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normandajc
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by normandajc » 28/07/15, 07:45

Hello,

large wind turbines must be braked or stopped when the wind becomes too strong. Not because they are producing too much but because they are under enormous stresses which risk breaking their blades.
I have designed a new type of turbine which transforms these constraints into additional energy. I made a small project presentation site
http://cyberquebec.ca/normandajc/
The mathematician Betz based his theory on the kinetic energy of the wind and by correctly choosing the parameters, it is possible to recover 60% of the wind energy. The remaining energy (40%) has not disappeared but it is potential energy. Why not transform this potential energy into kinetic energy?
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simplino
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by simplino » 04/12/15, 14:55

normandajc wrote:Hello,

large wind turbines must be braked or stopped when the wind becomes too strong. Not because they are producing too much but because they are under enormous stresses which risk breaking their blades.
I have designed a new type of turbine which transforms these constraints into additional energy. I made a small project presentation site
http://cyberquebec.ca/normandajc/
The mathematician Betz based his theory on the kinetic energy of the wind and by correctly choosing the parameters, it is possible to recover 60% of the wind energy. The remaining energy (40%) has not disappeared but it is potential energy. Why not transform this potential energy into kinetic energy?
Image


Small problem because these explanations have an error, Bernoulli alone does not explain the lift of a wing, because in laminar flow without vortices there is no lift (which means that we sink in mud or sands moving while moving without ever having a lift, the pressure on it decreases on a larger surface which gives a force from above equal and opposite to that from below, because Bernoulli is only the conservation of energy, and therefore without putting energy in vortices, there is no lift).
What makes the lift is the detachment of the air streams by approaching the wing tip, which gives vortices and lift !!
The lift is a kinetic effect which gives swirls.
https://en.wikipedia.org/wiki/Lift_%28force%29
There are lots of errors on the internet, given the complexity, even on wikipedia in French!
Try to have a lift with a wing in the viscous jam where Bernoulli is valid too !!

Finally its bizarre active lift is not explained at all, because the thesis is inaccessible !!

The investor is taken for an ignorant gogo !!!!!
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Gaston
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by Gaston » 04/12/15, 15:14

normandajc wrote:The mathematician Betz based his theory on the kinetic energy of the wind and by correctly choosing the parameters, it is possible to recover 60% of the wind energy.
What the Betz formula expresses is that the air must continue to circulate after passing through the wind turbine (if the air stops, there is no more wind) and therefore that it is necessary that the air conserves part of the initial energy to continue its movement without slowing the flow.
It is completely independent of the form or energy recovery system that can be used.

normandajc wrote:The remaining energy (40%) has not disappeared but it is potential energy. Why not transform this potential energy into kinetic energy?
It is already in the form of kinetic energy ... in the speed of the air that goes away ...
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normandajc
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by normandajc » 04/12/15, 15:53

Hello,

I agree, but the advantage of using Bernouilli makes it possible to present the concept in a simple way. There is indeed a discontinuity in the current lines at the level of the turbine rotors.
The thesis cannot be disclosed. The studies were done with Fluent and rotating and oscillating meshes
For my part, I studied flows with OpenFoam with rotating meshes.
on this following document, you have an example on the first page and we can clearly see the detachments.

https://www.econologie.info/share/partag ... QFu9Ca.pdf
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simplino
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by simplino » 06/12/15, 13:32

Hello,
With your pdf
https://www.econologie.info/share/partag ... QFu9Ca.pdf
the principle becomes very interesting and much clearer, by seeking to make work the large inactive forces towards the axis of rotation by well chosen axial movements, rods and gears !!

It would be useful to explain why the Betz limit can be clearly and convincingly exceeded in the demonstrations,
https://fr.wikipedia.org/wiki/Limite_de_Betz
http://eolienne.f4jr.org/demonstration_limite_betz
because this limit is very general considering the kinetic energy of the wind which decreases between before and after in the form of pressure variation and therefore of force on the wind turbine which the wind turbine receives and the pulse variation by reducing the speed, which cannot be canceled without reducing the yield.

It would be good to be clear to compare with this kind of known and functional turbine where the Betz limit does not apply with almost complete shutdown of the fluid:
https://fr.wikipedia.org/wiki/Turbine_Pelton
https://fr.wikipedia.org/wiki/Turbine_Francis

In principle we should be able to achieve the same with complete shutdown of air instead of water in complex wind turbines, more difficult because the air is not incompressible like water ???

A priori one could conceive a large number of types of complex wind turbines exceeding the limit of Betz which slow the air much more?

In your method with movable blades that recover energy from unused forces, we could also recover the energy from the deformation forces of the flexible blades of large conventional and functional wind turbines, without completely changing their design instead of doing it on a wind turbine Darrieus in general less effective ????
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by Gaston » 07/12/15, 11:09

simplino wrote:It would be useful to explain why the Betz limit can be clearly and convincingly exceeded in the demonstrations,
In fact, I don't think that normandjac pretends to exceed this limit, only to approach it a little more (but it would be nice to be clear on the subject) :?:


simplino wrote:In principle we should be able to achieve the same with complete shutdown of air instead of water in complex wind turbines, more difficult because the air is not incompressible like water ???
We can afford to stop the water because it then drains naturally by gravity.
If we stop the air at the wind turbine, what force will allow it to evacuate :?:
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simplino
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by simplino » 07/12/15, 13:21

Gaston wrote:
simplino wrote:It would be useful to explain why the Betz limit can be clearly and convincingly exceeded in the demonstrations,
In fact, I don't think that normandjac pretends to exceed this limit, only to approach it a little more (but it would be nice to be clear on the subject) :?:


simplino wrote:In principle we should be able to achieve the same with complete shutdown of air instead of water in complex wind turbines, more difficult because the air is not incompressible like water ???
We can afford to stop the water because it then drains naturally by gravity.
If we stop the air at the wind turbine, what force will allow it to evacuate :?:


Hello,
In
https://www.econologie.info/share/partag ... QFu9Ca.pdf
he draws a figure with Cp which exceeds CpBetz !!

So his simulation claims to succeed !!


Finally the almost stopped air can leave slowly in a very large section of nozzle 10 times that of entry, a little like the turbine which sees the stopped water also accumulate, as in the congestions one must widen to store the cars or people slowed down?
Flow by gravity of this water represents a loss of gravitational energy which has been forgotten.

Even vortex wind turbines placed after the first can recover energy and increase efficiency beyond Betz.


The derivation of the Betz limit has the problem of a single surface S of the wind turbine; as this area of ​​the flux lines grows as the current slows down, and therefore several wind turbines behind, larger areas, can recover more energy exceeding the Betz limit, in theory, because vortices make this very very difficult in reality.

A turbine does this better.

Kind regards.
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by Gaston » 07/12/15, 15:50

simplino wrote:he draws a figure with Cp which exceeds CpBetz !!
Effectively. :?

simplino wrote:Finally the almost stopped air can leave slowly in a very large section of nozzle 10 times that of entry, a little like the turbine which sees the stopped water also accumulate, as in the congestions one must widen to store the cars or people slowed down?
Precisely, the formula of Betz calculates for which section (and therefore speed) of the air at exit one recovers the maximum of the incoming energy.

If v1 is the speed of the air before the wind turbine and v2 the speed after, the power of the wind turbine is proportional to (v1²-v2²) * (v1 + v2).

If we increase v2, we increase the second term at the expense of the first, if we decrease v2, we decrease the second term by increasing the first.

We obtain the maximum for v2 = v1 / 3, ie when the exit surface is three times the entry surface.

simplino wrote:Even vortex wind turbines placed after the first can recover energy and increase efficiency beyond Betz.
Yes, in theory each can recover almost 60% of the remaining energy.

Ideally, the first recovers 60% of the total energy, the second 24%, the third 9,6% the fourth 3,8% ...


simplino wrote:The derivation of the Betz limit has the problem of a single surface S of the wind turbine.
The formula is valid for a wind turbine.
In the case of several wind turbines one behind the other, the formula can be applied to each wind turbine (taking into account the reduction in speed - or energy - caused by the first wind turbine).
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simplino
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by simplino » 07/12/15, 16:36

When we look at the derivation of the Betz formula we see that the speed just before and just after is taken as the same v with the same surface S in input as in immediate output:
"We apply Bernoulli's theorem twice, on the one hand between the upstream point and the point just before, on the other hand the point just after and downstream" implying with v unchanged and a very fine single surface S like the equations show it:

https://fr.wikipedia.org/wiki/Limite_de_Betz

if the wind turbine is complex with a large thickness by not respecting this hypothesis, then with V just before larger than V after, and the same reversed for the Savant and Sapr surfaces, there is no longer a Betz limit, very visible with wind turbines in series one after the other !!!

Conceptually for me the slightly hidden assumptions are essential, because by violating them we strongly improve !!

A real wind turbine is very complex with vortices, which destroy the simple flux lines for Bernouilli and therefore in fact the Savant surface with vavant with flow lines verifying Bernouilli, is not the same afterwards for the Sapr surface with vpress verifying roughly Bernouilli, because between, in the wind turbine the chaotic vortices make knots with the lines of flow.
This reason explains why it is conceivable to exceed the limit of Betz with complex structures with radial movements or others, to recover more energy.

Without swirls and preponderant inertial kinetic effects which violate Bernouilli at certain points or lines, there are no wind turbines or planes which work, because no lift !!

I'm just trying to understand.
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by Gaston » 07/12/15, 17:06

simplino wrote:Conceptually for me the slightly hidden assumptions are essential, because by violating them we strongly improve !!
Or not...

simplino wrote:I'm just trying to understand.
The best would be to leave normandajc explain to us (but unfortunately its calculation is not disclosed, we will not know :| ) ...

I am also wary of the results of numerical calculations when software is used outside the conditions for which it is qualified (some have thus "demonstrated" the reality of mechanical machines with perpetual motion).

Until now, all those who have tried to transgress a result as general as that of Betz have broken their teeth.
On the contrary, some have shown that with more realistic hypotheses, the Betz limit was in fact too optimistic : Mrgreen:
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