Savonius Rotor for Rooftop Windmill

Suggest source and anemometer from http://www.weathershack.com/education/anemometer.html and do more trial and error at different heights etc..

Savonius (that is a VAWT type Turbine) have many other good features as well if building near to housing, such as reduced noise in comparison to propeller (HAWT type) due to lower tip speed and simpler (which can also imply stronger) construction.

I think a good place to start is here, as it has many good links and references to reading material included near the bottom of the article.

I would also recommend looking at YouTube and searching there using various words, seperately of course such as "VAWT", HAWT, "Windmill", "Wind Turbine" etc. You get the gist of what to look for. There are many good videos, some with constructional tips as well.....

Please keep us upto date and include any Phots you take, we are all very interested in such devices....

i am not getting answer to my question, which is how much power generation can be expected from wind mill size; there are two parameters which determine this- one the wind speed and the second is area of the wind mill exposed to wind. i searched many sites but could not find the information. the costly alternative is to go on building vawt's of various dimensions starting from 1 meter dia upwards till i hit the right size - definitely not an engineer's approach.

If you can exactly answer the following questions, you might be able to do something with the design data you are looking for (that I personally have never found on the web....!)

What wind speeds do you have on average?

How many days a year do you have wind (blowing, not the painful internal sort!)?

From what direction(s) does the wind blow? Give the average for each point of the compass...

How much power do you want to generate exactly?

....and many other questions that you are probably unable to accurately answer (I could not answer them either for where I live!)

I would personally build oversize as the general consensus of opinion is that the wind blows probably only around 30% of the time at a useful speed in most places, so you have to make hay while the sun shines wind blows!.....

I would start like in one of the videos, the 50 gallon drum cut in half.....and plan to add extra ones till I achieved my goal!!

Having too much electricity is less of a problem than having two much!!! You can always switch on a few lights to burn excess once the batteries are fully charged......even not too difficult to completely automate that with the battery charging.....assuming that you will use batteries for storage.......producing a fixed frequency of 50 or 60 Hz directly from a windmill is not that easy....such designs get really complicated, unless you use an inverter...

I hope this helps further......

Your question is answered in detail in post #1. Click left mouse button on hyper-link to peruse information...

Check out this website - www.reuk.co.uk. This should be useful and answer your question.

Good luck. Let me know if this was NOT helpful. I may have additional info to share. I just need to find it.

The data on wind suggests that for most locations (especially in residential areas) it is best to have the windmill 40 feet (approx. 12 meters) above the ground. The wind is more constant up there above most trees and roof lines. Winds often blow at night which is good for supplementing solar. good luck

Be careful on height. In my neighborhood, zoning restricts heights of structures to 30 feet.

I would say normal in most countries. Also, be careful with regard to noise generation, both for your neighbours and yourself, therefore a VAWT will usually be better.....does not need to be so high, generates from fairly low winds and produces less noise than HAWTs.....

Rotor swept area

A=D*L

D - rotor diameter;

L - Wing length

eh?

inventing new types of math should come with an explanation.

Chris

Chris

"inventing new types of math should come with an explanation."

I'm with you, but did the guest really invent a new type of math?

At a guess he's using a formula, whether correct or not, for a turbine, since he details rotor blade length as part of his swept area function, where yours is fairly obviously able to handle any general form, since you deal with swept area (no blades, per se, in a Savonius, for example, but the upright wind-impinging surface could be called a blade, for lack of a better term) and rotor diameter. It looks to me like the same thing, but specialized to a particular design, rather than the more generalized form you use.

But maybe I'm wrong, and the guest who spoke will come back and enlighten.

Micah

Yes, I think Guest is right...almost.

The formila for area listed is for a HAWT, I think for a savonius rotor it would be

1/2 x Diameter x Height

The area that is capturing the wind would be directly proportional to the power produced.

Any other modification to the design that that improves the ability to maximize this process would be reflected in an increase in the Cp for your particular design.

An example might be some sort of baffle or diverter on the returning half of the savonius rotor that minimizes the drag produced by the wind hitting the back side of the rotor.