A study on performance influences of airfoil aerodynamic parameters and evaluation indicators for the roughness sensitivity on wind turbine blade

The roughness increase on horizontal axis wind turbine （HAWT） blade surface, especially on the leading edge, can lead to an aerodynamic performance degradation of blade and power output loss of HAWT, so roughness sensitivity is an important factor for the HAWT blade design. However, there is no criterion for evaluating roughness sensitivity of blade currently. In this paper, the performance influences of airfoil aerodynamic parameters were analyzed by the blade element momentum （BEM） method and 1.5 MW wind turbine blade, It showed that airfoil lift coefficient was the key parameter to the power output and axial thrust of HAWT. Moreover, the evaluation indicators of roughness sensitivity for the different spanwise airfoils of the pitch-regulated HAWT blade were proposed. Those respectively were the lift-to-drag ratio and lift coefficient without feedback system, the maximum lift-to-drag ratio and design lift coefficient with feedback system for the airfoils at outboard section of blade, and lift coefficient without feedback, maximum lift coefficient with feedback for the airfoils at other sections under the pitch-fixed and variable-speed operation. It is not necessary to consider the roughness when HWAT can be regulated to the rated power output by the pitch-regulated and invariable-speed operation.