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piggy back fans?

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Tc3 Toad

Member
Joined
Jul 22, 2003
Location
lynnwood, wa
Is there be any benifit to piggy back cpu fans? would it cool the air a little more as it goes thru the fans due to more turbulance? just a thought.

Toad
 
Welcome to the forums!!!

If you have 2 fans that turn in opposite directions, it would lessen the turbulance resulting in less noise. If they're turning in the same direction, probably not.

-Bobby
 
Bobby said:


If you have 2 fans that turn in opposite directions, it would lessen the turbulance resulting in less noise. If they're turning in the same direction, probably not.

-Bobby

Turning in opposite directions? As in one blowing and one sucking? lol I doubt that would be very effective. :D

As a general rule, stacking fans is usually not very efficient.
 
FIZZ3 said:


Turning in opposite directions? As in one blowing and one sucking? lol I doubt that would be very effective. :D

As a general rule, stacking fans is usually not very efficient.


i believe bobby meant ...opposite directions, as in: one fan spinning clockwise, and the other spinning counter-clockwise....but both fans assumably blowing on the heatsink....;)
 
madsam said:



i believe bobby meant ...opposite directions, as in: one fan spinning clockwise, and the other spinning counter-clockwise....but both fans assumably blowing on the heatsink....;)

Ah ok, well I'm still no believer in the efficiency of stacked setups. :)
 
FIZZ3 said:


Ah ok, well I'm still no believer in the efficiency of stacked setups. :)

i don't know if i am a believer either, but i don't think the 2 fans spinning in opposite directions will be quieter, i think it would be louder because it's 2 fans.....lol

i also think that stacking 2 fans would not increase airflow , but will increase static pressure instead. and some folk even claim the stacking fans that spin in opposite directions will stop the air from spinning like a tornado, which is believed to be better for some reason. ;)
 
i guess so taht if you have a heatsink with fins, the air will go straight down to the bottome?? maybe? my thinking is that if the air is like a tornado, when it hits fins like those on and slk, the fins will provide like a brick wall, and then not too much air is being directed downward?
 
Sorry I wasn't clear on my first post.

Yes, I meant air flowing the same way but each fan turning opposite of each other.

I first saw this design on kit planes that used dual propellers that counterbalanced each other and made it more quiet but also increased thrust. It's been a while so I don't know the specifics and doing a google search only showed hydrodynamic advantages of twin props. One link did show the precursor to the B2 bomber, the Northrop XB-35, that was prop driven with the dual props.

madsam - the whole idea of the dual props was to kill the "tornado" vortex that propeller blades (and fan blades) created. It really doesn't matter in a small computer case, good or bad.

The fan noise you hear mostly come from the fan blades and air being pushed around, not the fan motor.

-Bobby
 
the soviets also used it on a plane to spy on the us... many Helicopters also use this method, it would be interesting to test out... but i though most fans turned in the same direction.
 
I think the problem with case fans is that they have the brackets on one side (front usually) with vanes that come out to the outer casing that will interfere with the airflow negating any benefits.

Some older fans turned the opposite direction. I have a couple somewhere...

-Bobby
 
Tc3 Toad said:
Is there be any benifit to piggy back cpu fans? would it cool the air a little more as it goes thru the fans due to more turbulance? just a thought.

Toad

Fans don't cool the air, they simply use kinetic energy to move air from one place to another. The air going out is the same temperature as the air going in.

Fan stacking is non-beneficial unless setup in a push-pull sandwich on a radiator/heatercore which only has room for one fan per side. If one has a radiator/heatercore with room for two fans per side it would be better to place the fans next to eachother on the same side than to stack them in a push-pull sandwich.
 
wttf.JPG


and yes i agree, fan stacking really is not that efficient at all. The only way it would help is if the top fan was more powerful, but even then, it would be more efficient to ust use the more powerful one. In a way my cooling setup might kinda have fan stacking. but not really. in my case it is beneficial IMO but ill show you what im doing

fanduct.JPG


but that is just to help me draw air in from the boxfan.

mycollingidea1.JPG
 
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