Wind turbine Archimedes

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chatelot16
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by chatelot16 » 29/05/14, 15:35

aerodynamics still begins to be known: to make a high-performance aircraft or a wind turbine the clear solution is to make large elongations: narrow and long wing

this has been seen since the time of the windmill: we gain more by increasing the length of the blades than their surface

this turbine does the opposite: large surface without elongation: it seems impossible to me to obtain a good performance in this way

and it is so easy to show something completely wrong on the internet that I only believe what I see ... I also sometimes believe what I have not seen but that I can understand and hang on to what is on
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by jam » 29/05/14, 17:36

It sounds so interesting that I am thinking of trying a simulation.
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by chatelot16 » 29/05/14, 17:58

simulation with what? I saw using solidworks which has an aerodynamic simulation module: it gave absurd results, and the user pasted these results in his report

when I put my nose in it saying that my pifometre was not in agreement we modified the parameters of the simulation and that ended up giving realistic results

but it was a simple case to find the effort of an object which advances in motionless air ... translated in soliworks by a speed of air which arrives on the studied object

for a propeller it is more complicated: each blade passes through the air already disturbed by the previous blade ... if we neglect this fact and consider that the blade receives air at constant speed and undisturbed we find the result absurd that the more we increase the number of blades the more we increase the power: which is contrary to experience

my conclusion on the aerodynamic simulation of solidworks: it is longer and less reliable than making a small prototype
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by jam » 29/05/14, 18:24

OpenFoam,

Look what I’ve done before.
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by Remundo » 29/05/14, 19:11

it seems that the wind rushes into Archimedes' screw and escapes radially, having lost speed ...

it makes you think of a Francis turbine ... but it must "leak" a lot, a lot of kinetic energy is not absorbed. it must also generate a lot of turbulence when exiting the screw.

how does it work On the impact of the wind on the screw? Any internal lift? It's curious.

I would lean intuitively for the analyzes of Chatelot. I don't feel this high performance thing going upwind. "nose to the wind" if I may say so. :P But I remain open to Jam's enthusiasm as well as to his possible studies.
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by jam » 31/05/14, 00:35

More and more interesting.

They measured up to 53% efficiency in the wind tunnel despite the dimensions of the supports. They also explain how to make the canopy here

http://dearchimedes.com/pdf/Paper_2014_ ... eremet.pdf
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by Remundo » 31/05/14, 10:45

Thank you Jam for this paper ...

Well, I am still very hungry!

The authors speak well of resistance / lift (impact force / lift force) in general, but do not detail how these forces are distributed on their Archimedes rotor.

By the way, most of the document is here:
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It is well specified that the yield comes from a computer simulation.

I am also wary of the absence of simulation with slightly more realistic speeds: 10 m / s is 36 km / h, but it is very soft on the wind power plan ... because the power is eightfold in doubling the speed.

But I suppose that at higher speed, their simulation becomes erratic because of the turbulence / non-linearity of the Navier Stokes equation.

I agree with what Chatelot says, nothing beats making a prototype and really looking at the recoverable power compared to a given wind speed.

Since they would have done tests in the wind tunnel, there is clearly experimental data not communicated, and I fear that this screw is inefficient when the wind blows strong ... On the other hand in laminar (or almost laminar) flow, their simulation indicates a good return ...
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by jam » 31/05/14, 12:12

he he he he

You have to read it right.

under ... point ... the full sentence is: "... by way of computer simulations, windtunnel tests and field tests at 52% ..."


Secondly, this turbine is specially made for light and medium winds in situations generally not used by large projects: in the city for example.
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by Remundo » 31/05/14, 12:35

alright Alright 8)

Finally it is a bit vague ... however, if there is a high efficiency at low wind, it can be interesting on homes, urban areas, electric poles ...
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by chatelot16 » 31/05/14, 12:53

for weak wind it takes a very large dimension to capture enough energy

the classic propeller picks up on the entire swept surface, with a fairly small amount of material in the blades: therefore a favorable power-to-price ratio

it is a bizarre turbine for the same total diameter that the propeller will cost a fortune

even more serious drawback its surface is impossible to reduce: so it must be of enormous strength to withstand high winds

the classic propeller reduces its catch in the wind when its pitch changes: therefore can withstand high winds without exaggerated effort

wind turbine in town? you have to put the wind turbine or there is wind: so quite high mat ... and the more the ground has big roughness, the more you have to go up to have a good wind: with the huge construction of a city it would take pylon much higher than in the countryside

the stories of wind turbines at the height of the lampposts are simply eccentric ... on the same level as putting photovoltaics in the cellar!
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