"I'll toss this out on the back steps and see if the cat licks it up"
Long time ago (40 years or so) I worked at an furniture factory. This factory was four stories and had a pair of silos that stood better than 100 feet tall. On the roof was a set of collection fan/blowers that were better than 10 foot in diameter and were driven by 100 hp motors. These would "suck up" the dust from the cutting departments (on the first and second floors) and blow the blow the dust/wood chips up into the top of the silos.
While running the fans caused a annoying "rumble" in the building that was mostly covered up by all the other machinery that was running in the plant.
During summer plant shut down I worked in maintenance as "general labor". While helping with the PM on the roof top blowers the maintenance VP (been with the company less than a year) stopped by to check on our progress. He noted a large T shaped bar with a weight mounted on it setting in a corner. He asked one of the maintenance people what and where it belonged.
No one knew what it was and one said that it's been sitting there for years.
The Superintendent walked over to the blower motor (the thing was HUGE) and pointed at a couple of tapped holes on it's frame and said.. "it bolts on here" It took three of us to hold the thing in position so someone could install the bolts.
We started the blower and he moved the weight a couple of inches along the bar and .. that annoying vibration was gone.
I'm sure (but not positive) that he called it a "flying Dutchman".
That was my first encounter with a "vibration dampener".
Many years later I worked with vibrators that are used to move product along pans. They were tuned by various methods but the principles were always the same. These pans had the vibrators attached to them, and at times their mountings required "vibration dampening". Often a "counter weight" was used.
I'd guess that something similar, bolted to a tower could dampen a vibration. Granted, it wouldn't be easy to determine it's needed length/weight or mounting location but the concept/principle should hold true.
ax7
(very) interesting story.
You are correct, mechanical mass used to dampen vibration are analogues to capacitors on electrical circuits.
Math even works out the same.
Frequency tuned shock absorbing (hydraulic analogue) equipment could work out as well.
Last few Big Rotating Equipment projects I have worked on, the structural engineers have just gotten lazy on the design on put in Massive Concrete to cancel out the vibrations. Usually about 3 feet thick, by about 50 to 60 feet across. Nothing much moves when it is tied to that.
Canceled out some rotor vibration on aircraft by variable speed motors with spinning off-centered weights attached to the airframe.
But back to windymill applications -- looking at doing some "suburban" applications where this stuff (noise, vibration) will matter. Planning using 10 kW or so at 60 height overall (local restrictions), so I am willing to do any experiments on them to keep them quiet and smooth, if anyone would like to suggest some.
