homemade wind tunnel
 

Round cross-section is FAR better than square cross-section, but something is better than nothing (ha,ha)!

Interesting..... The mythbusters always used a wall of straws to diffuse the air from the fan to the item to be tested.

The comments section is pretty good, and they get why the fan should be in the back.

Julian Edgar at Autospeed could show why it needs 180° bell-mouths on the inlet.

Compare to Yoshi Suzuka
http://http://www.youtube.com/user/yshsuzuka/videos?flow=grid&view=0

His newest video 'Electramotive wind tunnel' was disappointing. I thought it would be about using ganged Dyson bladeless fans to eliminate turbulence. But it would take a lot of them @ 40 cubic feet per minute.