Consideration on performance evaluation and optimization of mixer

A Mixer is a general-purpose device widely used as a polymerization reactor and a mixing machine in the various process industries. This study investigates the prediction method of torque characteristic by means of CFD to establish a method that can predict the required power consumption with high enough accuracy for actual design. A new mixing concept is introduced in this study where a conventional two-stage pitched paddle and a two-stage wide paddle with a large projected area is utilized. The torque was measured by the physical measurements to compare the predicted values. The results show that while the two-stage pitched paddle forms a symmetrical flow in the tank, the influence of the wide paddle on the flow structure in the tank is so substantial that an asymmetric flow in the tank is formed. Therefore, while the former case can be predicted with an accuracy of 5% or less by the RANS k-ε model, the latter case is indicated to take effect on the calculation model by using the SST k-ω_model and DES which can accurately predict the effects of wall turbulence. This study shows a method of predicting the torque for designing various mixing impellers.