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Wind generator blade design  RSS feed

 
Larry Bock
Posts: 114
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I am in the process of building a wind generator. I'm kinda overwhelmed by all of the blade designs out there.  The horizontal Vrs the vertical and any thing from bike rims to snow shovel to 55 gallon barrels high tech store purchased ones.  I have two low rpm/ high output,treadmill style motors to work with. The system I pretty good on.  The type of blades ? Not so much. I'm more of a Diy guy and would like some imput. The simpler the better,the cheaper the better , the more efficient , the better.  My goal is to charge a 4 battery 12 volt system to start for an off grid camp. Ther will be a 750 watt solar system there also.  I guess what I'm shooting for is a good blade.   Oh number of blades as wee confuse me? Also
Design.  Thank Larry.  Oh happy belated turkey day
 
Alley Bate
Posts: 20
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Like most anything, It depends
HAWT - horizontal axis are generally most efficient if put in optimum conditions, VAWT - vertical axis generally have an advantage in swirling, gusty, low to the ground conditions and to most eyes look cooler.
Blades cut from pvc pipe or plastic barrels are popular for first efforts with treadmill or servo motors, this is the route I'll probably take for my first effort.
If you'd like to carve your own from wood, depending on how fancy you want to get, do a web search for NACA profiles.
Serious consideration must be taken to protect batteries from overcharging when adding wind to a system.
If you haven't been yet, check out http://www.fieldlines.com it's an awesome diy energy forum especially in the wind dept.

Looking forward to seeing what you come up with!
 
Larry Bock
Posts: 114
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Alley Bate wrote:Like most anything, It depends
HAWT - horizontal axis are generally most efficient if put in optimum conditions, VAWT - vertical axis generally have an advantage in swirling, gusty, low to the ground conditions and to most eyes look cooler.
Blades cut from pvc pipe or plastic barrels are popular for first efforts with treadmill or servo motors, this is the route I'll probably take for my first effort.
If you'd like to carve your own from wood, depending on how fancy you want to get, do a web search for NACA profiles.
Serious consideration must be taken to protect batteries from overcharging when adding wind to a system.
If you haven't been yet, check out http://www.fieldlines.com it's an awesome diy energy forum especially in the wind dept.

Looking forward to seeing what you come up with!



Thanks for the great link,seems to have a lot of info..I like that they have a forum on micro controllers and interfacing systems.....Larry
 
Al Freeman
Posts: 44
Location: North Texas plaines
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I'm new to this 4m, I have built 'windmills' for nearly 50 years; ya, I'm old.  I will outline what I currently use, after having tried EVERY possible design over these many years.

The problem facing most, who try to DIY a 'windmill' centers around a whirling mass, which must be aimed, controlled, BALANCED, ect.  Then, you have to get the electricity down off the tower without wires wrapping up all over the place -- big headache; I have designed a system, which circumvents ALL that and more.I designed, built and use a "horse-of-a-different-color" vertical axis wind turbine (VAWT). 

My design can be as large as you have room; really!  At any rate, what I usually use is a steel barrel with the open end down.  I cut long "C"s down the sides with a high-speed grinder (you could also use a plasma cutter), such that they can be bent slightly outward.  When bent out as such, this creates flaps, which catch in the wind and direct it inside to form a whirly vortex.  Horizontal to the side of the barrel and across the open end (facing down) I weld a post with a "V" cut in its end. Into the "V" I put the front hub of a bicycle, held there by a worm-strap, which threads through a slot ground in each side parallel to the direction the axle lays and tightened, holding it in place.  This gives me a threaded shaft on both sides of a VERY ROBUST bearing, for a cost of nothing (if you are a good scrounger) to only a few $.

One side of the little hub is attached to my home-made alternator** and the other is attached to the blade*.  I have designed a permanent-magnet-loaded 3-phase alternator, which is conceptually easy, but pretty intricate to build -- not hard by any means, just a bit complicated.  I'll take a shot at a description of the rotor here and if you want to take it to the next step, PM me and we'll go from there.

*BLADE

Instead of using a straight flow of wind to spin a blade (which must now be 'balanced', etc.) I choose to spin the wind into a vortex and immerse a flat blade in the flow.  I've been accused of thinking outside of the box, but frankly, I never knew there was a box.

The "blade" is nothing more than a sheet of light plastic.  It is fastened to a bar of angle-aluminum, which is bolted to the bicycle hub axle and extends up inside the barrel.  It doesn't need static balancing and all it does is spin.  "I" personally use two sheets and two angle-aluminum bars, making 4 blades, one each 90 degrees, but that's 'me'.  You do what you please.  At any rate, whenever ANY wind blows, no matter what direction, this thing spins.  Easy-peasy! 


*Alternator -- 

By the way, I have a lathe, which makes this WAY easier.  I take two sheets of HDPE (high density poly ethylene) plastic and turn two circles, with a hole in their center the same size as the axle on the bicycle front hub.  Just make a mandrel out of a bolt the same size for this.  Then, I use a special bit called a "Forstner" bit, which drills a very precise hole and drill anywhere from 6 to 12 holes about the circle, having laid out there positions RATHER EXACTLY before hand.  These holes will house neodymium magnets and should be a snug fit.  I shove a magnet into each hole in each disk, such that one whole side of each disk is "N" (north) and the other whole side is "S" (south).  Next, I fashion iron backing plates out of the ends of a coffee can, drilling each's center with a drill the same size as the bicycle hub bolt.  See where this is going?  Next, I cut the perimeter of each coffee can lid into little "picket-fence" points.  Each lid has to be exactly cut the same as the other, such that there are an even number (I like 12) of pointed sections on each lid.  Now, actually "before" you load the magnets, "INDEX" each lid, such that looking from one side through both sides of the disks, there is a point on one disk neighbored by a point on either side from the other disk.  If you're lost, think of a car's alternator and how the rotor halves appear to be interlocking fingers, which don't touch, but have their apexes running down the circumference, first one side, then the other, and so on.  At any rate, once you have installed each lid on each wheel and have pre-drilled the disks in several spots (remember to keep it balanced), then you can load the magnets and put the disks together.  Be careful not to pinch your fingers or crack the magnets -- they SHOULD NOT bang together or they will break!  Now, you have a permanent-magnet-loaded stator.  If you've gotten this far, now you need to build the pick-up-coil part of the alternator, which will be 3-phase and if you want me to tutor you, PM me, cause it will take a whole page or two to explain it here.  It's complicated, but not hard, although it will take a lot of "do this much and get back to me for more instructions" to build the thing.
 
John Weiland
Posts: 921
Location: RRV of da Nort
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@Al Freeman:  This sounds like an interesting design.  Do you or a friend have the ability to take a few photos of it and upload them here?  What do you estimate is the wattage output of this configuration (and at what voltage)?  Thanks.
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