Powder flow from an aerated hopper.

Abstract

Theory and experiments were 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 gave the velocity of each phase, particle stress, air pressure and particle flow rate; this increases with air rate until the inter-particle stress was zero at some point in the hopper. Further increments of air flow do not increase particle flow; this maximum was independent of particle size. The predictions were in qualitative agreement with experiments. (from author's abstract)