Fan stacking

[toutin]

I've read an interesting post (http://forum.hardware.fr/sqlforum/forum2.php3?post=200526&cat=2&config=hardwarefr.inc&cache=cache&interface=) on a french forum.
The poster is talking about superposing two fans BUT one is blowing clockwise and the other anticlockwise (he reversed the polarity of one fan) and both fans are blowing in the same direction. He said it creates a much more superior pressure (turbine effect as in plane engines and vacuum cleaner I think) than the simple superposition.
He's not mentionning about the noise level (sounds noisy) and the actual performance gain so I thought you might be interested.

It's worth trying heh?

[silent bob]

there are fans that spin different the opposite direction but I nhad also read that you have to have different RPMs of the two fans or there is too much turbulance if you dont get it right and temps could be worse than with only one fan , then there was something else about the pitch of the fan blades or the angle of the blades had to be 10-15% more for the top fan and really who wants to go through that much research for 2-3 degrees but... if you do good luck let us know how goes it

[It_The_Cow]

J'ai essayé mais je n'aie malheureusement pas de ventilo qui supporte la rotation inverse

That's a good point