Effects of different parameters on performance metrics in a vertical axis agitator: A CFD approach

Abstract

In this paper, a vertical axis agitator with four rectangular blades is studied numerically and
performance metrics such as the mixing power and power consumption are presented. Effects
of diameter, rotational velocity, and the twist angle of the blades on power consumption and
maximum velocity are studied extensively. Results are compared with theoretical formula to
mark the discrepancy and express the reasons. The effect of rotational speed on the maximum
velocity magnitude is more pronounced at higher diameters which means that if you double the
rotational speed of two mixers, the one with a larger diameter will experience a more significant
effect of velocity enlargement. There is a threshold for the rotational speed of mixers beyond
which the power consumed by it will increase in a way that there is no justification for diameter
enlargement. It is worth mentioning that the twist angle has negligible influence over the maximum
velocity value but installing the blade at some specified inclination leads to lower levels of power
consumption; a promising solution to be used in designing efficient vertical agitators.