Analysis of core velocity in the presence of solids using UDV and improved model for cloud height in stirred tanks

Formation of cloud height is undesired due to limited mixing between clear liquid and solids rich volume; therefore, an accurate prediction of the cloud height is crucial. In this work, ultrasound Doppler velocimetry was employed to analyze core velocity in the wall jet in the presence of particles. It was seen that core velocity varies linearly with tip speed. The location of the core velocity is influenced by geometry. The effect of solids loading on the core velocity was found insignificant; however, a decrease was observed in the core velocity when the density and size of the particles were increased. An improved version of the model developed by Bittorf and Kresta (2003) to predict cloud height is proposed based on the analysis of core velocity data for a PBT in six different geometries for solids loadings of 5 to 19 vol%. The model provides accurate predictions for these conditions.