ms, and a small particle size (3.50 μm); the maximum heat flux (125 kW/m²) is observed at an optimal particle size (20 μm) and a dust concentration of 400 g/m³, reflecting the asynchrony between flame dynamics and thermal radiation behavior. The simulation results are highly consistent with the experiment in terms of flame morphology and propagation trends, revealing the typical process of asymmetric flame core formation, fireball evolution, and radiative heat flux change. This study is helpful to understand the disaster-causing mechanism of aluminum dust explosion in open space, and provide theoretical basis for risk assessment and safety protection.