
The Mesmerizing Math of a Wind Turbine on Fire - stared
http://www.wired.com/2016/08/mesmerizing-math-wind-turbine-fire
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8ig8
I thought the post perhaps was this unbelievable flaming UFO...

[https://m.imgur.com/dm2o6h5](https://m.imgur.com/dm2o6h5)

(Starts slow, but worth watching past the initial smoke.)

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GeorgeHahn
Here's a video full of these!
[https://www.youtube.com/watch?v=RRQaXDafs_Y](https://www.youtube.com/watch?v=RRQaXDafs_Y)

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basicplus2
awesome! a bit like how power station boilers used to be lit.. "light blue
touch paper and retreat in haste"

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jacquesm
That has a longer story attached to it, another windmill in the background is
_also_ on fire. I suspect a fault in the grid coupling causing overvoltage
(which would cause the windmill to start acting as a motor, in which case it
could easily exceed it's designed maximum RPM, and with the air braking it a
fire is pretty much inevitable in that situation, the alternator windings are
not made for that situation).

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josh-wrale
Isn't it possible that whatever _might be_ keeping the foreground turbine from
disengaging could also affect the other turbine? Factory defect?

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jacquesm
Overvoltage can weld relay contacts together when the relay is opened, even
with AC the spark would be considerable. I'm sure that the wreckage was
studied extensively to figure out what exactly could have been done to prevent
this from happening.

It's one thing to have to design for fickle winds, it's quite another to
_also_ have to design for a fickle grid!

Windmills tend to have a destabilizing effect on a grid, if the grid is unable
to sink all the power pushed into it the voltage will rise.

Even so, you'd wonder just how much of a rise would be required to cause a
catastrophe like this.

Those people filming this are braver than I would have been in the same
situation, a mill considerable smaller than this one failed on the island
where I lived and the blade was found the next spring. It was embedded several
feet down in the soil and about a mile away from the base of the mill!

Dying windmills are dangerous, and to stand there to film it took a lot of
courage.

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vosper
> Dying windmills are dangerous, and to stand there to film it took a lot of
> courage

Or they were unaware of the dangers and wanted to shoot a cool video.

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jacquesm
The award for the coolest video is called 'Darwin Award'.

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tbabb
Very interesting video, but given this title I was expecting far more
interesting math than a simple helix.

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vpribish
that's one of the most frustrating videos ever filmed. what the hell,
cameraman.

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dsjoerg
what's so frustrating about it?

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diydsp
and at one of the most amazing moments - when the blades fly away - the
cameraman points away and stays away.

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jacquesm
That's because he has just had his wits scared out of him. Being that close to
a windmill that comes apart is super stupid and must have caused him/her to
think 'what the hell am I doing here?' at the moment it came apart.

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josh-wrale
Looks like the smoke helix is forming coils slower than rate at which the
turbine is rotating. Perhaps some drag on the smoke makes it this way.. Or
maybe it's just an illusion.

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jacquesm
You are spot on, that is more confirmation for my suspicion of overvoltage.
The power _drives_ the windmill, so the machine is rotating faster than the
wind it generates due to slippage.

Normally it would be the other way around, the wind would pass through the
turbine faster than it could move (Betz' law, in both cases but for the
opposite reason, just like it is impossible to extract all the power in the
wind due the air then having to 'pool' around the windmill you can't transfer
power with 100% efficiency from the rotor to the air either, you'd create such
overpressure behind the windmill that some of that air would have to move back
to the front of the rotor. This stuff is all not-so-intuitive and the video is
actually (accidentally) a _really_ nice illustration of Betz' law at work.)

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gus_massa
I'm confused. If the fire is in the center, why only one of the blades release
smoke?

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Artlav
Something like three fail-safe systems have failed or weren't installed in
this case.

All to generate a bit of neat smoke?

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kvajjha
Is it possible to use Vpython for Computational Fluid Dynamics? I'm interested
in making an animation of the Kelvin-Helmholtz instability.

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nether
You could use it for visualization. With the actual solution computation,
you'd probably want to use numpy/scipy.

