Automatic modelling of airfoil data points

This paper presents a computer-based technique to construct B-spline parametric models from a large set of airfoil data points, with a reduced number of parameters involved in the geometric representation of the airfoil profile. The proposed method uses different techniques related with the B-spline properties adapted to the geometry of an airfoil (a thin section with great changes of curvature) and produces a B-spline curve that is close to the data points maintaining a maximum tolerance distance. This curve can be used for calculations and is expected to provide a good framework for aerodynamic or hydrodynamic optimization, based on its reduced number of geometric parameters and on its calculation time, when compared with other methodologies. The method stresses the fitting of the airfoil's leading edge, which has a significant impact on the properties of the airfoil. B-spline curves and surfaces are used in this method because they are widely used in CAD-CAM software products and can be easily exported to other programs.