Abstract
A hydrodynamic model is proposed to predict the power consumption in close-clearance agitators. Apparently three-dimensional flow is divided into flow perpendicular to the blade and flow along the blade, both of which are two-dimensional flows. Asymptotic solutions to the above flows are obtained by the complex analysis method and the resultant wall shear stress is synthesized vectorially to get the following correlation for the power consumption:
NpRe= ?? In ??
in which d, H, nb, a and δ, respectively, are impeller diameter, impeller height, number of blades, inclination angle and clearance. A correction factor β1 is taken as 0.9 for paddle and 0.7 for anchor, gate, helical ribbon and helical screw with draft tube. The above equation is found to correlate successfully the experimental data reported for various types of agitators in about 30 references.
