The European program HORIZON2020 aims to have 20% of electricity produced by renewable sources. The building sector represents 40% of the European Union energy consumption. Reducing energy consumption in buildings is therefore a priority for energy efficiency. The present investigation explores the most adequate roof shapes compatible with the placement of different types of small wind energy generators on high-rise buildings for urban wind energy exploitation. The wind flow around traditional state-of-the-art roof shapes is considered. In addition, the influence of the roof edge on the wind flow on high-rise buildings is analyzed. These geometries are investigated, both qualitatively and quantitatively, and the turbulence intensity threshold for horizontal axis wind turbines is considered. The most adequate shapes for wind energy exploitation are identified, studying vertical profiles of velocity, turbulent kinetic energy and turbulence intensity. Curved shapes are the most interesting building roof shapes from the wind energy exploitation point of view, leading to the highest speed-up and the lowest turbulence intensity.

In this paper, calculus of variations and combined blade element and momentum theory (BEMT) are used to demonstrate that, in hover, when neither root nor tip losses are considered; the rotor, which minimizes the total power (MPR), generates an induced velocity that varies linearly along the blade span. The angle of attack of every blade element is constant and equal to its optimum value. The traditional ideal twist (ITR) and optimum (OR) rotors are revisited in the context of this variational framework. Two more optimum rotors are obtained considering root and tip losses, the ORL, and the MPRL. A comparison between these five rotors is presented and discussed. The MPR and MPRL present a remarkable saving of power for low values of both thrust coefficient and maximum aerodynamic efficiency. The result obtained can be exploited to improve the aerodynamic behaviour of rotary wing micro air vehicles (MAV). A comparison with experimental results obtained from the literature is presented.

Presentamos una experiencia piloto de aprendizaje sobre el uso de Realidad Virtual Inmersiva (VR) y Realidad Aumentada (AR), con el objetivo de facilitar la comprensión de la dinámica compleja de rotores, a estudiantes de Grados en Ingeniería Aeroespacial. Las experiencias en VR/AR permiten visualizar los movimientos de las palas de los rotores (hélices, aerogeneradores y helicópteros) así como los campos vectoriales de las acciones externas (aerodinámicas, inerciales y gravitatorias) que originan esos movimientos. Se consulta a los estudiantes sobre los pros y los contras de la experiencia piloto en comparación con los métodos tradicionales basados en representaciones estáticas de los resultados de la dinámica. La conclusión principal es que las experiencias VR/AR son herramientas valiosas para complementar los métodos tradicionales. Avila-Sanchez, Sergio; Cuerva-Tejero, Alvaro; Giraldo, Luis; Lopez-Garcia, Oscar; Gallego-Castillo, Cristobal; Fernandez-Aldama, Ricardo; Elagamy, Mohanad; Velasco