1/17/2006: Horizontal windmill - Page 2

xoxoxoBruce · 01-17-2006, 10:21 PM

Quote:

Originally Posted by richlevy

I saw the vertical eggbeater versions in a demonstration in 1976. The company claimed they were more efficeint than the propeller design, but all I see are the propeller style windmills, so something must be driving the selection.

IIRC, Popular Science showed a ship designed with several vertical eggbeaters powering the electric motor driven props.

zippyt · 01-17-2006, 11:29 PM

A few months back I was doing some work a a state scale here in Arkansas , there were all these trucks carryoin these MASSIVE pieces , some looked like propellers , others just looked like BIG ass poles , the props were so big they took up an ENTIRE 18 wheeler , and the poles were in sections , i was woundering what they all were for untill i start seeing central hubs , a trooper pulled one of these truck over and asked what they were hauling , they were BIG ass wind mills for some where up north ( Michigan I think )

wolf · 01-18-2006, 02:20 AM

Quote:

Originally Posted by Saknussem

Does anyone else want to just throw a huge eggplant through that thing when it is in a gale?

No, but I have a couple of people picked out.

VinDurzle · 01-18-2006, 04:07 AM

Quote:

Originally Posted by richlevy

I saw the vertical eggbeater versions in a demonstration in 1976. The company claimed they were more efficeint than the propeller design, but all I see are the propeller style windmills, so something must be driving the selection.

BTW, the kite idea sounds interesting, but if enough people did it I could imagine a real hazard to airplanes. It would be like having barrage balloons in WWI and WWII.

I wonder...If these are more efficient, why not have wind farms with this style on end for more efficient use of space? As you say something must be driving the prop style generators.

btw looks like a giant one of those weird head massage things people have at festivals! Itd certainly take care of any headache!

linknoid · 01-18-2006, 05:48 AM

Growing up in the middle of California, we'd occasionally take trips over to the coast, in or near the San Fransisco bay area. On the way there, there were hills covered with tons of windmills of different designs. I always thought it was strange, though, usually when we drove past only certain ones would be moving. But what I recall most about the egg beater type windmills is that none of them were ever spinning. I kind of suspect maybe they need a lot more wind to get started than an ordinary windmill.

Either that, or they just locked some of them down so they wouldn't spin to make the ones that were running more efficient...

onetrack · 01-18-2006, 07:58 AM

This eggbeater design is known as a Darrieus wind turbine .. named after its French inventor, who thought it up around 1927 ..

The interesting part about this design .. and linknoid has just touched on it .. is that the blades are built around an airfoil principle, and cannot self start - but must be cranked to get going.

Once running, they are more efficient than the regular propeller design, due to the airfoil design providing "lift" just like an airplanes wing.

Likewise, they have a lower velocity of the outer part of the blades, at speed .. unlike propellor designs, whereby the high speed of the prop tips starts to create drag at high rotational speeds .. as well as increased noise.

The Darrieus designs do have a problem with sinusoidal (pulsing) of the blades .. meaning at certain RPM's, they develop a "whip", which can break the blades if left at the critical RPM for too long.

This is a similar problem to the longitudinal whip which can develop in an internal combustion engine crankshaft, which can also break the crankshaft. Torsional dampers on IC engines help prevent crankshaft whip .. but they do not appear to be feasible with Darrieus turbine blades, because torque on the turbine blades is not a factor in the problem, unlike crankshafts.

The interesting part of the particular Darrieus wind turbine, pictured, is that they have crossed the design with a propellor design, by lying it down, and effectively turning it into a "horizontal axis" machine .. whereas most Darrieus arrangements are "vertical axis" generators.
By doing so, they have eliminated a major amount of cost, by not having to have, a massive base structure, bearing and guy wires.

The normal Darrieus vertical axis generators, although not needing a heavily-built tower for support .. are stuck with the problem of needing guy wires for support .. and the problem of needing to be nearly totally dismantled for any bearing or generator repairs.

To add complexity to interest .. high buildings generate substantial vertical wind currents .. and this particular turbine design above, appears to be following a Dutch design, known as the "Turby" design, which has blades with a helical cant, to take advantage of vertical air currents, as well as horizontal ones ..

More on wind turbine designs .. http://en.wikipedia.org/wiki/Darrieus_wind_turbine

I trust the "Turby" turbine design, performs far better than their website .. http://www.turby.nl/

Windwall is the Dutch company that installed the French unit pictured, and their website is quite informative ..

http://www.windwall.nl/eng/aboutwind02_eng.htm

chrisinhouston · 01-19-2006, 06:21 AM

Here is an another image of one on a building.

glatt · 01-19-2006, 08:48 AM

Quote:

Originally Posted by glatt

According to this, the average household electric power demand in the US in 1997 was 10,219 kWh.

Following the link above, (thanks onetrack!) we see that one module produces the following:

Quote:

A WindWall turbine consists of one or more interconnectable modules. The specification of a standard module is:

Rotor diameter: 1990 mm
Length: 5 m.
Mass: 1500 kg
Nominal capacity: 2 kW
Yearly production: 1500-4500 kWh/y dependent on wind and location

So the 9000 kWh quoted from the article is the absolute most that two of these modules can provide in a year. A typical US household uses 10,219 kWh in a year.

The bottom line? The turbines pictured in this IOD don't even produce enough power to run one typical US household, but if it's a very windy location, they come close.

capnhowdy · 01-19-2006, 04:49 PM

I bet the blades ice up bad. I would think they'd have to be maticulously balanced to work right. Wouln't take much ice to buffalo it prolly.

xoxoxoBruce · 01-19-2006, 05:39 PM

Teflon coat 'em.

capnhowdy · 01-19-2006, 05:49 PM

Is that what they do to airplane wings?

xoxoxoBruce · 01-19-2006, 06:02 PM

No, they use heaters but that wouldn't be practical here.

01-17-2006, 11:29 PM	#17
zippyt LONG LIVE KING ZIPPY! per Feetz Join Date: Mar 2003 Location: Arkansas Posts: 7,661	A few months back I was doing some work a a state scale here in Arkansas , there were all these trucks carryoin these MASSIVE pieces , some looked like propellers , others just looked like BIG ass poles , the props were so big they took up an ENTIRE 18 wheeler , and the poles were in sections , i was woundering what they all were for untill i start seeing central hubs , a trooper pulled one of these truck over and asked what they were hauling , they were BIG ass wind mills for some where up north ( Michigan I think ) __________________ "Success is getting what you want. Happiness is wanting what you get. " Brother Dave Gardner

01-18-2006, 07:58 AM	#21
onetrack Coronation Incarnate Join Date: Nov 2003 Location: Western Australia Posts: 99	This eggbeater design is known as a Darrieus wind turbine .. named after its French inventor, who thought it up around 1927 .. The interesting part about this design .. and linknoid has just touched on it .. is that the blades are built around an airfoil principle, and cannot self start - but must be cranked to get going. Once running, they are more efficient than the regular propeller design, due to the airfoil design providing "lift" just like an airplanes wing. Likewise, they have a lower velocity of the outer part of the blades, at speed .. unlike propellor designs, whereby the high speed of the prop tips starts to create drag at high rotational speeds .. as well as increased noise. The Darrieus designs do have a problem with sinusoidal (pulsing) of the blades .. meaning at certain RPM's, they develop a "whip", which can break the blades if left at the critical RPM for too long. This is a similar problem to the longitudinal whip which can develop in an internal combustion engine crankshaft, which can also break the crankshaft. Torsional dampers on IC engines help prevent crankshaft whip .. but they do not appear to be feasible with Darrieus turbine blades, because torque on the turbine blades is not a factor in the problem, unlike crankshafts. The interesting part of the particular Darrieus wind turbine, pictured, is that they have crossed the design with a propellor design, by lying it down, and effectively turning it into a "horizontal axis" machine .. whereas most Darrieus arrangements are "vertical axis" generators. By doing so, they have eliminated a major amount of cost, by not having to have, a massive base structure, bearing and guy wires. The normal Darrieus vertical axis generators, although not needing a heavily-built tower for support .. are stuck with the problem of needing guy wires for support .. and the problem of needing to be nearly totally dismantled for any bearing or generator repairs. To add complexity to interest .. high buildings generate substantial vertical wind currents .. and this particular turbine design above, appears to be following a Dutch design, known as the "Turby" design, which has blades with a helical cant, to take advantage of vertical air currents, as well as horizontal ones .. More on wind turbine designs .. http://en.wikipedia.org/wiki/Darrieus_wind_turbine I trust the "Turby" turbine design, performs far better than their website .. http://www.turby.nl/ Windwall is the Dutch company that installed the French unit pictured, and their website is quite informative .. http://www.windwall.nl/eng/aboutwind02_eng.htm __________________ Illiterate??? - Not a problem! Write today for more information!! .... Last edited by onetrack; 01-18-2006 at 08:41 AM.

01-19-2006, 06:21 AM	#22
chrisinhouston Professor Join Date: Sep 2001 Location: Houston TX Posts: 1,857	Here is an another image of one on a building. Attached Images

01-19-2006, 04:49 PM	#24
capnhowdy Blatantly Homosapien Join Date: Mar 2004 Posts: 6,200	I bet the blades ice up bad. I would think they'd have to be maticulously balanced to work right. Wouln't take much ice to buffalo it prolly. __________________ Please type slowly. I can't read very fast............... and no holy water, please.

01-19-2006, 05:39 PM	#25
xoxoxoBruce The future is unwritten Join Date: Oct 2002 Posts: 71,105	Teflon coat 'em. __________________ The descent of man ~ Nixon, Friedman, Reagan, Trump.

01-18-2006, 05:48 AM	#20
linknoid Superior Inhabitant Join Date: Sep 2002 Posts: 74	Growing up in the middle of California, we'd occasionally take trips over to the coast, in or near the San Fransisco bay area. On the way there, there were hills covered with tons of windmills of different designs. I always thought it was strange, though, usually when we drove past only certain ones would be moving. But what I recall most about the egg beater type windmills is that none of them were ever spinning. I kind of suspect maybe they need a lot more wind to get started than an ordinary windmill. Either that, or they just locked some of them down so they wouldn't spin to make the ones that were running more efficient...

01-19-2006, 05:49 PM	#26
capnhowdy Blatantly Homosapien Join Date: Mar 2004 Posts: 6,200	Is that what they do to airplane wings? __________________ Please type slowly. I can't read very fast............... and no holy water, please.

01-19-2006, 06:02 PM	#27
xoxoxoBruce The future is unwritten Join Date: Oct 2002 Posts: 71,105	No, they use heaters but that wouldn't be practical here. __________________ The descent of man ~ Nixon, Friedman, Reagan, Trump.

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