Triggering flow of jammed cohesive granular materials using modulated pulsed airflow

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.

Automated summary

The study shows that under the action of pulsed airflow with a smaller duty cycle, stable flow of jammed granular materials can be effectively triggered. Under proper conditions, hopper flow can transition from a classic arch-breaking mode to a liquid-like free-flowing mode. The flow rate of powder in the free-flowing mode decreases as the powder bed height decreases, overturning previous assumptions.