Flutter limit optimization of offshore wind turbine blades considering different control and structural parameters

The aeroelastic stability of highly flexible blades under complex sea conditions is one of the key issues restricting the reliability and efficiency growth of offshore wind turbines. This work takes the IEA-15 MW offshore wind turbine as the research object and uses the geometrically exact beam theory for structural analysis. For the flutter analysis, the blade element momentum theory is employed in conjunction with the structural model. These calculation methods proved to be valid for calculation result compared with other numerical methods and experimental results. The effects of control and structural properties on the flutter performance of the 15 MW wind turbine blades are investigated by considering the pitch angle, yaw angle, torsional stiffness and structural damping. It is numerically shown that the flutter speed can increase by 15.56% by adjusting pitch angle (from 0° to 5°) and the flutter performance can be improved by setting a yaw angle of 10 degrees. And the results of structural characteristics demonstrated that the flutter performance of highly flexible offshore blades can be improved by properly increasing the torsional stiffness and edgewise structural damping.