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wind power- any comments on this statement - Page 6

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Posted by harry on December 13, 2009, 6:48 pm
 



"Propellor" type wind turbines are by far the most efficient.
Any windmill creates vortexs downwind.   It slows the air down. That's
where it gets it's power from.  If there's no vortexs, it's not
working.

Posted by Michael B on December 13, 2009, 7:44 pm
 


That's vortices.

And yes, a prop style unit can get the most efficiency,
WHEN it's appropriately located about 30 feet above anything
that would cause turbulence and wind shift.

The drag-style unit, such as a Savonius, doesn't 'care' which
direction the wind is coming from, can operate from much lower
wind speeds, and can function well in an urban environment
where 'optimum' placement is not practical. So the cost of
a 45 ft or greater mast is eliminated. As well as being able
to pull maintenance more easily.

Regarding the 'slowing the wind down', the "slowing" doesn't
have to happen, it is 'sampling' the wind, especially with the
technology involved with something like the Maglev. And the
turbulence beyond a drag-style unit is lower than behind a
lift-dependant unit. Prop-style spacing needs to be greater
because of its vulnerability to turbulence and direction shifts.

The optimum unit will not introduce any turbulence into the
downwind side. That would not mean it isn't extracting power
from the air going past. The amount of turbulence produced
does not have a linear relationship to the amount of power
extracted.




Posted by vaughn on December 15, 2009, 10:53 pm
 



That's all well and good, but the video gave no clue why this "invention"
differs from other vertical shaft turbines in some important way that would make
it better than existing commercial wind power turbines.  Until I see something
convincing (like a proof of concept installation), all I see is sombody's
amateur video.

What do you see about the video than excites you?

Vaughn








Posted by Michael B on December 16, 2009, 12:08 am
 

wrote:

A savonius rotor is clearly not as efficient as a prop-style.
But it can run at low wind speeds, has a smaller level of
complexity....oh, wait. Let me go back to what I said in a
prior post.

The drag-style unit, such as a Savonius, doesn't 'care' which
direction the wind is coming from, can operate from much lower
wind speeds, and can function well in an urban environment
where 'optimum' placement is not practical. So the cost of
a 45 ft or greater mast is eliminated. As well as being able
to pull maintenance more easily.

Posted by Jim Wilkins on December 16, 2009, 12:14 am
 


Explain how to extract energy from moving air without changing its
velocity, KE = 1/2*M*V^2. Do you reduce its mass?


In a recent thread in rec.aviation.military on the supposedly laminar-
flow wings of a P-51 Mustang the aerodynamicists told us that any
dents, ripples, uneven rivets, dirt, bugs etc on the surface broke up
the laminar flow and caused turbulence, however the loss wasn't worth
maintaining a perfectly smooth clean skin.
http://www.aviation-history.com/theory/lam-flow.htm

AFAIK only racing yacht crews go to that trouble and expense, since
the skipper can see any turbulence in the wake.

jsw

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