Aeroelasticity and Structural Dynamics
Theoretical aeroelasticity outside the aerospace sector
Aeroelasticity of wind turbines
If a little work is done to adapt and validate those tools, the wind turbine industry will quickly be able to benefit from the tools and expertise acquired by Onera's Aeroelasticity and Structural Dynamics Department in the field of helicopter rotors. The Rotor code is an Onera/DADS tool widely validated in the helicopter field that has been used with some success for wind turbines. It is the only calculation tool of its type in France and has many highly developed options that can be directly applied to the study of a wind turbine:
- calculation of stability, periodic forced response and integrated in time,
- models of dynamic stalling and stipulated wake,
- coupling with a mathematical optimizer.
However, this code is not purely wind turbine oriented and it required developments to correctly simulate the operation of a wind turbine (models of turbulence, mask of the tower, etc.).
NREL experimental windturbine, tested at NASA/Ames, in the two-blade upwind configuration used for the validation of the different simulation codes
Since 2000, DADS has strengthened its role as expert with the Ademe. In 2002, the Ademe entrusted Onera with the coordination of the Prodema project (Advanced Multimegawatt Optimized Wind Turbine Rotor Project) carried out in partnership with Jeumont SA, Cnam IAT and USTL/LML and in 2005, a new Devamse project (DEvelopment and Validation of Models for Simulating wind turbine rotors), financed by the Ademe, was initiated. Within the framework of this project, the Ademe supports collaboration with the NREL (National Renewable Energy Laboratory) for the detailed exploitation of a database obtained from tests in the Nasa Ames giant wind tunnel on a highly instrumented wind turbine rotor. One of the configurations (photographed above) was proposed by the NREL for making a blindfold comparison between 19 different prediction codes (30 experts from 18 countries including 12 in Europe). The Onera/DADS Rotor code was evaluated on this configuration.
It turned out that, contrary the participants' results ("aeroelastic codes" category), Rotor is capable of correctly predicting the NREL machine's global behavior, for not only the torque (see figure) but also the loading of the different sections (30, 63 and 95%) and the blade root flapping moment.
In addition, this study indicated the sensitive points to be studied with greater attention: definition of the 2D polars in Reynolds and in the 15-40 degrees zone (often extrapolated from experimental results); correction of the 3D effects of rotation for the internal sections.
Predicted global behavior of the NREL machine (torque)
