Darrieus Wind Turbine; Performance Enhancement Due to the Blade Cross-Section Optimization

This research investigates the effect of optimization of blade cross-section on the performance of the Darrieus wind turbine. The fluid flow around a Darrieus wind turbine is simulated by URANS (Unsteady Reynolds Averaged Navier Stokes) method. And blade cross-section was modeled by the Bezier curve and optimized to increase the average torque of the wind turbine. We used a novel, simple way for remeshing new design points in the optimization process. The Nelder-Mead simplex method was used for optimization, which enhanced the Turbine’s performance by 33.7 percent. Results show that optimization of the blade cross-section is effective for increasing the performance of a VAWT (Vertical Axis Wind Turbine), and Nelder-Mead simplex is a proper and fast optimization method to be used in this case. Finally, the optimized airfoil was analyzed and compared with the initial one to understand optimization effects. It was concluded that optimization was more effective in azimuth positions of 90 to 160 degrees. And it decreased the performance in some regions according to changing nature of flow around each blade because of rotational motion. Analyzes show that optimization increased the Turbine’s performance by increasing lift force of airfoil in some positions or affecting interaction flow -even accompanied by decreasing lift force of airfoil- in other positions, and it decreased performance in some other azimuth points.