A simple arithmetic mean to ensure the convergence of models based on Blade Element Momentum theory applied to Vertical Axis Wind Turbines simulations

Abstract

The computer models based on the Blade Element Momentum (BEM) theory are able to predict the aerodynamic performance of wind turbines with good accuracy and efficiency. However, these methods may present some convergence difficulties. This work presents the development of a methodology adopting arithmetic mean in situations of flow instability to ensure the convergence of BEM models applied to Vertical Axis Wind Turbines (VAWT) simulations. This methodology was used in the creation of a program written in Fortran, called FASTEEVSIM. Tests were conducted in a Darrieus wind turbine using NACA0018 and DU06W200 airfoils as blade profiles. A comparison of the results using the FASTEEVSIM with experimental data from well-known literature sources has been done in order to validate the method. When comparing the power coefficients obtained for two types of blade profiles, one symmetrical (NACA0018) and another asymmetrical (DU06W200), the final validationresults showed a mean square deviation of 3.62% and 6.09%, respectively. The results showed that the developed methodology can assist the convergence effectively and that the FASTEEVSIM program is able to predict the performance of VAWT, providing data close to experimental values in a simple and fast way.