Re: [a-w-h] Winddams; some news items & David Mac's opinions.

-------------------------- eGroups Sponsor -------------------------~-~>
GET A NEXTCARD VISA, in 30 seconds!  Get rates
of 2.9% Intro or 9.9% Ongoing APR* and no annual fee!
Apply NOW!
http://click.egroups.com/1/7872/3/_/18088/_/968152059/
---------------------------------------------------------------------_->

· Here in New Zealand, a company (Vortex) built a ducted wind turbine; see:

http://www.eeca.govt.nz/content/ew_news/58june98/58renew.htm (which has image:
http://www.eeca.govt.nz/content/ew_news/58june98/58pix/58vortec.jpg ) :-

June 1998          Vortec reports performance results 

Vortec Energy < http://www.vortecenergy.com/news/links.asp > reports that
the power output from its prototype augmented wind turbine at Waikaretu is
less than expected. 

 Preliminary Computational Fluid Dynamic (CFD) modelling results validated
by measured site data, published by the University of Auckland in January
1998, have shown that the expected wind speed-up effect across the blade
plane is not uniform as was assumed by the initial developer Grumman
Aerospace. 

 The speed-up (augmentation) effect decreases towards the hub of the
turbine. This reduces the power output that can be expected. 

 Since the publication of the paper, several retrofits to the Diffuser
Augmented Wind Turbine (DAWT) machine have taken place. These include the
attachment of an aerodynamically shaped nose cone, the streamlining of the
nacelle and fitting of vortex generators to keep the flow attached to the
diffuser wall. 

 Vortec reports these improvements bring the measured site power
augmentation levels to around three times at high wind speeds and around
four times at low wind speeds. Further improvements to the prototype's
performance will attend to the surface air flows and the centre of the body.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
· More recently (June 2000), there was this note, at:
http://www.eeca.govt.nz/content/ew_news/66june00/66vortec.htm :-

June 2000          Vortec licenses wind turbines in Australia 

Vortec Energy Ltd < http://www.vortecenergy.com/news/links.asp > has
granted Australian company Primergy <
http://www.primergy.com.au/pages/f1_renew.html > an exclusive licence to
install, own and operate Vortec wind turbines rated above 1 MW in Australia. 

Primergy also has a non-exclusive 500 MW global technology licence
world-wide, and a non-exclusive right to manufacture Vortec turbines in
Australia. Primergy plans to commission construction of a Vortec 1MW
prototype in south-eastern Australia in early 2001. Vortec says the
agreements have a "book value of US$3.25 million". 

Vortec plans to license the technology and construction methods around the
world. It has made significant adjustments to its original design and
construction, and is developing machines for off-shore and underwater use. 

Vortec's wind turbine has a diffuser shroud to augment power output. A
prototype was constructed at Waikaretu on the Waikato coastline in 1998.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

· IMO as an amateur, even putting that stumpy heavy construction on a
circular track (to keep it facing the wind), you'd get better (stronger,
more stable) wind by putting a larger-diameter blade-disc higher up, i.e.
in the normal manner.

· The Venturi duct (BTW: much better than a hole in a "barn door") only
collects about twice (to 2.5 times) the flowing wind, and even with the
non-linear relationship of power with wind speed, to me, increasing the
swept area is the cheapest and most reliable way to get more power.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_

>At 13:55 4/9/2000 -0000, Mark Walker wrote:
>> Suppose you took a sail (like one from a sailboat) and poked a hole
>> say several inches in diameter through the center. The wind speed
>> through this hole should actually be faster
>(cut)
>> Do you know any attempts at larger scale versions of this idea?
>
At 09:15 4/9/2000 -0700, Daniel Day <.-.-.@teleport.com> wrote:
>I'm no expert either but am answering to perhaps save some of the
>writing time of the real experts on this forum. It's called a 'ducted
>wind turbine' and has been studied (for example, see "A performance
>prediction method for ducted medium loaded horizontal axis
>windturbines", Wind Engineering, Vol.19 No.5 1995).
>I think Paul Gipe described it in one of his books. He (or whoever the
>writer was) said that it _might_ be economical _if_ the wind comes
>consistently from one direction and deserves further study. If the wind
>shifts much, you have to spend energy to reposition the ducting, and it
>costs you more than you gain. Economic analyses showed that it paid more
>just to install a turbine with bigger blades.
>My apologies to the author if I have summarized incorrectly.
>
>
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
David.
(David MacClement) davd@ihug.co.nz 
http://www.emucities.com.au/member/davd/index.html#top
******************************************************

You have received this message because you are a subscriber to the American 
Wind Energy Association's Home Energy Systems list.  To view previous messages 
from the list, subscribe to a daily digest of the list, or stop receiving the 
list by e-mail (and read it on the Web), go to 
<http://www.egroups.com/list/awea-wind-home>.  To unsubscribe from the list, 
send a blank message to <awea-wind-home-unsubscribe@egroups.com>