CFD simulations of flow and classification characteristics of a circulating air classifier

摘要

In this study, we conducted computer simulations by using a commercial CFD program, ANSYS CFX, on a circulating air classifier which has an upper main fan and lower classifying vanes inside. Particle loading effects are ignored for computational accuracy and computational cost, and then only sparsely seeded light loading condition is modeled in this study.Variations of the size selectivity, the cut size and the cut sharpness were calculated and discussed. By controlling the rotating speed of the main fan, we can increase the cut size in large, however the linearity of the cut size variation according to the main fan speed is not sufficient enough to apply this air classifier into real field applications. On the other hand, by varying the rotating speed of the classifying vanes, we can control the cut size more precisely, because the cut size gradually decreases with the classifying vane speed. In this paper, we also visualized streamlines and particle pathlines and their variations with the main fan and classifying vane speed.