Wavegen: compression wave power plant and air turbine

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vinzman
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by vinzman » 26/03/11, 16:15

When I watch the video, I just see that the air that enters the room, exits through the same orifice.
In other words, there is nothing which indicates that the wind helps to make it turn in the 2 directions of circulation.
In other words, what I believe is that there is a mechanism similar to that found in a ratchet. The air spins the turbine, which is coupled to a large flywheel through a kind of "ratchet transmission".
We could make the parallel of this mechanism with an ordinary rower. The flywheel always turns in the same direction despite the cable which helps to make it turn, come in and go out.

http://www.youtube.com/watch?v=j6SWdP1YlpQ
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vinzman
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by vinzman » 26/03/11, 17:06

Ok, no, I found the why and how. It resides in the principle of counter-rotating turbine:


http://www.youtube.com/watch?v=8Sle8xUWtNI

study on the subject:
https://www.econologie.info/share/partag ... JVkKcF.pdf
http://iopscience.iop.org/


So one turbine spins the stator in one direction, and the other turbine spins the rotor in the opposite direction. It is so simple and at the same time so effective as a principle, that it is disconcerting!
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Janic
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by Janic » 26/03/11, 19:36

So one turbine spins the stator in one direction, and the other turbine spins the rotor in the opposite direction. It is so simple and at the same time so effective as a principle, that it is disconcerting!

No, the two turbines turn in the same direction, it is only the direction of the blades which is opposite.
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vinzman
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by vinzman » 26/03/11, 21:32

I'm not sure what you're saying.

The principle they use is that of counter-rotating turbines, so by definition, one propeller turns in one direction and the other, in the other direction.

source:
http://www.wavegen.co.uk/what_we_offer_limpet_islay.htm
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by Janic » 28/03/11, 09:40

sorry, i don't read english. but having a counter-rotating propeller would unnecessarily complicate the design of the turbine. While the reversal of the blades of the second turbine is simple effective and not expensive as the advertisement says.
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by Steeve_Osteen » 28/03/11, 10:06

Could it simply not be two propellers rotating in the same direction with reverse blades and mounted on reverse freewheels too?

like that in a way the wheel 1 drives the gene and the 2 is freewheeling and in the other direction the 1 is freewheeling and the 2 drives the gene?

cordially
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by Janic » 28/03/11, 18:24

steeve
Could it simply not be two propellers rotating in the same direction with reverse blades and mounted on reverse freewheels too?

like that in a way the wheel 1 drives the gene and the 2 is freewheeling and in the other direction the 1 is freewheeling and the 2 drives the gene?

it would indeed be the most rational to avoid the brake effect on the second turbine.
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vinzman
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by vinzman » 29/03/11, 02:52

Janic wrote:sorry, i don't read english. but having a counter-rotating propeller would unnecessarily complicate the design of the turbine. While the reversal of the blades of the second turbine is simple effective and not expensive as the advertisement says.


The explanatory video may be misleading because it turns the turbines in the same direction.

I will summarize what emerged from this study
https://www.econologie.info/share/partag ... JVkKcF.pdf :

When a traditional wind turbine with a single rotor system is used for energy conversion, only part of the energy available in the wind is exploited. The maximum power that can be extracted from the wind is about 59% of the available energy and that is if the velocity is well transformed through the rotor, according to Betz.

But in practice, the energy in the wake of a single rotor is not really small. Part of this energy can be extracted further by installing a second rotor in the wake.
Thus, at the same time, the maximum energy that can be extracted by two rotors of the same diameter increased from 59% to 64% of the available energy, energy which is the Betz limit for two rotors. As the wake of the first rotor turns in the opposite direction to the direction of rotation of the rotor, it is preferable to turn the second rotor in the same direction as the wake of the first, in order to efficiently extract the energy available in the stride .

A counter-rotating wind turbine can be described as a system composed of two rotors separated by an appropriate distance. One of the rotors is rotating counterclockwise and the other clockwise. In 2002, Appa technological initiatives [2] built a prototype in California and carried out some field tests. The prototype consisted of a 6 KW counter-rotating wind turbine with two 2-blade rotors.
The results of these tests indicated that a counter rotation system could extract an additional 30% power from the flow of the same wind.


What is said on the Wavegen website http://www.wavegen.co.uk/what_we_offer_limpet_islay.htm :

The design of the inner tube is important to maximize the capture of wave energy and the conversion of pneumatic energy.

The turbines are carefully adapted to the air chamber in order to maximize the output power.

The performance has been optimized for annual average wave intensities between 15 and 25 kW / m. The water column supplies a pair of counter-rotating turbines, each of which drives a generator of 250 kW, giving a nominal power of 500 kW.

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by Janic » 29/03/11, 08:12

there it is clear!
thanks.
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