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Forum Index : Windmills : Wind turbine noise solution
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| barrygun Newbie  Joined: 03/07/2011 Location: Posts: 7 |
This is my first post but I think I may have an interesting solution to the turbine noise problem.Aircraft now use wing tip "tail fins" to put a physical barrier between the high and low preasure areas of the wing,(an idea first put on my fathers man powered flight aircraft built in 1960 to cross the english channel........he should of patented it eh!),this increases not only the efficiency of the wing but also cancels the NOISE PRODUCING VORTICIES that trail behind the wing(or blade)tip,its like a long spiraling tornado of air that trails behind a plane for a couple of kms.In the turbine senario the blade tips are contiuously running in the vortex of the tip in front of it in an endless loop producing an annoying high pitched whistle,it will be worth your while to experiment with "blade tip fins".........and it will look really cool...Cheers,Barry  Hand Tools-The"Master Key"to Independence. |
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
barrygun I manufacture my own hollow coroflute plastic blades and I've found leaving the tips open also spoils that tip vortex and they run silently. Your wing-tip "tail fins" are called winglets. Your idea is good, but I'm not sure it will actually work here and the reason I say that is because I have a glider with "winglets" that literally screams through a loop or a low, high-speed pass. Perhaps the noise is caused by the entire wing, I dunno. It may be worth a try, so perhaps I'll install winglets on a set of blades and close off the tips just to test it out. Edit: Link . . . . . 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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| barrygun Newbie Joined: 03/07/2011 Location: Posts: 7 |
Thanks for the response Mcgyver,I hope you and others can do some experimenting,I dont have the resorces to do it myself,Cheers,Barry Hand Tools-The"Master Key"to Independence. |
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mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
barrygun, Hello Barry, Welcome to the forum, thanks for posting about the wing tips. If you read my posts - "VAWT, going in a big way" - you will see how I am also experimenting with this. ...Mac46 I'm just a farmer |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Barry, have you taken into account that on an aircraft wing the 'winglets' travel in a straight line through the air while on the end of windmill blades they would travel in a rather tight (relatively) circle. Me thinks this might change the vortex effect. After all, one does not see 'winglets' on the tip of aircraft propellors. Klaus |
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powerednut Senior Member  Joined: 09/12/2009 Location: AustraliaPosts: 221 |
The winglets just move the vortex further out beyond the edge of the wing so the vortex does not interfere with the airflow over the wing. There are some other benefits too, but I don't know enough about aerodynamics to be able to explain it. If you want to experiment you might want to examine a horner tip instead. This has a similair effect to a winglet, but with a much simpler construction. Essentially the wingtip is cut at 45 degrees, with a small radius at the bottom and a sharp corner at the top tip (from: http://www.zenithair.com/stolch801/design/design.html better references may exist). |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
There's a article on the main site that might interest you. http://www.thebackshed.com/windmill/articles/ChineseBlades.a sp Its about a few modifications we did to the noisy blades fitted to the cheap Chinese 200watt windmills you can buy from Jaycar, etc. Its my experience that a noisy turbine has a design problem. And I've heard some howlers! I remember trying a set of PVC blades ( not mine ) that were made from PVC pipe and were so long they needed their own guy wires attached to the hub to stop them bending back. When they got up to speed, they made this very loud whistle that could be heard 200m away! The dog was not happy. But I've also seen/heard some, like the extruded PVC/aluminium blades, which you would expect to be noisy due to its nill taper or twist, that are virtually silent! Also modern wind farm turbines are also very quiet, they are designed that way. Winglets do improve performance by a % or two, I dont know about noise though. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301 |
Hi Barry, Some reservation would arise with winglets particularly on HAWTs as wind speed increases the mast and props flex, reducing clearance between the two parts.Those mills with slightly inclined heads would be better candidates for trials,having less likelyhood of mast strikes.I wonder if they would slighly improve output in the fully furled position by presenting more surface area to the wind?With small scale mills the extra work doesn't justify the gain from ones who've tried them,is the feedback I've had.But don't let that put you off.Cheers Rastus see Rastus graduate advise generously |
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philb Regular Member  Joined: 05/07/2008 Location: United StatesPosts: 96 |
I had noisy blades once. I glued a piece of string trimmer line on top of the blade. It ran the entire length. The noise virtually went away. There is a commercial unit out that does something similar...1 KW Bergey I think. philb |
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vawtwindy Newbie Joined: 23/10/2010 Location: IndiaPosts: 31 |
slightly relevent to this topic "Aviation Partners Boeing claims that winglets on 737s and 757s have saved a collective 1.2 billion gal. of fuel since they were introduced and 11.5 million tonnes of CO2 while reducing those types’ noise footprint by 6.5%." 
Eurocopter's Blue Edge Rotor Blade Makes Helicopters Silent  |
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| barrygun Newbie Joined: 03/07/2011 Location: Posts: 7 |
Thanks for the input guys,I found that DUTCH AEROSPACE have been doing experiments to quieten wind turbines and they found that putting a SAW TOOTH PATTERN along the full trailing edge reduces noise by 50%.......interesting,thanks vawtwindy for the pics,I personaly like the eurocopter design just on looks alone!!!!!.P.S.as im a newbie let me introduce myself and list where Im at with ALT ENERGY,Mid 50's disabled pensioner and so far Ive collected 15 x F+P motors and shafts,1x 2400 cont inverter,2x 600cont inverters,1x B+S driven 12volt car alt,1x 1959 PETTER AVA2 10 KVA EX HOSPITAL STANDBY GENERATOR with only 501 hrs on it AND A SHED FULL of asst "project material",getting there slowly but surely!cheers Barry. Hand Tools-The"Master Key"to Independence. |
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