Pitch Optimization in Small-size Darrieus Wind Turbines

Small Darrieus wind turbines are standing out as one of the most promising technologies in view of a widespread availability of delocalized energy production from wind. In view of a performance optimization of Darrieus rotors, the application of a pitch angle to blades has been often suggested. In the present work, the pitch modeling in an advanced BEM code has been exploited to investigate different pitch control strategies. In particular, the prospects of a pitch preset based on both the maximum power and the maximum energy extraction have been evaluated and compared to those connected to a progressive pitch variation with the turbine revolution speed. The pitch effects have been discussed both in terms of aggregated power output and of variation of the airfoil functioning conditions throughout a revolution. The analysis confirmed that the application of a proper pitch angle could definitely provide an increase of the turbine performance, especially at medium-high solidities.