Powder Flow from an Aerated Hopper

Abstract

Theory and experiments are described for gravity flow of non-cohesive powder from a partially aerated hopper formed by two smooth sloping plates, each with a porous section for aeration at the exit. Equations describing the motion of the particles and of the interstitial air give the velocity of each phase, particle stress, air pressure and particle flow rate; this increases with air rate until the interparticle stress is zero at some point in the hopper. Further increments of air flow do not increase particle flow; this maximum is independent of particle size. The predictions are in qualitative agreement with experiments; the particle discharge coefficient is of the order 0.5 to 0.7.