Wind Tunnels of Linked Fans

[Hotwired]

There are certain features of my P180 mini which would permit a bank of fans screwed back to front in a tight push/pull configuration up to 5 deep.

I'm not likely to put in 10 fans just to suck air in through two 120mm grills but has that kind of fan stacking been done anywhere and what kind of results from it?

Alternatively. Two fans in a push/pull configuration but with a tunnel spacing them out so they aren't ripping air from each others blades?

Fans don't entirely create a one way airflow, some is thrown out backwards from the edges so butted up against each other without space could even be counterproductive.

Might double the fans on the intakes if results were favourable enough. Or just for personal interest

 

[bifday2k]

I had a friend do a test for me, on his work bench using a couple of same make fans...

he said it incresed the air pressure but not the cfm, that is when placed tight together, but if u had a bit of a gap then the cfm rises too.

so best case would be fan,shroud (or something slim to allow air movement),fan.

He tested for me, as i was planning to use 2 low rpm 35mm fans togeher on my rad, well 4 on totall, all doing push through.

 

[Hotwired]

Aha, posted while I edited in my ramblings

Sounds good. I may well do this, I've removed the HDD cages from my case as two bays for HDD plus one for optical are sufficient for me. I think I'll keep the fan makes the same to avoid any differences in flow/pressure/noise.

 

[Arachnae]

I'm not an expert in thermal dynamics, or cooling...

But logically several fans in this configuration will be subject to huge diminishing returns, almost to the point where I'd say any more than a push/pull with 2 fans isn't worth it.

The pressure will increase with more, sure, but as pointed out above the cfm will not increase by much because there is still the same amount of surface area in which the cool air can be pulled through.
Pulling it through at greater speed requires exponentially more energy.

IMO, you'd be better off getting a few deeper fans that bolting several together

Or maybe just modding your case to allow more a greater surface area for cold air to flow into.

 

[JonJ678]

I've not seen tests using more than two stacked, but skinnee labs have tested two stacked. They found a near doubling of static pressure, but as mentioned almost no impact on airflow. In your case more static pressure probably won't help, on a radiator it certainly does.

If however you put together two fans with shrouds inbetween, and have one fan spinning in the opposite direction to the other (need to get a fan designed to spin the wrong way, and try to match the spcs), it will be extremely effective. There are some counter rotating fans on the market which work on this basis. It removes a large part of the rotational momentum imparted by the blades, so all the air comes out moving fairly directly away from the fans. It is not quiet, but interesting.

On the P180 you probably care about noise, and don't really want to cut it up. So I'll second the above, a good 38mm fan running well under 12V is probably what you want.

 

[bifday2k]

Yate loon do a nice 38mm 1350rpm fan, i have 2, there quite, even quiter when undervolted.

Can't link to it sorry, rules lol.

 

[weescott]

Wind tunnels are great for CPU cooling. Try a sheet of paper wind tunnel with 2 delta fans over a CPU for ghetto watercooling temperatures

 

[FatRakoon]

Ah Deltas

And I wonder why I am partially deaf...!!!!