VENTURI MIXER

A common method for diluting a concentrated solution is to use a venturi mixer.  These mixers can provide precise control over the level of dilution achieved.  However, to obtain maximum performance the venturi section must be quite long.  To assist in designing a suitable mixer Stress Engineering has used CFD modeling of flow in these devices.

Two potential designs for a venturi mixer are shown below, one of standard length and the other compact.  In both cases the main flow enters from the left and the flow of concentrate enters through a disk-shaped port at the throat of the venturi.  The CFD results are illustrated by displaying flow streamlines for each model.  The presence of a large looping streamline in the diffuser section of the compact venturi indicates flow separation.  This suggests that the diffuser section for this design is too short and will degrade the performance of the compact mixer.

The plots below show the results of mixing two fluids in each venturi.  The main flow enters as 100% water (blue) and the concentrate enters at full strength (red).  The degree of mixing at any point is shown by the color contours, with green being fully mixed.  The results of the simulation show that separated flow in the diffuser section the compact mixer causes this design to draw only 76% as much concentrate as the standard mixer.  This calculation allows a quantitative comparison of the efficiency of the two designs which can be used to guide the design process as tradeoffs between size and efficiency are considered.