Analysis on Aerodynamic Characteristics of A Paraglider Airfoil

Paraglider sail (canopy) consists of a series of flexible boxes pressurized by special openings located at the leading edge, in the region near to the front stagnation point. Therefore, in order to avoid the deflation of the wing, the pressure inside the sail must remain above a certain threshold. To investigate this problem it has been considered an airfoil with a typical paraglider geometry equipped with air intakes. The aerodynamic behavior was determined performing experimental, Xfoil and CFD numerical analysis. Hollow models were made by a rapid prototyping and have been tested in a wind tunnel, measuring forces and moments on the profile and the pressure inside the canopy. Making different considerations, concerning the relationship between the internal pressure of the canopy and the upstream pressure gradient of the inlet, the results regarding the airfoil equipped with inlets have been compared with another airfoil with same geometries but without inlets. The pressure inside the airfoil has been satisfactorily related with numerical estimations and, subsequently, a new airfoil shape, with a different configuration of the inlets, has been developed by using an optimization process based on a multi-objective genetic algorithm. The new shape optimizes the internal pressure, especially at low angle of attack, according to the fact that the internal pressurization is a fundamental for safety flight requirements.