The effects of particle size polydispersity and median diameter on the diffusion characteristics of aluminum dust

Aluminum dust, a common metal dust, is prone to combustion and explosion. Here, computational fluid dynamics (CFD) software was used to study the aluminum dust diffusion process with four different particle size polydispersity (0.9, 1.2, 1.5, and 1.8) and five different median diameters (10, 20, 30, 40, 50 μm) in a 20-L spherical tank. Particle tracks, concentration, and turbulence were analyzed. Under a fixed median diameter, with the polydispersity increasing, the peak concentration and turbulence both decreased; the maximum concentration and turbulence with a polydispersity of 0.9 is 33.4%, 13.3% higher than the minimum of 1.8. Under a fixed polydispersity, with the median diameter increasing, the peak concentration increased and then decreased, while the turbulence decreased. The maximum concentration appeared at 20 μm, which is 5.78 times larger than the minimum of 10 μm. Turbulence with a median diameter of 10 μm was 57.5% higher than that of 50 μm.