화학공학소재연구정보센터
Chemical Engineering Research & Design, Vol.147, 561-569, 2019
Turbulent statistics of flow fields using large eddy ID simulations in batch high shear mixers
Large eddy simulations (LES) have been carried out for the first time to characterize the flow and turbulent characteristics in three different batch high shear mixers (HSMs) at a constant rotor speed of 4000 rpm. Three HSMs having different stator heads such as circular, square and inclined stator head with 6, 92 and 210 numbers of stator holes, respectively have been investigated. Dynamic Smagorinsky model with sliding mesh method is used for the sub grid scale stresses at a Reynolds number of 52,000, to overcome the prediction of RANS models. Numerical methodology is validated, in terms of Power number with the available numerical and experimental studies and found in fairly good agreement. The velocity flow patterns and fluctuations at different planes are predicted and vortexes have been observed within the stator holes and bulk fluid. It is observed that velocity magnitude fluctuation is a function of rotor rotations and stator holes size, and fluctuations in one jets emerging from stator holes affect the fluctuations in other plane jets. Further, it is found that smaller the stator holes size, greater is the energy distribution and hence greater will be the drop size distribution in the mixer. Therefore, the inclined stator head HSM can be used for the uniform size distribution in application to de-agglomeration and dispersion. It is found that the energy spectrum of Kolmogorov is followed over the entire length scale for all HSMs and LES provided the richer flow and turbulent information as compared to RANS model. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.