Analysis of the influence of blade design on the performance of an H-Darrieus wind turbine

In recent times, increasing interest is being directed to Darrieus VAWTs in terms of both experimental and theoretical research: in particular, much attention is being paid to small size H-type Darrieus. In order to reach a good overall performance and to ensure the start-up of these machines, the blade design can be considered as a key topic. The optimization of the main blade design parameters (i.e. blade shape, airfoil geometry, camber positioning, pitch angle), however, cannot be pursued without considering the geometrical and structural constrains which derive from the small size and from the materials used for their construction. In the paper, a sensitivity analysis of the influence of the blade design on the performance of an H-Darrieus small size VAWT has been carried out to outline some relevant trends and effective design solutions; more in details, the effect of each design variable was analyzed in terms of inducted changes in the torque profile either of the blade itself or of the whole turbine. In order to perform the analysis, a Double Multiple Streamtubes model was developed and validated with an extended experimental campaign in a wind tunnel.