I thought the post perhaps was this unbelievable flaming UFO...

https://m.imgur.com/dm2o6h5

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

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

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

Not a UFO, a girandola!

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).

Isn't it possible that whatever might be keeping the foreground turbine from disengaging could also affect the other turbine? Factory defect?

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.

> 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.

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

It's likely a design defect coupled with failing breaks and high winds. Modern windmills rotate their blades to keep operating at a range of wind speeds without that winds can apply insane amounts of force which may have lead to over RPMing the generator causing a fire.

Windspeed is quite low, see the speed with which the vortex separates from the tip, so failing brakes have nothing to do with this particular failure.

Every other windmill is stationary, so they are applying breaks. As to wind speed we don't see a when it actually failed, only the current speed which is not exactly slow.

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

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

I came here just to post this. Maddening.

what's so frustrating about it?

He keeps pointing the camera to the ground and he misses the moment the windmill finally breaks down. Suggestion:

1) look into the camera to keep it aligned

2) look at the subject and keep the camera off

Pick one.

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

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.

because the pretty spiral is never centered and/or completely in-frame.

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.

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.)

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

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

All to generate a bit of neat smoke?

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

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

This is definitely worth asking on one of the Stack Overflow or one of the Stack Exchange sites.