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Title:
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Enhanced approach for simulation of rotor aerodynamic loads
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Author(s):
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Published by:
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Publication date:
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ECN
Wind Energy
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6-2-2012
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ECN report number:
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Document type:
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ECN-M--12-003
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Conference Paper
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Number of pages:
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Full text:
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17
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Download PDF
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Abstract:
Uncertainty in aerodynamic load prediction is an important parameter driving the
price of wind energy, especially for offshore locations. Blade Element Momentum (BEM) theory
is the current standard for estimating the wind forces in load case calculations. The variety
between the several engineering extensions used in different BEM implementations is huge.
In addition to that, the assumption of radial independence of the annuli and the lack of wake
modelling are well known shortcomings of this method. A more detailed approach to model the
rotor aerodynamics is presented by a vortex line method with a free vortex wake. Contrary to
the BEM method, it is possible to accurately simulate innovative rotor geometries exhibiting
distributed control or non-straight blades.
A survey is made to investigate the influence of the various modelling options for several
operating conditions. Firstly a rigid turbine is subject of investigation by means of a comparison
to the NASA-AMES and MEXICO wind tunnel test databases. The predictive capability of the
BEM modelling falls short for yawed flow and dynamic inflow cases. Coupling the aerodynamic
solver to a structural dynamics code allows for a full aero-elastic wind turbine simulation in
the time domain. The results are in agreement with measurements of a turbine at the ECN
test site Wieringermeer. In addition to that the influence of the various modelling options on
the aerodynamic damping is investigated. The research sheds new light on the uncertainties
and capabilities of rotor aerodynamics modelling for design calculations. The long term benefit
lies in improved guidelines for wind turbine design, thereby reducing the cost of offshore wind
energy.
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