Environmental Engineering Reference
In-Depth Information
time of the UN conference to be quite conservative. Experiments
from the Gedser turbine indicated that “the dimensions of blades,
tower and cabin [were] rather on a liberal scale” (Juul, 1961). This
“over dimensioning” was then translated to the NIVE turbine which
itself, at 22 kW, was a much smaller turbine which would result in
even more conservative design dimensions. However, without a
better understanding of the physics and dynamic interaction of the
structure with the wind field, the over dimensioning was seen as
a good design principle.
“[Wind manufacturers] wanted to make a reliable blade. It was
the company that wanted to have a reputation for good quality.
The uncertainty over how to dimension such a turbine was quite
big, so let's make it strong enough. Later it was calculated that the
blades had a design life of 70 years when normal design life of such
equipment is 20. But, not knowing how to calculate it better, it got
a design life that was later proved to be 70 years—which was too
much you can say… half would be sufficient. Now [the turbine at
the Folkecenter facility] has been here for 25 years, so it's good it
was not 20 years… it seems to be of a durability that it can be there
for several more years. The gearbox is also over dimensioned, the
generator is over dimensioned, etc… the procedure we followed,
was if we were uncertain about the loads, then we took the highest
value, so it will never go down, not break down and so on. Where we
could see something critical we took the most cautious solution.”
(Maegaard, 2010)
This in part, Maegaard describes, was done because their client
base for the designs—the blacksmiths and small and medium
enterprises—were selling directly to the customers:
“These blacksmiths here were selling to their local clients, and if
they lose confidence, it could be a disaster of course. So we would
rather use too much material, make it too strong, than to lose
confidence in the use of it. I think this was an important principle
to have, because these wind turbines set the standard of high
reliability… they were part of setting the standards for what is wind
power in Denmark.” (Maegaard, 2010)
Indeed, during the years, the number of wind turbines that
would be manufactured by Danish companies would climb until the
Danish manufacturers all but dominated the entire international
market for wind turbines. While the parallels to the aviation sector
were important for wind turbine development, especially for blade
aerodynamics, when it came to the overall structure and the loads,
Search WWH ::
Custom Search