Wind Tunnel Desk Fan - Fan V5: PC 120mm

This is the fan version where I gave up and made something practical. I've got a few fan designs, including some that aren't uploaded (you won't find V4 because it's not very useful but I might upload later, for now we're skipping a version) but most of them are hard to make and noisy. With the way that the weather is at the moment I wanted one that I could use without the rest of the family wanting to throw it out of the window.

The design uses elements seen in wind tunnels so I'm not taking things from jet engines this time. The main element of this are the corner cascades, these are curved wing sections that turn the flow around the 90deg corner with low losses, they also straighten out the flow from the fan and make it smoother which is a bit more pleasant when it points at your face.

You might ask: "Why are you taking all of this effort to turn the flow 90deg when you could just point the fan where you want it to go? Isn't that a waste of effort?" and you would be right. It is not really practical, I just wanted some wind tunnel features. It does give the fan quite a small desk footprint though, so that's nice.

This fan uses a 12V 120mm PC fan which I'm running at a lower voltage to keep the noise down. Most PC fans should fit since there aren't any thickness constraints, if you have a thicker or thinner fan then the parts will fit around this.

The fan is modular so you can print what you want and perhaps design your own parts. I've included the OpenSCAD file but be careful, it's not really very parametric because I didn't take the time to make it so. Just making a new nozzle wouldn't be very hard though since the interfaces are quite simple.

The fan outlet fairing (boattail.stl) is optional, as is the guide vane pack - you don't have to use either but you can only use one of them as they don't both fit. The fan is slightly more compact with the fairing but should have slightly less vorticity in the flow with the guide vanes, the effect of this is that the flow is much more concentrated with the flow pack since the flow isn't swirling and so does not spread out as much.

You'll find a box body and lid that I use for a DC-DC converter to reduce the voltage of the 19V laptop power supply to about 7V. It has a hole for a socket, you might be able to find one the same.

The parts are all designed to be fixed with M3 screws. Parts that fix directly to the fan use M3x12 screws and nuts. All other parts are designed to fix together with M3x8 screws with M3 threads tapped into one part after reaming the holes to 2.5mm.

Assembly, discussion and background in this video: