Numerical simulation study of flow field characteristics in the scale‐up design of a turbo air classifier

Abstract To reveal the flow field change rule in the turbo air classifier during the scale‐up process from laboratory scale to industrial application scale, the geometrically similar turbo air classifier model was scaled up according to the dynamic similarity criteria, and its flow field distribution characteristics were compared by numerical simulation method. Based on similitude theory, the relationship between the Euler number and the Reynolds number for models of different sizes was analyzed. When the classifier was scaled up based on the Reynolds criterion and the rotational Reynolds number, from the dynamic similarity analysis of the flow fields in the annular and rotor cage regions, the tangential and radial velocity distributions remained consistent, indicating overall flow field similarity of the scaled classifier models; with a constant Stokes number, the cut size increased linearly with the characteristic dimension, with numerical predictions matching theoretical values to within 1.9% deviation. Furthermore, the critical Reynolds number for entering the self‐modelling regime was significantly influenced by scale: smaller models reached this regime at lower Reynolds numbers, whereas larger models required substantially higher values.