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.