A bit proud & sycophantic ...but so what!? (warning treacley goo alert)

[renewablejohn]

Mr Gus

In that case get a small steam engine (mamod) great piece of engineering and shows the conversion of energy into useful work really well.

[martin]

I'll second that! - can you still get those string-fired gyroscopes too?

[Richard Owen]

it doesn't matter a flying fig which way the blades are attached, or which way round it revolves - you've essentially got the same device! If anything I'd suspect that the vawt is more likely to vibrate as it is inherently a more unstable model because the wringing loads on the bearing are going to be far higher!
I'm somewhat at a loss to understand why you think a VAWT would vibrate less.......

Well for one thing, I've been in this pub when the wind was blowing. http://www.quietrevolution.co.uk/projects.htm

The turbine was whizzing round and there was no discernable vibration and little noise (couldn't hear it from inside, could from outside, but it was quieter than the wind shearing round the corner of the building.)

The big torque variations of the early VAWTs have been elimiated by the use of helical, odd numbered blades. Very smooth torque.

For another, the presence of a mounting pole on a HAWT means that there is always a dip in force and torque as blades pass it meaning that there will always be stress across the bearings, which means that there will always be vibration.

That's why I think a VAWT will vibrate less that a HAWT.

But I might be wrong.

[martin]

it's mostly bearing noise - honest, try it! - Either go up on the roof and stick your head against the pole while it's rotating, or try kipping overnight in the building! The best description I can give of the sound is that it's like the noise you sometimes get from wheels/rails in the underground..........its FAR worse than the "shooshing" noise of the blades
I suppose another analogy would be to get a really big electric drill, and clamp the handle to one of the main timbers in your roof, then when it's all quiet at night, switch it on, and try to get some sleep.........then you'd know what I mean!

[Ivan]

I know it's not related, but there was a quiet revolutions (or lookilikey) fitted to a pub roof in Melton. After a few weeks it had fallen down 

If the turbine is unloaded, then you won't get anywhere near as much vibration (although it may overspeed and then fail mechanically - possibly what happened in Melton). When a turbine is loaded, it doesn't matter if it's the best balanced turbine in the world, and even if there was no torque variation whatsoever during spinning it would still cause vibration. This is because every time a magnet passes a coil, a force is generated. This force makes both magnet and coil shudder. The more current passing through the coil, the greater the magnetic flux, and the greater the amplitude of vibration.

Any vibration is carried very well through solid objects, as Martin's tried to illustrate. I speak from experience. I have a turbine mounted in such a way that it is braced against my garage. Only a 300W, but still quite noisy inside the garage in terms of transmitted noise - Martin's absolutely right - it's like a low rumbling, whirring noise. My garage is detached from my house, so it doesn't matter, but I'd get a right ear-bashing from the Mrs. if I had done this to the house!!

Martin's only trying to give advice - he's not saying don't do it!! I really like the vertical axis wind turbine design, but it is fraught with practical problems. One for example is the stress on the bearings, and of course, bearings rumble (try knocking your car out of gear, turn the engine off, and trundle along whisper tarmac road - you can usually hear the bearings rumble quite merrily). One noise advantage of the vertical axis wind turbine is it's lower rpm (a disadvantage in other respects) - on a big machine, such as the QR, this presumably reduces the frequencies, perhaps to less audible frequencies.

[billi]

Hello


This guy sells stirling and steam engine castings  and kits  even to produce power  

This is a google translation
http://translate.google.com/translate?u=http%3A%2F%2Fwww.sk-vespadat.onlinehome.de%2Fstirling%2F&hl=de&ie=UTF8&sl=de&tl=en

of the original website   http://www.sk-vespadat.onlinehome.de/stirling/

I think he askes about 300-400 euro for a small stirling -chp system ( about 50 Watt power produced) attached to a stove

Just a thought

billi

[MR GUS]

Thanks for that billi, (& everyone else) ..A mamod or a useable mini stirling may be just the thing, definitely on the list of things to do as she grows.

[Richard Owen]

I know it's not related, but there was a quiet revolutions (or lookilikey) fitted to a pub roof in Melton. After a few weeks it had fallen down 

<snip>

.... but it is fraught with practical problems. One for example is the stress on the bearings, and of course, bearings rumble (try knocking your car out of gear, turn the engine off, and trundle along whisper tarmac road - you can usually hear the bearings rumble quite merrily). One noise advantage of the vertical axis wind turbine is it's lower rpm (a disadvantage in other respects) - on a big machine, such as the QR, this presumably reduces the frequencies, perhaps to less audible frequencies.

Last post on this topic here: It's well away from Mr. Gus' original thoughts and all the examples quoted are for HAWTs, limiting the scope for discussing VAWTs.

As for the Melton turbine, it was there last Wednesday when I drove through on my way back from Oakham.

As for bearings rumbling, that's more of a design issue than an intrinsic one. Car wheel bearings aren't a great example because they have to cope with lots of shear loading because, unaccountably, people insist on trying to turn the wheel across the plane in which its rotating. So, any attempt at keeping them quiet is secondary to keeping them strong. It you were sure that your bearings weren't going to suffer that sort of stress, you could do lots to silence them such as using tapered rollers rather than balls (oooh eeer mrs.) and mounting them in a nylon rather than metal cage. Also, it would be very difficult to do in my car. At 236,000+, everything makes a noise.

And I think the argument comes down to this in general: Is vibration an intrinsic feature of all wind turbines (as you and Martin suggest) or is it a matter of design (as I am suggesting.) Unless someone has direct experience of living with a VAWT, then this is a bit of a sterile debate. If I had access to any meaningful amount of wind, I'd add a VAWT to my list of things to do at YTC.

I'll leave it there for now.

[martin]

I'm sorry, your argument leaks like a sieve - to say that unless someone has direct experience of a VAWT, that it's a sterile debate - it is for you to prove that they have somehow rewritten the laws of physics so that the alternate "pulling" between magnet and coils has been done away with, that they have made the first-ever completely silent bearings, and have somehow solved the preciously insoluble problems of  making "silent mounts"
I would suggest having a good read of  http://www.wind-works.org/articles/small_turbines.html
and most particularly http://www.wind-works.org/articles/FantasyWindTurbines.html
and this too http://www.wind-works.org/articles/RoofTopMounting.html
You'll find that he says in no uncertain terms that there are no shortcuts, magic wands, or wonderful new developments in wind turbines. You'll find a great many turbine companies making the most ridiculous and impossible claims for their products, particularly regarding roof mounting, VAWTs, ducted turbines, and the latest joke, a triangular section VAWT - you cannot rewrite the rules of physics just so you can make money from the mug punters out there...........

[MR GUS]

No worries, informed debate is healthy!

 from my uninformed view & living by the "wobbly bridge" in london when it was being constructed & opened amidst fireworks that didn't work (thames on fire..anyone) the obvious answer to me & south bank skateboarders was to put in place elastomer shocks (which they subsequently did, at incredible remedial cost, ..a skateboarder would've put it in en route) & took around 6 more months to sort before re-opening.

Elastomer damping blocks for skateboards come in differing types, ..and recent (well 80's) things like sorbothane are put to good use for smoothing out bumps, quirks & vibrations in hi-fi for years, now it's commonplace in footwear.

 So what sort of damping is used in both of the design types for turbines OR what could sort out problems thats not already utilised in say ..masts / mast holders et al?

..The reason I say this now is it BASICALLY seems to be shock absorbtion & dissapation at the end of the day, (to the uninitiated) something that plagues most things with moving parts.

 Where for instance does a damper sit on a turbines mast? whether its affixed to a building or tower to ground all the way along, in stages or not at all?
The wobbly bridge is probably comparable as  random footfall & no's differ (like wind) in laymans terms, ...& the bridge wobble pattern was all over the place. look at before & after pics (of available) then at the trucks of a skateboard, ..why was the result so expensive & missed  in the first instance?

[martin]

it's actually one of those problems that's more of academic than practical interest - roof -mounted wind turbines don't work anyway, due to turbulence problems induced by the building upon which they're mounted, so even if you could solve the noise transmission problems, you'd have a silent roof-mounted chocolate teapot that still didn't work.........
As far as I understand shock-absorbing with turbines, it depends on interposing chunks of bungy of some description between the turbine/pole/mount, which can only work to some extent (once it's shoved to the extent of it's travel, the bungy will effectively become solid, and transmit noise)
The one bit of research I have seen that may just work silencing bearings is to use a sort of "air-gap *maglev" system whereby the bearing surfaces are kept apart by electro-magnetism   -(but I believe one of the big problems of the maglev system is the large amount of power consumed (theoretically, I suppose you could literally "float" them on air using high pressure air,) but again that's going to consume a load of power, and knowing compressed air, is going to be noisy........which rather gets you back to where you started!
*"Maglev" is the terminolgy now used to describe an ENGLISH invention of the "linear motor" - that I saw demonstrated by a Professor Eric Laithwaite on TV in the 60's......... http://en.wikipedia.org/wiki/Eric_Laithwaite (one of my childhood heroes)

[frank2]

many cars use a harmonic damper (rubber mounted pulleys) on the end of the crankshaft, to reduce whip in the crank.
one of these fitted inside the nosecone "might" reduce vibration 

frank

[martin]

I came over all misty there for a moment at the words "whip in the crank"
Took me straight back to the days when I ran a 1936 Austin 7 Ruby Tourer as everyday transport, with the newfangled "3 bearing" crankshaft........ for some years the Austin 7 had run quite happily with 2 main bearings - the crank "whipped" like billyo, the relatively soft white metal solid bearings rapidly got rounded off, and it'd run happily for years...... then some plonker came along, and awarded it a third (centre) bearing, just before they made my Ruby...
The centre bearing would give up the ghost after anything from a few hundred miles to 3,000, and would then happily "clank" for years.......what was annoying was that the earlier 2-bearing job could be tuned to within an inch of it's life - the 3 bearing was deemed "unable to take it"......(really must get a "come over all misty" smiley)

[Ivan]

Ah, Eric Laithwaite. Did you see him on the Christmas lectures? I've got an avi file on a CD somewhere. Exactly how the Christmas lectures were meant to be.

Billi,

Is the guy in Germany selling ready made Stirling engines? Your link mentioned plans and drawings, but I don't have the time or skill to make them. If they are available ready-built, I'd love to have a go with his CHP stirling engine on my woodstove during the winter.



Ivan