The Design Of Wind Turbine Blade And The Simulation Of Flow Field

As the world energy issues increased seriously, various countries pay more attention on the development and utilization of new energy resources, especially on wind energy. Blade is one of the most important components in the wind turbine, which is used for converting wind energy to kinetic energy. In overseas the research on its design was begun very early. And many theories and methods were developed. As the same time, the study was just emphasized from the end of last century in our country. In this paper, the summary of the design theories and methods was made. At the same time, the numerical method was used to simulate the air flow field around the wind turbine blade.First, the design theories of wind turbine were summarized. And on the basis of this, the method of Glauert was derived. Then the loss factor of blade tip was brought into the derivation. So the method of Wilson is got. Based on the analysis of Wilson method, the program of Wilson method was written with MATLAB language. The space coordinate of every blade element were got by the MATLAB program. And these coordinates were written into text files, which can be imported into the drawing software.Second, the commercial CFD software Fluent was used to simulate the two dimensional air flow field around NACA4412, which was chosen as the airfoil for the wind turbine. And the curve of the lift coefficient, drag coefficient and pressure coefficient on the wall were known, when the Reynolds number was 300000 and the angle of attack was less than 30 degree. On the basis of this, the influence of the attack angle's change on boundary layer separation was analyzed. While the influence of boundary layer separation on the lift coefficient, drag coefficient and pressure coefficient on the wall was analyzed. The analysis indicate that NACA4412 was suitable for the wind turbine airfoil, because the boundary layer separation did not occur and the characteristics of lift-drag was good when the attack angle less than 13 degrees.Finally, the paper took the 10KW wind turbine blade design as a calculation example. And the blade was modeled by Solidworks. Then Fluent was used to simulate the three dimensional air flow field of the blade in the design conditions and in the non-design conditions. By this way, the wind energy utilization coefficient and axial thrust coefficient and torque coefficient were got. So the aerodynamic performance was estimated and analyzed. In addition, in order to analyze the aerodynamic load, the blade was divided into nine parts. And Ansys was used for blade static analysis. The maximum displacement and maximum stress were got. Based on the analysis, some suggestion for optimization of blade structure was proposed.