Fluctuation properties of streamwise wind speed around wind turbine blade

This paper applies the large eddy simulation method to study the fluctuation properties of streamwise wind speed (u) around a wind turbine blade and its correlation with the fluctuation of the lift coefficient (CL) and drag coefficient (CD). Results show that the inlet boundary conditions need to consider the actual u fluctuations. There are differences in statistical and spectral properties of turbulent motions in high-speed and low-speed regions. In the high-speed region, the logarithmic power spectral density decays approximately linearly with increasing logarithmic frequency. Affected by the flow around the thick and blunt airfoil, the power spectrum in the low-speed region presents a local elevation or a plateau in the mid-to-high frequency range. The scale of large-scale turbulent motions in the low-speed region increases. In the frequency domain, the u fluctuation on the surface of the wind turbine blade has a good correlation with the incoming u fluctuation. Low-frequency u fluctuations have better correlation than high-frequency u fluctuations. Moreover, the spectral form of CL is similar to that of u, and the CL and CD fluctuations have a high correlation with u fluctuations, and the correlation of the high-frequency part is better than the low-frequency part.