Environmental Engineering Reference
In-Depth Information
structural motions. These limitations became more evident as designs of advanced turbines
incorporated lexible towers, teetered hubs, and variable-speed power trains.
The effects of unattended, all-weather operations on loads, fatigue life, and damage
mechanisms became better understood as irst-generation turbines (heavily instrumented
with anemometers,
strain gages
, and
accelerometers
) provided the irst valid ield data (Fig.
3-26). Various computer models (with a plethora of acronyms) were soon developed which,
in turn, led to more accurate load predictions and better insight into design and operating
issues [Spera 1977, Thresher 1981]. Codes such as
REXOR
,
MOSTAB
,
FLAP
[Wright
et
al.
1988], and
DYLOSAT
[Finger 1985] incorporated more and more capabilities, although
limitations were still signiicant.
Figure 3-26. Typical comparison between measured and calculated dynamic loads on the
blades of irst-generation HAWTs.
Early Mod-0 loads are shown here. [Spera 1977]
Today, codes named
HAWTDYN
,
VAWTDYN
(for the Darrieus),
NASTRAN/FFEVD
,
and
DUWECS
[Bongers
et al.
1993], and models using the general-purpose
ADAMS
soft-
ware
1
[Wright
et al.
1993] enable the structural analyst to include
statistical techniques
,
non-linear
damage accumulation
models, integrated
rotor/tower/controls coupling
, and
complex wind inlow conditions. A wealth of ield test data has led to signiicant validation
of structural modeling techniques and the identiication of remaining limitations.
Public Acceptance
Research on the public's acceptance of the
aesthetics
of wind turbines has not produced
any deinitive conclusions, a not wholly unexpected result. Early research in the vicinity
of isolated prototype turbines and subsequent experience with multiple installations have
shown that the presence of a few turbines normally does not create more than isolated
complaints. The same is true for wind turbines in larger numbers if they are located in
relatively remote areas, are not exposed to much public visibility, and do not occupy
particularly scenic ground. With only a few exceptions, most medium- and large-scale
turbines in small numbers were usually greeted as beneicial, as potential tourist or
advertising attractions, or as representative of the pioneering spirit of the community. The
apparently leisurely turning of the larger rotors with their slender blades has generally led
to a positive aesthetic reaction, in most surveys undertaken. Conversely, some
wind power
1
ADAMS
is a registered trademark of Mechanical Dynamics, Inc.
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