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Forum Index : Windmills : VAWT New to group
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slow2cool Newbie  Joined: 24/07/2010 Location: United StatesPosts: 3 |
Hello All I am thinking of building a VAWT. It will be based on the Lenz2 turbine. What I have in mind is 20 feet dia. about 10 feet hight with 8 blades. I know that weight on the center shaft is a problem. What I will do to solve this, is put a wheel under each blade maybe a bike wheel. I will try to build it as lite and as strong as I can so it will have a slow wind cut in speed. I don't think I will produce much rpm but with a 10 foot lenght from the shaft I should get a lot of torque. What I would like to know is 1. Has anyone ever done anything like this? 2. Should I use a less number of blades? ( is so how many ) 3. How many rpm will the turbine have to spin in order to produce a fair amount of electric? ( I know I will have to use some type of belts or gears ) Any info, feedback, good or bad, will help. Thanks Joe |
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Quite plainly i think you are wasting your time, Low rpm........useless Belts or chains........losses, losses, losses. Support wheels....Losses,losses, losses. By talking about using wheels i take it you intend to have this on the ground, which is also the worst place to have it. My advice would be to build a smaller more efficient HAWT. Pete. Sometimes it just works |
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| slow2cool Newbie Joined: 24/07/2010 Location: United StatesPosts: 3 |
Hi Pete I hear ya I am not in a area that would be good for a HAWT. I would have to have a very very high tower. If I am going to build or buy one it will be a VAWT. So that's a must. So where do I go from here? Joe |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Slow You could use a diff housing for your main support as wheel bearings have a high load rating and you can use the diff as a step up drive as well, reduce the diameter to 8 ft and use a bird cage frame with a star frame on the top for your top bearing mount. Lock the planetary gears in the diff and block the lower tube, and use ATF oil to reduce oil drag. I have never used the lenz blade system but with normal airfoil blades it should do 120 to 140 rpm in a stiff breeze 5ms. I found that with airfoil blades that 6 blades worked the best, as to many blades caused to much internal turbulence reducing the lift on the blades. How much power do you need? A 2 to 1 step drive off the pinion should give 500 rpm loaded and that would drive a F&P alternator. Also as Pete said it will need to be well of the ground, at least 10 ft to the bottom of the blades. All the best Bob Foolin Around |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
slow2cool I'm with Pete. Look around at "fans" in general. How many run on a vertical axis? Sure, there are a 'few' but for the most part, it's a horizontal-axis ball game. Look at the commercial ventures; how many vertical applications do you see in use out there? The only vertical application that really works as far as I can see is the anemometer, that little three-cup dealy that twirls atop a weather tower and measures wind speed. Now, don't get me wrong. They're "fun" to build and watch (when they actually spin!) but for doing any kind of meaningful 'work' they run dead last in that race. An exception to the rule might be one that's here on the 4m called the Miller Rotor. Give that link a look-see. . . . . . 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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| slow2cool Newbie Joined: 24/07/2010 Location: United StatesPosts: 3 |
Hey Guys Thanks for getting back to me. Bob and Mac I see what you are talking about and I will give it plenty of thought. Thanks again. Joe |
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| electrondady1 Senior Member  Joined: 12/02/2009 Location: CanadaPosts: 208 |
Ed's design works. it's primarily a drag mill with a little lift at the top end. but not so much that it wants to blow up like a Darius. scaling it up to the size your talking about could lead to some real dispointment. especially if this is your first project. consider building multiple mills with smaller swept area. once you get a configuration that works you can just clone them I'm placing my mills along my fence line. there is good wind there and it's out of the way. |
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