|Contents|| ||Wind Turbine Airfoil Families|
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NREL's S-Series airfoils come in thin and thick families. The thin
airfoil families lend themselves to stall regulated wind turbines where
performance losses to airfoil soiling are significant. For variable-pitch and
variable-speed turbines, airfoil soiling is not a major problem.
Generally, a primary airfoil is grouped with root and tip airfoils. Most
wind turbine blades have a circular section that attaches to the hub.
This is especially important for pitching blades. There is then a
transition from the circular section to the root airfoil section, which
usually occurs around the maximum chord. Between the circular section
and the root airfoil section, the transition is faired. The fairing
process should avoid concavities to prevent buckling. The primary
airfoil usually occurs in its pure state around the 75% radius and the tip
airfoil is usually pure around the 95% location. Various interpolation
methods are used to define airfoil shapes between the three pure
airfoils. The tip airfoil is also usually retained out to the tip of the
blade, but some allowances can be made to accommodate special tip
shapes. The root airfoil usually has the greatest thickness ratio
(maximum thickness to chord ratio) and the thickness ratio gets smaller as one
approaches the tip. At the blade root, large airfoil thickness is needed
to accommodate blade structural considerations and toward the tip thinner
airfoils are needed to minimize drag and blade soiling losses.
The following table lists our S-series airfoil families and their applications:
This page was last updated by M. Buhl on 6-July-2012.
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