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Forum Index : Windmills : Lowering the Drag...
| Author | Message | ||||
| mbombay Newbie  Joined: 17/09/2008 Location: IndiaPosts: 5 |
Any idea's to lower the drag on the rear of the blade(in a VAWT) that's moved around in to the wind ?? There are windmills (SideWinder wind-turbine or the Disk Wind Turbine) which have shutters/louvers that open up like a book by the wind itself and close/shut after turning around either by their own weight or by the force of the wind. Such systems make a lot of noice because none at present come with soft-landing pneumatic or hydraulic shock-absorber system for the wind-shutters/louvers when they shut or open. Wish to build a bigger Vertical Axis Wind-mill for myself. With shutters that open and shut in a controlled manner. Will probably be talking more on this in the future. Thanks. |
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vawtman Senior Member  Joined: 14/09/2006 Location: United StatesPosts: 146 |
I think they would make great yard art.Toooo slow for electrical generation.I don't recall them even having an alt attached unless i missed that. Think about it when the shutter is forced open by the wind what happens in front of the shutter.It can only make power for a tinsy part of the rotation and the rest is lost. Hope you plan on a monster and best wishes. My thoughts only |
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| mbombay Newbie Joined: 17/09/2008 Location: IndiaPosts: 5 |
What I mean is a Vertical Axis Wind Turbine with blades that activly turn to catch the wind. Like ... 
OR... 
OR... 
( This one is Chinese ) What I have in mind is a real power generating system big enough and a one that moves slowly with the wind. The problem with such a system sure would be that it won't move at all at lower wind-speed. In such a VAWT the shutters that open and shut in a controled manner would make less noise which indeed is a problem with the others that are available. The slower the wind turbine moves, the slower the blades turn to face the wind thereby making the thing less noisy. Who is going to be the end user of that electricity remains a fundamental issue though... There aren't many benefit's economically unless you're planning to do it to power your own work-place or factory(as in my case), or unless you happen to be a bit of a romantic environmentalist and discount IRR etc. or you're a manufacturer who believes you got something patentable. The big question still remains. How to turn the blades to catch the wind according to the wind direction that will keep changing ? Thanks. |
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GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
I remember seeing a picture of one of the above that Gizmo made. The top two pics look like Gizmo's. Gordon. become more energy aware |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5117 |
I'm not a fan of any vertical windmill with shutters. There are many good VAWT designs out there, like the modified Savious or Lenz, and these dont need any moving parts ( ie shutters ). I dont think a shutter based VAWT would give any more power than a Sav' VAWT, but it sure would make a lot of noise and wear out quicker. That windmill of mine with the tail was based on Ed's design. It worked, but fell apart after a few weeks. It also convinced me a VAWT should never have a tail! Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| vawtman Senior Member Joined: 14/09/2006 Location: United StatesPosts: 146 |
I agree Ben.Why not build a hword  if he's goin through all that trouble. |
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| vawtman Senior Member Joined: 14/09/2006 Location: United StatesPosts: 146 |
Oops Gizmo(glenn)sorry bout that  I think i'm loosin it. |
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| Jarbar Senior Member Joined: 03/02/2008 Location: AustraliaPosts: 225 |
Hello all,not sure how to add to this without offending anyone.This line of thinking is reminding me of another thread where capacitors are being shown to improve electrical output on an F&P generator.Initial claims that it was possible were treated with disdain.Not that I can say I really understand it but it appears to work. I will now add my observations. I have found a tail useful in increasing the power of my VAWT . I have found that valving arrangement in the blades adds power to the VAWT with some small increase in noise. I have found my tree useful for getting my VAWT above other ground level structures. Can I quantify my observations electrically no.But many hours of visual observation and experimentation has me convinced that it is possible and desirable to include all of the above features to build an econonomic and efficient VAWT.Currently it is driving a F&P unmodified motor with a 1:3.25 ratio.Last week in a gale it was turning 2 F&P unmodified 1:3.25 ratio.How much more load is created once motor is modified and connected to a load I am yet to find out.Now is just to find the scale needed to be useful.So where I am up to is refining my working prototype so that from the smallest physical size I can derive the maximum out put using easily available recycled products. Again health is my greatest adversary but felt this thread needed some alternative viewpoint.So mbombay don't be disheartened.Some radical ideas come up here and sometimes they just need a little push.As Anthony Robbins once said and was plagerised by Donald Rumsfeld There are Unknown Uknowns,Known Unknowns,and Known Knowns.The Hedron collider is a good example.Who knows what it will find. Meanwhile as I try regroup my health the next evoloution of my VAWT is sitting patiently in the garage.While its mate rotates gracefully in the tree.I watch it daily from my bed.Gee I can rave on. Jarbar.  "Creativity is detirmined by the way you hold your tounge".My Father "Your generation will have to correct the problems made by mine".My Grandfather. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5117 |
Hi Jarbar Point taken. I agree a there are some types of VAWT that work well with a tail or shutters. But I figure if you want to use a tail, then a HAWT is the most efficient design you could use. HAWT's are a lot easier to make and offer a large swept area with small blades. VAWT's on the other hand, the types without a tail, work better in turbulent wind. I found my Lenz VAWT worked great in the months of the year where the wind comes from the SE, behind my hill, wind direction changes every few seconds. The rest of the time the wind is from the NE and my HAWT windmill performed better, it needs its tail to find the wind. So I find a tailed HAWT is the best option of clean wind, and a tailess VAWT is best for turbulent wind. But this doesnt mean other windmill combinations cant work. Hope your health picks up soon. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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