CFD Simulation of Mixing Tank Design

In an effort to inspect the factors affecting power draw and torque to optimise the design of mixing tanks, a CFD analysis a stirred tank was developed and carried out. This was done by generating a 3D representation of the mixing tank with the stirrer consisting of 2 non-inclined paddles with diameter, D=12, 14, 16 and 18 cm. The clearance was also varied in 2.5 cm increments. The fluid of choice for CFD analysis was water since it is in abundance.

Torque was observed to increase with increase in impeller diameter values while keeping the clearance and rotation speed constant. The torque was also observed to increase slightly with increase in clearance. It also increased with diameter. Power number however was observed to decrease with increments in diameter. It also increased but only slightly, with clearance.

Velocity distribution graphs also showed that high rotation speed impellers were most ideal for mixing as this contributes to better agitation and by extension better mixing. The same is applicable for higher radius stirrers as the velocity magnitude is seen to rise.