Flow pattern in a pulsed-flow extraction column during the pulsation cycle

A CFD (Computational Fluid Dynamics) study of the flow pattern in a pulsed column with packings of discs and rings is carried out. The evolution of flow pattern is studied during a pulsation cycle, in the course of which the flow velocity is changed from zero to its maximal value, and the flow direction is periodically changed, too. A mathematical model is used, based on Reynolds averaged equations of Navier-Stokes with k-epsilon turbulence model incorporated. The solution gives access to the local velocity field and stream lines that characterize the flow pattern. Two stationary vortices are detected on the stage. Their shape and space position change during the pulsation. Their rotation velocity is also changed corresponding to the instant velocity of the main flow. However, they preserve constant their rotational direction although the main flow alternates periodically its direction. The flow pattern does not change significantly when pulsations with different intensities are applied. It is evidence for existence of stable turbulent regime. The flow pattern detected by means of CFD simulation is experimentally observed in real apparatuses of the same type.