My first two VAWT's

[ralphius]

I've recently got into experimenting with wind power, and this is my first post on the forum. Here's my first two cheap and cheerful attempts.

Dead simple and cheap drag type VAWT made out of a couple of pieces of scrap guttering (youtube video)
youtube.com/watch?v=j1b7n6nCgIQ
Rotor height is 680mm, diameter is 192mm, 0.13m², overlap\gap in the centre is 34mm to allow air from one side to pass to the other


I also 3D printed a helical darrius design that had good reviews on thingiverse (youtube video)
youtube.com/watch?v=JAakWow5a4k
(NACA0024 aerofoil, 375mm high, 330mm dia, 0.12m²)
Unfortunately the performance is much worse than my couple of pieces of guttering despite having only slightly less swept area. Not sure how to improve it at present, it seems to start moving ok but just not get up to a decent speed?

[MagnetJuice]

Welcome Ralph,

It is always good to see people experimenting with wind power. Hands on experience is the best way to learn.

"I also 3D printed a helical darrius design that had good reviews on thingiverse"

If you keep improving the design, soon you will get good reviews from someone that knows about Volts and Amps.

Thanks for posting.

Ed

[ralphius]

Thanks for the positive response :-)

Tried to improve my PVC gutter turbine by cutting the rotor in half and turning the top half 90 degrees out of phase to the bottom half to reduce torque pulsations and therefore vibration. New video here:
https://www.youtube.com/watch?v=_3HUFiiWd34

I think its still vibrating a bit at high RPM but difficult to tell as wind speeds have been a lot lower today.

---

With the 3D printed darrius design I've taken it apart to try sanding some of the blades smoother, hopefully that will help. I'm tempted to print some more blades to either increase the height of the rotor, or put another 3 blades offset 30 degrees to the current set to double the solidity ratio within the same swept area.

[SparWeb]

Thanks for sharing the video links, Ralphius,
I've enabled the link in the latest one for you.
Anyone who wants to see this and the others can click on the link, follow your YT channel.

Welcome to Fieldlines!

[ralphius]

Had more wind yesterday, unfortunately too much wind and my turbine flew apart and disintegrated. Weather forecast was for gusts up to 40mph although I don't have a weather station so no way of knowing what it actually was in my back garden.


The blades had come out previously so its had silicone sealant in the past. This had just pulled off the surface of the material and obviously wasn't strong enough. I next tried dabs of superglue and this was what failed yesterday. It actually pulled some of the wood apart vertically and pulled chunks out of the PVC. I have obviously vastly underestimated the forces involved when this thing gets up to a few hundred RPM.

While it was apart, I checked the ball bearings top and bottom. They don't look so healthy anymore and they're making a grinding noise. I guess these were under-specified too!

[SparWeb]

Yea nature does that to stuff.
All the time.
For everyone.

Some of us stick with it, despite the futility!

See if you can get a cover around the bearing when you replace it.

[ralphius]

Since this is a drag type wind turbine, its tip speed is going to be less than 1. If I assume it might reach 0.9, then at 40mph wind speed, I calculate this thing is going to be trying to reach 1,500 rpm due to its small diameter! That'll work nicely for the direct drive generator I've got planned but the centrifugal force and balancing is going to give me issues.

So I spent yesterday designing, iterating and 3D printing a furling mechanism :-)

I had a look online, but similar ones either didn't furl, or they tried to move the blades further in or out where they have to fight against wind pressure to furl and that seems like a bad idea.

I've come up with the following system where the wind turbine furls by opening out around the central shaft, spilling wind safely through the centre of the turbine. Hopefully the following pics help (ignore the routed groove, its not used anymore)


The base and top discs are mirror images of each other, and the moving inner edge of the gutter has an independent spring (currently borrowed my wifes hair ties, don't laugh!) that are independently tensioned on the outer edge of the blade so that I can balance the spring force so they both open together.

I mounted the turbine to a variable speed drill to test and it starts opening around 1000rpm.

Video of the furling system on youtube here:
https://youtu.be/o0Oly06qnv4

Not the clearest thing to see while its spinning but you can see sky through the centre of the turbine at the start of the video as its slightly furled from a wind gust. As it spins down, the gap closes and the turbine turns back into a more efficient shape again.

I can put the CAD files up somewhere if anyone else is interested. I know its a lot smaller than some of the projects I've seen on this forum!

[DamonHD]

At worst put what you can up in thingiverse or similar, I suggest.

If you really can't find a better spot, at worst I can host your designs on my own site!

Rgds

Damon

[Mary B]

Be interesting to see it under load... may change furling point...

direct link to the video https://www.youtube.com/watch?v=o0Oly06qnv4

[DamonHD]

Thanks Mary: I fixed this link in his post too.

Rgds

Damon

[electrondady1]

cool

[ralphius]

As suggested have put the CAD for the 3D printed parts I've done so far  up on thingiverse. I've got the same username on there DHD: link fixed up https://thingiverse.com/thing:5194030

[Crockel]

That's an interesting design. Is the unfurling under centrifugal load to slow it down under high winds? 

I was thinking that maybe centrifugal loads could be used open up a savonius drag type turbine into a darrieus turbine to make it self starting.

[ralphius]

@Crockel Yes, it essentially makes the design less efficient at very high rpm to reduce the risk of damage in high winds.

I have a lot less free time now so progress has slowed. The turbine is still mounted to the pole and spinning happily but it vibrates when it starts furling. I suspect one blade is furling more than the other so I'm designing a linkage so that they can only move together by the same amount. I'm also playing with a small bipolar stepper motor that I'm considering using as a generator on my toy turbine.