Characteristics of dust cloud formation: The effect of conveying speed on flow field of tea powder

Tea dust is classified as combustible agricultural dust. Manufacturing processes of tea frequently involve a falling stream of tea powder and induced smaller dust to the surrounding, forming a dust cloud. Under certain circumstances, there are potential for rapid combustion and serious explosion to occur. Herein, experimental research results are reported in this study, focusing in particular on the flow field of tea dust during free-falling. This investigation shows that the axial velocity is found to increase significantly with increasing conveying speed, however the RMS turbulent velocity shows slight fluctuations from each other. Both velocities are found to increase linearly with increasing drop height, and similar flow field patterns are found for a all conveying speeds. Also, high flow field is observed towards the core of the particle-driven plume and decreases to the wall. The results presented here may facilitate fundamental knowledge on dust cloud formation to enhance awareness for dust control and prevention in agricultural industries.