Homebrewed Electricity > Wind

My First Vawt Project

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tjm2000:
My journey with darrieus vawts started with a small model 1ftx1ft that was made out of some thin strips of wood and some plastic sheet curved into a crude symmetrical airfoil. It ran really well. it would start in very little wind and wouldn't stall at higher winds. Eventually a storm came through and ripped off one of the blades. It still ran pretty well though.

I then started planning my next project, A vawt with 2m tall blades and a 3m diameter.
About 12 months ago, I started buying parts as I could afford them.

For my first project, I thought building a generator was a bit ambitious, so I based my project around a 1kw 150rpm generator I brought on Alibaba. Communication and shipping was really good, and the generator appears to be well made. I did some testing on a friends lathe and found the output to be very very close to what was advertised.

Due to minimal experience and tools, I wanted this build to be as simple as possible.
I decided to use 50x25x5mm rhs aluminium as the arms and the spars of the blades, I chose this as it is light, strong, cheap and readily available.
I used 10mm mild steel to make the plates for the hub. I had a friend of mine build and extension for the top of the generator to the 'upper' hub. It is all held together with m10 stainless hardware.
Attached is a pic of the completed (unpainted) hub assembly.

tjm2000:
The blades are cut out of sheets of polystyrene used for building insulation. I cut these in an airfoil shape by using a homemade hot wire cutter. I made 2 templates out of plywood and screwed then on each end of the polystyrene block. This worked very well and it didn't take long to get 3 good foam blades. There is a 50x25mm cutout where the Aluminium spar will be glued in.
Next I put 1 layer of fiberglass cloth (200gsm) in the cutout. This was to fill in the excess space as it was cut slightly oversize. I then drilled and glued the mounting bolts to the aluminium spar. I then glued the spar into the cutout with thickened epoxy.
Now it was time to fiberglass the blades. I used 2 layers of 200 gsm cloth, which is probably overkill but it will make a strong blade. This was my first time doing fiberglass so it was a big learning curve. It is not perfect but I am mostly happy with how they turned out. total weight of each blade is 4.5 kg. This was lighter than I was expecting and they are very strong.

tjm2000:
I did a test fit of the blades today to see if it would all go together as intended. It went pretty well. The blades are held on by bolts through aluminium 'L' brackets. I have not yet decided if they will be strong enough. So far i am very happy with how it is progressing. I hope to have a temporary stand finished by the end of the week.

MagnetJuice:
Welcome to the Forum tj,

That VAWT looks really nice. That should be able to produce about 1Kw with 9 m/s wind.

Can you share how you decided on those dimensions? The blade chord looks like it is .33 meters. If that is the case, that is good solidity.

Ed

tjm2000:
There is nothing scientific about my dimensions, The blade chord is 0.35m because that was the width of the foam sheets I had and it looked about right.. I expect a tsr of 2.5-3, so I made the diameter 3m to achieve around 150 rpm in 10ms wind.
I will eventually be used to power an office/sleepout that will not be grid connected. The wind on site is a steady 8-10ms during the day, and dropping down to nothing during the night. Im hoping I wont need much in the way of storage.

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