What's the secret behind Dyson's new bladeless fan?

[pixel01]

Here is the news:
http://uk.news.yahoo.com/21/20091013/ttc-dyson-launches-bladeless-fan-e1d36ba.html
Who can explain to me what is behind the fan?

Thanks

 

[mgb_phys]

The fan is in the base - it pushes air through the circumference of the ring where it comes out along the axis through tiny holes.
The idea is a smoother airflow and no whirling blades - so quieter and safer

 

[pantaz]

There's a write-up on Wired:
http://www.wired.com/gadgetlab/2009/10/first-look-dysons-blade-free-wonder-fan-blows-our-minds/

"The unit is essentially one of Dyson’s vacuum cleaners working in reverse. The gray base station sucks up air and forces it through the circular blue thing that sits atop the rig. When the air jets through the front of the circle, it creates a suction behind and to the sides that draws more air through the loop and makes the fan more powerful. Dyson claims the Multiplier increases pressure 15-fold and spews 118 gallons of air every minute."

"The Air Multiplier will go on sale on this fall and will cost $300 - $330."

 

[FredGarvin]

That is an insane amount for an air inducer with iPod styling. This is one item I will wait for the Chinese to get a hold of and reverse engineer for 1/10th the price. I give Dyson credit for his vacuum, but he is losing touch with reality.

 

[Topher925]

So the thing isn't really blade-less is it? Its just that the fan itself is housed in the base. Wouldn't a regular fan be a lot more efficient (along with cheaper) than one of these iFans?

 

[pixel01]

So the thing isn't really blade-less is it? Its just that the fan itself is housed in the base. Wouldn't a regular fan be a lot more efficient (along with cheaper) than one of these iFans?

The inventer just wants to have a smoother fan for the first reason.

 

[FredGarvin]

I know. I can't think of how many times I have sat in front of a fan and said "Gee...I wish the flow from my fan was smoother."

The only things he's got going are possible energy savings and safety.

 

[seb7]

I'm assuming that the moving air lowers the pressure in the centre thus dragging in more air to move with it.

Looking at this, I'm wondering, can the same principle be applied to an electric current. Could a small DC electrical current be applied in such a way as to creates a current flow 15 times more greater?

 

[mgb_phys]

Not quite.
It drags more through the hole at low speed by having a very high speed airflow at the edges - you don't gain any extra airflow. In fact it's less efficenct because of the energy lost as the high pressure air expands out of the small holes.

In electrical terms it's like short circuiting something - you get a lot more current flowing at a reduced voltage. But you don't get something for nothing

 

[FredGarvin]

Looks like there are others that are not being fooled by Dyson:

http://hackaday.com/2009/10/14/it-has-blades-dysons-little-white-lie/

 

[DaveC426913]

OK, technically the "bladeless" claim is false, but functionally (i.e. as a user uses it), it is true. I think that is a valid claim, since he's selling a product, not an engineering design. All the user-focused things relevant in a bladed fan do not exist in this device. And that's what's important.

Tell me, would anyone likewise cry foul at the claim that a hovercraft is a wheelless vehicle? I could probably find hundreds of wheels in a hovercraft, yet...

 

[Blenton]

Still, what a conversational piece to have.

 

[minger]

OK, technically the "bladeless" claim is false, but functionally (i.e. as a user uses it), it is true. I think that is a valid claim, since he's selling a product, not an engineering design. All the user-focused things relevant in a bladed fan do not exist in this device. And that's what's important.

Tell me, would anyone likewise cry foul at the claim that a hovercraft is a wheelless vehicle? I could probably find hundreds of wheels in a hovercraft, yet...

I don't really think you're talking apples and apples here. Sure, in a hovercraft, there may be wheels that support secondary systems and such; the wheels aren't integral to the concept and idea of a hovercraft.

When I think of a fan, or even an "air moving device" that has claims of "bladeless", then I sure as hell don't expect circular ducting sitting on top of a normal desk fan.

 

[mgb_phys]

Well zero emission vehicles have emissions - they are just hidden somewhere else that you can't see them. Same principle really.

 

[DaveC426913]

I don't really think you're talking apples and apples here. Sure, in a hovercraft, there may be wheels that support secondary systems and such; the wheels aren't integral to the concept and idea of a hovercraft.

When I think of a fan, or even an "air moving device" that has claims of "bladeless", then I sure as hell don't expect circular ducting sitting on top of a normal desk fan.

My point is that, as a product, it is a bladeless fan.

It does not operate like a bladed fan; it does not have the dangers or annoyances of a bladed fan. (Also, I'll bet dollars to donuts it is not a normal desk fan in the base.)

He's selling a product, not trying to wow physics buffs with some alleged new technology.

 

[minger]

I'm not trying to argue for the sake or arguing, but I guess this does bring a decent conversation in claims. At what point does it go from bladeless to blades then?

Right now a fan drives flow through a perforated torus (essentially), and we call it bladeless.

If the torus becomes simply a torodial opening, is it still bladeless? What if the opening becomes circular, essentially making it a ducted fan, is it still bladeless? What if the ducting shortens to just a protective shroud over the blade?

To me, it's analagous to saying that things like biodiesel and hydrogen are clean energy, when it requires an abundance of "dirty" energy to make them.

 

[FredGarvin]

I think I'll still stick with the "rip off" label myself.

 

[DaveC426913]

I think I'll still stick with the "rip off" label myself.

What is it being ripped off of?

 

[FredGarvin]

What is it being ripped off of?

I mean a rip off in terms of $300 for a cheap fan.

 

[DaveC426913]

I mean a rip off in terms of $300 for a cheap fan.

How do you know it's cheap?

 

[FredGarvin]

How do you know it's cheap?

Please. It's a DC brushless motor in a plastic housing with a plastic hoop on the top.

 

[russ_watters]

My point is that, as a product, it is a bladeless fan.

It does not operate like a bladed fan; it does not have the dangers or annoyances of a bladed fan. (Also, I'll bet dollars to donuts it is not a normal desk fan in the base.)

He's selling a product, not trying to wow physics buffs with some alleged new technology.

Yes its probably a centrifugal blower, required to generate the extra static pressure. If you see a $300 sc
ulpture fine but I see a $300 fan that is inferior to my $12 desk fan. I also see advertising that DOES intend to imply technical superiority.

 

[russ_watters]

Also advertising the performance in the nonstandard units of gallons per minute can only be an intentional effort to mask truly pathetic performance. It wouldnd even be a passable PC case fan.

 

[mgb_phys]

I worked for a company that did some work for Dyson. They have (or had) a lot of really bright engineers.
The original vacuum cleaner is amazing - it doesn't compare to the later bagless knockoffs, I immediately went out and bought one.
Their washing machine was ok but wasn't really worth the 2x markup. the more recent stuff is just marketing.

I think this is definitely aimed at the ($Money > $Sense) crowd, but it might be amusing for your cat to play with.

 

[FredGarvin]

I own a Dyson vacuum and I give them credit for that. It's the best vacuum (and the most expensive) I have ever owned.

I did have to laugh at the GPM performance. I gave them benefit of doubt in that how many people know what an SCFM is? Heck, I know engineers that have a tough time with that.

 

[sanman]

x-posted from Mechanical Engineering forum:

That makes me wonder - could similar principles be used to come up with a bladeless wind turbine? Some environmentalists are concerned that wind turbine blades could pose a hazard to birds. I'm wondering if Dyson's approach couldn't be used to rectify that?

Also, many residential areas might have zoning laws against things like wind turbines, but if they could be made bladeless then perhaps they might be exempted from such restrictions.

So rather than being an "air multiplier", I suppose it would be an "air concentrator".
Is such a concept possible? If so, would such a device prove to have comparable efficiency to standard wind turbines?

 

[FredGarvin]

The big issue I would see with that is that the inducer requires a high velocity jet to entrain the extra air. On such a large scale that may not be economically possible and may create a lot of aero noise.

 

[IMP]

This is not bladeless, blade is in the bottom. The only truly bladeless designs I know of are magnetohydrodynamic drives for ships and submarines (which only work in sea water) and the ION air purifiers...

I do like the design of this fan though, I would pay up to $29.95 for one.

 

[sanman]

How long until Chinese-made knockoffs appear?

And what are the limitations on this design? Could you have a giant ceiling fan of this type?

Could you turn it into a CPU-fan or power supply fan for your PC or laptop?

Could this thing be used in a propulsion system, to propel a vehicle and give it lift?

Could it work in water or a similar liquid?
Could it propel a ship, or a submarine, or motorboat? Sometimes you hear about whales or manatees being cut by propeller blades from boats. Could this be a cure for that?

 

[IMP]

How long until Chinese-made knockoffs appear?

And what are the limitations on this design? Could you have a giant ceiling fan of this type?

Could you turn it into a CPU-fan or power supply fan for your PC or laptop?

Could this thing be used in a propulsion system, to propel a vehicle and give it lift?

Could it work in water or a similar liquid?
Could it propel a ship, or a submarine, or motorboat? Sometimes you hear about whales or manatees being cut by propeller blades from boats. Could this be a cure for that?

Chinese knockoffs in 5...4...3...2...1

It looks like it uses a venturi effect to me. High pressure and low volume air drags in surrounding air to become low pressure and high volume.

I don't see why it couldn't be scaled up.

My leaf blower has an optional attachment on the discharge nozzle designed to funnel ambient air into the air stream, and does seem to greatly increase overall air volume.