This work focuses on a particular type of vertical-axis wind turbine, in which a number of inclined arms with airfoil-shaped cross-sections are mounted to connect the principal blades to their hub. While the majority of the known studies on vertical-axis turbines is devoted to the role of principal blades, in most of the cases without taking into account other parts of the wind turbine, the objective of this work is to investigate the effect of uncommon arm geometries, such as the inclined arms. The inclined arms are known to have a potentially beneficial role in the power extraction from the wind current but, due to the complexity of the phenomena, the investigation on aerodynamics of this type of turbine is often impossible through analytical models, such as blade-element momentum theory. It turns out that adequate studies can only be carried out by wind tunnel experiments or CFD simulations. This work presents a methodical CFD study on how inclined arms can be used on a selected wind turbine configuration to harvest additional power from the wind. The turbine configuration, geometry, and some fundamental definitions are introduced first. Then an in-depth CFD analysis is presented and discussed.

The design and analysis of a new airfoil to be employed on a ultralight aircraft with short takeoff and landing is presented. An inverse design philosophy has been applied and is described; the numerical analysis performed used XFOIL, MSES, and TBVOR computational codes and the effects of airfoil shape on complete aircraft performances were taken into account. A high-lift configuration, including slat and single-slotted flap geometries, has been developed and is illustrated in this paper. Exhaustive wind-tunnel tests were performed at the Department of Aerospace Engineering and the experimental results are described here. To validate numerical results and to analyze the effect of laminar bubbles on airfoil performance, the pressures on airfoil surface and in the wake were measured and flow visualizations were done using fluorescent oil. The landing configuration was also tested and an experimental optimization of flap and slat positions was carried out to obtain a high maximum lift coefficient