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Forum Index : Windmills : A counter rotating Lenz2

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Tinker

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Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 01:41pm 19 Oct 2009

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The subject of counter rotating VAWT was discussed on this forum quite some time ago as another way to increase the effective RPM of the alternator. Nothing was seen here since about that idea, perhaps you all had put it into the 'too hard' basket.

Well, not I, there was sufficient challenge in this so that I just had to tackle it

.

For the VAWT I chose the Lenz2 design, I used the dimensions shown in the Lenz2 notes but instead of 3 full lenght wings I made 6 half size ones.

The counter rotating alternator was also an interesting project, I used the F&P I already had and it is not too hard to modify by anybody who has a lathe.
I wired it in the 7 phase arrangement with on board Schottky rectifiers and 2 slip rings.
Balancing the stator was not too difficult by using symmetrical wiring & rectifier placement, just a few small blobs of silastic in the deep plastic recesses on the back did the trick.

And did it work you ask? Unfortunately not with the F&P but it could be a goer with an AXFX alternator.

The 7 phase F&P has very little cogging drag but what it has was sufficient to spoil each wing assembly spinning up independently.

What happens is that in light winds the wings just rock back and forth, each preventing the other turning.

With an increase in wind either the upper or lower rotor will start turning, dragging the other one backwards. If the wind increased further still the backward turning unit would slow and stop before starting to counter rotate.
But by this time the wind gust had usually fizzled out
at my location.

Here is a picture of this project:

The plan now is to lower the tower and modify the Lenz2 for simple rotation with the 2 wing assemblies offset by 60 degrees on a common shaft through the F&P.
A single shaft would be easier to keep aligned too, with the counter rotating idea the 2 shafts & 6 bearings used required perfect alignment and a rather sturdy frame.

Now you all can cave a good laugh at my expense

Klaus

fillm

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Joined: 10/02/2007
Location: Australia
Posts: 730

Posted: 11:00am 20 Oct 2009

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Hi Klaus , all I can say is Well Done , I can see all the work that has gone into this and in theory it should work , have you tried twisting the poles to reduce the cogging .

At least you are having a go at something different , keep up the good work ..

PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits

Tinker

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Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 11:56am 20 Oct 2009

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Thanks Phil.
No, the pole faces are straight not twisted, I felt the 7 phase conversion F&P should work for that idea as is. Actually, today we had a strong sea breeze and the thing did counter rotate for a short time and made the Amp meter needle move up the scale

.

Having the the frame on a tilt up mast makes it easy to experiment with different alternators and building a small AxFx was always on my list. That size Lenz2 makes less than 100W according to its designer so the F&P is over sized for it anyway.

Klaus

daveames
Newbie

Joined: 19/09/2009
Location: United States
Posts: 30

Posted: 10:47pm 20 Oct 2009

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Hi Klaus,

"Now you all can have a good laugh at my expense"
holy cats! absolutely no laughter over here, in fact this is yet another one of your masterpieces.

i have a feeling that you had the plan "b" option already in mind during the build..and also just happened to have some vertical structures at hand for those horizontal guy wires. well thought out.

i hope you continue to dip your hand into that 'too hard' basket, as your fabrication abilities seem to have no limits.

thanks for the look,

kind regards, dave

Tinker

Guru

Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 03:23pm 31 Oct 2009

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Thanks Dave, you were right ,a plan B is included with just about all my projects

Anyway, its up and running now, you can view it at the link below.

It was my first time to use my camera foe a movie, sorry about the poor quality - turn the sound low

Those guy wires are not horizontal BTW, just the camera angle makes them look so. I was glad to include the top guys, they are required when that thing gets hit by a strong wind gust.

lenz2 running

Klaus

GWatPE

Senior Member

Joined: 01/09/2006
Location: Australia
Posts: 2127

Posted: 11:31pm 31 Oct 2009

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Hi tinker,

the link only points to a Utube registration screen for me. A no go.

Gordon.

become more energy aware

Tinker

Guru

Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 02:14pm 01 Nov 2009

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GWatPE said Hi tinker,

the link only points to a Utube registration screen for me. A no go.

Gordon.

Sorry Gordon, this was my first go at posting anything on Utube.
Strangely, the link works when I click on it, is it because the video is not on the public domain (I chose the private setting?

I'll cut and paste the address:
http://www.youtube.com/watch?v=22H8FQ--C4I

Klaus

KarlJ

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Joined: 19/05/2008
Location: Australia
Posts: 1178

Posted: 02:35am 02 Nov 2009

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Yes, sill doesnt work, need to list as public I guess.

Karl

Luck favours the well prepared

Tinker

Guru

Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 02:47pm 02 Nov 2009

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KarlJ said Yes, sill doesnt work, need to list as public I guess.

Karl

Thanks Karl, its listed public now.
I guess I should have read the Utube instructions better

Klaus

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