Bionic design and test of small-sized wind turbine blade based on seagull airfoil

Power of the existing small-sized wind turbine blades is much less than the theoretical value. This study improved 100 W wind turbine blades to increase the power of wind turbine. First of all, Spalart-Allmaras model which was suitable for airfoil stalling characteristics research was used to analyze the aerodynamic characteristics of seagull airfoil and standard airfoil with different angles of attack (AOA). Seagull airfoil and standard airfoil were got from seagull wing and standard blade by portable three-dimension scanner, Imageware software and Geomagic Studio software through standard blade scan, seagull wing scan, point cloud processing, reverse engineering modeling and cross section capture. Lift coefficients and lift-drag ratios of seagull airfoil and standard airfoil were calculated by Fluent software. Secondly, bionic blade was designed based on standard 100 W blades and Glauert theory. Thirdly, numerical simulations of bionic blade and standard blade were performed by using SST(shear stress transport) k-ω model which was suitable for blade performance research to analyze the aerodynamic characteristics of bionic blade and standard blade. Last of all, efficiencies of bionic wind turbine and standard wind turbine were measured by using self-designed test platform to compare the effects of these 2 kinds of wind turbines. Lift coefficient of seagull airfoil was higher than that of standard airfoil with different AOA of from 0 to 20°. The maximum lift coefficient of seagull airfoil was 2.19 times that of standard airfoil with the AOA of 8°. Lift-drag ratio of seagull airfoil was also higher than that of standard airfoil with different AOA of from 0 to 20°. The maximum lift-drag ratio of seagull airfoil with the AOA of 3° was 1.34 times that of standard airfoil with the AOA of 5°. Static pressure color map showed that surface pressure difference of seagull airfoil was larger than that of standard airfoil with the same AOA. With the AOA of 15°, upper surface of standard airfoil was separated with airflow totally, whereas for seagull airfoil there was only half separation. Numerical simulations manifested that static pressure of standard blade was distributed from tip to root, whereas in bionic blade it was from tip to middle. Efficiency tests indicated that power of bionic blade was larger than that of standard blade within the wind speed of 0-10.7 m/s, which increased by 25.77%. The lift coefficient of seagull airfoil was higher than that of standard airfoil, which proved that seagull airfoil provided more lift than standard airfoil under the same working condition. The lift-drag ratio of seagull airfoil was higher than that of standard airfoil, which proved that seagull airfoil provided more power than that of standard airfoil under the same working condition. With the AOA of 15°, airflow was totally separated with standard airfoil but partly separated with seagull airfoil, which proved that stalling AOA of seagull airfoil was larger than that of standard airfoil. Therefore, it can be concluded that aerodynamic characteristics of seagull airfoil are better than that of standard airfoil, and seagull airfoil adapts to more complex working condition. This research provides the reference for improving the design of small-sized wind turbine.