Question Experimenting with fans

[Eigencentrality]

I've been playing around with my case fans trying to increase efficacy. A series of two fan in a small duct seems to have made the air flow more laminar and increased the pressure yielded. (I ordered an anemometer to get some real measurements.)

Another approach to try is adding a cone in the center of the fan to decrease turbulence by creating a boundary layer.

What other methods might be interesting to apply?

 

[CountMike]

When combining two fans in series it's beneficial to put some kind of grid in between them to smooth airflow by eliminating turbulence. That same way is done when creating turbines. If both fans are of same size, it's better to have secondary (exhaust) fan have higher air flow than primary.