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Forum Index : Windmills : VAWT -- A Different Approach
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Crew Itsandbits1 posted a reply to charlie_ruizpr down here somewhere and in his reply, he posted a very nice video of his latest VAWT. On the same Youtube page, next in queue was another VAWT HERE. At any rate, watch the video and then look at the two comments I left (read the second one first, as I ran out of room and had to come back to finish my thought, but the second comment actually posted first -- go figure). I made one similar to this about 40 years ago and it worked great, but I did something a little different. I reverse-engineered it so instead of an aerodynamic blade spinning as it sliced through the wind, I spun the wind, creating an enclosed vortex and merely immersed a flat-plate blade in that swirling air. The look of the thing was similar to that shown in the video, but I installed at least 2 to 3 times as many "scooper" vanes around the outside and I use sheet metal (aluminum), creating a close spiral inside, with about 4" openings and 6" openings along the outer perimeter. Doing this, created a swirling vortex something on the order of a funnel cloud (like the one that snatched up Dorothy's aunt's house in the Wizard of Oz). When a flat blade is sitting inside, housed on a bearing, it just spins (drags) in the motion and the torque (plenty by the way) is transferred down a shaft to the ground, where I had my generator. Having the working gear on the ground meant I didn't have to climb up the thing to fix stuff. The one I built 40 years ago was about 3 feet tall and 6 feet in diameter and had enough torque to rip your limbs off. With VAWTs, torque is the name of the game and this worked great. I'm not so much into VAWTs any longer. In fact, I made someone a standing offer to shoot me if I ever got back into it, but maybe I'll toss another one of these together, just to peak someone else's interest. I don't have any pictures, unfortunately, so you'll just have to grab your compass, a sheet of paper and use your imagination if you want to "see" anything. Edit: Okay, I relented and drew up a little picture so you get a better idea of what I'm talking about: 
This is a top view. The dark bar is the flat rotor within the structure. The one I built had a solid bottom and the top had a hole cut in it to let air escape after it became a vortex. The center of a vortex has higher pressure, at least that was my thinking when I built this thing, so I made a vent for it to escape through. I don't know how much truth there is in that, but it seemed to work quite well just the same. About 1/3 of the vertical face was always pointing into the oncoming wind, no matter which way the wind blew. The outer openings were about 1/3 as large as the inner ones and this helped air to swirl instead of merely blowing through and escaping. I used an automotive (trailer) hub and axel, fastening the hub and letting the axel spin freely, hanging below the unit, which was mounted on a small tower. The floor of the thing was plywood. Like the pig says, "Th . . th . . th . . That's all, folks!" 
. . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| itsandbits1 Regular Member  Joined: 13/08/2010 Location: CanadaPosts: 81 |
it sure would get some power if you made it as big as you say and you got a good wind swirling in there you say. did you ever put 3 wings in? the reason i ask is that the balance and power peak in windpower seems to be with 3 in the normal range. easier to balance too; not that you'd need it if your not going too fast but if you got a vortex as you say, it could really take off. maybe that's what these guys that make them with vanes are missing when the wind just blows through. I tried it last year when I first started playing with the wind with a furnace fan by putting a flat plate across the inside but had no luck. of course the wind was not blowing that day much so nothing would have worked. |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
itsandbits1 I only ever tried one single blade. My blade was a slab of styrofoam, but anything, even a sheet of metal or plastic would do the trick. As for balance, it was just a matter of centering the axel on the framework that held the styrofoam. Before I used the single blade, I had the idea of using a flat blade that covered only one side; from center to the edge of the inside terminations of all the little wind scoops, but never actually tried it. The reason I went with the single full-width blade was I set it up and held a smoking rag inside and watched what the smoke did. It swirled and exited only very slightly as it distributed itself around the circle. My assumption was that the "power stroke" would be only on the 1/3 facing into the breeze, but I was wrong. The wind inside the contraption swirled forcefully all the way around the inside and was readily visible using the smoke test. I think multiple blades would work, but I doubt if it would be an improvement. I've always held with that basic tenant, "Simple is best." The cool part about this rig is you can make it out of nearly anything. Plywood would work fine; all it is really is a big wind scooper-upper that reorients the flow. Once the air is spinning inside, almost anything could be used for a "blade". Using an automobile hub gives you a whopping-big bearing surface and since it's a tapered bearing, centering is automatic. Also, it makes extracting the power at ground level a reality; no slip rings & no climbing rickety towers! . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| itsandbits1 Regular Member Joined: 13/08/2010 Location: CanadaPosts: 81 |
well i just aquired a couple of furnace motors so i will block one end and try it again with some wind when it comes up again. Right now I need to find a better way to clamp my fibreglass struts to the rotor because I broke one last night and its' because I weaken them by drilling mount holes. I am going to make a serrated clamp and that way I can balance them by sliding the struts in and out slightly. |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
itsandbits1 If by "furnace motor" you are referring to the squirrel-cage fan apparatus, this won't work the same as doing what I've described. It'll work a little, but what you have to do to create a vortex is move the pathway of the wind ever so slightly and compress it a little bit at the same time. I made my outer openings 1/3 larger than the inner outlets as well as position the wind vanes so they acted much the same as flat shingles on a roof, so the wind has no easy way of escape. The goal was to drive it into a vortex, which would seek that center hole as a vent and drive itself faster and faster as it approached center. Once the wind is made to spin, a static blade plopped into it just goes along for the ride. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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