Structural analysis of a small H-Darrieus wind turbine using beam models: development and assessment

In the present wind energy research, Darrieus-type vertical-axis wind turbines are increasingly appreciated, especially in small installations. In particular, H-shaped turbines can provide attractive spaces for novel design solutions, aimed at reducing the visual impact of the rotors and then at improving their degree of integration with several installation contexts (e.g. a built environment); moreover, novel small rotors are thought to be able in the near future to make large use also of new and cheaper materials (e.g. plastic or light alloys) which could notably reduce the final cost of the produced energy. As a consequence, the structural analysis of the rotors becomes more and more important: a continuous check between the design solutions needed to maximize the aerodynamic performance of the blades and the structural constraints must be provided. In addition, the requirements of international standards for certification encourage the development of proper numerical tools, possibly with low computational costs for the manufacturers. In this study, the structural analysis of a novel three-helixbladed Darrieus turbine is presented; the turbine is a real industrial machine almost entirely produced with plastic with a new complex aesthetic design. In detail, a structural modeling based on beam elements has been developed and assessed in comparison to more complex models, as it was thought to provide a notable reduction of the computational cost of the simulations with an acceptable decrease of the accuracy. Moreover, the 1D structural model was exploited to verify the capabilities of a novel software, able to verify the dynamic response of the wind turbine in real functioning, i.e. with mechanical loads and interactions with the wind flow. Benefits and drawbacks of the proposed modeling approach are finally discussed by analyzing both the calculation time and the accuracy of the simulations.