commercial shrouded design

[Stewart Corman]

It looks like a firm in our NY back yard is going commercial with a novel design.

http://www.pressconnects.com/apps/pbcs.dll/article?AID=20108250332

I am NOT a fan (no pun intended) of shrouded HAWT because of extra hardware
blowing in the wind

The concept is simple ... the shroud is downwind and expands behind rotor, causing a pressure drop at the exit side, which supposedly causes additional air to get sucked through the rotor. There are also claims that the shroud enhances the efficiency by reducing the air throw off at the blade ends.

some details here and note BTW the multiple bladed rotor:
http://www.windtamerturbines.com/windtamer-turbines/request-a-quote/windtamer8-0gt/

Ken Visser at Clarkson tested it:
http://www.windtamerturbines.com/comparing-wind-technologies/independent-testing/

I just read the report and it has some very interesting numbers
and comparison to a Bergey XL

Not new design ie the references date back to testing done in the 70's and 80's

If anyone is interested in discussing particulars here, we can enhance the thread.
I do NOT understand how they don't require furling ie how do they manage rotor speed control?
If anyone is in the Rochester area, perhaps we can get feedback on one of their test sites?

Stew Corman from sunny Endicott

[Russ Bailey]

Regarding the WindTamer:

1) I suggest you refer to http://www.wind-works.org/articles/FantasyWindTurbines.html
an article by Paul Gipe - covers shrouded turbines as well as others. The WindTamer site manages to violate about all of Paul Gipe's warning signs for hucksters.

2) Roof mounting - I certainly would not consider mounting one of these on a roof that was not designed for the load plus vibrations that they declare will not be there.

3) The comparing technologies section of their site is pure fiction.

4) The 6 year warranty is meaningless if the company folds as is likely.

5) An article on Paul Gipe's site specifically about the WindTamer - http://www.wind-works.org/SmallTurbines/WindtamerHypeNeedsTrimmed.html

Quote, 'Windtamer has posted report 11 in a series of private, for hire, studies by Dr. Visser on their web site. The beating Betz press release was loosely based on Dr. Visser's Report 11. I say loosely because the report doesn't really support the claims in the press release.

Let me repeat that so it is clear: The report doesn't really support the claims made in the press release.' end of quote

Overall the article above is quite negative (say 100%) about this turbine and the claims.

Scamsters in action looking for subsidy/incentive money - nothing more in my opinion.

[Steven Fahey]

No photographs of an actual machine - it's all CAD renderings. Big warning flag for me.

[Russ Bailey]

I expect they are welcoming investors!

[Stewart Corman]

Russ,
thanks for the Paul Gipe link, as I had already read Visser's report.
I also did a patent search and note a few new novel design features.

firstly, my bones of contention:

1) Efficiency cannot be measured using the rotor diameter, when the intercepted
area of the shroud is 2x. So if area is doubled , then power should be 4x and they are reporting 2x ...I can live with that
2) advertised on a short tower ...total BS
3) downwind design and no furling ....hmmmm...not enough info to make a comment.
They did talk about a "fluid-driven, vacuum-enhanced generator" ...a novel braking mechanism is possible
4) roof mount .... not on a residence unless specially designed like Les's house.
5) Visser's data report is very suspect ....I would have thought he did better testing and conclusions....definitely looks like a paid for report ....not what we expect from a university
6) don't like specs that reads wind in m/s coming from Rochester, USA
Surprised they didn't report power in Joules!

Here are the possible + aspects:

1) multiple blades = lower TSR, lower noise, lower wear, less vibration, higher efficiency ( Claus Nybroe and the Windflower is the authority on this last subject ).
2) no gravity actuated side furling can be a great benefit in both power delivered ( no wander) and less failure mechanism (reads many DIY self destruct from tail faults)
3) the "throw off effects" and vortexes from conventional 3 blade designs are well documented
4) my buddy near Rochester who runs a 10ft Otherpower HAWT, has seen one installed a few miles from his home ...so at least some prototypes exist, but he has no data
5) there is a hubless design that incorporates an outer rim fixating the ends of the multiple blades, and this allows magnets mounted on the shroud at the rotor outer diameter for a novel high voltage direct drive generator

My bottom line is why should they attempt mass produce a novel design unless they can adequately substantiate data that shows it's benefits

Stew Corman from sunny Endicott