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Forum Index : Windmills : Yaw moments of small wind turbine
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| james6008 Newbie  Joined: 19/04/2014 Location: United KingdomPosts: 2 |
Hi all I am looking at a small wind turbine such as Marlec 913. I came across some equations for furling moments on the website but I was wondering if there is any material or any simplified equations available to represent the turning moments on the rotor during yaw. The wind turbine has a tail vane so I know there will be force on that and there will be gyroscopic forces trying to resist the yaw as its a passive wind turbine. Any help will be appreciated. |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi James The pages about furling are really just a guide line. Experience has taught us that trying to use maths to calculate furling is just not going to work out that well. There are so many other variables, and the maths will just give you a general idea of the best starting angles, but only trial and error on the tower will get it working correctly. Factors such as rotor weight, direction, alternator loading, etc, all play a part in furling, its very complex. In my view its a lot easier to set the angles for a early furl, and add weight to the tail through trial and error until you get a furling action that you like. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| james6008 Newbie Joined: 19/04/2014 Location: United KingdomPosts: 2 |
Hi Glenn Thanks for the reply. I understand that furling can get very complex which is why I am ignoring it for the time being. I am just looking at yawing with change in wind direction. I am interested in calculating the yawing moment/forces due to the actual rotor as it responds to the change in wind direction. For time being furling can be ignored. |
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
You sound like a young engineer that is designing a project and would like to know all the black arts of furling in a simple math calculation. As Glenn has said furling dont work like that, and each mill and each mill design is different when you come to furling. Its a balance act between several factors, and the factors are affected by the actual mill itself. There is degrees of pivot layback and degrees of offset, and amount of offset distance from the yaw bearing, then tail weight, and tail length, and the blade diameter, and blade weight, and tail vane size, and ?, and ?, and.............? All effect furling, so do you see its a black art, and not a math solution. We offer the best advice we can, but so far you have given Zip to work with, other than thinking we know all the answers and dont tell anyone. If there was a simple solution to working out furling it would be on the forum years ago and we would all use it, thus far out of the many folks here who have built mills noone has the furling solution you ask for. Should you find the holy grail of furling then please tell the rest of us. Pete. Sometimes it just works |
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| anteror Senior Member  Joined: 06/10/2009 Location: FinlandPosts: 189 |
Wind generator HAS to be, very heavy duty, robust built. Read my story about "factory made working good"; http://www.thebackshed.com/forum/forum_posts.asp?TID=5285&PN =1 .." No matter how you have the furling etc, there is a lot of rapid custs in a stormy weather and the blades get overspeed, because the centrifugal force of the blades, cancels the furling, for a while etc This stuation I have seen countless times and now when wind speeds are rising, in our time.. SO  , wind generator MUST be heavy duty, robust built and withstand
very high winds. The safety factor, must be in every section = 2-3 times ! My Huyaturbine has seen very strong storms and have worked without any faults, 8 years now, here in Finlands violent and harsh climate. It is promiced to withstand over 50m/s = 112Mph winds ! If you want to have easy and hardwearing wind generator, that also REALLY !!, gives you power ! My blade area is 12m2 = 129 ft/2, blades are 1,9m each = 6,23ft. Diameter is with the hub 4m = 13ft. They sel windgenerators with blade area  , that is just a fraction about
this and they give the same power reading. Picture about Huyaturbine 2-3kw(I have got over 4Kw..) blades. With just moderate wind you REALLY get energy 1-2Kw. For dimension, to understand, Honda CRV; 
Antero |
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