1989 Volume 22 Issue 4 Pages 413-418
Measurements of the circulation time for pseudoplastic liquids in an agitated vessel of 0.128 m diameter equipped with a variety of helical ribbon impellers were carried out in a wide range of apparent Reynolds number by means of a small tracer particle. Seven impellers of different dimensions (clearance between blade and vessel wall, impeller pitch and blade width) were employed in this work.
Whilst previous investigators have suggested that the dimensionless circulation time is independent of the Reynolds number, a number of data obtained in this work have proved that the dimensionless circulation time of pseudoplastic liquids with a helical ribbon impeller decreases slightly with decrease in the apparent Reynolds number in the laminar flow region. It was also found that the circulation time increases as the liquid shear-thinning property increases. These results are explained by considering the relation between the motion of a tracer particle and the non-uniformity in viscosity created in a vessel.