Effect of Tangential Tertiary Air in the Volute on the Flow Field and Performance of the Vortex Air Classifier

To address the issues of low classification efficiency in traditional vortex air classifiers and the difficulty of completely separating fine powder entrained in coarse powder, an improved structure equipped with a settling chamber and tangential tertiary air is proposed. The settling chamber utilizes gravitational settling to buffer and collect agglomerated coarse particles, effectively reducing the powder load in the classification zone and helping to stabilize the overall gas-solid two-phase flow field. The tangentially introduced tertiary air performs secondary pneumatic cleaning of fine powder on the surface of coarse particles during the settling process, using shear dispersion to bring the attached fine powder back into the classification zone, thereby significantly suppressing the carryover of coarse particles into the fine fraction. This combined structure enhances classification accuracy, improves flow field stability, and achieves efficient separation of fine and coarse powders. The modified classifier exhibits good practical engineering value in applications requiring high powder purity. After numerical simulation analysis, the following results are obtained: with a main air inlet velocity of 12 m/s, a tertiary air velocity of 2 m/s, a rotor speed of 600 rpm, the classification accuracy K = 0.74, and the cut size \mathrm{D_{50}} = 39.95μm. This study provides a theoretical basis for the optimization of vortex air classifiers.