engleski

Offshore wind-turbine wake in the vicinity of coastal mountains and islands

Wind-tunnel experiments are carried out to analyze the wind-turbine wake downwind of a mountain. A single wind-turbine model in the wake of four different terrain models is studied. The wind turbine model corresponds to commonly used prototype wind turbines. Terrain models include flat terrain and three mountains of different size and shape. Wake characteristics analyzed with respect to the mean wind velocity, turbulence intensity and velocity power spectra indicate several important findings. The observed flow retardation is more exhibited near the ground surface and the mountains, while this shadowing effect weakens further downwind from the mountains. The mountain-induced flow disturbance enhances with increasing the size and complexity of the mountains. Mean velocities are nearly constant in the lateral direction for all terrain types. Turbulence intensity in the wake of the mountain and wind turbine is considerably larger than in the atmospheric boundary layer due to strong flow pulsation and recirculation, as well as a reduction in the mean wind velocity. Turbulence intensity is larger for more complex terrains, it dies out when moving further downwind from the mountain. Velocity power spectra are strongly influenced by the terrain complexity, whereas the effects of the mountain and surface roughness are mostly constrained up to the double mountain height. There is a strong energy content at frequencies corresponding to a free shear layer separating from the mountain ridge.

Offshore wind turbine; coastal mountains and islands; aerodynamics; wake; wind-tunnel experiments

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