Science and technology question

Storm · Posted: Wed Aug 06, 2008 3:45 pm Post subject: Science and technology question

I'm building a cardboard wind tunnel for someone I'm interning for. The tunnel is built, and everything works, but the fan is a mystery fan. I need to find the CFM that an old 22", five-blade box fan moves. It's six inches deep and I think it's a Galaxy fan, from the 1989-90 manufacturing year. It's a three-speed fan, and it looks exactly like this Linky except for the fact that the speed knob broke off long ago. I can't find the product manual, original packaging, or a part number that gets me anywhere that helps.

Does anyone know the formula to find CFM of a fan? I know how to convert CFM to airspeed, but I need the first number.
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Asa · Posted: Wed Aug 06, 2008 3:57 pm Post subject:

Try going to www.tinyurl.com and shorten that link, it's so long that it doesn't work.
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thespaceinvader · Joined: 23 Mar 2008 Posts: 650 Location: Cardiff, UK

Nah, it doesn't work cos it's a IMG link and the file type is not an image.
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Asa · Posted: Wed Aug 06, 2008 5:06 pm Post subject:

Oh. But usually, the link will still work, just not the img tags, I thought?
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Nem: "It's the sort of face you just know is getting ready to poke you with something sharp."
BS: "...then insist you eat a brownie."
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If we shadows have offended,
Think but this and all is mended...
Give me your hands if we be friends,
And Robin shall restore amends.

Tyris · Posted: Wed Aug 06, 2008 5:16 pm Post subject:

The image wanted is http://lh4.ggpht.com/_9M-0_ybkxtA/RxK5eilfKJI/AAAAAAAAAEU/wh2uD4W4IQU/P1000578.JPG rather than that ridiculous Googly link.

But anyway... don't know a standard formula, but you could always just measure it. Find a nice long windsock-like bag, measure its dimensions, time how long it takes the fan to inflate it, then divide volume by time. It won't be fully accurate because resistance will increase at the end, but hey, better than nothing, right?

Speed measurements are so much easier when the fluid is a liquid...
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theBSDude · Posted: Wed Aug 06, 2008 5:19 pm Post subject:

Asa · Posted: Wed Aug 06, 2008 5:23 pm Post subject:

And this h-scrolling is ridiculous. Can someone please fix that link so it's small?
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Self-styled Forum Grandmother, because I hand out nicknames and hugs whether you want them or not. ^_^

Keeper of the Library and the Gateway to Haven

Nem: "It's the sort of face you just know is getting ready to poke you with something sharp."
BS: "...then insist you eat a brownie."
__________________
If we shadows have offended,
Think but this and all is mended...
Give me your hands if we be friends,
And Robin shall restore amends.

thespaceinvader · Joined: 23 Mar 2008 Posts: 650 Location: Cardiff, UK

Done. But get firefox 3. No h-scrolling issues over here =D it seems to cope with them automatically.
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Keeper of Tristram's rings, and Felucca's very expressive ears.

Asa · Posted: Wed Aug 06, 2008 5:45 pm Post subject:

Well I'm getting a laptop in a few days, so we'll see about it then.
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Self-styled Forum Grandmother, because I hand out nicknames and hugs whether you want them or not. ^_^

Keeper of the Library and the Gateway to Haven

Nem: "It's the sort of face you just know is getting ready to poke you with something sharp."
BS: "...then insist you eat a brownie."
__________________
If we shadows have offended,
Think but this and all is mended...
Give me your hands if we be friends,
And Robin shall restore amends.

Tyris · Posted: Wed Aug 06, 2008 6:37 pm Post subject:

Storm · Posted: Thu Aug 07, 2008 10:16 pm Post subject:

Um, guys? The windsock idea didn't work. The fan's too powerful. That's why I really need help here. And sorry about that link, but it's the best I could do.
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The universe is really interesting. It's also screwed up, but that's what makes it so interesting.

Miho's Young Padawan

Dubbed "Poodle" by Asa and "Teh Stormy Poodle" by Ponce