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Title design tools for horizontal axis turbines

In this project, the impact of non-steady (deterministic and stochastic or turbulent) inflow of wind on the loading and unsteady aerodynamics of horizontal axis wind turbines is simulated numerically to develop a new generation of design tools. First, existing models have been evaluated in detail to detect inherent deficiencies. These have subsequen tly been improved with respect to new measurements covering a wide range of turbines. Next, elaborate new models have been developed and validated.

Structural, aerodynamic and wind simulation models have been analysed and developed separately before coupling. The beam and shell structural models (BEAMDYN and NISA-II) were evaluated on the basis of eigenvalues and static tests, and results from lamination theory were used to define a homogeneous technique which determines the elastic characteristics over the blade skin. These properties were then averaged over each section of the blade, according to the thin wall shell theory, to give the equivalent beam characteristics (PROBEAM).

The classical blade element model has been improved to give correct predictions over a wide range of operational conditions and specifically in the case of dynamic inflow (CBEM+). The free wake vortex particle model (GENUVP) has been upgraded into a complete aero-elastic model and also simplified to give intermediate vortex models (LIFTL and LSURF) which are equipped with semi-prescribed wake and correspond to the lifting-line and lifting surface formulations of the rotor aerodynamic problem. For the turbulent wind simulator, the Veers model was analysed and generalised for complex terrains (INWIND). Combined with aeroelastic calculation the use of INWIND provided data for the in time behaviours of wind turbines. Signal processing techniques were then applied in order to detect the basic non-linear mechanisms. The optimisation of wind turbine design allows cost reductions and energy savings in the order of 10%.

Reported by

National Technical University of Athens
9 Heroon Polytechniou Street
15773 Athens
Greece