The flow field in the wake of a an horizontal axis wind turbine was studied through wind tunnel tests at the Mechanical Department of the Politecnico di Milano. Aim of the research is to measure the wind flow in different points in the wake in order to characterize the flow blowing on structures that are positioned downwind a wind turbine and specifically on overhead power lines (OHL). The gathered experimental data consist in anemometric measurements and in the study of the dynamic response of an aeroelastic model of a OHL positioned in the wake of the wind turbine. The wind turbine model represents a 1:50 scaled model of a 3MW full scale wind turbine with a rotor diameter equal to 90 m. The model is equipped with an electric motor able to control the rotor angular velocity to reproduce the correct kinematics in the different wind speed operating conditions. Moreover, a mechanical system allows to change the blade pitch angle in order to have, on the blade profile, the correct velocity composition between the wind velocity and the motion velocity, as it happens in full scale. Figure 1 reports a picture of the model in the wind tunnel test section and a rendering of the model highlighting the structural scheme inside the nacelle. Contact person: D. Rocchi, Mechanical Department of the Politecnico di Milano, Via La Masa 1, 20158 Milano, +39 02 2399 8485, FAX +39 02 2399 8492. E-mail daniele.rocchi@polimi.it Wind tunnel investigation on wake effects of a wind turbine G. Diana, D. Rocchi, S. Giappino. Mechanical Department of Politecnico di Milano – giorgio.diana@polimi.it – Via La Masa 1 20158, Milano – Mechanical Department of Politecnico di Milano – daniele.rocchi@polimi.it – Via La Masa 1 20158 Milano – Mechanical Department of Politecnico di Milano – stafano.giappino@polimi.it – Via La Masa 1 20158 Milano PAPER NOT RECEIVED