Desktop Wind Tunnel Brings Aerospace Engineering To The Home Gamer

Computer simulation is indispensable in validating design and used in every aspect of engineering from finite element analysis to traffic simulation to fluid dynamics. Simulations do an amazing job and at a fraction of the time and expense of building and testing a scale model. But those visceral ah-ha moments, and some real-world gremlins, can be easier to uncover by the real thing. Now you don’t need a university research or megacorp lab to run aerodynamic study IRL, you can just build a functional desktop wind tunnel for a pittance.

[Mark Waller] shows off this tidy little design that takes up only about two feet of desk space, and includes the core features that make a wind tunnel useful. Air is pulled through the tunnel using a fan mounted at the exhaust side of the tunnel. The intake is the horn-like scoop, and he’s stacked up a matrix of drinking straws there to help ensure laminar flow of the air as it enters the tunnel. (The straw trick is frequently used with laminar flow water fountains). It also passes through a matrix of tubes about the diameter of a finger at the exhaust to prevent the spin of the fan from introducing a vortex into the flow.

For analysis, five tubes pipe in smoke from an vape pen, driven into the chamber by an aquarium pump. There’s a strip of LEDs along the roof of the tunnel, with a baffle to prevent the light shining on the black rear wall of the chamber for the best possible contrast. The slow-motion video after the break shows the effectiveness of the setup.

Whether you’re a Hackaday Editor cutting their own glider wing profiles using foam and hot wire, or just want to wrap your head around how different profiles perform, this will get you there. And it’ll do it at a fraction of the size that we’ve seen in previous wind tunnel builds.

[via r/engineering]

10 thoughts on “Desktop Wind Tunnel Brings Aerospace Engineering To The Home Gamer

  1. Looks great. Pretty good laminar flow for such a small scale. Drink straws are definitely the way to go for these. A little cotton wool filter between the fan and straws can work well to eliminate most of the chopping associated with fan blades and further smooth the air slow. Smaller diameter straws don’t always mean cleaner air flow.
    I’ve used some bluetack mixed with water wrapped around some coiled nichrome wire as aa switchable source of smoke before. Although chimney smoke test pellets work okay you can’t turn them off very well. A separate smoke box with a bellows or pump can work. I tried pressurising a carbonated drinks bottle filled with smoke but it didn’t last as long and the pressure wasn’t easy to regulate. Fog machine smoke would seem like a good option. I considered a modified soldering iron to make small volumes of smoke on demand but I’ve never tested the idea.

  2. Made one with 9 leaf blowers once – 3 per phase. Accidently wired it so one ended up between phases rather than to neutral. Very noisy!

    It was for blowing arcs across simulated aircraft wings to test paint dielectric.

  3. The comments on the original Reddit post about the undesirable turbulence in the smoke stream should be mirrored here – the smoke circuit needs more flow and a single, moveable streamlined probe would probably be an improvement.

  4. Could someone enlighten me about this subject a bit. I remember from fluid dynamics course that there are some problems when using miniature models for wind tunnel testing but I can’t remember what was the explanation. Something related to Reynold’s number?

    1. Low Reynolds number: yeah. Although you make the windspeed scale with the wing size, there are funny effects when the wind starts sticking to the wings.

      Also boundary conditions with the edge of the chamber, etc.

      If someone wants to post up good links here, I’d read them too! :)

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