Author Topic: Science guys/gals - air horns/movers/multipliers - how do they work? (Read 6799 times)

Stand_watie · « **on:** July 27, 2011, 08:33:00 PM »

http://www.accordintl.com/Resources/S10_P15_AHB.pdf

We use these at work and I'm curious about the physical principle(s) at work here. Compressed air at the inlet is forced through a little ring in the housing and the end result is the narrow end drawing a vacum and the large end blowing a breeze that is disproportionate to the amount of compressed air started with.

I spotted one of these at the home improvement store recently...

http://www.abcwarehouse.com/product_catalog/pc_proddetails.asp~assort_id~1237~prod_ID~53347

...and I'm sure they use the same principle, I just want to be able to put a better name to it than "magic".

AmbulanceDriver · « **Reply #1 on:** July 27, 2011, 08:41:32 PM »

Two principles:

Inducement and entrainment.

These guys do a lot better job explaining than I could:

http://electronics.howstuffworks.com/gadgets/home/dyson-bladeless-fan1.htm

birdman · « **Reply #2 on:** July 27, 2011, 09:41:37 PM »

Bernoulli. But ambulance driver's answer was likely more useful.

RoadKingLarry · « **Reply #3 on:** July 27, 2011, 10:14:15 PM »

Quote from: Stand_watie on July 27, 2011, 08:33:00 PM

...and I'm sure they use the same principle, I just want to be able to put a better name to it than "magic".

Any technology sufficiently advanced from your own is indistinguishable from magic.

birdman · « **Reply #4 on:** July 27, 2011, 10:15:27 PM »

Quote from: RoadKingLarry on July 27, 2011, 10:14:15 PM

Any technology sufficiently advanced from your own is indistinguishable from magic.

Whoa, how do you magically make your thoughts appear on this glowing box?!

280plus · « **Reply #5 on:** July 28, 2011, 11:57:26 AM »

It's called an air ejector, or that's one term for it. The air coming out around the ring creates a low pressure area within the circmference of the ring that draws air through it. The same principle is used in an eductor which is a water powered device of similar design. Water is forced out around an opening (correct term "venturi" represented by the ring of the Dyson fan) which creates a low pressure are that draws water through the venturi.

http://en.wikipedia.org/wiki/Injector

Harold Tuttle · « **Reply #6 on:** July 28, 2011, 12:32:55 PM »

Quote

Upon its launch, Dyson made available two sizes of the Air Multiplier. The larger model has a fan with a 12-inch diameter (about 30.5 centimeters).
The smaller model has a 10-inch diameter (25.4 centimeters).

The stylish fans weren't cheap -- the smaller model's suggested retail price was $299.99, while the larger fan would cost you $329.99.
That's a pretty steep price for a device that pushes air at you.

There's no question that the Dyson Air Multiplier is a striking invention. Its sleek design and innovative technology set the blogosphere abuzz when it launched.

Perhaps in the future none of our fans will have visible blades.

280plus · « **Reply #7 on:** July 28, 2011, 12:50:17 PM »

Hmmmm, $329 vs $9,,,tough choice...

Stand_watie · « **Reply #8 on:** July 28, 2011, 01:25:49 PM »

Quote from: 280plus on July 28, 2011, 11:57:26 AM

It's called an air ejector, or that's one term for it. The air coming out around the ring creates a low pressure area within the circmference of the ring that draws air through it. The same principle is used in an eductor which is a water powered device of similar design. Water is forced out around an opening (correct term "venturi" represented by the ring of the Dyson fan) which creates a low pressure are that draws water through the venturi.

http://en.wikipedia.org/wiki/Injector

I got a 2fer on that post. An explanation for the steam injector on my boiler as well.

sanglant · « **Reply #9 on:** July 28, 2011, 01:32:17 PM »

some of us are willing to spend big money on quite. but on this thing, i'm still waiting on the ~59.99 walmart special.

i just don't see this as a freedom loving company.

280plus · « **Reply #10 on:** July 28, 2011, 01:45:00 PM »

Quote from: Stand_watie on July 28, 2011, 01:25:49 PM

I got a 2fer on that post. An explanation for the steam injector on my boiler as well.

right, they can be used to inject water into a boiler or remove air and non condesibles from a steam drum. We udes steam powered air ejectors to remove air from our main condensers and pull them all the way down to 24" vacuum. Imagine the steam would enter the main turbine at 1200 PSI and exit into the condenser at below atmosperic pressure. Now that's squeezing all the power out of your steam.

Brad Johnson · « **Reply #11 on:** July 28, 2011, 06:22:58 PM »

They sell the Dyson on the no-fan thing. Problem is it's still relatively noisy... a LOT more than you'd think.

Brad

zahc · « **Reply #12 on:** July 28, 2011, 07:12:04 PM »

Quote

Hmmmm, $329 vs $9,,,tough choice

Just think how much air you could move with 36.5 of the walmart fans that you could buy with the same money as one Dyson fan.

I agree they are cool, though.

HeroHog · « **Reply #13 on:** July 28, 2011, 07:39:56 PM »

Quote from: Brad Johnson on July 28, 2011, 06:22:58 PM

They sell the Dyson on the no-fan thing. Problem is it's still relatively noisy... a LOT more than you'd think.

Brad

And it HAS a fan! Yes, it's hidden in the base but...

sanglant · « **Reply #14 on:** July 28, 2011, 09:48:20 PM »

i wonder if you could swap in a quieter, faster, and or bigger fan. heh, fan hacking.

CNYCacher · « **Reply #15 on:** July 28, 2011, 10:39:27 PM »

Quote from: Brad Johnson on July 28, 2011, 06:22:58 PM

They sell the Dyson on the no-fan thing. Problem is it's still relatively noisy... a LOT more than you'd think.

Brad

Really? They have one setup at the door of our local Lowes and it seemed pretty damn quiet to me. Actually I remember not knowing if it was on until i got close enough to feel the wind on my face

sanglant · « **Reply #16 on:** July 28, 2011, 11:00:51 PM »

you still have the fan noise, i didn't try taking the display in BB&B apart(for some reason that seems to make 'em mad.

) but it sounds like a computer fan.

edit: forgot, unless it's on high, (first thing i did was to turn it all the way up

) i doubt many people will be able to hear it, but if you have good hearing you'll probably be able to hear it across a quite room on lower settings.

freakazoid · « **Reply #17 on:** July 29, 2011, 02:04:35 AM »

Saw one of those on display at Walmart. When I first saw it I was all WOAH! How is that creating air!? Then I saw that there was in fact slits where the air was coming out of and I was disappointed.

birdman · « **Reply #18 on:** July 29, 2011, 07:38:04 AM »

Quote from: freakazoid on July 29, 2011, 02:04:35 AM

Saw one of those on display at Walmart. When I first saw it I was all WOAH! How is that creating air!? Then I saw that there was in fact slits where the air was coming out of and I was disappointed.

Get an electrostatic fan...no moving parts (of course, not much airflow either)

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Author Topic: Science guys/gals - air horns/movers/multipliers - how do they work? (Read 6799 times)