Diode wind concentrator...

[SebastianL]

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 circular it is, the less the effect, the more the air bypasses it without much separation).

Well that said, a good simulation is not refused!

What you describe is similar to what this video offers, something that only works with one wind direction

[Remundo]

if you put a shroud that captures a larger section upstream of the turbine, in theory (and only in theory) you may have captured more power.

In practice we are often disappointed because, I repeat, many parasitic effects of aerodynamic turbulence, already around the blades, but also when the air rushes into the fairing.

there is no magic power, and I repeat, tightening a pipe does not provide power to the fluid flowing through it. In general it even removes some, but it can put the fluid under conditions of more adequate speeds for the turbine.

[FALCON_12]

if you put a shroud that captures a larger section upstream of the turbine, in theory (and only in theory) you may have captured more power.

In practice we are often disappointed because, I repeat, many parasitic effects of aerodynamic turbulence, already around the blades, but also when the air rushes into the fairing.

there is no magic power, and I repeat, tightening a pipe does not provide power to the fluid flowing through it. In general it even removes some, but it can put the fluid under conditions of more adequate speeds for the turbine.

If you allow me I would like to point out the fact that it is not a question of shrinking or tightening a pipe but rather, if I am not mistaken, of leaving the pipe as it is while forcing more flow to borrow his section.

We start from a circular section for example, of surface S perpendicular to an air flow F. We place a wind turbine in this section we recover a power P.

Now we place in front of S an exponential pavilion or a cone of section S'>S which abuts at S.

We did not decrease or tighten S we only allowed it to collect more F through S'.

Let's imagine, to fix ideas, that S faces 1 m2. I put it down in a flow F of 100 km/h (storm), I collect a power P.
Now I give it a surface S' of 100 mx 100 m, so I have multiplied the section of flow intercepted by 10.

In these extreme conditions only imaginable but which can serve to reflect,
would you say that the wind turbine will not provide more power?

[Remundo]

intuitively we could say yes.

But in practice it is not obvious.

It's like a faucet that you turn off.

After a while the viscous forces create huge pressure drops.

For fluids like air, it is the turbulence and eddies that dissipate a lot of energy.

[Christophe]

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 ... )

Probably yes (I used him recently it's quite easy) even if I didn't understand anything in the 2 videos, for me he just did Venetian blinds or is the energy generation... the self-centered talk that not worth a good schematic...

Why do you mention diodes in the title? These are air valves...(do you want me to change the title?).

The performance of this thing must be bad and necessarily less good than an equivalent surface of a free blade since the blades create pressure drops and turbulence... And if I guess correctly the generator must have a vertical axis, so again a big pressure drop moreover (change of angle to 90°...)!

If you want to concentrate the wind: just take a huge funnel... and still not sure that it works well because the air is compressible and this will considerably increase the turbulence therefore the efficiency of the blades (and it is better to have compressed air than turbulent...)!

Believe me I know what I'm talking about: https://dragonfly-paramotor.fr/ (eh Remundo?)

Anyway, retirees and youtubers have to take care of it, huh!

Unsurprisingly, Solidworks will show you that this increases turbulence.

[FALCON_12]

if you put a shroud that captures a larger section upstream of the turbine, in theory (and only in theory) you may have captured more power.

In practice we are often disappointed because, I repeat, many parasitic effects of aerodynamic turbulence, already around the blades, but also when the air rushes into the fairing.

there is no magic power, and I repeat, tightening a pipe does not provide power to the fluid flowing through it. In general it even removes some, but it can put the fluid under conditions of more adequate speeds for the turbine.

Well I did a little manipulation, I took a fan that I placed 60 cm from a hot air gun (which blows cold, the heating resistor is dead).

Without a hub, I have an RMS no-load voltage of 55 mV.
With concentrator (roughly perforated oyster box, the joint is far from perfect and
in use the clogging is very sensitive) I get 330 mV, more than 5 times more.

It remains to measure the maximum extractable power by loading the fan with the optimal resistance for
each case but it doesn't seem possible to me that the power with the hub isn't greater than without.

[FALCON_12]

Probably yes (I used him recently it's quite easy) even if I didn't understand anything in the 2 videos, for me he just did Venetian blinds or is the energy generation... the self-centered talk that not worth a good schematic...

Two wings pierced with ducts are placed one in front of the other vertically. The depression created on the flanks
of the wings (the one that induces the lift of the airplane wings) sucks in the air which is driven to a turbine.

https://www.revolution-energetique.com/ ... batiments/

Why do you mention diodes in the title? These are air valves...(do you want me to change the title?).

The valves act as check valves like the PN diodes do in a bridge rectifier.
The idea is to collect all penetrating flows and to exclude all flows that tend to leave the tower.
On the principle we use the same idea: collect the flows that interest us and block the others
(positive currents in electronics, inflows in aerolic).

The performance of this thing must be bad and necessarily less good than an equivalent surface of a free blade since the blades create pressure drops and turbulence...

Yes, it's true. But it could make it possible to concentrate the flow thus to increase its speed and to take advantage of the fact
that P is proportional to V^3. With an equal surface opposite the wind, we hope to take advantage of the cubic exponent
and get at least as much power from a smaller wind turbine.

And if I guess correctly the generator must have a vertical axis, so another big pressure drop (change of angle at 90°...)!

I do not believe. The air rises in the tower is the wind turbine is placed facing the flow, it is a conventional horizontal axis wind turbine
placed in a different way.

If you want to concentrate the wind: just take a huge funnel... and still not sure that it works well because the air is compressible and this will considerably increase the turbulence therefore the efficiency of the blades (and it is better to have compressed air than turbulent...)!

A funnel that could pivot and oppose the wind could do the same thing. Here the advantage
sought and to have a fixed system capable of "straightening" (diode) the winds from all directions.

Believe me I know what I'm talking about: https://dragonfly-paramotor.fr/ (eh Remundo?)

Gorgeous ! ;)

[Christophe]

Well I did a little manipulation, I took a fan that I placed 60 cm from a hot air gun (which blows cold, the heating resistor is dead).

Without a hub, I have an RMS no-load voltage of 55 mV.
With concentrator (roughly perforated oyster box, the joint is far from perfect and
in use the clogging is very sensitive) I get 330 mV, more than 5 times more.

If you recover more energy it is because the concentrated flow of the gun flares up, so you will refocus it.

Repeat the same test at 30 cm and 10 cm… the results will tend towards the same value…

[Christophe]

The valves act as check valves like the PN diodes do in a bridge rectifier.
The idea is to collect all penetrating flows and to exclude all flows that tend to leave the tower.
On the principle we use the same idea: collect the flows that interest us and block the others
(positive currents in electronics, inflows in aerolic).

At a time T out of 1 minute, except for a heavy storm or tornado, the wind always blows in the same direction...

I still don't understand the physical logic…of this “thing”…it would be valid if the wind was going back and forth, that's not the case….

A funnel that could pivot and oppose the wind could do the same thing. Here the advantage
sought and to have a fixed system capable of "straightening" (diode) the winds from all directions.

]

No problem rotating a funnel (it will do it on its own but a fin can help)...the problem is to make it resist extreme winds...except to play on its pitch angle, you can't feather it...

ps: if you have a diagram that would be great...

[SebastianL]

Forcing the air to change direction at 90° imposes an infinite acceleration. With what energy do you accelerate this mass of air? With the kinetic energy of the flow which is transformed into pressure > patmo and therefore manages to pass the "valve" fins for a small proportion, the rest preferring to pass by.
You can wiggle as much as you want, the upward flow of your tower will not have more kinetic energy, than the flow arriving on one side of your tower.
The only advantage is the aesthetics and the reduced noise, these days and given the hatred that is developing around wind turbines, it remains a good concept provided you do not dream of a cubic exponent of power