Blade design for a horizantal axis variable speed wind-driven generator

First of all, blade element theory is presented in this paper. Based on this theory, the power outputs of the wind turbine are calculated from aerodynamic parameters of airfoil. With these, pitch control concept and speed control concept are presented. Then, different pitch angle distributions along the radius and corresponding power outputs are analyzed. A blade for a variable speed wind-driven generator can be designed to decrease the speed variation range through designing the pitch angle of the cross section of the blade properly, on the condition that the power output is stable from rated wind speed to shut down wind speed.