469803 Computational and Experimental Determination of the Hydrodynamics in a Scaled-Down Pharmaceutical Vessel Provided with Angle-Mounted Impellers
Despite their industrial relevance, especially for the pharmaceutical industry, extremely limited information is available on the hydrodynamics of vessels provided with angle-mounted impellers. Therefore, in this work, experimental and computational tools were used to determine the hydrodynamics of fluids in a Plexiglas, custom-made, scaled-down version (diameter: 304 mm) of an industrial vessel with an elliptical bottom and provided with two angle-mounted (by 5 off the vertical) A-310 Lightnin impellers. The system was operated under different operating conditions in order to replicate the mixing characteristics of the industrial system. Computational Fluid Dynamics (CFD) was used to quantify the hydrodynamics of this system under different geometric configurations (such as liquid level), agitation speeds, and for different fluid rheologies. In all cases a multiple reference frame (MRF) computational approach was used and turbulence was modeled using the k-ε method. In addition, Particle Image Velocimetry (PIV) was used to experimentally determine the velocity flow field in water for some of these configurations in order to validate the CFD predictions, thus providing guidance on the optimal operation of these industrial systems.
The results obtained here indicate that there is substantial agreement between the CFD predictions and the PIV experimental results. The flow in the vessel appears to be very complex. The axial pumping action of the impellers produces a downward flow impinging the bottom of the vessel resulting in flow splitting and in the formation of a less well-mixed zone near the vessel bottom that persists even when the impeller velocity is substantially increased. This zone could be the preferential location for the sedimentation of settling solids in the liquid.
See more of this Group/Topical: North American Mixing Forum