Airfoil Selection for a Small-Scale Vertical Axis Wind Turbine; A Numerical Study
Author: Babak Ranjbaran
Year: 2021
Supervisor: Ármann Gylfason
Abstract:
This thesis is conducted with methods to select an airfoil for a small-scale vertical axis wind turbine to operate at relatively low tip-speed ratios. With the application of Computational Fluid Dynamics (CFD), the aerodynamic performance of the selected airfoil is then compared to the commonly used NACA 0018 airfoil.
Our approach is to focus on the tangential force employed in the selection of the airfoil. To do so, an approach was developed using MATLAB software to use NACA four-digit algorithm to generate the geometry of the airfoil and, then by the implementation of Xfoil V6.99 to the code, the values of tangential force coefficient for a range of angles of attack are then predicted. These values are then compared to the NACA 0018 airfoil. The airfoil that yields the highest tangential force coefficient at a range of angles of attack is chosen.
The selected airfoil is then used to model an H-type Vertical Axis Wind Turbine (VAWT), which is then used for CFD simulations. The results show that the power coefficient of the turbine equipped with the selected airfoil exceeds that of equipped with NACA 0018 for a lower rotational rate (TSR <3), and the maximum relative growth rate of 56% occurs at the tip-speed ratio of 1.