Air multiplier wind turbine

[MarkB]

I'll step in to defend Dyson. We have one of his upright vacuums, and it has been great. Excellent suction and very flexible. The way the hose is stored around the handle is genius and makes it very easy to switch to using it. Removing and emptying the dust cylinder is also very easy. Yes, there is a filter to clean, but it's easy to get to, and just needs to be rinsed under the tap and left to dry.

We also have one of the little handhelds. This is great for quick tidy-ups, particularly when the kids have left crisps/biscuit crumbs all over the place.

Finally, I like the airblades. I first saw something similar in Japan over a decade ago and it struck me as a really good idea then. The airblades are quicker and more efficient, albeit pretty noisy. We have a couple of airblade knock-offs at work. The sort of work, but have a water bottle that keeps needing to be emptied and grow mould unless cleaned daily.

Dyson products may be expensive, overly designed, but our experience of using them has been great. It's a shame they're now built int he far east, but thsi was always inevitable.

[SimonHobson]

OK just to add to the mix I have been researching contra rotating turbines and the efficient generators you get due to the contra rotation and found this article which I have found fascinating.

Interesting. I was under the impression that the benefits were well known, but people are put off by the problems. The front rotor is fine, but the one behind it gets quite a high cyclic perturbation in the wake from the front rotor. And then for anyone/thing downwind, there are noise effects as the rotors chop the wake up.

In any case, there's a whole industry geared up to 3-blade, single rotor designs - and I doubt they are going to admit their designs are "wrong"

[martin]

Whenever "revolutionary" designs (there's a pun in there somewhere!) for turbines come up, I remember the sage words of Paul Gipe -

"What lessons have we learned from 30 years of modern wind turbine development?

There are

No Panaceas
No Cheap Solutions
No Breakthroughs--No Miracles
Numbers Matter (Wind Energy is Always about Numbers)
Experience Matters (If They Haven't been Building these things for Years then How Do You Know that it Works)
Size Matters (You can't get Blood from a Turnip nor a lot of Electricity from a Small Rotor)"

from here - http://www.wind-works.org/articles/FantasyWindTurbines.html  -loads more here - http://www.wind-works.org/articles/small_turbines.html#Inventions & Questionable Wind Turbines

[SimonHobson]

...  -loads more here - http://www.wind-works.org/articles/small_turbines.html#Inventions & Questionable Wind Turbines

great stuff
I love seeing some of these things, except you have to feel a bit sorry for the suckers who've been duped into parting with their cash. I meant to snap a pic of one I spotted in Manchester at the weekend (I'll try and remember next time I'm there) - sat on a rooftop, surrounded by large buildings, and just merrily swinging about. No generation, just swinging on it's pivot as the turbulence played with it. It should have been working, it was a nice windy day

[biff]

i have to second markB and also defend mr dyson,
                       We needed a vacuum cleaner with low wattage because our income was only 2kw.before we got the dyson we had to switch everything else off in the house.She went online and bought a 600watt upright job with all the attachments for doing the stairs and curtains.its a brilliant little job and makes her housework a lot lot easier.There is no bag,just a transparent round cylinder that you can see what is happening,and it is easy emptied.
    It is the best performing vacuum cleaner we have had to date.
                                                                  biff

[Philip R]

Contra rotating turbines, nothing new.

There used to be a steam turbine from way back when called a Lungstrohm from Sweden, was used in the UK by Brush many moons ago.

The latest GE 90 Aircraft engine uses contra rotating stages.

With these designs, the blade passing frequencies double, so the dynamics of the blades harmonic vibrations need to be carefully modelled. If the design can be build with less material and has higher efficiency than other non contra roting designs, so be it.

PhilipR.

[Ivan]

I got 'sucked into' the dyson vacuum thing when they came out. I hate hoover bags, so I though it sounded like a good idea. I had two of his vacuum cleaners. The first is a single cyclone - filters block pretty quickly and the motor overheats. Then I bought the multi-cyclone. This time the filters block pretty quickly, but so do the tips of the cyclones (NEVER SUCK PLASTER DUST IN A DYSON - guaranteed to block it up within 5minutes). I soon learnt that replacing dyson filters is an expensive business, so I had to discover that the hepa filter would withstand washing (not a great idea for hepa filters). But unblocking the cylones was a hard job as you presumably need special tools to dismember them from the cylinder - a pain to do, every time.

My Dyson advertising slogan is 'Goodbye Bag.......Hello blocked filter'