On the analysis of a coarse particle free falling material stream

Abstract In many industries across the world, the topic of dust control is a major concern. Within the bulk material handling process the action of material free fall is generally unavoidable. In this case, the adjacent air surrounding the free falling stream is induced into the stream of bulk material as the particles naturally dilate, which results in generation of dust upon subsequent compaction of the stream. Obtaining a better understanding of the way air is induced into the stream of bulk material, and the quantity of the induced air, will assist in the design of more efficient dust control systems. In this paper the interaction between the particles and the air is reviewed. A series of computer simulations and physical experiments have been carried out. The particle image velocimetry (PIV) technique has been employed to measure the fluid velocity within a free falling stream of coarse material. Each experiment was also simulated using Ansys CFX. Particle and air velocities as well as air entrainment readings from simulation have been compared with experimental measurements and theoretical formulas. The experimental programme was designed and conducted to classify the effect of particle diameter and particle density independently. This paper presents several distinct sections that detail the experimental and simulation results as well as a comparison of these two methods while also including a discussion of existing theories.