Numerical study on deposition of non-spherical shaped particles in cascade impactor

This study investigated the deposition of non-spherical particles in a cascade impactor using numerical simulations based on computational fluid dynamics and a discrete phase model (CFD-DPM). An optimum drag force model of non-spherical particles was used to calculate the dynamic behavior of the needle-shaped particles. The trajectory of these particles in an elbow pipe was computed and measured using a high-speed video camera. The computed trajectory agreed well with the experimental trajectory, and it was confirmed that the drag force model of non-spherical particles correctly expressed the drag force in the CFD-DPM numerical simulation. Next, the motion of the needle-shaped particles in a cascade impactor was numerically simulated and compared with that in the experimental results. The simulated classification efficiency agreed well with the experimental results. Additionally, the relationship between the aspect ratio of the needle-shaped particles and their behavior in the cascade impactor was numerically analyzed. The cut-off diameter decreased with the aspect ratio at a 50% classification efficiency in the cascade impactor. This was because the drag force of the particle was assumed to increase with the aspect ratio, and longer particles fell at a lower stage in the cascade impactor.