I know this is a little off our usual line of topics but as the subject has
been presented I thought I would throw this out along with it.
I have been working with a small developer who has been doing extensive R&D
on a VAWT. They are currently in the middle of construction with their
"production" model and hope to have it operational by the first week of
December.
I cannot refute any remarks pertaining to previous VAWT machines at this
point but have a strong feeling these guys might be on to a little something
here.
You can go to www.newharvestenergy.com to get some basic information about
them and view a short clip on their last prototype machine built last year.
I can try to answer any questions you might have but for technical data the
information will be limited to what they have been able to learn with other
models they have built to this point.
Happy Thanksgiving to all who celebrate it and enjoy this time with your
families.
----- Original Message -----
From: "Kirk McLoren" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Saturday, November 20, 2004 10:35 PM
Subject: Re: [Biofuel] Vertical axis wind turbines Another approach to wind
Not Swedish. Bohemian Celt actually.
Was madly infatuated with a little Norwegian girl when
we were in the 8th grade though. She told me ufda was
being at the airport when your ship comes in.
As to your other question --
Fatigue stress is much higher in a VAWT than a HAWT.
Inescapable.
To quote Hugh Piggott
http://www.fieldlines.com/comments/2004/1/20/103054/698/2?mode=alone;showrate=1
I'm going to paste in my standard reply to this
question.
Vertical axis wind turbines are very popular in
universities and with many home-builders. Attractive
features include the ability to take wind from any
direction and the ability to site mechanical parts at
ground level. In spite of a huge amount of research,
vertical axis wind turbines have failed to become
widely accepted.
Low speed vertical axis wind turbines of the
'Savonius' type are useful for really basic simple
rugged machines with low efficiency, and low rpm. But
the same amount of effort put into a horizontal axis
machine will yield much greater returns.
High speed Darrieus 'egg-beater' or alternatively
H-rotor type vertical axis (VAWT) wind turbines are
popular in university engineering departments but have
never been successful in the marketplace, except
briefly in California. In brief, the main problem
with high speed vertical axis wind turbines is the
fact that the blades suffer from reverse buffeting by
the wind every single revolution. This causes severe
fatigue loading which shortens the life expectancy of
blades. This is usually the main reason why they fail
to become commercially viable.
some vertical axis urls
http://www.awea.org/faq/vawt.html (good overall
comparison)
http://www.solwind.co.nz/
mailto:[EMAIL PROTECTED] (leo laza is/was
a VAWT fanatic)
http://www.windside.com/painik/menu1.htm (check out
the prices)
http://www.southcom.com.au/~windmill/ (savonius)
http://www.iteva.org.br/tecnologias/energetica/rotor/index.asp
http://www.nexwindenergy.com
http://home.inreach.com/integener/
http://www.massmegawatts.com/
http://www.ecoquestintl.com/eqwindtreepop.htm
http://www.ropatec.com/en
http://www.aerotecture.com/
there are good books available concerning
Savonius rotors made of drums.
One of the best is:
Savonius Rotor Construction.
J.A.Kozlowski.
VITA USA.
1977. 0-86619-062-7.
Available from
http://www.vita.org
'PicoTurbine Deluxe Windmill Plans' text
is a good one. Available from
http://www.picoturbine.com.
At 10:28 pm +0100 14/7/02, Christopher William Turner
wrote:
There was hard vertical test results (from 1979!) at
http://www.sandia.gov/Renewable_Energy/wind_energy/topical.htm
In rough summary, a 1.5m high x 1m diameter
Savonius managed a Cp of 0.22-0.25
Two bucket with 0.1d overlap is best. Use 2,
vertically stacked at
90degree rotation to get even torque.
A Darrius managed a Cp of 0.3-0.35. NACA0015 airfoil
seems good.
Solidity 0.15 to 0.2. TSR 4-6. Not self starting.
I think HAWTs manage Cp of 0.48 and use much less
blade material.
--
Christopher William Turner, http://www.cycom.co.uk/
Hugh Piggott http://www.scoraigwind.co.uk
--- [EMAIL PROTECTED] wrote:
Kirk,
There's nothing wrong with vertical-axis wind
turbines (VAWTs), in principle.
All turbines deal with "turbulent" loads more or
less. The problem is with
business attitudes-- companies dropped the VAWTs
when they were not looking
competitive, and now few people are willing to go
back and take a second look.
I think I know how to solve the VAWT problems when
somebody is ready.
Now, to jog your sense of reality-- it may be that
the next move into "VAWTs"
will be for use under-water. You know, wave and
tide power.
Are you Swedish?
(OOPS, forgive me, I guess we're a little off-topic,
aren't we! )
Ernie Rogers
In a message dated 11/20/2004 11:07:48 AM Mountain
Standard Time,
[EMAIL PROTECTED] writes:
All the VAT I know about suffered fatigue and broke
due to reversal every revolution. It is a design
weakness. All you can do is select materials etc to
extend mtbf but it is built in.
I used to be enthusiastic about them as I wanted to
avoid the problems in the conventional designs.
They aren't the answer either.
Ufda.
Kirk
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