MOD-2 Wind Turbine: Aeroacoustical Noise Sources, Emissions, and Potential Impact

This report summarizes research into characteristics of acoustic noise emissions of the DOE/NASA MOD-2 wind turbine. The results of this study showed that the MOD-2 noise levels are well below annoyance thresholds within residential structures a kilometer or more from the turbine rotor. It was also found that the inflow turbulent structure has a major influence on the level and characteristics ofthe low-frequency-range (2-150 Hz) acoustic emissions which, in turn, have implications for the associated structural response of the rotor assembly. The high-frequency-range (A-weighted) levels were found to vary primarily with the mean hub-height wind speed. The rotor inflow turbulence characteristics at the Goodnoe Hills site were found to be controlled almost entirely by the diurnalvariation in the vertical stability of the first 100 m of the atmospheric boundary layer.