Hi,
My name is Dimitar,
In my opinion this is not so good design. For small
power you can use wood blades cover with epoxy resine
with glass
--- "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote:
>
>
> Hey,
>
> As soon of you may know from a previous posting, I
> and three classmates are
> currently working on developing a low-cost, durable,
> locally constructable
> Darrieus type water turbine for use in rural
> sub-Saharan Africa. We have chosen
> the Darrieus turbine (Or possibly the slightly more
> complex Gorlov helical
> turbine) because it can be used in streams with
> heavy sediment load and variable
> heights. No civil works are necessary as we are
> planning on attaching this
> turbine to a raft system that will also contain a
> generator. We are planning on
> using DC current and running a pump / mill / battery
> bank on shore in a small
> power house.
>
> Currently, we are looking at designing the blades
> for the turbine. Most turbines
> now are constructed using expensive, unavailable
> techniques, such as extrusion
> or composites. We have a limited set of materials
> and machining techniques that
> can be used to make these blades.
>
> What I am currently experimenting with is a turbine
> blade constructed as
> follows:
>
> PROFILE: NACA 0020
> TIP TO TAIL LENGTH (not chord): 6"
> HEIGHT: 30"
>
> The blade will be constructed by placing three
> different PVC (or possibly steel)
> pipes along the center axis of the blade. The first
> pipe will be 1" in
> diameter, the second 1.25", and the pipe in the tail
> will be 0.5". A
> sheet of 20 gauge stainless steel will be wrapped
> around these pipes (once they
> are properly placed to give the correct hydrofoil
> shape) and pop riveted at the
> end. The sheet will also be pop riveted (using
> countersink rivets) to the pipes
> themselves. When attached to the holder plates at
> the top and the bottom, the
> blade will be welded to the plates to make the
> interior waterproof. The PVC
> pipes themselves will extend through holes made in
> the plate so that they can
> add structural support to the system. Three blades
> will be arranged on a 40 in
> diameter holder plate at 7-9 degree angles of
> attack. A stainless steel rod will
> be used as the turbine shaft to join the turbine
> with the raft and generator.
>
> QUESTIONS I HAVE:
> 1) Has anyone tried / seen anything similar to this
> before? I know ribs have
> been used in the tip to tail direction, but this
> ribbing system seemed to not
> have been used.
>
> 2) How would I calculate the bending / buckling of
> the blade's center? Would I
> just need to consider the PVC pipe and find how it
> would bend? How would I model
> the system?
>
> 3) Is there some sort of waterproof coating that
> could be used over the steel
> plate to further prevent leakages?
>
> 4) How will the higher weight of the steel (When
> compared to composites) play
> into the system dynamics?
>
> 5) Any questions or comments? I really am looking to
> get feedback on this design
> and also suggestions about alternate designs.
>
> Thanks for all your help!
>
>
> Matt Zedler
> MIT Class of 2007
> Mechanical Engineering
> (804) 814-7197
> [EMAIL PROTECTED]
>
>
___________________________________________________________________
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>
>
>
>
>
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