Optimizing a vertical axis wind turbine with helical blades: Application of 3D CFD and Taguchi method
Sepehr Sanaye, Armin Farvizi
Abstract
Vertical axis wind turbines (VAWT) with helical blades are being interested in urban areas due to the low dependency on the wind direction and also due to low noise production. In spite of good self-starting and smooth operation as the advantages of this type of turbine, its optimizing has not been reported in literature yet and is the subject of this research. A primary investigation by 3D computational fluid dynamics (CFD) to simulate the air flow about the above type of VAWT in the first step showed the importance of three design variables of tip speed ratio, helical angle, and airfoil chord length. However, in the second step, CFD runs were very time consuming and costly. For considering five values for each design variable, 5 3 = 125 cases had to be simulated by 3D CFD. Thus, by the use of Taguchi method and with definition of an orthogonal array named L-25, the number of required 3D CFD simulations reduced from 125 to 25. Then, the optimum values of variables were obtained as 1.33 for the tip speed ratio, 30 degrees for the helical angle, and 0.4 m for the airfoil chord length. At the optimum point, the average power coefficient increased to 0.17542. The presented research is novel for optimizing VAWT with helical blades. • Optimizing of a vertical axis wind turbine with three helical-blades are investigated here. • Tip speed ratio, helical angle, and airfoil chord length were assumed as design variables. • Airflow analysis about the turbine was performed by 3D CFD simulation method. • Taguchi method used for experimental design and for lower number of simulation runs. • The objective function (average power coefficient) at the optimum point was 0.17542.