"pyotr filipivich" wrote in message
...
"Stu Fields" on Thu, 15 Jul 2010 08:17:58 -0700 typed
in rec.crafts.metalworking the following:

Cleaning maybe accomplished by the wind that we get around here. If it
only
blows 45mph, no one thinks much of it. Probably a good wind generator
area
also, but I don't like whirling things above my head unless I'm in my
helicopter.

This is one of those questions I have, why does a wind turbine
_have_ to look like a airplane propeller?
I keep thinking of the roof top 'turbines' used to draw hot air
out of an attic space. So it seems to me that it would not be that
difficult to build a "squirrel cage" fan on it's side so that the axis
is vertical. If you want, you could make a pivoting shroud to open
into the wind. Might want to make the intake 'larger' than the exit,
get a little boost ...

There are several types of vertical-shaft turbines, including some that draw
air in at the bottom of a column and exhaust it at the top. One type uses
solar energy to heat the column and force the draft.

But more common vertical-shaft types are the Darrieus and Savonius rotors.
The latter is a simple drag rotor, like an anemometer, and designs are
available that have an efficiency of 16%. A conventional, horizontal-shaft
turbine averages around 35% at best. This is disregarding a lot of physics,
including the Betz limit, which the technoids will now jump on and use to
complicate the issue beyond all recognition. g

Savonius rotors are fun to build and make a nice hobby project, including a
rare-earth-magnet alternator you can make from junk, and use to generate
20W - 50W in modest sizes. (Don't put cores in the alternator poles or
you'll get a nasty cogging effect that makes them hard to start.) They're
good in gusty conditions, compared to other types.

--
Ed Huntress