Calibração do modelo de turbulência k-ω SST para turbinas eólicas de pequeno porte através de avaliação numérica e experimental

Abstract

In this work it was performed a numerical and experimental investigation of the aerodynamic performance of two small three-bladed wind turbines with diameter of 3m. The airfoils used, NACA 0012 (symmetrical) e NACA 4412 (unsymmetrical), were designed for low speed applications, such as the horizontal axis wind turbines. The wind turbines were built and tested at the Solar Energy and Natural Gas Laboratory –UFC. This allowed the attainment of the performance curves, enabling the comparison between the results of the numerical analysis. In order to calibrate the turbulence model k-ω SST to applications in small wind turbines, it was performed numerical simulations using the open source package for CFD solutions OpenFOAM, version 1.7.1. The numerical and experimental results were compared, in a way that, from the variation of parameters such as turbulence intensity, characteristic length and β* (calibration constant), it can be concluded that the numerical results were little sensitive to the first two parameters, while the variation of β* impacted significantly the numerical results. The change of airfoil did not modify the value of β* that best adjusted the result. This, beyond the success of the calibration process, indicates that the camber did not affect the calibration of the turbulence model, which is very positive because it allows an evaluation of different scenarios, such as blades designed with other airfoils.