Is It Possible To Use The "Dyson" Principles In A Wind Turbine?

[David Chu]

Hey Everyone,

Unfortunately, I know about as much about engineering as Lindsey Lohan, but I can't help but see the latest Dyson product, the blade less fan and think if the same principles of vortex and induction can't be used to make more efficient wind turbines?

http://www.dyson.com/technology/airmultiplier.asp#HowItWorks (http://www.dyson.com/technology/airmultiplier.asp#HowItWorks)

Is it because the the dyson products are actively pushing the air?
Is it impossible to passively shape the air?
Do these concepts have nothing to do wind turbines?
Should I just die my hair blond and get a miniature dog?

Thanks in advance to anyone who can explain this to me!!!

- David Chu

[Rob Beckers]

Hi David,

If, or how, this works I can't really tell you. Short of running CFD simulations it would be hard to say anything about it. I would like to add a few general remarks though. There is no such thing as a free lunch when it comes to energy. If air is accelerated this requires energy (air has mass, so the kinetic energy is 1/2*mass*velocity^2). Meaning that for wind turbines this wouldn't really work. People have done similar things for wind turbines using ducted fans, and they do indeed speed up air to some extend, but at the end of the day it just doesn't justify the extra expense and complexity.

About Dyson in particular: They have in the past shown to be quite unashamed in (ab)using real, working technology and claiming that their vacuums used this to function better, even though their implementation is merely a caricature of the real thing and otherwise worthless. For example, they claim to use cyclone technology to spin out the dust, and make their vacuums more effective without needing a bag. Cyclones do work, in fact they can work very well. It's amazing to see a large industrial cyclone spin out micron-sized particles so they don't go out the exhaust. However, they require a certain size and shape to work, and even though a vacuum has a higher air speed (which would help scale down the cyclone size) those little things on a Dyson have zero effect. Still, they make the claim. In other words, there are lies, damned lies, and advertisements....

-RoB-

[David Chu]

Hey Rob,

Thanks for the response. I'm taking a break from vacuuming with my Dyson right now. Lol. (Their marketing pitch really worked on me!)

[Rob Beckers]

I have one too David. :embarrassedt:
It's getting a bit old these days, so we bought a Miele last year. Now that is a real vacuum! (Though I've heard North Americans don't like the European style vacuums because they lack that rotating brush).

-RoB-

[Ralph Day]

Hi Rob
My daughter bought a Miele and love it. They wanted it to remove any asbestos in the house dust (an attic full of vermiculite). We have a good old Beam central which exhausts outside...no old bag smell from a vacuum anymore.

Ralph

[Grumpy Bunsford]

re: the "bladeless" fan as a turbine.

Firstly, from my understanding of the Dyson bladeless fan thingy, the principles in place are sound, but technically, there are blades of sorts in the form of an impeller in the base of the unit, which "pumps" air into the ring around the unit. The ring squeezes the air through a shaped slot in the ring, which accellerates the airflow over an airfoil profile. The profile directs the airflow outwards like a cone.
The fast flowing air, combined with the outward direction of flow creates low pressure in the centre,to the front of the ring, drawing air from the rear of the ring & sustaining a flow of air.

In marketing speak they've named this an "air multiplier effect". Roughly the same profiled ring device has been seen in the past, stuck on the end of compressed air lines at F1 races to use as a cooling fan for drivers in the garage.

Onto the wind turbine part; it may be possible, but I'm not sure it would be efficient.
A similar ring device, placed in a flow, could be used to "draw" air through the slot, creating a flow up through the base...
...much like the impeller in the Dyson thing, you still need a turbine of sorts in the base to gather the energy.
I think the problem is efficiency. It will create a low pressure area at the base, which needs air to feed it to keep the flow running - so you might be better putting it in the flow rather than at the base.
\
someone with more brains might be able to design something efficient using this effect, but not me!

[Dale Sheler]

There are and have been quite few HAWT style turbines with forcing cones and funnels in just about every variation imaginable, but to my knowledge none have ever significantly improved on a normal HAWT.
It is mostly because of the fact that air coming into contact with any surface creates friction and causes it to slow down or change direction in a totally unexpected way.
So, basically, anything you put in between the collectors (blades) and the alternator is going to cause a reduction in the efficiency of the collectors.

[Dave Turpin]

The Dyson air blade works by fluid shear. It would not work backwards, and, to be honest, it doesn't work very well forwards. The air blade uses far more energy to move the same air volume as a standard fan.

[Grumpy Bunsford]

Hi Dave,

The air blade is a different product.
That's a hand drier.

The "bladeless fan" is something very different, aimed at replacing office-type "air mover"/ cooling fans (see my explanation a couple of posts back)

[Dave Turpin]

I just used the wrong name.

[Grumpy Bunsford]

Cheers for clarifying.

Any chance of expanding on how the bladeless fan "works by fluid shear"?

I'm not familiar with fluid shear, though it sounds like it would define the stress force where 2 parts of the same flow are moving at different rates.
Is that about right?

If so, how do you apply that to this application vs the explanation above?

[Dave Turpin]

Fluid shear is simply the fact that since air has some viscosity, the movement of air causes adjacent air to move. If you create a step-velocity at the walls of a tube (as in the Dyson), the velocity profile over the cross-section will end up being a strange shape, with a 4th-order parabola subtracted from a second-order parabola... The math is unimportant. The fact is that the Dyson is hugely inefficient and despite marketing claims, a venturii effect has nothing to do with how it actually works. As stated above, the engineers at Dyson are pretty loose with their fluid mechanics...

[Grumpy Bunsford]

I think I see your point.

Creating a static are of low pressure wouldn't create motion in one direction, so that has to come from the flow at the rim hitting the adjacent static air in the middle.

The setup being better than a flat profiled ring, but nothing special really.

[Cor van Houtum]

We called this in the past a compressor
blowing into the room

lol :laugh:

[Filipp Kogan]

Check out HEWS at www.hewstech.com
This high-efficiency distributed wind power system passively engages the additional ambient wind energy at higher elevation to produce a pressure differential (vacuum) and induce an evacuation force for the airflow through a turbine at lower elevation to increase the overall system effectiveness and efficiency.