Designing an Open Source Kite Ring Generator: DC Generation Ring Suitability

[Roderick Read]

OK, I'm designing an Open Source Kite Ring Generator.
See kitepowercoop.org for details.

I have designed a system which uses a large inflated torus with kites attached radially around the axis on which it spins. I believe that removing the inside hub of a standard wind turbine by working in tension with kites... I can, with a large diameter torus efficiently add many blade tips (high ring solidity) without roots. I am quite convinced that I will get less turbulent airflow behind and easily as much power for less material than a standard turbine.

I will be working at the top speed of ram air kites, which is less than tip speed of a solid blade.
Therefore, for my ground based generator, I propose a large ring to house my generator wires.

For ease of engineering I would prefer to work with a single large toroidal coil,
Is there a configuration of rings of magnets, one either side of the coil ((North pole pointing out , South pole inward) or (North clockwise, south Anti clockwise) or (North upwind south downwind)or any alternating variation on the previous) running around the single coil which produces DC current?

Why am I wrong? Why am I right?

 

[Roderick Read]

Some IEEE papers will really help this answer..
Structural mass minimization of large direct-drive wind generators using a buoyant rotor structure by Deok-Je Bang Delft University and
Ring-shaped transverse flux PM generator for large direct-drive wind turbines

 

[Robin07]

As I followed the kite coop site to see what you are working on, the first thing that I was imagining, for the torus shape you reffer to as well as concideration to tubulance. I would adoped a Zylo, I think they call it. It's a plastic cylinder with a machined edges that looks like an AC sine wave. When thown, its stability is quite apparent. Since your apparatice is spinning you may be able to stabilize it using the Zylo trailing/leading edge of your Torus.

What interested me in this is, has there been no issues in addressing gyroscopic effect that the torus ring is experiencing or is it the magnet essembly that's spinning? In any case how is this not an issue.

To address your question in regards to generating current in your torus. You would need to consider that the magnet essembly will need to spin perpendicular to the winding of your torus. To be clear here the PM, permanent magnet essembly, and the Torus are at or near ground level. Only because I don't fully understand all the integrities in generating current with kites.

This is very interesting...

 

[Roderick Read]

Xylo is an awesome toy, yes I had one myself and there is a pronounced steer to the right (if you throw it right handed) not long after release ... it then stabilises and goes for soooo long. amazingly efficient. That shape would reduce drag of the structure and some exoskeletal rigidity may improve the flight carachteristics... I'm making a prototype so for now, a simple inflated torus is an easier structure to manage. I have drawn a few thinner wall designs.. not so easy to turn out.

Yeah while I'm taking torque out of the bottom of this spinning tower (clockwise from below) I'll be taking it evenly on the axis so that doesn't incur a precession force.
Whereas side gusts and the fact that I'm not dealing with a straight axis does mean that I will incur gyroscopic forces which could make the tower "jumpy" I'll need progressivly large diameters or more lift to compensate for this... and some CFD and scale modeling before full world dominating production begins.

The kites don't do any generating...(maybe a bit of static) they purely drive the rings round. Because the rings are tied together under tension, torque can be passed down to the generation set (like a maglev circular track), joining lines less than 1 dia stops line twist.

Any clearer?

 

[Robin07]

If I understand you correctly. There are two rings one inside the other. The inner ring, let's say, is tethered to a grounded achor of sorts. The outer ring is tethered cable/twist to an inflated donuts/torus, evenly spaced around its outer perimeter, which serves as a stability platform as well as an anchor for the wings/airfoils to be mounted on.

Xylo...Thanks

I'd really like to see more detail in regards to the architecture of the two rings in a track and how is it like Inductrack/maglev. Does the outer ring contain nullflux 8 coil configurations? and the inner ring would then be the PM array, I suppose?

My interest is more in the gyroscopic effect around a spoke-less wheel. And the bearing/lack there of, of the mechanism that's involved. Flux was also one of the words.

Would be glad to donate when my situation gets better.

Thanks
Robin

 

[Roderick Read]

Robin,
Thank you very much for your suggestions. On further study I'm less sure about Inductrack/maglev technology being apropriate for wide diameter ring generation. An axial flux design such as NGenTec propose may be more suited.

As for Gyroscopic forces, There will be a futher destabilising force caused by the fact that the rings are lifted in a string by their axis, this causes the top edge to be slightly more upwind. so that when a kite goes from top to bottom it goes slightly downwind, I expect it more resultant ring propulsion. Also when a kite goes from bottom to top I expect more drag as it goes upwind slightly...

So with the tower going clockwise from below I "think" this tends to push the tower down and left ?..

 

[Roderick Read]

Oh the way I had designed the floating system was an outer bouyant ring with an inner generation race track.

 

[Robin07]

Your very wellcome, It all seems very involved. Including that one needs to be attending the whole essembley, lighting strikes, birds , airplanes etc.I ran into a fellow, surfing the net and he developed a wind generator that has PM mounted on a reed that fits inside a soleniod type coil. The coil is attached to the reed that runs parallel with the other reed for approximately 2'(60cm). Just imagine two flat ribbons running parallel anchored on each end. One reed houses the magnet and the other houses the coil that fits over and around the magnet. As the wind blows the reeds vibrate and produce current. Construct a framed panel large enough to produce the volts you require.

Anyway good luck with it all.
If looks like we all are trying to do our part to save our collective asses.

I know a bit about PM orientation to the coil and direction of winding, so if you have any questions just let me know.

Robin

 

[Robin07]

http://www.designboom.com/weblog/cat/16/view/9195/spokeless-bicycle.html

Try this as your hub. Mount your manets in the inner ring and your coils in the outer ring. This way you have no commutation to deal with. Attach all your cables on the toothed gear peices.

If you should find one, please let me know. I would like to protype R+D the generator I'm building. This type of wheel without an inner motor is what I"m looking to manufacture or buy and engineer to suit.

 

[Roderick Read]

Thanks Again Robin, yes that's a bit more like it.
For this first single ring set prototype, since I am releasing it as open source hardware, I am trying to use off the shelf only components. yes there have been modifications, welds, cuts, knots, stitching etc. but it's all really accessible.
I have a bunch of rollerblade wheels in a box beside me. I like the idea of setting them on the inner ring (with the magnets mounted on it) so it has a predetermined path in, around and on the outer ring (with the fixed coils set on it close to the magnets path) .
Can't wait till I have this CFD modeled with finite element analysis done, made, packed, all ready to ship...

 

[Robin07]

Well, I don't know but me thinks I have the bug.

Earlyer today I stacked two paint can nylon rings one to each other so that it provides a inner guideway for dozens of steel balls in the track. Works amazingly well. At the moment I have 5/8(12mm) nib N42 holding the rings to each other, pinching the balls in between. Allowing my weight to rotate it, it's much like a turn table. The lower ring is to be housed with and to the kite. The upper ring achors the whole essembly. I'm going to change the steel balls to glass marbles of a similar size.

I've allways used recycled materials and what's around me. I've found this not only successful but gratifiing as well. I'll see if I can do quik sketch for you so that it a little clearer. Let me know what you think. Sounds like your pretty busy good luck with you CFD wraped, packed, ready to ship... You have a kite that is that close to market? wow.

 

[Roderick Read]

It's an highly adictive project. That's why I can't wait to kick it out on a ship. Nowhere near market stage yet, although I have offered the sale of my first prototype on pleasefund.us
Some pretty grand experiments need to take place first. However anyone could make the catenary line towers version right now (check the youtubes from my loft for that) And if they were ganged together you can pull more energy with a diameter of dyneema rope than you can pump oil energy through the same diameter. just sayin... this is a worthwhile project.
I really really want to see those paint tin rings pleeeeze
rod

 

[Roderick Read]

Oh, did I mention the ... it would work underwater in tidal flows when the bladder is filled with water... now you're torquing