Study on classifying particle size and spatial internal flow field of T-shaped tooth structure in a disturbing rotary centrifugal air classifier

•A model for classifying particle size of a perturbed air centrifugal classifier was established.•The internal flow field properties of different perturbed rotors were investigated.•The critical rotation frequencies of the anomalous pressure distribution for different perturbed rotors were obtained.•Critical rotation frequency formation of particle sidewalls was revealed.•Optimal operating parameters for different perturbed rotor structures were obtained.