VAWT Postings Welcome

[monte350c]

Hi Ed,

I started testing this one with the top fastened in a bearing. That's 1/2" threaded rod for the vertical shaft. Very bad to actually make anything out of but convenient and fast for testing.

I used a small piece of Delrin for the bottom 'bearing' and it was interesting to watch it self govern in the wind. Without adding any weight to it it stayed at about 300 rpm. As the wind increased and decreased the bottom would rise and fall keeping the speed about the same. It was a nice controlled sort of response.

For the larger (full-scale) machine I hope to have it kneel downwards. I think the center shaft will be hollow. A couple of cables with pulleys at the top of the shaft would connect to weights hanging inside the shaft. The top will move downwards against the weights when speed rises above the govern point.

The advantage I think to doing it this way - the guy wires will be easier to arrange, and the unit should be more stable.

Time will tell!

Ted.

[electrondady1]

mike, you shure got lots of hits with this posting, maybe a record. anyway, dont throw out your sail technoligy you might come back to it.  

[nvmike]

Electrondady,  I will keep the sails, they may go back up if the half barrels do not work out.  I will get this going and hooked to the PMG, then next want to try Windstuff Ed's darriues design with the cam to control pitch.  I figure I can use all the parts i have now, shaft bearing etc, wish I had room to put up a couple at once.  Thanks for all the advice.  I hope I can report some output data soon.

NVmike

[nvmike]

Monte,  what airfoil are you using on your diamond design?

[monte350c]

Hi nv mike,

There have been several versions of this thing. Some with 2 blades and some with 3. Mainly I have tried 2 wing sections - NACA0012 and NACA0015.

As mentioned above, one of the biggest problems with testing smallish models is Reynolds number. In order to try to get the Reynolds number up a bit, it helps to increase chord width. But by increasing chord width, the solidity goes up (not good).

At least high solidity rotors will usually self-start.

Most of those problems should go away on a full scale unit - I hope to give it a try this summer. As Ed mentioned above, the full size unit will probably need a push to get it above a TSR of around 2, then it will take off on its own.

Ted.

[ghurd]

Has anybody thought about a VAWT like thess?

Pretty much think of a 2, 3, or 4 bucket blade design.

But...

The active blade(s) are solid.

The blade(s) coming upwind are not solid.

Kind of like venician blinds open or closed.  

Or like that gravity sail PGS thing.

Add Ed's 'articulated darrieus' (right name?) setup to control what is open (going up wind) and what is closed (blowing down wind).

It seems to me the problem of the working side having to pull the not working side into the wind, would be reduced greatly.

Seems simple?

It would still be high torque and low speed, but better... I think...

Or, I thought about this years ago, but never got it to work on paper.

I think this one has many more problems than first appear.

It is still an idea.

Cloth blades on 2 vertical sticks.

Going down wind, the sticks are far apart. Big drag.

Going up wind, the sticks are close together. Small drag.

They would need to open and close quite quickly.

Noisy I bet, with the blades or sails going Crack, Crack, Crack as they fill with wind.

These have been in the back of my mind for a long time.

G-

[ghurd]

Self starting some of these that will not start on there own...

Add a ratchet and simple 3 bucket VAWT on top?  Just to get it moving.

G-

[nvmike]

Ghurd

I an experimenting with something similar to your posting,  four triangular sails, as one catches the wind, the lower corner has a rope attached and as it pulls down it pulls the sail 180 degrees from it up and out of the wind . the one going upwind is then horizontal into the wind.  Seems to work but I have taken them down and going to resew them with more of a cup design than just flat rip stop nylon.  Hope to graph a little more wind that way.  If you are interested I could try to draw a diagram of my sail and pulley arrangment.

[monte350c]

Hi Ghurd,

Have a look about half way down the page at Nov. 24 2003:

http://www.me.dal.ca/~dp_03_7/pictures.htm

There's some wings that open and close - to get the unit up to speed. It's a Dalhousie University project.

The rest of the site is pretty interesting too.

Ted.

[healerenergy]

Ted I hope you don't mind me using the diamond shape for an extreamly modified version of your mill.

[monte350c]

Hi Ghurd,

Maybe not so tough. If we started with Ed's articulated Darrieus. Place a hoop at the top and bottom of the unit. Then a slide extending out from that. The inner sticks would be attached to the hoop. The outer sticks would be attached by pushrods to the cam device on Ed's sketch.

There would be a cam at the top, and another the same ot the bottom of the turbine.

Each revolution the sticks would be alternately forced out (open) and in (closed).

By shaping the cam, you could control the opening and closing speeds and timing which could be optimized for energy capture and/or noise.

Ted.

[monte350c]

Go ahead!

Please post your results - it would be great to see your idea!

Ted.

[healerenergy]

Will do Ted I hope it works like I think it might. Im thinking about building smaller scale verson.

[ghurd]

Ted and nvmike,

I would like to see the rope and sail sketch.

Everytime I see Ed's machine I have to wonder if the concept would have helped me.

It was 15 years ago. Wish I still had the 10,000 coffee shop napkins!

I guess I thought more along the lines of the hoop, or maybe 2 different diameters on seperate centers.

The most 'promising at first look designs' had major problems after it was drawn out every 22.5' along the rotation...

Things like spokes/sticks had to pass through each other in ways not possible.

Sails that would wind up around parts.

A 30 tooth sprocket, with 20 teeth on 1 side, 10 on the other.(never thought cam)

Stuff like that.

Probably started with a 55 gal drum, with 6 parachute halves attached so they would blow open one way, closed the other...

Of course it went all the way to absurd.

Things almost like a horizontal radial aircraft engine,

but naturally a lot more complex than just a silly old aircraft engine!

But Ed's machine has some properties of a radial engine too, doesn't it?

All of them had opening and closing, or parallel and perpendicular, sails or blades.

And physical changes to the drag, more than areodynamics.

One I still would like to play with...

I will call it a "Horizontal VAWT with a Tail and Changing Drag".

Maybe 4 hinged blades and a barrel of the same radius. The blades are connected flat against the barrel. Like a 4 section barrel around a barrel.

From the axle end. A circle with a rainbow over it (folded blade) and a 'C' under it (open blade).

Following 1 blade.  Gravity pulls it down, it catches the wind, around the back side it folds flat against the barrel for the ride back to the top, a little farther around gravity pulls it down and the wind catches it again.

Sounds do-able with a few 2 liter bottles, a couple coat hangers, and tape.

Dang!

I just talked myself into another wasted day doing something I know won't work!

G-

[electrondady1]

thats an interesting idea fin, if the wind was 30mph and the mill was say 6 ftdia thats a c. of 18.8 ft. i cant realy remember but amile is some thing like 5680 ft  so it's 5680 x 30 over 60 minets over 18.84  some thing like 150 rpm. if the driven wheel was .5 ftdia thats a bout 1800 rpm on the generator shaft. i think i'd use three or four generators. to help stabilize the big dia.  

[electrondady1]

i was thinking on a savonas type design the larger the dia. the lower the rpm. and the only way to increase torque would be to go taller.

[finnsawyer]

Its easy to find 8 inch or 10 inch wheels.  It also doesn't look like it'd be hard to change the hubs. I get 140 rpm for your example (30 miles an hour is 44 feet per second).  So, for an eight inch tire the alt would spin at 1260 rpm.  Definitely looks promising.

[electrondady1]

 hey!! lets make it 12' dia. and build it like a deck. when the winds not blowing  we can sit and have our drinks on it

[ghurd]

When the wind is blowing, it would be like the magic tea cup ride at Disney World!

[electrondady1]

sound like a lot of fun. can we charge the kids 10.oo to try to hang on? i'm thinking  a car/truck axil for a central support , and the generators on the cercomference act as support bearings against the horizontal moment.

[ghurd]

Well, 1/2" all thread should be good enough.

Car parts will cut into the profit margin.

[ghurd]

Yes.  Like that, but a lot wider blade / sail.

Their open: closed is maybe 10:1.  I was thinking 20:1 or 50:1!

But that is the 1st one I ever saw with something like I was thinking.

There was a post a long time ago. Link to a movie clip. Kind of close.

The guy had a horizontal disk rotor.

With 3 pair of wings. Each pair had a wing on top and 1 on the bottom.

They were connected to be open the same amount.

The wind opened the down wind side and closed the up wind side.

It was probably back in September or so.

I should try to find it.

G-

[electrondady1]

i can't check inventory untill spring(too much snow in my back yard) but i think i have a lot of whats required in stock. i saw a documentry a while back , this guy built his house on the rotating mechanism of an old steam shovel/ highhoe type digger thingme. it was powered up and he could rotate his house with the push of a button.

[nvmike]

Gjurd, this may be what you were refering to.

http://www.greenwindmill.com/index.html

[pyrocasto]

Counldnt you use two windmills for that? The big diamond one to generate power, and a small maybe 5 gallon bucket type to get it started? Make it like a bicycle pedal so once the diamond takes off, it wont be trying to drag the torqe mill faster with it slowing it down.

[monte350c]

Yes a combination Darrieus/Savonius would work. There have been several designs out there for this. In fact Sandia labs spent quite a lot of time analyzing 2 and 3 bucket Savonius designs with this in mind.

You can download a really good performance summary from their web. If you need it let me know and I'll find the link.

One way for starting could be a hide-a-way Savonius. At startup the two halves are fully extended. As the speed comes up, they close together to form a pipe. At overspeed they open again but in the opposite direction to provide some braking.

Another possibility is to use Ed's cam and linkage. Let it start like that - then when operating speed is reached disengage the cams so it becomes a pure Darrieus. At overspeed reengage the cams and pitch the blades the "wrong" way for effective braking. Could be a little noisy?

It's been mentioned elsewhere on the board but it's interesting to visit the US Patent site and do a search on Darrieus, and another on Savonius. There have been lots of patents issued for both types. Some are "wacky" but others contain ideas that look like they should work.

There are many different ways to get power from the wind. There may well still be some room in this field for the little guys to put something interesting together. I doubt whether there's much money in it - but you never know. I must say I have great admiration for guys like Hugh Piggott who have helped some of the less developed parts of the world get some power. Maybe a new design from someone on the board will succeed either commercially or in power to villages that really need it. Worthwhile either way.

Ted.

[pyrocasto]

I may play around with the idea because it would need no electricity or monitoring system to start. It will not happen for a while though because next I have a windmill, then solar heating, and hopefully after that I'll have time for another prodject.

[ghurd]

No, the one I saw was all silver metal, sails and all.

I would guess 15~20" around, and up in the air about 2~3' is all.

But put those sails on the side of something is like the one I thought about.

(I'm sure their way is better)

G-

[finnsawyer]

I always thought that a teeter-totter on a ratchet setup where the whole thing would rotate as it went up and down would be neat.

[electrondady1]

i'm not getting an image from your decription fin, but this very large dia. savones design we were talking about won't leave my head. i'm building a 10" pmg now . bench tested it , it functions ok and i can light up a 12volt bulb or maybe charge a battery at 150 rpm but it's a drop in the bucket compared to my power consumpsion.i think i've got to rethink the direction ive been heading and go very big.  

[electrondady1]

this might be apples and oranges but one thing that might be concidered in comparing hawt to vawt is what could be considered  the "foot print"  a hawt might be 10' dia. but it also  rotates on a horizontal plane occupying a space of 10' dia.  so it would be 3.14 x5 x5 x10 or 785 cubic feet. add to this a 40'tower and we have a cubic volume of3.14 x 5 x5x45 or3532.5 cubic ft.  now a vawt occupying the same cubic volume would be 10' dia. by 45' tall. so the area acted apon by the wind would be 450 sq. ft for the entire profile or 225 sq. ft for the down wind or active swept area as oposed to 78.5  fo a 10' prop.  i wonder if i should include the area encompased by the guy wires required to stabilize the hawt?

[commanda]

What about a friction drive, like clutch plate material. The savonius on the bottom has a flat plate on top. The bottom of the diamond sits on this, with weight. When the savonius turns, it turns the diamond. As the diamond picks up speed, the bottom starts to lift, and disengages itself from the savonius.

Amanda