## 1 Introduction  
With the continuous improvement of wind turbine power, wind turbine blades are becoming longer and longer. In order to ensure the strength of the blade, the trailing edge of the blade often uses a blunt trailing edge airfoil of large thickness [1, 2, 3]. Larger flow separation occurs at the trailing edge of the blade during operation, which reduces the efficiency of wind energy capture by the wind turbine. Therefore, knowing how to accurately predict and effectively improve the aerodynamic performance of the wind turbine airfoil has very important practical significance. Processing the trailing edge of the airfoil is one of the effective ways to improve aerodynamic performance. At the same time, many scholars have conducted much research on the thickness of the airfoil trailing edge. The main methods of thickening the airfoil trailing edge are the direct truncation method [4], the symmetric thickening method [5], the asymmetric thickening method [6, 7, 8], and the airfoil rigid rotation method [9]. [PERSON] [10] conducted a wind tunnel test study on a blunt trailing edge airfoil obtained by direct truncation of a Gottinggen-490 airfoil. It was found that the maximum lift coefficient of the airfoil could be increased by increasing the thickness of the trailing edge, but this method will change the relative thickness of the airfoil or change the centerline distribution of the asymmetric airfoil. In this case, the modified airfoil and the original airfoil are not comparable. It is difficult to clearly show that the thickness of the blunt trailing edge of an airfoil changes its aerodynamic performance. [PERSON] et al. [11] cut a DU97-W-300 airfoil directly after 79.3% of the chord length and extended the chord length to 1.0 in proportion to the truncated airfoil. It was found that the aerodynamic performance of the modified airfoil was worse than that of the original airfoil, indicating that not all airfoils modified to blunt trailing edge airfoils by direct truncation show improved aerodynamic performance. [PERSON] et al. [12] symmetrically increased the thickness of an airfoil on both sides of the airfoil mid-curve through an exponential mixing function method that does not change the maximum thickness of the original airfoil and the centerline distribution. [PERSON] et al. [13] found that blunt trailing-edge modification can not only provide a number of structural advantages, such as increasing the cross-section area and inertia moment of bend for a given maximum thickness and chord, but it also produces a great improvement in the lift coefficient and reduces the sensitivity to surface soiling. [PERSON] [14] analyzed airfoils with a symmetric blunt trailing-edge thickness through the experimental method. The research results indicated that a moderate trailing edge thickness increase could increase the lift-drag ratio and reduce the leading-edge roughness sensitivity. [PERSON] et al. [15] studied the effects of four different blunt trailing edge shapes on the performance of wind turbines and found that circular and blunt trailing edge airfoils have an important impact on the performance of wind turbines. [PERSON] et al. [16] found that using a blunt trailing edge airfoil at a specific position at the root of a large wind turbine can improve the inner force of the blade to a certain extent; compared with a pointed trailing edge wind turbine, the axial power of the whole blade is increased by 1%, and the bending moment of the blade is reduced by 0.5%. [PERSON] [17] proposed that increasing the absolute thickness of an airfoil during blade design can increase the flapping stiffness of the section. Many scholars have conducted a lot of other research on airfoil trailing edges [18; 19; 20]. However, most studies were modified for a single airfoil, and there was no parameter control for modification of the thickness of the trailing edge, which cannot achieve the purpose of precise modification.