blower principle of operation?
OK, I know a bit about axial fans.
I'm now wondering about "cage" blowers. I assume the vanes in the cages are wings. They certainly have an angle of attack and relative wind (wind direction being perpendicular to the opening of the cage). So... in spite of it looking like a centrifugal water pump it's really a fan (?) Is that right? I'm trying to figure out if they'd be over-sensitive to restriction on the inlet side (the way centrifugal water pumps are). Anyone know? Yes, I realize they're called "blowers", not "suckers" :) - but that's what I'm thinking about using them for. I'm also wondering if the outer housing is actually necessary for the operation of the "suction side"? I don't believe it does, as long as the inlet area is shrouded away from the outlet area. Have I got this right? I've ordered a couple of these from AllElectronics. They don't have the "oomph" BB is looking for, but may actually be fine for my use (low noise, pretty good cooling). And if they don't work for me, I'll have learned something - and have yet another interesting "desk gizmo" :) Thanks! Bob PS: If all this info is on a web site (or in a book I can get) please just point me at it -thx! |
A centrifugal pump for air is not a bad analogy for how they work.
They are good for sucking. They are the type of fan that many vacuum cleaners use. The outer shroud is only needed for the directional flow of the outlet air. It will suck just as fine without it. In essence they are not all that different to a turbo-impeller, which is great for sucking air in. |
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Blowers are lower flow, higher pressure devices. They're probably better suited for radiators, but they have an annoying shape, so people use axial fans (which work well enough).
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Axial fans, when undervolted to be quiet, have a really hard time pulling air through a heater core type radiator. I don't have a curve for the blowers above, but I've been looking at other cage blower curves - and it looks like they both start out generating lots more pressure and lose it less quickly as the volts/revs drop. What I don't know is how quickly the noise drops as the volts/rpms drop. As it is now, I have two undervolted panaflo axial fans "stacked" with a spacer between so as to pull air quietly through a heater core. IMHO the cage blower size/shape isn't any more annoying than this... |
Yeah, the shape and size is really not easy to deal with:
http://www.wbta.us/bigben2k/Tellie-R1-13A.jpg |
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Cage/shroud is under construction. See link in my sig. The pic is just for showing the general placement of a typical 5-6" blower.
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I got a couple of those blowers I linked to above (at $4 each, might as well have a spare) and finally got around to mounting one.
I happened to have a coolingworks 6x6 plastic shroud and a cover plate for the hole for a 120mm fan (comes shipped with the FS020 - and now I'm wishing I hadn't tossed the others). It appears to work fine as an impeller - starts OK at 6.25VDC, and at that voltage it moves what appears to be more air through a 6x6 radiator than a L1A at 7V and is fairly quiet - once I disassembled the one I was using, removed the ball bearings and repacked them with decent (amsoil) grease. I now know that it's fairly difficult to get an impeller that pushes over the outside of a motor housing on exactly straight. And exactly centered seems almost impossible. The closer I get it, the quieter it seems to run (duh!). I've left this one running "on the bench" for the last two days to check "infant mortality" (turned it off to take the photo, though). http://koure.org:800/temp/mounted_impeller.jpg More details when I get it installed - although, again, all I have for measurement is a CPU diode - should be able to leave everything else in place so at least there'll be a hint as to how it performs relative to my current 2-stacked-L1As-at-5V, which in turn were about the same (cooling-wise) as a single L1A at 7V but noticeably quieter. Anyway, I was struck by how easy it was to get this mounted on a radiator and thought a photo might be of interest to someone else here (even though it's not a big-assed blower on a big-assed heater core :) ) |
Very nice. Looks like my theory that they'd be well suited and very annoying to work with was dead on ;)
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Excellent work bobkoure. That's exactly the way in which they should be used. Would be nice to see some "slim-line" blowers of a similar nature to what you've constructed for radiator use. As in say a 30mm deep blower that attaches much like an axial fan would, just like how you have it, with all the orifices and stuff centered properly from the factory.
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Details here: http://forums.procooling.com/vbb/sho...rized+impeller |
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Does that make this officially the "little-ass blower"? :) More seriously - any idea how much (and where) to get some of the non-surplus ones? Or, better yet, impellers using the "silent blower" fanwheel from japan servo (see this PDF from our "links" area) Quote:
Given that I already had a plate designed to fit exactly where a 120mm fan went and a shroud also designed for a 120mm fan, using four long bolts was a no-brainer (and cheap). The aluminum sheet was $0.25 at the hardware store and cut fine with scissors (good thing because I broke my aircraft snips trying to cut a PC case - Mr. Ham-fist himself). Cathar - I totally agree. It wouldn't be hard for Rotron to do that. Short of that happening, maybe our friends at coolingworks might look at putting together an "impeller kit"...? Want me to ship a couple of these "little assed blowers" down your way? |
I wonder if there are any blowers that would fit directly onto a 120mm fan mount?
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Try here: http://www.surpluscenter.com/sort.as...c&keyword=EBSD |
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http://www.surpluscenter.com/item.as...tname=electric |
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