Environmental Engineering Reference
In-Depth Information
when the Gedser, Tvind and NIVE prototype turbines were
designed and built. In particular, the coupling of meteorological
models with the aerodynamics and structural dynamics had
not been achieved for wind specific applications and thus the
structural behaviour of a turbine under extreme conditions and
over its lifetime was highly uncertain. This translated to
conservative design principles for the NIVE turbine and other
contemporary Danish wind technology development eforts. As
Maegaard highlights, “There were many such rules of thumb. They
were more on the safe side”. Without well-developed physical
models, the NIVE team relied on information in particular from the
Gedser project which influenced the design of the NIVE blades then
adopted and subsequently developed by Økær. The UN conference
on new energy again became a reliable resource in guiding these
“rules of thumb”:
“We know from the Gedser windmill that [the turbine] should be
induction type—asynchronous type—but you know the size of the
rotor, and we had some standards… [From] New Sources of Energy
we had all the information from the Gedser windmill. There were
some rules of thumb—30 kg/m
2
—this was the axial pressure on
the rotor, and from that one could calculate well the tower—what
kind of steel, how the lattice system should be. You could calculate
the size of the foundation, and once you have these basic figures,
the rest of it is conventional. There will always be some sellers you
can go to once you have the loads and you could go to an engineer
saying, can you help us to know the size of the steel.”
The measurements taken during the initial operation of
Gedser windmill did in fact provide a basis of information over
expected loads that may occur both during operation and with
the wind turbine stopped. Measurements from the Gedser
windmill indicated that axial pressures, the aerodynamic pressure
on the rotor, during operation ranged from around 20 kg/m
2
at
2
25 m/s wind speeds to nearly 35 kg/m
for wind speeds in excess
of 30 m/s (Juul, 1961). As mentioned before, it was a factor of
30
2
pulled from the report that NIVE used in its
dimensioning for the rest of the system design. Thus, combining
the dimensions of the NIVE turbines with the rules of thumb
obtained from the Gedser experiments served as a basis for
design when understanding
kg/m
physical models were not yet
available. Of course, these rules of thumb were known even at the
via
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