how do you make a wind tunnel?

Answer 1

You decide how big a test section you need based on your model size. The wider and taller the section, the less interference there will be with the walls, but the wind tunnel will be that much more elaborate to build. If the cross-scetion of your model is 10% of our test section, you'll get okay results. Less than 5% would be better.

You want even, smooth air flow. That means a leading (upstream) section of several diameters in length (test section = 12" x 12"; leading section = 36" or so). Upstream of that, you want a grid of parallel baffles to get all the air going straight and, somewhat, to make the airflow more uniform. Think of the cardboard dividers in a case of glass beer bottles or fancy fruit. Like that, about 10 cells by 10 cells across the tunnel.

Upstream of that, you need a fan. A big box fan of sufficient horsepower will be easiest - it impart airflow to a large crosssection of the air. Buy a size that fills the tunnel and seal it to the sides. Look in a Graingers catalog for lots of options.

You can do a return loop, but why? Serious, high-velocity tunnels do that because they want temp control and don't want a bird strike at 500 knots. Just do a one-pass tunnel. Put baffles on the downstream outlet if you want to be thorough.

Easier yet, get a mess of scales and tension meters and strap your model on your car roof. Do runs in opposite directions to cancel ambient wind effects.

Research what the Wright brothers did. They had both a wind tunnel in their bike shop and also testing models on the road by peddling really fast.

Have fun.

Answer 2

I thought everyone was born with a wind tunnel.Isn't its where the fart comes out?.

Just kiddin!.Google 'wind tunnel' and you'll get the answer.

Answer 3

build a tunnel and put a big fan at one end