Validation of a coupled atmospheric-aeroelastic model system forwind turbine power and load calculations

Abstract. The optimisation of the power output of wind turbines requires the consideration of various aspects including turbine design, wind farm layout and more. An improved understanding of the interaction of wind turbines with the atmospheric boundary layer is an essential prerequisite for such optimisations. Using numerical simulations, a variety of different situations and turbine designs can be compared and evaluated. For such a detailed analysis, the output of an extensive number of turbine and flow parameters is of great importance. Usually simulations are either specified to the output of turbine parameters or the detailed simulation of the flow. In this paper a coupling of the aeroelastic code FAST and the Large-Eddy Simulation tool PALM is presented. The advantage of the coupling of these models is that it enables the analysis of the turbine behaviour, i.a. turbine power, blade and tower loads, under different atmospheric conditions. The proposed coupling is tested with the generic NREL 5 MW turbine and the operational eno114 3.5 MW turbine. Simulating the NREL 5 MW turbine allows for a first evaluation of our PALM-FAST-coupling approach based on characteristics of the NREL turbine reported in the literature. The comparisons of the simulations to the NREL literature values show very promising results. Furthermore, a validation with free-field measurement data for the eno114 3.5 MW turbine for a site in Northern Germany is performed. The results show a good agreement with the free field measurement data. Additionally, our coupling offers an enormous reduction of the computing time, in comparison to similar methods with the same detail, and at the same time an extensive output of the turbine data.