Investigation on Performance Influence of Maximum Thickness Position on Vertical Axis Wind Turbine Airfoil

Airfoil geometric configuration is very important for aerodynamic performance of a straight-bladed vertical axis wind turbine (SB-VAWT). In recent study, Islam et al have pointed out old NACA-4 are not perfectly suited for SB-VAWT operating at low Reynolds number and special purpose airfoils is needed. Islam has singled out four required geometric features which would be suitable for SB-VAWT airfoil. However, the maximum thickness position, considered one of the important geometric parameters, was not involved in Islam's research. In this paper, NACA0015 airfoil was chosen as the basic airfoil, whose maximum thickness position was shifted to generate another four airfoils. With the approach of combining XFLR5 program and Viterna-Corrignan psot-stall mode, airfoil characteristics in attack angle range from 0 degree to 90 degree have been calculated. It has been found in this paper that, with the Reynolds number changing from 50,000 to 500,000, altering the maximum thickness position has varying degrees of affects on airfoil aerodynamic characteristics. The maximum thickness position should be involved in the SB-VAWT airfoil design, and the optimum maximum thickness position needs to be determined with the consideration of the Reynolds number range where the SB-VAWT operates.