engleski

Experiments on wind-turbine wake in complex terrain

The ability of wind turbines to harvest energy from the wind decreases in complex mountainous terrain due to a decrease in average wind velocity at the wind-turbine hub height. In addition, unsteady wind loading of wind energy structures in those areas is characterized by some additional, unknown features as a consequence of enhanced atmospheric turbulence. Hence, experiments are designed and carried out in the CRIACIV boundary layer wind tunnel in order to characterize flow and turbulence in the wake of an offshore wind turbine placed downwind of a coastal mountain. The wind-tunnel simulation of the atmospheric boundary layer (ABL) developing above the flat terrain created by using the castellated barrier wall, vortex generators and surface roughness elements is in good agreement with the atmospheric flow and turbulence. Three different mountain models are separately exposed to the ABL simulation in order to study wake characteristics of an alone-standing offshore wind turbine placed downwind from the mountain. The wind turbine is in the parking position in order to study wind characteristics for a strong wind situation when there is no rotation of the rotor blades. Experimental results indicate a velocity decrease and stronger turbulence in the wind-turbine wake in presence of a coastal mountain. Velocity at the hub height downwind of a mountain is considerably retarded in comparison to the freestream velocity. This shadowing effect weakens further downwind from the mountain. Strong velocity gradients observed around the hub height may create large bending moments due to strong winds acting on the higher part of the wind turbine along with different vortex shedding characteristics for different parts of the structure resulting in deteriorated structural stability. This work is supported by the FP7- MARINET Program.

Wind-turbine wake; complex terrain; wind-tunnel experiments

nije evidentirano