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Forum Index : Windmills : The Column 700w-3b-12f VAWT
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Perry Senior Member  Joined: 19/11/2009 Location: Posts: 190 |
You seem very interested in rpm that it achieves. It's kinda a useless number, especially for an unloaded turbine. Why the push for such high rpm? design a decent AX-FX for around 150 rpm cut in and you won't have to stress the heck out of all your components. Regarding the balance issue I think you have a dynamic balance issue, not a static balance one. You have a long thin shaft supported on the ends. The wind force on your 'rotor' causes it to bend, cycle after cycle. I think that is why you are really seeing the imbalance issue at higher rpm's. Not because it is spinning so quick but because the wind is strongest and the side loading greatest then. Shouldn't really matter though as when you have a generator keeping your freewheeling rotor in check you won't see those crazy rpm's. Perry |
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GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Readers, there are so many ways to alter the cut in alternator speed, without resorting to mechanical gearing components. If the loading is a fixed battery system, then an AxFx can be designed/wound to suit. If the alternator is fixed and has a too high system rpm cutin, then either a DC-DC converter or cap doubler can be used to boost the cutin voltage to the lower rpm. I doubt that the power in these small VAWT mills will overtax a modest electrical system. Boost arrangements are preferred to buck converters, as they only pass a portion of the maximum power. I have to agree with Perry, in that there is not much to be gained from unloaded mill behavior. Kinetic art may be OK with it. The only way to confirm a static or dynamic balance issue would be to mount the rotor horizontally and test it this way. It is very difficult to static balance a vertical rotating object. This will also make it easier to see if there is any flex in the rotor that would contribute to imbalance dynamically. Gordon. become more energy aware |
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| faroun Regular Member  Joined: 18/09/2008 Location: Posts: 62 |
Here is and update, i tweaked it a bit more and added tension wires. Better YOutube video Many Ideas One Brain. http://www.wrapwind.com |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Its getting better, definately working on lift. A unloaded lift based windmill will spin like crazy, but it might not be capable of making any usable power once loaded, you need to take the next step and see. Like you say in your video, next thing to do is add a load and get some figures. Its only a small windmill, so do go overboard with your load. Have you got a DC motor, like a electric scoota motor, car heater fan motor or a treadmill DC motor? Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| faroun Regular Member Joined: 18/09/2008 Location: Posts: 62 |
Glenn, at 305rpm, i am expecting it to make 40/60 watt. I am ready for any results, i made the turbine to test a design and based on many calculation, it should produce 450w at 500rpm. If it fails then so be it. Regards Sam Many Ideas One Brain. http://www.wrapwind.com |
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| itsandbits1 Regular Member Joined: 13/08/2010 Location: CanadaPosts: 81 |
Sam, as another good ol Canuck, I support your venture , and I know it is going to work. These warm countryers get everything handed to them on a silver platter and don't know what fighting off grizzleys all day does to make a man persistant and tough. Now you come on back to where you are appreciated and let these boys play in their sandbox where you can just stick anything up in the air and if it falls the only thing it will hurt is next year, sh*t they fly washing machines, you've got nothing to apologize for. Lloyd |
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| Perry Senior Member Joined: 19/11/2009 Location: Posts: 190 |
hehehe, That's kinda funny. No sand in my washing machine, I live about 100 miles south of you. Any pic's of your power producing VAWT to post?..................A Sharp perhaps :) Perry |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi readers, I don't know what the fuss is about re rpm really. My HAWT has really high aspect blades at the moment, that tend to vanish once it is spinning. All you see when it is going is the alternator with the tail. My AxFx HAWT, windmill makes about 250W @ 200rpm and about 750W @ 300rpm. I traded up my washing machine to an AxFx design. I know that faroun really wants his VAWT to make some good power. I have seen some commercial VAWT performance graphs, and these have outputs from 0 and up to 30m/s windspeed. I think that one of the many readers that owns a VAWT, could provide some empirical power performance curves of their own VAWT mill. Even power v rpm would be useful. I certainly could become a believer if I was provided with some objective performance data. Gordon. PS :- There are many who want to build a VAWT for purposes other than electricity production and their wish to do so is noted. I built a small VAWT unit early on in my hobby development. I reused the alternator in my first [still flying] HAWT. become more energy aware |
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| electrondady1 Senior Member Joined: 12/02/2009 Location: CanadaPosts: 208 |
i don't post here much, but i have been checking out this forum for many years. there are some very knowledgeable and experienced builders posting here. i think the advise SAM has received is sound. and reinforces the advise garnered from other forums. there is a balance problem with the devise.(curable) as well,the centrifugal force on the blades wants to compress the axis, allowing deflection.(curable). not sure about the 700 rpm ceiling. that's pretty fast. but i build drag verticals so i am no expert. |
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| faroun Regular Member Joined: 18/09/2008 Location: Posts: 62 |
I have been modifying the turbine, the hadrest to mod is the shaft, i am tryinf to avoid doing that. i am fine untill 375rpm, after that all hell break loose. but like you said, at least we know why it is doing it. It is the Shaft for sure. next one i will have it right...right..eh! thanks sam Many Ideas One Brain. http://www.wrapwind.com |
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| electrondady1 Senior Member Joined: 12/02/2009 Location: CanadaPosts: 208 |
prototyping is not easy, but your project has real potential so keep at it. when i noticed your vanes being thrown outward i realized there must be compression as a result. hence the idea of putting the central shaft under a bit of tension. if you are using pillow blocks i don't know how you could do it but if you are using a flange bearing , and the mounting plate is strong enough you could tighten the locking collar on the shaft beneath the bearing first, leaving a bit of space between the base of the flange bearing and its mounting plate. and then torque down the mounting bolts. putting some tension on the shaft. it may not work. it might make the bearing too stiff. you could place additional support disk at the point of maximum vane deflection. and control their movement outward. or you could use the central support disk as the only torque transfer point and let the end disks float on the central shaft. maybe all three are required |
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| faroun Regular Member Joined: 18/09/2008 Location: Posts: 62 |
i am going to try complete some mods this week, that will include few of your suggestions. thanks for the support. regards sam Many Ideas One Brain. http://www.wrapwind.com |
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| itsandbits1 Regular Member Joined: 13/08/2010 Location: CanadaPosts: 81 |
yep http://www.youtube.com/watch?v=glwaXdBGbKw http://www.youtube.com/watch?v=1gTqX7xE21c enjoy Perry. |
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| electrondady1 Senior Member Joined: 12/02/2009 Location: CanadaPosts: 208 |
one thing you might consider as you fine tune your machine is the method you are using to support it. i know you wanted to do the side by side comparison on column f and r. what you built makes perfect sense for that purpose. but i got the idea somewhere that getting up on top of the scaffolding makes you uncomfortable. a support tower that holds a single mill and pivots down so the mill is horizontal would make experimenting a lot easer. especially with winter coming on ! |
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| Perry Senior Member Joined: 19/11/2009 Location: Posts: 190 |
Looks good. Is there a gen hooked up in that second vid? I follow your stuff now and then on the VAWT forum. Don't post there as I have nothing really constructive to add. Is your machine dependable? Wat type of performance? Perry |
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| faroun Regular Member Joined: 18/09/2008 Location: Posts: 62 |
looks like you are having fun. i think you got the vawt bug just like me. your projects are much further than mine. best regards sam Many Ideas One Brain. http://www.wrapwind.com |
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| faroun Regular Member Joined: 18/09/2008 Location: Posts: 62 |
You bet it is scary up there, and yes the idea was to compare the R and F. in the future the idea is to mount it on a "F" shape pole, where the column will be bettween the "F" teeth. and yes we can make it pivote. thanks again for finding and thinking in details. regards sam Many Ideas One Brain. http://www.wrapwind.com |
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| faroun Regular Member Joined: 18/09/2008 Location: Posts: 62 |
Perry, if you are asking me, i am at the mid point in making a gen that works for my beast. thanks sam Many Ideas One Brain. http://www.wrapwind.com |
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
faroun Hey, here's an idea: Like was just mentioned, why not make it so the holding contraption hinges mid span like home movie screens (this dates me!) used to do? That way, it would be easier to test it and work on it. You could merely fold it down so it's like a giant lawn mower (reel type) and face it into the wind, should the wind get out of hand. Doing it this way, you could drive a stake through its heart to keep it at bay if winds kick up to hurricane strength and resurrect it (remove the stake) as the wind speed dies off to normal. I saw on another page here where the fellow used a carbon-fiber tube as an axle and maybe this would also lessen it's desire to wobble at higher speeds. Here; I borrowed a picture from the guy's site to show you that carbon-fiber shaft: 
. . . . . 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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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi itsandbits1, I could only get the first link to show anything. I can only assume that the LED's were the only load. It is good to see a few watts made from these VAWT's. I am not sure about using a "hand brake" to stop a mill is good though. Gordon. become more energy aware |
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