When we think of wind turbines, the first thing that usually comes to mind is the typical Sim City-esque type – 3 blades, gigantic, and wired into the municipal power grid. In truth, the world of wind power generation is far more varied indeed – as [Vittorio]’s vertical-axis wind turbine shows us.
So what exactly is a vertical-axis wind turbine, you ask? Well, rather than the typical setup with blades rotating about a horizontal axis, as in typical utility turbines or a classic electric fan you might use to cool off on a sunny day, instead a vertical axis is used. This necessitates a very different blade design due to the orientation of the rotational axis relative to the flow, so such turbines can be quite visually striking to those unfamiliar with such designs.
[Vittorio]’s design is a great way to get to grips with the type. The blades and supports were initially created out of PVC gutter channel, though 3D printed versions have also been developed. The motion is turned into electricity by using a simple brushed DC motor as a dynamo.
While the scale is small and the output only in the tens of watts, it goes to show that there’s always more than one way to do things. We’ve seen some vertical-axis wind projects before, too. Video after the break.
” In truth, the world of wind power generation is far more varied indeed – as [Vittorio]’s vertical-axis wind turbine shows us.”
Same could be said with hydro.
Might be hard to find its source at 3m high balcony. Unless water meter is broken and neighbors are easygoing.
A water meter IS a small turbine isn’t it? Powering a meter.
My understanding is that the bladed fans are shaped more like wings than propellers, and take advantage of lift, so it’s not just the wind speed pushing on the blade but rather force generated by the difference in speed across the two sides of the blade itself.
They are commonly either drag (Savonius) or lift (Darrieus) type.
Propeller blades ARE wings. The cross section of a propeller blade is an airfoil., so …
Good grief. Vertical axis wind turbines have been around, and studied, for ages. I saw my first one forty years ago. If they are not being used on a large scale then there must be some valid engineering reason.
They have been around a while. These simply block one side instead of using a curved profile, but that’s from 1000 B.C.:
https://govschoolagriculture.com/2015/07/24/whats-up-with-wind-turbines/
The principal reason is that the blades go from being “pushed on” to being “pulled on” in every revolution, and this shifting of forces makes them shake themselves apart (or require unreasonable amounts of material) at large scales. Compared to the blades on a horizontal-axis machine which, in a rotating frame of reference, experience nearly constant forces the whole way around their circle.
Incidentally, this is why the towers are taller than the blades are long — the wind speed is so much lower near the ground, dipping into that layer of relatively slow air would substantially change the forces exerted on the blade. It’s economically sensible to build the tower taller and the blades shorter, so the blades can operate in smoother air.
Just because something is better doesnt mean it is the one used. The style, or technology accepted is based on more then just what works best, or is most efficient its based on various things such as: costs, availabiltiy, and (sorry to say) better lobbying. Additionally, you have to consider purpose and scale. These types windmills are good for smaller generation; they dont scale as well as the gigantic blades. Since government only thinks on large scale, they go with the design that is easier to scale up. Thats what everyone sees, so they try to follow suit.
The efficiency of scale is in the amount of energy needed to make one unit vs. the energy it produces. Tiny turbines are really bad in this regard, whether they’re the savonius type or three bladed ones.
The payback time is too long for them to make economical sense, and given the indirect costs of the economy needed to make them happen, these small turbines end up a net negative – they’re losing energy (resources) rather than making any.
The blade design is crap! I also remember this cut-up oil barrel design at “green” festivals in the 70′. The purpose of using such a simple design is that turbines like that can be manufactured with local materials from just a drawing, so suitable in 3’rd world countries. With modern fluid dynamics simulation it has been found that the twisted Darrious design is the most efficient and also uses the least materials. A US Russian, “Garlov” also patented such a design: https://www.thingiverse.com/thing:1524384
The airfoil is symmetrical and the turbine is self starting. Also it has a high shaft speed to wind speed ratio, which is not the case with the cutup barrel design, which usually requires gearing to run a generator
Kind of look like the blades on a reel mower.
Darrieus is not self-starting. For that reason, often a small co-axial Savonius is used to get it started. Or synchronous motor, which becomes generator as the Darrieus reached its operating speed.
I have one of these that has been a project to finish for a long time. The blades are made out of a 55 gallon drum that has been cut in half and welded together to make an “S” shape. That sits on an old car axle bearing and some pieces of pipe as spacers. There is a homemade wooden pulley on the spinning part and the fixed part will be lagged into the top of a post. For this one I am planning on having an arm come off the side and use an old treadmill permanent magnet DC motor as a generator. This one is going to drive a small submersible pump in my pont, that will go into a stand tank, an old steel pressure tank that someone donated to me, that will sit about 8′ above the ground and gravity feed a hose for watering my greenhouse. I use about 8 to 10 gallons every other day.
BTW, is there anybody out there that has any interest in helping to design some 3D printed parts for a piston water pump? My idea is to use PCV pipe for the body of it, so it can be scaled to have a lot of amounts of volume (length and diameter) and displacement (length), with an emphasis on being inexpensive to build.
“BTW, is there anybody out there that has any interest in helping to design some 3D printed parts for a piston water pump?” Yep, contact me at https://hackaday.io/yetihehe . I design primarily in openscad, so you will have parametric design for any pipe. Just give me some constraints.
Wind turbines are not as cost efficient as solar
…at domestic scale. At utility scale wind is definitely cheaper than PV with todays prices (subject to change depending on technology and global economics).
That entirely depends on how you define efficient. I am time rich but cash poor, so for me solar cells are not possible. A 55 gallon drum and an old car axle bearing, and an old treadmill motor are easily within reach. And I think my requirements are modest enough, and I will have enough storage in the stad tank, and the tower made out of old pallet 2×4’s that this is a viable solution. Every aspect of it can be had for free or very near free.
Would I get more watts per cubic inch of property consumed with solar? I guess it depends on the solar. The solar I could afford would not win this contest.
When you are talking about free energy the idea of efficiency gets abstracted quite a bit. To some anything they get us considered a gain. I built a spiral pump years ago, and someone told me it was not efficient, but *I* had running water under enough pressure to go up a hill to hydrate my shiitake mushrooms in place while they still had to pick their logs up and put them in an old cattle watering trough to soak them. They also had to fill the tank with gallon jugs and change the water when it got yucky. My set up was a lot more efficient to me than theirs was.
The big drawback of this setup is the fact that it us impossible to turn the thing off when the wind speed gets too high. Propeller type generators set the propeller in the fane position or turn the propellor off the wind direction. This serup cannot do that
These types of turbines don’t really need to be “turned off” as they naturally saturate above certain wind speeds. If you construct them to withstand the forces, they can’t spin any faster.
With (possibly) vibrating systems I’d recommend using one-hand-clamps which don’t get loose that easy. At least that’s what I’ve been told when using a plunge router.