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View Full Version : Is there a future for fan blades?



Jon Pert
13-Oct-09, 08:21 AM
So, will we still be using fans in 30 years time? ;)

http://www.dyson.co.uk/fans/

John Robertson
13-Oct-09, 08:39 AM
Superb bit of product design!

However, there is still a fan - it's in the base!

atters
13-Oct-09, 09:52 AM
Maybe a diagram of how it works would help. I am as confused as the guys on the video.
:confused::confused::confused::confused::confused: :confused::confused:

falconer
13-Oct-09, 11:01 AM
Looks like its using the venturi or jet pump effect - would that be correct?

John Robertson
13-Oct-09, 11:16 AM
Explanation (and video) is at http://www.dyson.co.uk/technology/airmultiplier.asp

Just checked the price :eek: - 200 for a desk fan!!!!

Jon Pert
13-Oct-09, 01:43 PM
Just checked the price :eek: - 200 for a desk fan!!!!

Ah yes, but the difference is you don't get "chunks" of air like with a standard desk fan.

Chunky air, ffs! http://www.jonrb.com/emoticons/hehe.gif

Ross Floyd
13-Oct-09, 02:40 PM
I seem to recall Jetex did something similar on their model engines about 40 years ago?

Ross

Keith Oakley
13-Oct-09, 03:48 PM
'Chunky air' = air turbulence= noise. So at first glance this should be quieter, but the Dyson website makes no claims as to noise. Is it because the high pressure fan in the base isn't quiet?
Is the website suggesting the fan in the base is shifting 27 litres/min then because of the 15X amplifier effect the whole thing is shifting 400 litres/min?
So why isn't this applicable to a hovercraft thrust 'fan'?
Keith

smallw1449
13-Oct-09, 09:35 PM
This technology has been around for years, anyone in the agricultural / farming business uses them all the tine for moving grain along long pipes. Small compressor supplies air to an anulus just inside the belmouth.

I had a 75mm dia one to play with about 15years ago but you do need quite high pressure air > 100psi to really create a good airflow


Keith

Bob Rennick
14-Oct-09, 01:00 PM
I've also seen this before (quite a few years ago) in a barn where compressed air was used to move grain along a pipe. I recall it being rather noisy and a *lot* of compressed air to make it work. I suspect the fan in the base of Dyson's 'new' invention is making quite a racket and using a fair bit of power (if it's really moving as much air as they claim it is). In addition, there appear to be quite a few inefficient bends and turns the air has to make from the fan to the annular exit.

Bob

atters
14-Oct-09, 01:04 PM
I agree with all of you, BUT, it looks FUNKY, so it will sell I am sure of it.

Jon Pert
14-Oct-09, 01:05 PM
'Chunky air' = air turbulence= noise. So at first glance this should be quieter, but the Dyson website makes no claims as to noise. Is it because the high pressure fan in the base isn't quiet?
Is the website suggesting the fan in the base is shifting 27 litres/min then because of the 15X amplifier effect the whole thing is shifting 400 litres/min?
So why isn't this applicable to a hovercraft thrust 'fan'?
Keith

Make your own mind up on the noise front! Video here. http://www.telegraph.co.uk/technology/news/6306352/James-Dysons-latest-invention-bladeless-fan.html

Bob Rennick
14-Oct-09, 01:25 PM
Well it certainly sounded noisy to me! I couldn't hear a thing when they turned on the conventional fan and they also remarked that the Dyson was set at its lowest setting!

Bob

Keith Oakley
14-Oct-09, 02:12 PM
They also confirmed that both fans had the same 40watt power consumption. I can't believe the Dyson shifts 15 times more air for that 40watts - it would be too strong in the office!
Keith

John Robertson
14-Oct-09, 02:35 PM
It's just marketing spiel Keith. It uses 1/15th of the volume of air to move the remainder - it is no more efficient (and may even be less efficient) than a conventional axial fan (they wouldn't have missed the chance to say so if it was more efficient :rolleyes:).

It's still a cool looking device!

Ian Brooks
14-Oct-09, 09:38 PM
They also confirmed that both fans had the same 40watt power consumption. I can't believe the Dyson shifts 15 times more air for that 40watts - it would be too strong in the office!
Keith

It can't be more efficient. The air coming from the annular ring is at high velocity, and the power is proportional to V^2. On top of this, there will be significant losses as the high velocity air entrains the low velocity air - its a submerged jet, just a funny shape, like the submerged jet at the heart of the servovalves we make. It's not an efficient system...

Ian