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Posted by RicodJour on May 15, 2009, 10:31 pm
wrote:
> http://www.aerotecture.com/
> The inherent problem with low level windmills regardless of type is
> the land surface drag and there's no way around it.
> None the less, I see all kinds of upgrades to get around that problem.
> Think *ramjet*, essentially, a horizontal tube 20' in diameter and
> 200' long with jet engine like vanes running the full length. As the
> wind traverses the interior of the tube pressure builds causing the
> Bernouli principle on the vanes. Thus a 5 mph wind could cause the
> movement of a 50 mph wind. Stacked ball bearings and graphite races,
> in other words, extreme efficiency. Pressure switches and high speed
> equalization vents throughout. This could generate 100,000 RPM's so
> noise could be an issue.
Bernoulli's principle wouldn't seem to apply for a number of reasons.
There are also issues with the ramjet analogy. Ramjets require the
air to be compressed, but a tube with significant drag due to laminar
flow, the turbine and bearing friction, etc., would not work well at
typical wind speeds.
Along the same lines, you might find this interesting:
http://www.guardian.co.uk/technology/2008/aug/07/research.waveandtidalpower
R
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> The inherent problem with low level windmills regardless of type is
> the land surface drag and there's no way around it.
> None the less, I see all kinds of upgrades to get around that problem.
> Think *ramjet*, essentially, a horizontal tube 20' in diameter and
> 200' long with jet engine like vanes running the full length. As the
> wind traverses the interior of the tube pressure builds causing the
> Bernouli principle on the vanes. Thus a 5 mph wind could cause the
> movement of a 50 mph wind. Stacked ball bearings and graphite races,
> in other words, extreme efficiency. Pressure switches and high speed
> equalization vents throughout. This could generate 100,000 RPM's so
> noise could be an issue.