Video of a wind turbine brake failure

Is this old news? I happened across this on some TV disaster-porn show last week. I had to admit it was pretty impressive. It threw chunks of itself a half-mile.

http://www.youtube.com/watch?v=CqEccgR0q-o

In central NY, these are sited less than 1/2 mile from houses. However, there's no reason why thses couldn't ne made safer - hopefully they already are.

There will be some balance struck between safety and cost, as with any human product.

I don't know how tall it was but that's not a super wide radius. I'll take my chances with this over a fire at a coal, oil or natural gas plant. Additionally it looks like they had plenty of warning. Otherwise there wouldn't have been a camera there.

Plus it looked cool!

I don't know the rotor diameter of the unit that failed, but when catching winds of about 20mps a turbine with a rotor diameter of about 300 feet has a tip speed of around 170 mph. Of course, the closer you get to the hub, the lower the speed.

Glad I wasn't in the throw zone

I can remember exactly. That said the governor failed allowing it to "freewheel" It was spinning at the speed for over half a day I believe. This the only known failure of this type that I can find.

YOu do this on a prop plane if one engine goes dead. Otherwise the prop spins until if flies apart. Saw picture of a C-130 that the pilots could not feather the prop (decoupling of the prop) of a dead engine. There was a slash in the fuselage where one of the prop blades passed right through it. Fortunately, it passed through BEHIND the pilots!

At least that's what it seems to be. I don't have high speed, so I'll leave it to others to follow the links.
http://www.nawindpower.com/e107_plugins/forum/forum_viewtopic.php?48.last

Basically the renewables will save us cults couldn't care less about the huge external costs associated with their yuppie toys, if you ask me.

They're heavy into make believe and denial in those cults.

Basically, these shitheads don't give a rat's ass about country or wilderness. Their approach is to litter the forests, the mountains, the grasslands with spent wind junk.

Actually what I don't give a rat's ass about are the rants of a paid propagandist pushing on nuclear energy on an internet bulletin board.

huge external costs.

A blade-out on a jet engine.

The engines are designed so engine blades don't decapitate the passengers if the jet hits a bird. Supposedly. :popcorn:

Cyclic stresses and vibration

Cyclic stresses fatigue the blade, axle and bearing; material failures were a major cause of turbine failure for many years. Because wind velocity often increases at higher altitudes, the backward force and torque on a horizontal-axis wind turbine (HAWT) blade peaks as it turns through the highest point in its circle. The tower hinders the airflow at the lowest point in the circle, which produces a local dip in force and torque. These effects produce a cyclic twist on the main bearings of a HAWT. The combined twist is worst in machines with an even number of blades, where one is straight up when another is straight down. To improve reliability, teetering hubs have been used which allow the main shaft to rock through a few degrees, so that the main bearings do not have to resist the torque peaks.

When the turbine turns to face the wind, the rotating blades act like a gyroscope. As it pivots, gyroscopic precession tries to twist the turbine into a forward or backward somersault. For each blade on a wind generator's turbine, precessive force is at a minimum when the blade is horizontal and at a maximum when the blade is vertical. This cyclic twisting can quickly fatigue and crack the blade roots, hub and axle of the turbines.

http://en.wikipedia.org/wiki/Wind_turbine#Cyclic_stresses_and_vibration

I don't think it applies to at least one of the incidents. It may be related to the bolt failure cited in the second. From the North American Windpower (trade magazine) bulletin board:

"...the dramatic overspeed event was a Nordtank* 600 near Hornslet, Denmark. The associated tower collapse was due to a tower strike by the overspeeding blades. The brakes had been set for maintenance during calmer weather. The blade angles were not appropriate for the higher winds blowing when the brakes were released. No personal injuries.

At http://gramtrans.com/gt/url/?url=http%3A%2F%2Fjp.dk%2Findland%2Farticle1277561.ece&pair=dan2eng&x-form-id=translate_url you may read local press of the event. After you open this site, click the Translate box (then it takes a minute or two to translate/load).

The referenced blade incident (660kw V-47 near Sidinge on Odsherred, Denmark) was two days later. One blade came off (bolt failure ).

*Nordtank Energy Group (NEG) merged with Micon in 1997 to form NEG Micon which later merged with Vestas in 2004, hence, the Nordtank turbine was over ten years old.

< Edited Sat Mar 29 2008, 03:34PM >
David Schroeder, Finance & Risk Management forum moderator and Global Insurance Consultant at Project Risk Limited, has been involved with hundreds of utility class wind farms totaling over ten gigawatts of capacity."

It's the second to the last comment:
http://www.nawindpower.com/e107_plugins/forum/forum_viewtopic.php?48.last

They were developed by NASA's Langley Research Center's good NDE people:

http://www.techbriefs.com/content/view/1811/118/

http://www.sti.nasa.gov/tto/Spinoff2005/ip_3.html

I'd suggest it is better described as exceeding design load limits.

Exceeding load limits will accelerate fatigue. Vibrations at higher amplitude, and/or higher frequency, for example. Start bending materials past their elastic limit, and fatigue happens very quickly. You can bend a wire back and forth by 1 degree for a very very long time. But if you bend it back and forth by 90 degrees, you'll break it in a few bends.

I'm only guessing, but looking at that video, I bet a lot of components were suffering more deformation than was designed for, and that caused fatigue to happen in a few hours that would otherwise have taken years.

But it might have happened even without fatigue per se. The system was certainly experiencing forces it wasn't designed for.

exceeding load limits is about fatigue.

Chernobyl

:evilgrin:

at a much higher rate.

In fact, the wind energy kills regularly in this country, but as usual arbitrary people don't give a fuck.

In fact, although wind is a trivial form of energy - and has remained as such for all the years that yuppies have been hyping it here - now approaching 8 - and all the years that yuppie have been hyping it before this website was founded going back to the 1970's, it has killed more people in this country than nuclear power.

http://www.wind-works.org/articles/DeathsDatabase.xls

Imagine if wind ever got to two exajoules...not that it will.