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Forum Index : Windmills : Slow running hawt
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| nzdrunkricknz Newbie  Joined: 08/08/2013 Location: New ZealandPosts: 4 |
Hi all I am new to this forum and firstly thanks to everyone that has put their part into this website and forum. I currently have just over 1Kw of PV on my shed charging a 24v 840AH lead acid battery. It runs a great part of my house in summer but falls short in the winter for obvious reasons. I tried a 300w Chinese wind mill with peak power at 900 rpm and found it quit noise and it needed to spin very fast to make descent amps. So I sold it and though may be I will try a lenz2 with an F&P generator ,so after some testing and reading of this forum I thought, I will probably be wasting my time. So I have rewired an F&P stator to a 7Phase 1X6C with a late model hub (when I was testing for the lenz2) and got good amps at low rpm. So if I make a small hawt with over all blade length of 1.2 -1.5 meters using the 7 phase F&P also using 9 to maybe 11 blades to get a slower running turbine and hopefully less noise. Note:- I live in a city with my closest neighbour about 10 meters away What do people think? Be nice I’m new to wind mills. Rick |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
In theory, it should work, so long as you don't expect too many watts from it. 9 to 11 blades may be a bit much, I would be inclined to try 5 to 7 blades, with a higher angle of attack. Usually 3 blades are used with a small angle of attack ( under 5 degrees ) to get the RPM up. And higher RPM equals more power. If you used 5 to 7 blades with a angle of attack over 10 degrees, I guess it would have more torque in low winds, and run at a lower RPM. But this will also mean less power than you could expect for a 3 blade turbine. 1.5m blades means a turbine over 3 meters, and that's getting pretty big. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| nzdrunkricknz Newbie Joined: 08/08/2013 Location: New ZealandPosts: 4 |
Hi Glenn Thanks for your reply. Sorry i ment the blade lenght would be 600mm to say 800mm, so overall diameter would be 1.2 to 1.5 meters. What would be the best way to cut the noise down on a hawt? Thanks Rick |
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| Midwoud1 Newbie Joined: 25/12/2012 Location: NetherlandsPosts: 23 |
You can go to a larger blade diam. with 3 blades. Hawt The secret of low noise is sharpen the trailing edges. I have good results with it. - Frans - |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
HAWT's are only noisy when they are experiencing turbulence, or have a poorly designed blade. Most HAWT's are nearly silent, its just a few that have given them a bad reputation. See this article on how I modified a set of Chinese windmill blades to make them quiet. http://www.thebackshed.com/Windmill/articles/ChineseBlades.a sp 1.2 to 1.5 meter diameter turbine is very small for a F&P, I wouldn't expect any more than 30 or so watts in a average wind speed. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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