Investigations of the flow phenomena inside square cyclone separators with different prismatic heights

• 7 geometric configurations of square cyclones were analyzed. • Variable flow conditions and solid phase properties are considered. • Proper configuration of prismatic heights allows for increased separation efficiency. • In the process of designing square cyclones, it is important to choose PHs for specific operating conditions. This research investigates the impact of various prismatic heights (PHs) on the performance of square cyclones at three Reynolds numbers, viz. Re = 27626, 37,985 and 48345. We have accounted for seven different PHs, viz. 1.0 D , 1.5 D , 2.0 D , 2.5 D , 3.0 D , 3.5 D , and 4.0 D – here, D represents the prismatic section dimension of the square cross-sectional area. Model 2.0 D is the reference model used to evaluate relative performance. A high-performance turbulence model large-eddy simulation has been used to calculate the separation efficiency and pressure drop. The assumptions made in the numerical studies were validated using experimental and PIV studies. Considering the latter, solid particles with three different densities viz. 1100, 2100, and 2800 kg/m 3 are analysed. We also present the flow details in the form of variations in the mean and standard deviation values of scalar and vector quantities. It has been observed that with an increase in the PH, given a Re value, there is a marginal variation in pressure drop values, which amounts to a maximum value of less than 5 % at Re = 48345. Compared to the mild variations in pressure losses, the differences in the collection efficiencies are significant but slightly dramatic (in context to the particle density). A maximum enhancement of more than 26 % has been observed for particle density 1100 kg/m 3 at Re = 48345. Conclusive results indicate that model 4.0 D outperforms all the variants, and this model works more efficiently, particularly for low-density particles. It was shown that in the case of square cyclones, it may also be important to adapt the geometry of the separator not only to the flow conditions of the fluid phase but also to take into account the properties of the solid phase. In this case, the selection of PHs may be crucial.