CFD-Based Structural Optimization of Rotor Cage for High-Efficiency Rotor Classifier

Abstract

Due to the uneven materials dispersion and high dust concentration in industrial applications of turbo air classifiers, a high-efficiency rotor classifier was designed. Numerical simulations by ANSYS-Fluent 19.0, the effects of rotor cage shape, the number of blades, and the blade profile on the inner flow field, as well as classification performance, were investigated. The simulation results indicated a significant improvement in flow field distribution near the classification surface with the conical rotor cage. Furthermore, there was an average reduction of 10.1% in cut size, as well as a 23.6% increase in classification accuracy. When the number of blades was 36, the flow field distribution between the blades was relatively uniform and a smaller cut size was obtained at a higher classification accuracy. A streamline blade with 52° as the inlet installation angle effectively reduced the impact of the airflow on the blade and eliminated the inertia anti-vortex between blades. The cut size reduction was 4.7–6.3%, with a basically unchanged classification accuracy. The material classification experimental results were in agreement with the simulated results. The discrete phase model (DPM) could well-predict the cut sizes and classification accuracy, but it could not present the fishhook effect. The present study provides theoretical guidance for the structural optimization of an air classifier with a rotor cage.