Experimental benchmark data for H-shaped and troposkien VAWT architectures

Most of the experimental research on vertical axis wind turbines was carried out during 1970–1980s but, recently, the potential of wind energy harvesting in new environments has renewed the interest on VAWT technology. Unfortunately, this interest still collides with an immaturity of aerodynamic modelling tools and detailed experimental analyses are now highly recommended to convert flow field comprehension into novel design techniques. This paper critically revises the main extensive wind tunnel campaigns conducted on VAWTs during the last 15 years. Moreover, a direct comparison between two widely adopted lift-driven rotor architectures, i.e. H-shaped and troposkien, characterized by the same swept area and blade section, is presented. After being instrumented to characterize aerodynamic performance and thrust as well as flow characteristics in the wake, the rotors were tested in the Politecnico di Milano wind tunnel using an open configuration, allowing real-scale measurements of micro wind turbines. A complete characterization was obtained by recording steady-state torque, thrust and flow velocity in the wake as a function of the unperturbed wind speed, while the angular velocity of the rotors was kept constant. The measurements were conducted with high accuracy and can represent a useful experimental benchmark for the validation of computational tools.