This paper aims to disclose the mechanism of the screw conveyor and detail the particle flow inside this type of conveyor. To this end, the author discussed the relationship between the trajectory angle of particle motion and several key parameters based on the fluid mechanics. Then, a theoretical model of particle flow was established for screw conveyor of sand, considering the lateral sliding efficiency, the fill rate and the theoretical maximum mass flow rate. The theoretical analysis shows that the outlet mass flow rate depends on such parameters as the inclination angle, rotation velocity and pitch. Through several tests, the author obtained the variation patterns of the fill rate with rotation velocities and pitches, and those of the outlet mass flow rate with inclination angles, rotation velocities and pitches. After that, the change law obtained by our theoretical model was contrasted with that observed in Reference. The comparison shows that the two laws are basically the same. Thus, the proposed model is accurate enough to be applied in the practical design of the screw conveyor.
screw conveyor, outlet mass flow rate, fill rate, trajectory angle, particle flow
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