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dswindle
Starting Member
USA
1 Posts |
 Posted - 26/06/2009 : 17:13:55
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I have tried several Ametek motors, and found they all cannot develope
enough voltage at low rpms. I have tried several diffrent blade designs to get faster speed, but even that has it's limitations.
I was looking at using a sprocket and a chain drive at a 3 to 1
ratio, to see if I could get the rpms up to the point that the design was usable. Any one have any suggestions on either the chain or the blade design?
Thanks Dave in Nevada...
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gotwind
Forum Admin
United Kingdom
1565 Posts |
Posted - 26/06/2009 : 20:49:53
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Hi Dave.
I have to agree, The ameteks are good but the rpm is pretty high to hit cut-in volts.
A 3Ft diameter prop should be o.k in a medium wind, maybe 16 mph, If your not seeing this kind of performance, maybe you don't have the best windspeeds in your location.
Gearing up would be a last resort personally 2:1 probably adequate, a well aligned chain and sprocket may work - maybe look at bicycle gears. but be aware of mechanical noise and frictional losses.
Good luck.
Ben. |
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Mertz
Junior Member
USA
115 Posts |
Posted - 26/06/2009 : 20:56:30
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I have learned the hard way but now that I have faster blades, I am getting 24v out of my Ametek 30 in 15 mph winds.
AS ghurd taught me, the blades are the key to any motor. Even my Indiana didn't perform well with slow blades.
Mertz |
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Fish4Fun
New Member
94 Posts |
Posted - 28/06/2009 : 05:00:27
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dswindle,
Gearing, regardless of mechanism, always introduces mechanical losses, sometimes these losses are acceptable. Instead of choosing chain and sprockets, you might consider using timing pulleys and a timing belt. Belts are a lot quieter and can be more efficient. Choose your bearings carefully, and give a fair amount of consideration to the RPM range. Long before I started ordering any gearing bits I would test my Ametek at various RPMs and loads, and I would track my blade RPM vs Wind Speed in a wide range of wind conditions. With this data I would then consider all available options, including building an alternator designed specifically for your wind turbine's RPM range in your prevailing wind range.
Unlike most here, I have ZERO real world experience with wind turbines, that is, I spend my time thinking, designing and calculating. I have built plenty of things; I have designed a myriad of things, and I have had a maelstrom of thoughts about things, but I am certainly not an "expert". I am actually building an Ed Lenz variety VAWT, and I have already decided that I started down the wrong path in my construction approach, but I am going to see the project through and document it here in the hopes of preventing others from taking a simple design and "over engineering" it. I don't have any noble Ideas about making electricity, I want to do something a bit more simple, I want to pump water, but I will likely end up using a gear reduction system to minimize "cyclic cogging"; of course, I am going to "gear down" not "up", but that will come after a great deal of data collection. I will build an alternator for the VAWT so that I can accurately capture energy data, and later on use the "dump load" as a "brake". I plan to use a water heater heating element as a "dump load" and use a uController to capture the data and control the "dump load". I have no intention of "using" the heated water, just using it as a "power sink".
Most people in this type of forum are all about "being green"; I think that is a noble pursuit, but I frequently question "the bottom line". If you drive a "Prius" because you "want to be green", it is highly improbable that you have considered the vested energy consumed in producing the vehicle. You are paying for it, and, honestly making an investment in the future, but IMHO, it is not a "good investment" from a strictly economic perspective. It is a fabulous investment in the "future", a bad investment of cash.
But back to your question: a wind turbine is an engineering solution to energy production. Ultimately all engineering is about compromise, that is, if "one size fit all" then there would only be one solution, but in the real world engineering is about maximizing return against investment of time and money. "Gearing" an alternator or generator is a design consideration that should be carefully considered. In some cases it is a question about gearing ratio, in some cases it is a question about the suitability of a particular alternator/generator for a particular set of blades and wind conditions. Do not make the mistake of attempting to force one particular part of a system to perform in a less than ideal situation and expect physics to exempt you from her laws. She won't, she is a B*tch about that. Get some real numbers about the performance of your blades and your alternator and then seek the path of minimal expenditure for maximum gain. Don't go into finding the solution with a pre-conceived notion about the solution, let the facts and the numbers guide you.
Fish |
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Using Sprockets and chain drive