power consumption and Metzner constant Kswere measured for 19 types of helical screw impellers with a draught tube in the laminar regime. On the basis of an analogy between this mixer and a screw extruder
the semi-theoretical correlations of the circulation number Ci
power consumption Kp and Metzner constant Ks were obtained. The influence of elasticity on circulation number Ci was also studied. The elasticity seemed to dampen the axial circulation and the circulation number Ci of viscoelastic fluids was lower than that of Newtonian fluids.