Collect. Czech. Chem. Commun. 1981, 46, 2007-2020

Process characteristics of screw impellers with a draught tube for Newtonian liquids. The power input

Pavel Seichtera, Jiří Dohnalb and František Riegerb

a Research Institute of Chemical Equipment, 638 00 Brno
b Department of Chemical and Food Apparatuses, Prague Institute of Chemical Technology, 166 28 Prague 6


An expression has been proposed for the power input of a screw impeller with a draught tube in the creeping flow regime based on the analogy with extruder screws. Experimental verification has confirmed practical utility of the expression in a wide range of geometrical parameters of the impeller and for the Reynolds number for mixing below 20. The total power input of the impeller is expressed as a sum of the input inducing the drag flow and the input to create the pressure flow. The former of the inputs may be deduced from the theory of extruders while an empirical approach based on experiment has been used to formulate an expression for the latter.