From the video it was an ‘egg-beater’ type on a vertical mount. Looks like the blades went first then the anchors. I am not sure that these ‘egg-beater’ types can be ‘feathered’ in extreme conditions to reduce the wind loads. One or more engineer types may be (legitimately) worrying about their ‘PE’ stamps on the application & construction documents. Happy that there were no human injuries!
I am not sure that these ‘egg-beater’ types can be ‘feathered’ in extreme conditions to reduce the wind loads.
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It’s a good point and it’s not clear what technology this type had. With horizontal axis IWTs, they can both change the blade pitch as well as rotate the whole nacelle so that the blades can be positioned edge into the wind for extreme wind velocity conditions. The only option for a vertical axis egg beater type would be if it has a good brake on it. I can’t imagine any PE putting her/his stamp on such a project in a populated area without it having brakes.... but then again, I can’t imagine any project being approved that involves highly stressed rotating machinery being located above peoples’ heads regardless of what kind of brakes it has. Very simply, these things need to have a wide ‘clearance zone’ around them. As far as I’m concerned, this is like walking into a plant that has large overhead cranes that are allowed to move materials above workers.... that is a serious no-go safety condition for all plants (at least in the civilized world). In fact, this is worse since it involves an unsuspecting public.....
For the record, all rotating machinery is subject to fatigue inducing conditions.... and vertical and horizontal axis wind turbines are no different. However, I highly suspect that vertical axis wind turbines are much more susceptible to fatigue since with every revolution, there is an oscillating force applied to the blades (and/or blade support structure) on top of all other loads..... this is due to the fact that for half the revolution, it’s acting with the wind and for the other half, it’s against the wind. It might be that this particular turbine had an ‘event’ that caused it to go much faster than it normally should have (i.e. failure of some sort with the generator that removed the restraining torque and allowed it to accelerate) but what I would want to know is what fatigue analysis and testing records can be produced? I think I already know the answer to that......zero.
The conditions weren’t extreme. 35 mph gusts