A serious open source VAWT in the making. How to scale an airfoil profile

fsec · December 2021

I am currently designing and prototyping a DIY VAWT that actually will produce useful output at 60 to 120 rpm. At least that is the goal.

Any higher rpm and blades can become projectile weapons in a game of lawn darts.

I am already well underway with the alternator and am now thinking about the turbine blades.

I have traced an 'optimized' airfoil profile from here;

Aerofoil optimization for improving the power performance of a vertical axis wind turbine using multiple streamtube model and genetic algorithm | Royal Society Open Science

Then I scaled it to have a width of +- 50cm so that it will have some body when I scale the whole turbine up to 2m diam. and 3m height. Now here comes my uncertainty. I can't find, or I have and simply did not see it, any resource that describes the relationship between VAWT turbine dimensions and the dimensions of the blades.

Please see a model of what I have planned. (turbine is 2m width x 3m height)

Image: https://us.v-cdn.net/6024911/uploads/editor/cx/vw07dbokz1au.png

Can anyone please advice on how to proceed with airfoil profile scaling when going for this size helix VAWT?

mike95490 · December 2021

How do you plan to support the upper bearing ? Solve that before the airfoil, which i know nothing about.

BB. · December 2021

We do not have many folks here talking about DIY wind turbines... Here are some other sources that can probably help more:

www.otherpower.com (good forum for DIY Wind Power)
Hugh Piggott - Scoraig Wind Electric site for tons of info (from mike90045)
Scoraig Wind "Recipe Book" for DYI Turbines (from Chris Olson... From his 4/11/2013 post)
www.greenpowertalk.org (added from "russ"--Like here but more wind/less solar)

Personally, I am not a fan of small wind. But horizontal axis wind turbines (HAWT) are much better than VAWT at harvesting wind and can be more mechanically more reliable.

Turbines need to be installed on towers, generally 30 feet or taller to get into "clean air" (60-120 ft tower is better) . Turbines need non-turbulent airflow (above up wind obstructions, buildings, trees). Turbulent air has very little useful energy--VAWT are sold as better for turbulent airflow--But they are not.

Not that I am in the "wind" business--But I have yet to see any VAWT that harvested more that a small amount of energy--And most seem to not harvest any energy at all.

Here is a turbine that seems to match your design--And a fairly large diameter VAWT rated at 2.5 kWatt (circa 2008):

https://www.renugen.co.uk/turby-b-v-2-5kw-wind-turbine-discontinued/

Image: https://cdn10.bigcommerce.com/s-7wpeis/products/2102/images/1077/turby_large__59585.1407221752.500.750.png?c=2

And tested on a 10 meter / 33 foot tower in a "windy region" of Holland (flat land, no buildings/trees/etc.) produced (link to post in thread from 2009 testing of multiple small wind turbines "designed" for urban use):

https://forum.solar-electric.com/discussion/comment/62874#Comment_62874

- Turby (21,350 euro) : 247 kWh per year or an average output of 28.1 watts [24 hours per day @ 365 days a year average]
Power: 2 kW with the supplier an estimated yield of 1485 kWh / year

Prediction Accuracy: 17% of predicted output

Here is the only VAWT that I ever saw that was submitted to NREL testing... Major structural issues (tall straight blade design) with loose/lost bolts, broken welds:

https://www.nrel.gov/docs/fy09osti/45552.pdf

If you want to experiment with small wind and VAWT--Have fun.

If you want to generate/harvest a useful amount of energy, I highly suggest starting with solar, or at the very least, use HAWT on a 30-60+ foot tower in a very windy location (see DIY links at beginning of this post).

-Bill

clockmanfran · December 2021

Hi,

VAWT is a dead end, but looks good.

On the Fieldlines.com: The Otherpower discussion board Vawt are being allowed to be discussed.

Some experimentation has taken place and the results are all there.

Like all wind turbines its matching blade efficiently against wind speed against generator load. All Have to be absolutely spot on.

Mechanically VAWT is a constantly stressed structure, and in the end they normally just disintegrate.

I have 3off 3.7m (12 footers) diameter HAWT flying and producing since 2007, and they are a Hugh Piggott design, and his stuff is one of the best designs in the World after his 45 years of work. But they still need servicing and keeping and eye on, and this year they all had there 5 year rebuilds.

But today 2021, they are just not economicall viable against PV. And advice those that ask that me, "Just Install PV."

fsec · December 2021

thanks all, I'll see of any of the links one has suggested will lead anywhere.

A serious open source VAWT in the making. How to scale an airfoil profile

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