THE EFFECT OF PARTICLE-SHAPE ON THE SPOUTING PROPERTIES OF NONSPHERICAL PARTICLES

The spouting properties of thirteen types of particles (twelve being agricultural seeds) were measured in a 150-mm diameter cylindrical column with a 60-degrees conical base. The particles, with sphericities varying from 0.39 to 1 (one being 0.39, others being in the range of 0.66-1.0), were investigated to determine the effect of shape factor on the minimum spouting velocity and the fountain height of non-spherical particles. By using the effective particle size, phi-d(v), in the Mathur-Gishler correlation, the minimum spouting velocity was predicted within +/- 20%. Using the volume equivalent size d(v) overpredicted the minimum spouting velocity for particles with sphericities less than 0.75. The fountain height is calculated by first solving the mass and momentum balance equations in the spout to calculate the particle velocity at the bed surface. By including the effect of particle shape on the particle drag coefficient in the spout, the fountain height could be predicted reasonably well (within +/- 40% for 12 of the 13 types of particles). If the effect of particle shape was ignored, the predicted fountain heights were much lower than the experimental values.