Internal circulation in vessels agitated by screw impellers

Abstract The paper deals with the axial discharge rates, circulation times and axial velocities in vessels stirred by helical screw impellers rotating in a draught tube. Data have been obtained for a viscous Newtonian liquid as well as for liquids showing shear-thinning and elastic properties. Some pressure-drop measurements were also obtained mainly from the view-point of testing some of the arguments presented. It has been observed that within the experimental ranges the circulation capacity is independent of Reynolds number and shear-thinning characteristics. The elastic properties, however, seem to dampen the circulation capacity under some circumstances. The correlations presented in this publication could be used to predict discharge rates, circulation times and axial annular velocities and to estimate the pressure-drops.