HELICAL STATIC MIXER

Many flow problems in the process industries involve multiple components or phases. Processes involving multiphase flow or multiple components are notoriously difficult to scale up from laboratory models. Computational fluid dynamics provides an alternative to scale-up by simulating the actual equipment at full scale.

The figures below show a simple example of a multi-component flow simulation. The model simulates the mixing of two fluids in a six-element helical static mixer. The geometry and computational grid on the helical elements is shown in the top two figures. Each element splits the oncoming flow in half and then turn it through 180 degrees. The succeeding elements are oriented at 90 degrees to one another so as to constantly subdivide the flow. The lower plot shows the results of the CFD analysis of the mixer. Two fluids enter the mixer, one tagged as red and the other blue. The dividing and overturning motion of the mixer can be seen as the two fluid mix to form the green flow that exits the mixer. In this case the fluids diffuse together quickly and are fully mixed after traversing six elements. In other cases 12 or 24 elements may be needed to obtain complete mixing.