[a-w-h] 500 kW two-bladed turbine www.windflow.co.nz

· I used to belong to this list years ago, but have just joined again 
in order to post this.

· The New Zealand windturbine engineering-and-production firm 
Windflow produces a 33m-diameter 500 kW two-bladed turbine.
  Rather bigger than usually considered on this a-w-h list, but just 
right for a small village or co-housing estate.

http://www.windflow.co.nz/windflow500/
  has:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
It is the first wind turbine to combine two new technologies, the 
patented torque limiting gearbox (TLG) system of power control and 
the pitch regulated two-bladed teetering rotor.

The combination of the TLG system and the two bladed rotor design 
effect major reductions in fatigue loads. The Windflow 500 design 
results in weight and cost reductions of between 20-50% compared to 
currently available commercial windmills of similar power rating.

The end result combines cost-effectiveness, simplicity and 
reliability in a world leading design.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

· Their first operational turbine (on Banks Peninsula near their 
production facility in Christchurch NZ) is unfortunately near a very-
well sheltered valley with people who required, as part of the 
resource consent WIndflow had to get to operate the pre-production 
machine, night-time sound levels lower than any I've ever heard of: 
30 dbA!

· Windflow has, in its current (333 kB PDF) Newsletter:
http://www.windflow.co.nz/archives/newsletters/WFnewsletter8.pdf :-

Certification

  As part of the IEC certification process, we will be putting 
another blade through it paces. Unlike the destructive testing (which 
was carried out last year) this fatigue test will not be as 
spectacular, but this does not make it any less important.
  The fatigue test involves bending the blade back and forth about 
three times a second, twenty four hours a day, for a couple of 
months. The lucky blade has already been selected (it will be number 
9) and all we need now is a big shed, which we can take over and 
convert into a fatigue-testing laboratory.

Acoustics

Over the past two months the team here at Windflow has been working 
extensively on solving the noise problem. We're finding out at first 
hand just how frustrating the science of acoustics can be; when one 
dominant source of excessive sound is identified and remedied, 
another (previously masked by it) becomes apparent.

The frustration has been intensified by wind conditions: no wind 
means the windmill will not operate, too much means the wind noise 
masks the windmill noise. And for some work we need "just right" 
conditions when we are trying to measure the effect of a modification 
on a "before and after" basis. (The "after" measurement has to be in 
very similar wind conditions as the "before" measurement).
And we're not talking of a loud noise; it is the volume of a 
whispered conversation!

Nevertheless we are systematically working towards the solution. The 
sound levels inside the tower have been reduced by 8 dBA by gluing 50 
mm thick sheets of rubber to the inside of the tower to absorb the 
structure-borne vibrations. However it made only a small difference 
at a distance. This `free layer damping' has also been applied to the 
gearbox casing with little discernible effect.

The next step was to add Acoustop flexi-barrier to the nacelle 
cladding, the result of which was to uncover the sound of the outlet 
duct of the generator cooling fan as being another significant sound 
source. We are currently designing a suitable muffler for the outlet 
duct.

We expect that the cumulative effect of all these measures will 
ensure that we comply with our resource consent. There remains the 
possibility that the blades themselves are picking up the gearbox 
vibration structurally, ie in a similar way that the tower was. If so 
the solution will be to inject foam into the blades to absorb those 
vibrations.

The Banks Peninsula District Council has arranged for an independent 
acoustic consultant to do compliance testing, once we have completed 
all necessary modifications. It is worth noting that at no time in 
this process have we ever exceeded the District Council's normal 
night-time sound level of 40 dBA. For comparison a refrigerator is 
typically 43-44 dBA. In working towards 30 dBA we are committed to 
achieving international best practice.


- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
sent-on to awea-wind-home by David. I won't be staying on this list.
(David MacClement) - Civis Mundi  d1v9d @ bigfoot.com
ZL1ASX http://www.geocities.com/davd.geo/index.html



------------------------ Yahoo! Groups Sponsor ---------------------~-->
Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark
Printer at MyInks.com. Free s/h on orders $50 or more to the US & Canada.
http://www.c1tracking.com/l.asp?cid=5511
http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/FGYolB/TM
---------------------------------------------------------------------~->

==========================================================
THANK YOU FOR PARTICIPATING IN THE HOME ENERGY LIST.
----------------------------------------------------------
. Please feel free to send your input to:
  awea-wind-home@yahoogroups.com
. Join the list by sending a blank e-mail to:
  awea-wind-home-subscribe@yahoogroups.com
. To unsubscribe from this group, send an email to:
  awea-wind-home-unsubscribe@yahoogroups.com
. 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.yahoogroups.com/list/awea-wind-home .  
. An FAQ on small wind systems is located at 
  http://www.ndsu.nodak.edu/ndsu/klemen .
. This e-mail discussion list is managed by
  the American Wind Energy Association (AWEA):
  http://www.awea.org .  AWEA maintains the Home 
  Energy list as an "open discussion space" for 
  those wishing to learn more about home energy 
  systems, and takes no responsibility for the 
  opinions or technical advice provided on the 
  list.
----------------------------------------------------------
 

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/