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patb2009
User Rank
Gold
Re: Good idea
patb2009   3/17/2014 11:39:17 AM
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If you Look at a HAWT, turbine all the Blades face all the wind.

So you get 100% blade loading.  However it means you have to put the generator

on a lazy susan (No Insult intended), and run power down some slip rings.

A solution the industry is very comfortable with.

 

If you look at a VAWT,  the Front blade does all the work, the 2 side blades to nothing,

and the rear blade is heavily blanked by the machine shafts.  

Max Loading?  maybe 33%.  

That means the machine won't run well in light winds due to the extra drag forces.

 

VAWT seems very clever but the physics are just awful.  

 

It's an idea that is superficially clever but practically stupid, 

 

 

 

 

Elizabeth M
User Rank
Blogger
Re: Good idea
Elizabeth M   3/17/2014 6:06:06 AM
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Thanks for the comment and perspective, patb2009. I will take a look at the link you sent--seems interesting.

patb2009
User Rank
Gold
Re: Good idea
patb2009   3/17/2014 3:22:14 AM
NO RATINGS
Liz

 

Vertical Turbines have a way lower effective blade loading then a Horizontal turbine.

The big turbines have all settled on 2 and 3 axis Horizontal blades with minor

aero-optimization.  Vertical turbines put over half the blade area out of surface.

The measures are $/watt, $/KWH and $/Site.  I suspect HAWT turbines are winning

across the board.

 

if you want to see a little skepticism, look at 

http://barnardonwind.com/2013/06/03/good-and-bad-bets-new-wind-technologies-rated/

and

http://www.wind-works.org/cms/index.php?id=335&tx_ttnews%5Btt_news%5D=19&cHash=223c17f4046bb06bf9621a6abeeda995

Ann R. Thryft
User Rank
Blogger
Re: Good idea??
Ann R. Thryft   7/30/2013 5:13:35 PM
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Thanks for that explanation, vandamme, in the absence of comments by an ME or AE. Are there any out there who can enlighten us further about the differences between HAWTs and VAWTs?



patb2009
User Rank
Gold
Re: Good idea
patb2009   7/29/2013 2:02:29 PM
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if on average you are grid neutral, you are ahead of the game.

vandamme
User Rank
Silver
Re: Good idea??
vandamme   7/29/2013 1:52:33 PM
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Like I said, I'm an EE, so an ME or aero engineer should jump in with an explanation. Seems to me that VAWTs run on the small differences in forward vs. backward air resistance of the blades to give torque to the rotor. They have no way of aiming the air flow; but this is an advantage when you don't want the complexity of steering, or the wind is variable in angle. HAWTs rely in the inclined plane principle and most of the incident air is used in pushing on the blade. I've seen VAWT designs that use ducting or blades that feather into the wind on the return side; they increase the forward/backward resistance to give greater output, but are much more complicated or bulky. But you can put the generator on a fixed point at the bottom, a big advantage. You can't generalize and say one is better than the other. I'd expect that big turbine buyers do their calculations carefully, and for their given constraints the HAWT is the obvious answer.

Ann R. Thryft
User Rank
Blogger
Re: Good idea
Ann R. Thryft   7/29/2013 1:21:57 PM
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vandamme, thanks for the honest answer. You said VAWTs had been studied a lot so that tells us they're not a new idea. But it also makes some of us wonder why they haven't been deployed more. You said they are less efficient than horizontal ones, so I was wondering why/how, hence my question about some comparative data between VAWTs and horizontal designs. Just because 99% of what's being used is Version A, that doesn't mean it's the best technology, only that it's the current dominating technology. It does sound like VAWTs would be worthwhile in some locations and situations and it would be interesting to know which ones.

Ann R. Thryft
User Rank
Blogger
Re: Good idea
Ann R. Thryft   7/29/2013 1:20:34 PM
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Wind farms must be big enough so that changes in wind coming from one turbine to another can be balanced out. Beyond that, many (most?) of these farms are tied into utilities which do load balancing, just like on any other complex distributed system.



Battar
User Rank
Platinum
Re: Wake turbulence
Battar   7/26/2013 11:51:31 AM
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T J, wouldn't that increase the wind resistance of the train ? I don't see a free sandwich on the table. here.

AnandY
User Rank
Gold
Re : X-Wind Envisions Wind-Powered Electric Railways
AnandY   7/25/2013 11:37:35 PM
NO RATINGS
@ Nancy Golden, You are right in saying that people often jump on bandwagon without asking the right counter questions. Your horse and slaughterhouses example is not off the topic at all and points in the right direction. Euphoria of going green is all right, but it should not stop the experts from pondering over the relevant points. If someone asks critical questions, he is not necessarily against the idea. He is actually trying to raise the question so that it can be addressed before it's too late.

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