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  • Another Hub Project

    I wish to make a more interesting Propellor Hub for the Wind Mill Generator. Something that will automatically declutch when the propellor speed gets too high. I have had one (wooden) propellor explode ? fly apart during testing.Took a long time to carve . New one is cut from a large dia piece aluminumn pipe. How would you build the declutching mechanism guys? Thanx Mike

  • #2
    Madman-
    Have a look at http://www.thebackshed.com/
    Lot's of great info on all sorts of windpower projects.
    Rich

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    • #3
      I am not clear on what you mean by declutch. If you mean to let if freewheel when the speed is too high - how will that help? The prop will just go faster and faster. It seems to me that you need to design the system so that when the torque exceeds a certain limit, the pitch of the prop drops to compensate.

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      • #4
        Interesting - if the Gen was engaged and producing electricity as the wind velocity increased you should have been increasing your excitation current to produce more electricity - that would have produced enough resistance to prevent the fan blade from overspeed.

        Once these things are synced and locked into the 60Hz of the grid, they can't be pushed out of sync.

        I was in a office some 500' away from a 25 MWatt peaker unit that the computer (PLC) screwed up and tried to throw in slightly out of sync. The ground shook and it nearly toasted the transformer

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        • #5
          That was an interesting site. Maybe Madman needs the furling process.

          http://www.thebackshed.com/Windmill/Docs/Furling.asp
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          Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

          It is true, there is nothing free about freedom, don't be so quick to give it away.

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          • #6
            I have seen furling done another way. Make the entire turbine horz. hinged hold bladed end down with a weight or spring. When the wind blows too hard it tips out of the wind.

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            • #7
              A couple of thoughts:
              1. Consider a composite prop (wood core with fiberglass covering), built on one - 3 blade - in about 12 hours of work over about a week for an experimental aircraft- pretty easy actually. The design process is fun too!
              2. I saw a documentary on the tube about a fellow who is using helix shaped wind turbines on buildings in Chicago as I recall, claimed the turbines wouldn't over-speed no matter the wind velocity and the turbines are not sensitive of wind direction. He had vertical and horizontal versions. lots of stuff comes up with a google search, may be worth consideration.

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              • #8
                Originally posted by madman
                I wish to make a more interesting Propellor Hub for the Wind Mill Generator. Something that will automatically declutch when the propellor speed gets too high. I have had one (wooden) propellor explode ? fly apart during testing.Took a long time to carve . New one is cut from a large dia piece aluminumn pipe. How would you build the declutching mechanism guys? Thanx Mike
                Is it the goal to disengage the prop from the generator, or to arrest the prop? If you simply disengage, the prop will speed up.

                A solution, though, is to steer the head such that the wind is at an inefficient angle to the prop. That steering can be automated based on wind speed and direction.

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                • #9
                  Add a torque converter or fluid coupling at the back end of the prop-shaft. The faster the prop turns, the more resistance created. With a little fluid control, it will act as a governor. It will generate heat so a fluid cooler would be needed. Just a thought.

                  Another thought: Drive a hydraulic pump and have the pressure control "feathering" the prop angle.
                  Last edited by CCWKen; 02-28-2010, 06:02 PM.

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                  • #10
                    Some types of generators have a centrifugal governor mounted on the shaft so that when the blades starts to go to fast the governor is pushed out and has vanes that catch the wind which causes drag and slows the shaft down to a safe speed.

                    Another type has a governor attached to the rudder or "fin", what ever it is called, and if the speed is to high it moves the rudder of to the side so that the blades are no longer at the right angle to catch the wind efficiently and they slow down. If the wind is too fast the rudder will turn the blades right over to 90 deg.s to the wind and they stop working all together.
                    The shortest distance between two points is a circle of infinite diameter.

                    Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                    Southwestern Ontario. Canada

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                    • #11
                      Nah, go read that site that Your Old Dog linked to. All these things have been discussed and the problems solved.

                      Their furling method (which swings the mill out of the wind when things get too hectic) is the best. They have electrical circuits that spread the effectiveness of the mill so you do not need variable pitch props. Everything you have thought is needed they already have the answers for.

                      Cheers.

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                      • #12
                        Info

                        Thanx Guys This will be the third one im making with a friend of mine.

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                        • #13
                          I too have played around with various types of wind generators.
                          The one pictured uses a PM 130v dc motor.
                          Still playing around with blade designs and waiting for wind!
                          Rich

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