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

[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?

Hey, I think I found something - a wind turbine without big blades:

http://greenlivingideas.com/topics/alternative-energy/wind-energy/generation-wind-turbine-produces-3-times-power

It seems to concentrate the flow of wind into a smaller cross-sectional area, and vaguely resembles a jet engine.

 

[russ_watters]

I don't know if that's for real, but the description in the link is pure nonsense:

The fundamental flaw in every wind turbine is that none of them actually speed up the air...

No.

The current systems extract less than 50% of the wind’s energy and are only working about a third of the time!

According to Dragonfly, the nature of the new turbine’s inner wing design increases the air speed to create more power – up to three times the average of a standard wind generator.

50%*3=150% efficient? No.

The chambers act as defusers so by the time the air reaches the third chamber, the smallest, the air inside is moving as fast as the air outside.

Uh, diffusers diffuse. They decrease air velocity, they don't increase it! By definition!

The nacelle of the Dragonfly was inspired by the technology of the SR 71 Blackbird, with a unique nose cone capable of expanding over 600% in size, increasing or decreasing the air speed and flow passing through the unit.

No, that's not what the SR-71 inlet cone was for. The SR-71 inlet cone basically just ensured that the cone shaped shock wave generated by the tip of the cone hit the inside of the inlet. The shock wave gets tighter as the plane accelerates, so the cone moves out.

From the picture, it looks like a jet engine - it looks like they are claiming the first three stages are fans/compressors that pull air in and accelerate it while the turbine is at the back. That can't happen.

According to Dragonfly Industries, two computer dynamic fluid (CDF) tests on the design were completed by an independent software company, SolidWorks, and the results are promising for moving forward with prototypes.

Solidworks is a software company, not an engineering company. They don't do the analysis for you!

Also, a simulation isn't a test.

and proves that more than 59% of the wind’s power can be harvested with the right design.

Uh - above it said that a typical turbine is 50% efficient and that this generated 3x more power...

 

[FredGarvin]

That article was written by someone who has no clue but likes being the mouthpiece for a questionable start up company. 3X power? Please...

 

[minger]

No. Uh, diffusers diffuse. They decrease air velocity, they don't increase it! By definition!

No, that's not what the SR-71 inlet cone was for. The SR-71 inlet cone basically just ensured that the cone shaped shock wave generated by the tip of the cone hit the inside of the inlet. The shock wave gets tighter as the plane accelerates, so the cone moves out.

Solidworks is a software company, not an engineering company. They don't do the analysis for you!

haha, those are the first things that jumped out at me too.

 

[dylanchong]

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

Yes, I buy one chinese "Shanzhai", more quieter and safer.