Diode wind concentrator...

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FALCON_12
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Diode wind concentrator...




by FALCON_12 » 30/12/22, 13:22

Hello,

I recently discovered this concept of "wind concentrator" thought by an ascendant of Charles Darwin: Erasmus Darwin. It is a tower pierced with holes allowing the wind to enter but not to leave (non-return valves). Inside a wind turbine that the concentrated wind turns. I understand that the power produced by a wind turbine increases with the cube of the wind speed and the idea is therefore perhaps interesting! That said my specialty is not fluid mechanics and I would like to have the opinion of knowledgeable people on this wind concentrator which looks like a Graetz bridge (diode rectifier : Wink: )!

A video shows a miniature realization here:


And a bigger one here:


Maybe someone has already tried such a full-scale system or wants to do it, I will be very curious to know if it can really work! : Wink:

Happy holidays to all! : Lol:
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Re: Diode wind concentrator...




by FALCON_12 » 30/12/22, 14:39

Subsidiary question: does anyone know a software capable of simulating (easily ...) such a system? (I have solidwork and I wonder if the Flow simulation can do this with a few hours of acquisition of the operation ... :( )
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Re: Diode wind concentrator...




by izentrop » 31/12/22, 13:00

The bullshit is not enough, you need a demonstration with real measurements.
Sorry but it's just windy.
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Re: Diode wind concentrator...




by FALCON_12 » 14/01/23, 21:14

izentrop wrote:The bullshit is not enough, you need a demonstration with real measurements.
Sorry but it's just windy.



The "it's windy" izentrop! it is indeed windy! ;)

Joking aside from what I understand this gentleman is going to give it a try, I'll report the results here if that happens.
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Re: Diode wind concentrator...




by Remundo » 14/01/23, 21:36

FALCON_12 wrote: the power produced by a wind turbine increases with the cube of the wind speed and the idea is therefore perhaps interesting! That said my specialty is not fluid mechanics and I would like to have the opinion of knowledgeable people on this wind concentrator which looks like a Graetz bridge (diode rectifier : Wink: )!

It's true, the incident kinetic power of the wind is 1/2 ro S v^3

where S is the section where the wind flows at speed v.
ro is the density.

That said, channeling the wind into a fairing decreasing its section does not increase the power. In stationary flow, the product ro x S xv is constant, as well as the Bernoulli quantity P / ro + v²/2

In reality channeling the wind is often a bad idea. This generates a lot of aerodynamic turbulence and the losses are great. This also increases the mass of a wind turbine and the mechanical stresses on the bearing mast.

The stories of valves that open and close; it's not good aerodynamically.
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Re: Diode wind concentrator...




by FALCON_12 » 14/01/23, 21:55

remundo wrote:
It's true, the incident kinetic power of the wind is 1/2 ro S v^3

where S is the section where the wind flows at speed v.
ro is the density.

That said, channeling the wind into a fairing decreasing its section does not increase the power.


If channeling the wind increases V and P is proportional to V^3 why does P not increase?
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Re: Diode wind concentrator...




by Remundo » 14/01/23, 22:14

v is not the only criterion, the section varies to increase v, as well as the pressure and the density.

You have 3 conservation equations

1) Bernoulli's equation of the perfect fluid reflects the fact that the energy of a fluid particle is conserved.
P + ro v²/2 = cte1.

2) mass flow conservation
ro x S xv = side2

3) conservation of power on the flow axis between 2 sections 1 and 2
1/2 ro1 S1 v1^3 = 1/2 ro2 S2 v2^3 = cte3

and again that is on the assumption of a perfect fluid.


In practice, turbulence and viscosity will degrade part of the kinetic power into heat.

The more you try to "manipulate" the flow, the lower the extractable power.

All tests of shrouded wind turbines have been inconclusive.

If you know a bit about hydraulic turbines, shrinking the section of a pipe does not increase the extractable hydraulic power. And shrinking the pipe induces pressure losses due to viscosity.
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Re: Diode wind concentrator...




by SebastianL » 14/01/23, 22:51

FALCON_12 wrote:
remundo wrote:
It's true, the incident kinetic power of the wind is 1/2 ro S v^3

where S is the section where the wind flows at speed v.
ro is the density.

That said, channeling the wind into a fairing decreasing its section does not increase the power.


If channeling the wind increases V and P is proportional to V^3 why does P not increase?


No, to accelerate the wind which has a mass you need an additional pressure, pressure which will be higher than that which surrounds the valve tower, the wind will just bypass it cf limit of beltz
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Re: Diode wind concentrator...




by FALCON_12 » 14/01/23, 23:19

SebastianL wrote:
FALCON_12 wrote:
remundo wrote:
It's true, the incident kinetic power of the wind is 1/2 ro S v^3

where S is the section where the wind flows at speed v.
ro is the density.

That said, channeling the wind into a fairing decreasing its section does not increase the power.


If channeling the wind increases V and P is proportional to V^3 why does P not increase?


No, to accelerate the wind which has a mass you need an additional pressure, pressure which will be higher than that which surrounds the valve tower, the wind will just bypass it cf limit of beltz



Hmmm .... let's imagine that this tower has a square section and that the wind meets it perpendicular to one of its side faces. Let's also imagine that it is 5 times higher than it is wide. Behind the impacted face, on the symmetrical face, a depression is created due to the separation of the air layer (the square section prohibits laminar flow). You can follow this column of depression to the top of the tower and arrive at the exit of the tower, at the very top. There the air leaves and can join the column of depression while returning downwards. It is therefore perhaps established a flow which enters by the valves, goes up inside the tower and joins the column of depression to return to the equality of pressures and speeds in the distance.

In this diagram the tower has created a detachment, therefore a depression which is compensated by the air which it absorbs and rejects at its top. There would therefore be a flow whose speed increases with the ratio Sout/Sin (Sin: elevation surface of the tower, Sout: lateral surface of a profile of the tower). In this hypothesis it is perhaps counter-productive to increase the facets of its section polygon because the more it is circular, the less the effect is, the more the air bypasses it without much separation.

Well that said, a good simulation is not refused!
Last edited by FALCON_12 the 14 / 01 / 23, 23: 35, 1 edited once.
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Re: Diode wind concentrator...




by FALCON_12 » 14/01/23, 23:33

Remundo wrote:v is not the only criterion, the section varies to increase v, as well as the pressure and the density.

All tests of shrouded wind turbines have been inconclusive.



- Do you mean, with these equations, that it was formally demonstrated that the concentration of flux could not lead to an increase in the extracted power and that in accordance with this all those who tried it lost? (and therefore no wind concentration test has ever been conclusive).

- Or do you allow certain side effects the possibility of invalidating this and do you admit that there are situations where a gain in power, even small, has been observed? https://wind-energy.ucoz.com/
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