AUTHORS

microphone array, windturbine noise, trailing edge noise, inflow-turbulence noise Aeroacoustic wind tunnel tests were performed for six airfoils that are candidates for use on small wind turbines. One additional airfoil (NACA 0012) was tested for comparison to benchmark data. The acoustic measurements were performed in NLR's Small Anechoic Wind Tunnel, for a range of wind speeds (U) and angles of attack, with and without boundary layer tripping. Besides the airfoil self-noise measurements in a clean tunnel flow, the models were also tested with a turbulence grid in the nozzle, to investigate airfoil noise associated with inflow turbulence. A 48-microphone out-of-flow acoustic array was used to locate noise sources and to separate airfoil noise from extraneous wind tunnel noise. Special techniques were applied to translate acoustic source plots to absolute airfoil noise spectra. The acoustic results indicate that in a clean tunnel flow trailing edge noise is dominant for all airfoils. In the untripped condition a number of airfoils exhibit intense tones, that disappear after proper tripping is applied. Broadband trailing edge noise levels are found to scale with U 4.5. The agreement with the benchmark data was generally good. In case of inflow turbulence, leadin