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Why are wind turbine blades long and skinny instead of short and fat? - Page 12

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Posted by wmbjkREMOVE on April 14, 2010, 2:35 pm

I remember it as Southern Ontario, but IIRC he claimed to have a place
in Michigan as well. His ISP referred to him a troll and it looks like
they finally got rid of him. As solar flare said he had a big
solar/wind setup. Now as josepi it's a dead Ebay special, dead 125AH
batteries, and PV that needs mounting. It's about time for him to
change nyms again. I wonder what his new story will be?


Posted by amdx on April 11, 2010, 6:38 pm

  My point was, if you double the diameter of the blade you get four times
the power.

Posted by Guido on April 12, 2010, 4:51 am

Energy Guy wrote:


Wings are pull up from the top and pushed up from the bottom. The
combined force is called lift.

Then explain why a sailplane can stay aloft for hours, even climb,
without engine thrust then? I'll tell you. A combination of inertia,
thermals, and wind speed, that overcomes an extremely low drag
coefficient. (along with a pilot skilled enough to make use of these)

In fact, they precisely do! The only difference being that the angle of
attack changes with the radius on a propellor.

Posted by Ade on April 14, 2010, 4:52 pm

Energy@Guy.com did gone and wrote:

Both of the above use power to drive the blades, which is a completely
different ask to moving blades by air.

If fat blades were so efficient, then a prop-powered aircraft wouldn't
need to feather the prop in the event of an engine failure (the prop is
feathered to reduce drag).

Turbines (and turbos) use a massive pressure drop (relative to
atmospheric pressure differences, i.e. wind) to drive their blades.
Again, it's a completely different ask.

Why? Explain, with maths please.


Posted by Ron Rosenfeld on April 11, 2010, 7:08 pm

I think I know what you mean, but I would express this as either doubling
the length of the blades, or doubling the diameter of the swept area.

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