Particle flow fall process: a systematic study of entrained air under unconfined and semi-confined fall conditions

Industrial bulk material transfer and handling processes often result in large dust emissions and seriously threaten workers’ health. Both dust dispersion and ventilation for dust removal are related to the entrained air flow rate under the particle flow fall process. Based on the air jet theory, this paper presents a model for unconfined and semi-confined particle flow fall processes. Theoretical formulas for the entrained air flow rate were developed, and a numerical simulation was performed to analyze the particle velocity and entrained air under unconfined and semi-confined particle flow fall processes. The results show that as the distance from the particle source to the wall’s surface decreases, the particle velocity slightly increases; however, the value of the particle velocity always varies between that of unconfined fall and fall in vacuum. It is found that when the distance of the particle source from the wall’s surface s is less than five times the width of the particle source d ( s