An Annotated Database of Low Reynolds Aerodynamic Coefficients for the NACA0018 Airfoil

Wind industry needs high quality airfoil data for ranges of the angle of attack (AoA) much wider than those provided by the relevant technical literature, especially for aerospace applications. This kind of data is useful both in case of horizontal-axis wind turbines (HAWTs) for the root region and for vertical-axis ones (VAWTs), where the AoA varies continuously during the revolution. Moreover, the need of accurate results is even more urgent in case of low Reynolds conditions, where the standard tools for the prediction of the aerodynamic coefficients (e.g. panel methods) need to be properly set and are often contradictory in comparison to experiments. Moving from this background, in this study an extended survey of the technical literature has been carried out for the NACA0018 airfoil, which is a typical profile widely used in wind energy applications, and especially in VAWTs. Both experimental and numerical data have been collected, compared and critically discussed. Original simulations and tests from the authors are also provided. The scope of the study is to provide the scientific community with an annotated database of aerodynamic coefficients for this airfoil, making accurate and robust results available to any researcher willing to use this airfoil in wind energy applications.