Wind power: for or against the wind?

[moinsdewatt]

Storm Carmen: a 250-tonne wind turbine uprooted in Vendée

The incident is a testament to the strength of the gusts of wind in the region. A wind turbine had never been dug up in France.

Jan 1, 2018

In Vendée, a wind turbine 62 meters high and 250 tonnes collapsed in Bouin (Vendée), severed at the base under the power of the wind. The incident testifies to the strength of the gusts of wind in the region. A wind turbine had never been dug up in France.

"It looks like a plane that crashed on the ground, with a lot of debris all around. The shock must have been violent," said Ouest-France, who visited the scene. It is one of the most dramatic material incidents caused by the storm. An investigation should determine the causes of the incident. The hypothesis of a mini tornado is studied.

http://www.rtl.fr/actu/societe-faits-di ... 7791654211

This same wind turbine had survived many other climatic phenomena, such as Xynthia. The other seven wind turbines in the Bouin municipality park are intact. "It had been there for 15 years, it can't just be the force of the wind. According to the first hypotheses, it would be a mini-tornado the cause ", estimates Alain Leboeuf, president of Sydev (departmental union of energy and equipment of Vendée).

The wind turbine had been “feathered” on Saturday at 16 pm (propeller placed parallel to the wind and not functional).

https://www.ouest-france.fr/pays-de-la- ... de-5480134

[moinsdewatt]

Properly cut at the base the wind turbine in question:

[Christophe]

Spectacular rupture by shearing due to improper feathering (locked nacelle) and a swirling wind (it pushes to the right it pulls to the left, or vice versa ...)

I do not understand that the nacelles are locked = immobilized during the feathering on these models ...

[Remundo]

wouldn't it be a composite material?

it seems to crack easily ... it looks like a woodcutter has passed ...

[Did67]

I do not understand that the nacelles are locked = immobilized during the feathering on these models ...

Maybe a flag windmill would do like any flag: twirl in the wind. And that it would be worse, with oscillations ???

[I am not a mechanical engineer; it is the observation of the flags - in fabrics - that makes me think that; when you see how they end up!]

But does the lock not take into account the direction of the wind? A sort of "average fixed position" ???

[Ahmed]

Remundo, you ask yourself:

wouldn't it be a composite material?

The tear conforms to the behavior of the steel sheet. It is obviously the bottom of the mast that takes the most mechanical stress, so this is where the metal "tires" before tearing ...
A boon for locals who would like to cut a cylinder for a hydraulic inertia construction?

[Remundo]

no, the tear does not conform to the steel, but I think I know why: it is the weld which has cracked, which explains this so regular "cut".

According to this document
http://lewebpedagogique.com/dtrouillard ... ennes1.pdf
the masts are stacks of steel cones, welded together.

everyone can try to twist a steel tube at home, he will never have that ... he will not even have a rupture, but a plastic deformation.

[Ahmed]

everyone can try to twist a steel tube at home, he will never have that ...

Of course, since here the rupture is not the result of a continuous and strong push, but of an accumulation of stresses of the metal having led to its embrittlement, then its clear rupture during an additional stress: you will obtain the same type of cutting by performing multiple deformations of any steel tube, provided not to exceed the limit of elastic deformation, which was the case with the mast ...
The weld of the first two elements is located much higher (a break occurs moreover rarely on a welded joint *).

* Unless, of course, if the weld is defective ... but I think that the manufacturers of wind turbine masts pay attention to quality.

[Remundo]

this break is entirely suspect. Cyclic fatigue failure has never been observed on a mast.

I'm not the only one to say it
http://www.leparisien.fr/societe/vendee ... 480869.php

While 6 wind turbines are today anchored to the ground in France, this accident surprises the profession. "Since the 000s, there has been broken blades and some bent masts, recognizes Sylvie Meray, western regional delegate within the France Energie Eolienne union. But it is the first time in France that a pylon has been completely sectioned by the wind. "

the operators evoke a local "mini tornado", nevertheless that does not explain very well this break so clear.

[sicetaitsimple]

The weld of the first two elements is located much higher.

I have no specific opinion on the cause of this accident, but I think there may well be a weld (defective or not) at this level.

These are rolled-welded sections that are assembled by welding to constitute the mast, it would surprise me that they roll-welded to these diameters over several tens of meters in length.