The Analysis of the Flutter Region of Wind Turbine Blade

Abstract

As the wind turbine blade is becoming larger and larger, the flutter of the wind turbine blade has been paid great attention by many fields. The flutter region of the wind turbine blade airfoil was focused on. The equation of motion for the flutter of blade airfoil was established, based on the simplified aerodynamic force and torque. The flutter analysis of wind turbine blade was carried out with the four-order Runge-Kutta methods, and so the flutter region of the blade airfoil can be obtained. The results show that, there are two critical tip speed ratios for the given blade airfoil. When the tip speed ratio is below the low critical speed ratio, the blade airfoil is convergent. At the low tip speed ratio, the blade airfoil system will become divergent from convergent condition. When the tip speed ratio is between the low critical tip speed ratio and the high one, the blade airfoil system will diverge. At the high tip speed ratio, the system will become convergent from divergent condition. When the tip speed ratio is above the high critical tip speed ratio, the blade airfoil system will converge again. In addition, the torsional angular displacement and velocity always keep convergent, the flap velocity is slightly divergent, because they are not sensible to the change of the tip speed ratio, and they are difficult to cause flutter, so the torsional motion will be more stable than flap motion for the given blade airfoil. It can provide one of references for the determination of the blade airfoil.