The Study of the Effect of Impeller Shape and Location on the Mixing Behaviour Using CFD Modeling

This project presents on predicting the flow and mixing behaviour inside the mixing
tank and to investigate the effect of impeller design or shape and location on the mixing
characteristic. Impeller location is defined as the distance between the base of the tank
and the surface below the impeller’s blade. It is generally believed that mixing in stirred
tank is dominated by the turbulent diffusion or dispersion compared to the convective
mixing. Replace a new impeller inside the tank without properly tested, designed and
modelling will cost much. If bad mixing occurs, it may lead to increase cost due to
further modification and the production also will decrease. Prototype also incurred cost
to build and operate it and require looking like the same as the real one. Therefore, in
this project, FLUENT 12.0.6 will be used to simulate the flow inside the mixing tank.
The impeller shape and location will be investigated to know how they will affect the
flow and the mixing behaviour inside the mixing tank. The existing mesh created by
GAMBIT® for the tutorial will be re-used and modified its impeller design and to
simulate the flow by using FLUENT®. The objective of this project is to predict the
result which design for the impeller is the best for better and efficient mixing in the
tank. It is clearly shown that the lower impeller location inside the tank gives better
mixing condition than others. The time to reach settling time for this impeller’s location
also is optimum and acceptable. Recreate the impeller shape cause the weight of
impeller to increase thus reducing the impeller’s rotational speed. This will lessen the
efficiency of the mixing tank.