http://mystic.math.neu.edu/gorban/Gorlov2001.pdf http://www.mos.org/cst/article/2806/1.html http://www.recipeland.com/encyclopaedia/index.php/Wind_generator
- Hannu
" Conclusions 1 Despite only a narrow class ~1-parameter family! of the flows has been considered for optimization, the result obtained allows us to conjecture that the efficiency is maximal when the resistance is rather small and a large part of the flow ~61 percent! goes through. In other words, the maximum efficiency could not be noticeably greater than what was obtained here. 2 The model of a free-flow turbine reveals a new class of problems about streamlining with partial penetrating through an obstacle; some of these problems could admit explicit solutions and could have other applications. 3 The velocity of a flow vanishes at the origin of the proposed plane model. This makes the model specifically applicable for two-dimensional propeller-type turbines in free ~nonducted! currents. The theoretical limit of the efficiency given by the model is 30.1 percent. A number of tests, as well as constructed power farms, support this thesis in regard to both hydraulic and wind applications. The efficiency of most water and wind propellers in free flows usually ranges from 10 to 20 percent. On the other hand, the three-dimensional hydraulic helical turbine develops an efficiency of about 35 percent in similar free flow conditions @2#. This high efficiency might be explained by modeling a 3-D rotor as a combination of two plane turbines that reflect power contributions from the front and back parts of the original cross-flow turbine."
What I find significant is the "35%" efficiency claims for the Gorlov design.
Also here is a commercial wind power helical reference: http://www.turby.nl/downloads/Turby%20ENG.pdf
I have been trying to come up with common materials that could be adapted to make an efficient home sized helical Gorlov wind turbine however with little sucess. Comments are welcome!
I think that it is possible to use wood for the blades and also metal tubes with wood air foil pieces. Please see:
http://www.fieldlines.com/story/2004/11/29/10155/497
Also it could be possible to start with a drum and to cut it open a suitable way and to build up 'the blades' with some material for airfoils?
- Hannu[ Parent ]
here are some ideas how to make a 'gorlov type' turbine.
The first pictures illustrate the idea that the blades are made using metal or plastic tubes. Airfoil shapes are formed by covering the tubes with cloth.
If tubes cannot be bent, the airfoil sections will be longer on the ends of the turbine wheel. But if the tubes can be bent easily it might be better to bend them to follow the same outer circle all the way from one end to one end.
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The second construction starts with a drum. The drum is cut open so that only three rather narrow 'strips' are left from the surface. These strips will work as the blades of turbine.
There are in the picture two ideas, how to make airfoil shapes of the strips.
With the first construction the other ends of the strips are bent piecemeal. The result is a J-shaped airfoil, quite similar as with 'Lenz' turbine. (www.windstuffnow.com)
With the second construction in this picture a metal or plastic tube is fitted on the leading edge of the blade strip. Then the outer side of the blade is covered with cloth.
I think that the air pressures will form the airfoils perfectly...
I think that you could start with a similar solidity as used with Darrieus machines. There is available one really good web page:
http://windturbine-analysis.com/index.htm
In his prototype the guy is using a rather high solidity Nc/D = 0,42
the airfoil profiles you have drawn look "right". This is where the real science is required, to produce the optimum ratio between vain thickness and vain width. You are considering using cloth as a surface, to allow the airfoil to form itself?
Yes, if you'll use a tube on the leading edge, I think that cloth could be a good choice.
I think that the airfoil would form itself quite well.
One of my friends In Finland has made HAWT rotor blades using a tube in the thickest part of the airfoil, polyurethane on the leading edge, a steel wire on the trailing edge and covered the blades with cloth. They are working really well.
consider this, if the sections of the surface removed to form the rotors (waste)were reapplyed along with the tubing over the remaining sections it would create a profile similar to that which you have drawn.
I think that would be a good idea.
Do you think to use a tube on the leading edge?
One more drawing with also some new suggestions. You might try using polyurethane on the leading edge and cloth to cover the vanes?
Which kind of tube have you tried to use? Metal or plastic?
How thick are the walls of your bucket? Is the bucket made of metal? Have you got any pictures of your prototype?
your material sounds very nice.
I think that also metal buckets might work.
I'm looking for similar buckets to make some experiments, too.
I made yesterday still more drawings.
This draft above is quite similar as I made earlier, suggesting developments of 'WindstuffEd's 'Lenz' turbine. But if you will make your machine with skewed vanes like in 'Gorlov' turbine, you can using waste materials from the bucket, make 'the crossflow turbine' inside skewed, too.
Then still another possibility would be to use waste material from the bucket to fill the vanes outside with strips. I'm not sure, if it is necessary to fill the leading edge rough shapes with some kind plastic. The vanes might work well without filling, too.
That sounds good. I've been myself as well looking for such a design, which could be built in a factory besides being a good design for handicrafts people.
One of my good friends here, Erkki Nousiainen has built maybe the biggest Savonius of the world using old paint buckets. But he opened them and used the metal plates by bending them into new shapes.
Please see an old picture of his Savonius below. It is about 15 m tall...
I'm becoming quite exited with this project. I started to think about 'a gorlov design' already more than half year ago, but I've been now outside my country for a while and did not have time and possibilities for that project.
I think that some kind of Gorlov turbine might be the best design for urban areas. I will start making a prototype myself also soon.
I made still a couple of more design drawings.
I think that using the waste material from the bucket as the last picture even without 'the savonius vanes' inside will probably work.
We just need right dimensions and airfoil shapes.
I tried to see your video, but unfortunately that video format doesn't work in my machine (I'm using debian gnu/linux). Maybe you could convert it into another format?
