Discrete Element Modelling of Flow Rate during Hopper Discharge

Powder flowability can be characterised by measuring the flow rate during hopper discharge. An implicit feature of the standard methods is that discharge occurs in open atmosphere.

 Research into die fill using linear and rotary powder feeders have identified the importance of atmospheric pressure conditions at the point of discharge. An apparatus was developed to study hopper discharge into a low pressure enclosure. It was shown that a very small amount of vacuum can increase flow rate significantly.

 This problem was examined using discrete element modelling (DEM) coupled with computational fluid dynamics (CFD). The coupled model was verified experimentally. Flow rules developed using numerical simulations are presented. The potential impact of the results and the proposed model is significant for the design of die fill operations on tablet presses and other powder dosing processes.