Wind speed regulation against gusts (Mistral)?

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Re: Wind speed regulation against gusts (Mistral)?




by dede2002 » 04/03/16, 12:10

Forward, downwind ... so backward : Wink:

Not the one I had seen was more artisanal, somewhere towards Burkina-Faso, the blades were elastic.
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Re: Wind speed regulation against gusts (Mistral)?




by simplino » 04/03/16, 21:08

Amusing the video of a simple wind turbine in the swirls of the mistral between the trees that spin endlessly !!
The wind turbine with its wind vane can do nothing in a mistral stuffed with whirlpools in all directions, the wind vane without wind turbine will turn like these whirlpools which turn in circles, often faster than the weather vane!
In windsurfing and especially worse in hang glider and plane, these whirlpools are very dangerous, very fatal !!
In windsurfing the mistral of land is very difficult to go up, all the more whirlpools and therefore difficult, that one approaches the land, and it is necessary to know to compose by using only the good moments when the turning wind has a good orientation to bring up the windsurf board, without falling into the water in the whirlpools, I know some who desperate, called the rescue and others who ended up swimming !!

So a wind turbine must do the same, hold on, in excessive vortices, and take advantage of the rare moments with the right wind for the blades that rotate.
Very efficient commercial wind turbines with elongated thin blades of great finesse are completely incompatible with the swirling mistral, because the wind does not keep the right incidence to have the necessary lift, exactly like for an airplane or a dellta-plane, which then fall !!
So there is no solution for these very efficient wind turbines for very regular wind, far from any obstacle giving vortices.
That of simple video inefficient performs quite a bit at all, even oscillating constantly like the wind, but with little useful power !!

If you visualize the whirlpools with smoke, their rotation in all directions, shows that there is no solution at all in such a stormy wind among the trees !!
We can do better with the types of wind turbines without a wind vane, accepting all wind directions like the Darrieux type, or rides turning with sails on, vertical blades that accept all horizontal wind directions, but even this type, will work poorly with low efficiency with the vertical components of the vortices, because their pale, like the sails, use the lift given by the wind which is destroyed by the enormous quantity of vortices of all dimensions.

Finally, a 100 km / h mistral wind exerts shaking forces of around 100 kgp / m2, which generally forces it to be put in safety mode, because even if they resist, its efficiency becomes zero.

So in the mistral, there are all the less solutions that the wind turbine is efficient !!
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Re: Wind speed regulation against gusts (Mistral)?




by Grelinette » 05/03/16, 12:19

Thank you for your answers ... but I would still have been happy to have some suggestions of simple systems to limit the speed of rotation when the wind turbine is racing with a gust.
I thought of small weights around the axis of the wind turbine and which open by centrifugal force and come to rub a surface. I think it would work, but maybe not long because of the wear and tear.

There remain the 2 questions that bother me:

1) is the orientation system facing the wind with a small wind turbine perpendicular to the main one (as in the drawing above of an old mill) is it effective? (I have never seen one)

2) When the blades of a wind turbine turn quickly, is the imbalance of forces caused by the Earth's attraction, mainly on the blades facing down, systematic?
Is the gravitational force perhaps negligible compared to the centrifugal force? there is also perhaps a gyroscopic phenomenon coming to restore this balance? ...
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Re: Wind speed regulation against gusts (Mistral)?




by Christophe » 05/03/16, 12:22

Grelinette, this subject becomes interesting: I therefore did well to divide it from the humor section :)
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Re: Wind speed regulation against gusts (Mistral)?




by Grelinette » 05/03/16, 12:32

Christophe wrote:Grelinette, this subject becomes interesting: I therefore did well to divide it from the humor section :)

When you can combine the useful of interest with the pleasant of humor! ...

I'm going to make a little windward orientation system with an old hand puppet that I just found and observe its behavior in the wind.
Old hand drill.jpg
Old hand drill.jpg (4.74 KB) Viewed 2654 times

By putting a small wind turbine on the chuck and a perpendicular wind vane on the handle, it should work ...
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Re: Wind speed regulation against gusts (Mistral)?




by Christophe » 05/03/16, 12:34

Ah yes not stupid :) this re-use!

You will have to grease the gear well and protect it from the weather if you want it to last a little longer!
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Re: Wind speed regulation against gusts (Mistral)?




by simplino » 06/03/16, 20:03

Grelinette wrote:Thank you for your answers ... but I would still have been happy to have some suggestions of simple systems to limit the speed of rotation when the wind turbine is racing with a gust.
I thought of small weights around the axis of the wind turbine and which open by centrifugal force and come to rub a surface. I think it would work, but maybe not long because of the wear and tear.

The centrifugal brake like the Watt regulator, will limit the speed before explosion by centrifugal force, if it is strong enough for winds of more than 100 km / h, (moreover it risks being unstable, if poorly designed, stopping too much. strongly, then restarting too quickly), but losing energy from the wind, while an alternator gives energy which can be used to limit the speed, if this alternator is powerful enough to supply energy in the mistral wind of more than 100km / h where the power increases like the cube of speed because the (kinetic) force of the wind is like the square of this speed and the power like the product force by speed, (force about 100kgp / m2 at 100km / h of wind).
The big problem is that this power of the vortices of the wind varies enormously over a few seconds (factors 10 to 100) like their wind direction, which makes regulation with energy use very difficult, with mechanical or electronic brake! !
For this reason it is difficult to use except for complex special design.
The simple choice in a storm is to put the wind turbine in a safe position, blocked or even folded up !!
There remain the 2 questions that bother me:

1) is the orientation system facing the wind with a small wind turbine perpendicular to the main one (as in the drawing above of an old mill) is it effective? (I have never seen one)

At high wind the wind turbine can be much smaller for the same useful power of the mill, (for an inefficient wind turbine like the old mills, with fabrics like pale which give a useful force even in whirlpools) and the large wind turbine is then put in safety by hand more or less parallel to the wind to undergo less destructive forces, often with less tissue on it, otherwise they are torn !!
The old solutions were not bad at all for a simple technology !!
Even these simple wind turbines were put in open places, free with much less vortices than in the middle of trees, where they do not work properly, with only vortices in spurts, vicious!
2) When the blades of a wind turbine turn quickly, is the imbalance of forces caused by the Earth's attraction, mainly on the blades facing down, systematic?

the earthly attraction must not have any effect on the pale who must at least resist their own weight.
If the blades are soft, they deform under their weight, and in rotation this easy deformation at the rate of their rotation, gives vibrations of imbalance, which also exist if the blades are not perfectly balanced in static and dynamic, exactly as for car tires !!
Is the gravitational force perhaps negligible compared to the centrifugal force? there is also perhaps a gyroscopic phenomenon coming to restore this balance? ...

The centrifugal force is like the square of the speed and therefore easily much higher than the weight by gravitation of the blades to the point of breaking the blades and exploding if the wind turbine gets carried away if not braked enough.
The force rather gyroscopic torque is different, that which gives an angle torque must with the speed of change of orientation of the axis of rotation of a wheel or router, which prevents a router from falling, and that one feels in holding a fast spinning bicycle wheel in his hands.
On a wind turbine this torque is low.
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Re: Wind speed regulation against gusts (Mistral)?




by simplino » 06/03/16, 20:13

Grelinette wrote:
Christophe wrote:Grelinette, this subject becomes interesting: I therefore did well to divide it from the humor section :)

When you can combine the useful of interest with the pleasant of humor! ...

I'm going to make a little windward orientation system with an old hand puppet that I just found and observe its behavior in the wind.
Image

By putting a small wind turbine on the chuck and a perpendicular wind vane on the handle, it should work ...

The wind rotating the chuck with blades will turn the crank and the vane on it in circles endlessly in the reduction ratio without ever orienting, and if the strong wind on a large vane is orienting, it will block the rotation of the wind turbine in a strange orientation, competition between the weather vane and the forces on the wind turbine blocked in a weather vane function too !!!
Fun, but not a solution !!
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Re: Wind speed regulation against gusts (Mistral)?




by Grelinette » 06/03/16, 21:39

simplino wrote:The wind rotating the chuck with blades will turn the crank and the vane on it in circles endlessly in the reduction ratio without ever orienting, and if the strong wind on a large vane is orienting, it will block the rotation of the wind turbine in a strange orientation, competition between the weather vane and the forces on the wind turbine blocked in a weather vane function too !!!
Fun, but not a solution !!

Good evening simplino,
The reduction of this chignole is not enough for it to turn with a small wind turbine ... but the system seems coherent to me: the small wind turbine being more sensitive will rotate before the big one until it is feathered, and in this position is the large one facing the wind. It is certainly not very precise but the inertia of the movement should limit the brutal rotations of the wind turbine due to gusts, knowing moreover that even by large mistral, there is a dominant wind well oriented.

Do you think this mechanism does not work?
wind-up mechanism of old mill.jpg
wind-up mechanism of old mill.jpg (31.63 KB) Consulted 2640 times
bembridge_orientation_s.jpg
bembridge_orientation_s.jpg (12.17 KB) Viewed 2640 times
mechanical_butterfly_s.jpg
mecanique_papillon_s.jpg (9.5 KiB) Viewed 2640 times
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