Study on Coupled Mode Flutter Parameters of Large Wind Turbine Blades

Abstract As the output power of wind turbines continues to increase, the blade size and flexibility increase. In actual operation, unpredictable airflow caused by natural changes in wind speed leads to aeroelastic instability of the blade structure, increasing the possibility of blade flutter damage. Under the same design, different manufacturing processes result in different structural performance of blades. The parameter changes in different regions of the blade will have an impact on the flutter characteristics of the blade coupling mode. Taking NREL 5MW wind turbine blades as an example, the blades are divided into tip, middle, and root regions to study the influence of structural parameter changes in different regions on blade flutter characteristics. Research has found that the flutter characteristics are most affected by parameter changes in the blade tip region; as the waving stiffness increases, the flutter velocities in all three areas of the blade decrease and tend to stabilize; the blade flutter speed increases with the increase of torsional stiffness; the blade flutter speed is least affected by the centroid shift, but is more affected by the centroid shift in the tip region; The turning radius is inversely proportional to the blade flutter frequency and flutter speed. In blade anti flutter design, increasing the torsional frequency can effectively prevent the occurrence of blade coupling mode flutter.