Aerodynamic damping in the model of blade

In this article is presented the modal analysis of the blade in pitch regulated horizontal axis wind turbine. The structural model of the blade is modelled as beam elements in MSC Nastran. As a result of modal analysis are received the mode shapes with the frequencies of blade vibration. Than is made attempt to describe the influence of the aerodynamic damping phenomena on dynamics of the blade. To calculate the wind components and aerodynamic damping coefficients is used the modified blade element momenthum method. The final result is the modal damping expressed by logarithmic decrement in a function of the blade's pitch angle and the free-stream wind velocity.