Enhancement of Laminar Mixing in Stirred Vessel using Geometrical Perturbations

Abstract

Geometrical perturbations by using single and coaxial impellers configurations have been investigated in the laminar

regime (Re = 2.68) in unbaffled stirred vessels. Combinations of one and two coaxial radial discharge flow impellers

under centered and eccentric conditions were studied with viscous Newtonian fluid. The study of geometrical

perturbations has been made in terms of the mixing times, energy consumption and the flow fields. Homogenization

degrees and mixing times, determined with a color-discoloration technique, were evaluated by means of image

processing. The flow fields were investigated using the particle image velocimetry technique. The use of off-centered

impellers increases the pumping capacity; however, little effect of eccentricity was obtained when using two coaxial

impellers under off-centered conditions obtaining the best results with a novel configuration consisting of a dual

turbine with connecting plates.