Wind Tunnel Measurements at LM Wind Power

The optimization of airfoil profiles specifically designed for wind turbine application was initiated in the late 80’s [67, 68, 30, 15]. The first attempts to reduce airfoil noise for wind turbines made use of airfoil trailing edge serration. Themodification of airfoil shapes targeted at noise reduction is more recent. An important effort was produced in this direction within the SIROCCO project. This latter work involved measurements on full size wind turbines and showed that trailing edge serration may proved a viable solution for mitigating wind turbine noise though it has not been implemented on commercial wind turbine yet. It should be mentioned here that the attenuation of turbulent inflow noise using wavy leading edge has recently been investigated [55], but this technique has still to be further validated for practical applications.
In this paper, it is proposed to optimize an airfoil which is used for wind turbine applications, namely the NACA64-618 airfoil. The optimization procedure is performed with the in-house code AirfoilOpt. The objective is to reduce trailing edge noise, preserving some of the aerodynamic and geometric characteristics of the original airfoil using constraints at the same time. In this way, the resulting airfoil
should remain a realistic candidate for wind turbine applications and comparisons between the original and optimized airfoils remain fair. As for the verification in wind tunnel, the reader is referred to Section 7.3.