Triggering flow of jammed cohesive granular materials using modulated pulsed airflow

• Published in: AIChE journal Vol. 68; no. 1
• Main Authors: Zhu, Lizhuo, Lu, Haifeng, Guo, Xiaolei, Liu, Haifeng
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.01.2022; American Institute of Chemical Engineers
• Subjects: Air flow; Cohesion; cohesive powders; Dynamic characteristics; Flow rates; Flow velocity; granular flow; Granular materials; hopper discharge; Powder beds; pulsed airflow; stress transmission; Working conditions
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.17411

Realizing the stable high‐flux flow of cohesive granular materials is a complicated subject. We experimentally studied the dynamic characteristics of cohesive granular materials discharged from hopper under modulated pulsed airflow. Results show that pulsed airflow with a smaller duty cycle can effectively trigger the stable flow of jammed cohesive granular materials. Furthermore, under proper working conditions, the hopper flow will change from the classic arch breaking mode to a free flowing mode like liquid. The flow rate of the powder in the free flowing mode will decrease as powder bed height decreases, which overturns the consistent recognition. The oscillating shear provided by the pulsed airflow eliminates the Janssen effect and achieves a liquid‐like stress transmission, which supports the above findings. Through energy analysis, we gave the scaling relationship between the pressure gradient and the pulse parameters to cover the experimental data and revealed the internal mechanism.