Skin friction reduction obtained with riblets

Riduzione resistenza d'attrito tramite tecnica riblets. The main goal of this thesis was to study and characterize the drag reduction capabilities of the riblets technology. Riblets are essentially grooves that protrude through the viscous portion of the boundary layer and they have been proven to reduce the skin friction drag. The first step was to optimize a procedure that would allow for repeated and fast substitution of various surfaces covered with different types of riblets. We developed a support and a measuring system from the ground up, while ensuring high accuracy in data collection. We then proceeded to test and collect data for longitudinal riblets, the most common type in the literature, along with two surfaces equipped with sinusoidal riblets with amplitude equal to 150µm and 600µm, measured as the maximum distance from the longitudinal axis. The experiment was carried out in the "Modesto Panetti" laboratory using the Fucsia wind tunnel, specifically designed for the study of the boundary layer. The obtained results were consistent with the literature on the matter, achieving average drag reduction rates of 6.18% in case of the longitudinal riblets, and close to 9.5% in the cases of the sinusoidal riblets.