中文摘要：

风力机叶片根部过渡段和圆柱段会产生较大的流动阻力，影响风力机的气动性能。延伸叶根翼型段是提高风力机气动性能的方法之一。本文采用翼型截面来代替过渡段和圆柱段，对2．5Mw风力机DF90叶片根部进行改进，并分别采用两种扭角规律进行造型，与原始叶片进行对比。结果表明，叶根改型后会改善一部分叶展区域的流动，从而提高叶片的功率，高风速条件下更为明显。在低风速条件下，叶根处翼型截面扭角的增大有利于功率的提高；在高风速条件下，扭角的增大有助于减小轴向推力的增加值。

英文摘要：

Blade root of horizontM axis wind turbine, which includes the transition section and the cylindrical section, would produce great flow resistance to influence the aerodynamic performance of wind turbine. So extending airfoil section is one of the methods to improve the aerodynamic performance. And this method was used in this paper based on a 2.5 MW wind turbine DF90. Two twist angle distributions were used in the paper, comparing with the initial blade. The results showed that the modified blades can improve the power, which was more obvious at high speed condition. In addition, increasing the twist angles of the root can improve the power at low speed condition. At high speed condition, increasing the twist angles can reduce the increment of axial thrust.