The present investigation provides the first field characterization of the influence of turbulent inflow on the blade structural response of a utility-scale wind turbine (2.5MW), using the unique facility available at the Eolos Wind Energy Research Station of the University of Minnesota. A representative one-hour dataset under a stable atmosphere is selected for the characterization, including the inflow turbulent data measured from the meteorological tower, high-resolution blade strain measurement at different circumferential and radiation positions along the blade, and the wind turbine operational conditions. The results indicate that the turbulent inflow modulates the turbine blade structural response in three representative frequency ranges: a lower frequency range (corresponding to modulations due to large eddies in the atmosphere), a higher frequency range (corresponding to flow structures in scales smaller than the rotor diameter), and an intermediate-range in between. The blade structure responds strongly to the turbulent inflow in the lower and intermediate ranges, while it is primarily dominated by the rotation effect and other high-frequency characteristics of wind turbines in the higher frequency range. Moreover, the blade structural behaviors at different azimuth angles, circumferential and radial locations along the blade are also compared, suggesting the comparatively high possibility of structural failure at certain positions. Further, the present study also uncovers the linkage between the turbulent inflow and blade structural response using temporal correlation. The derived findings provide insights into the development of advanced control strategies or blade design to mitigate the structural impact and increase blade longevity for the safer and more efficient operation of large-scale wind turbines.
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