A numerical study of blade thickness and camber effects on vertical axis wind turbines

This paper presents the results of a two dimensional computational study into the effects of rotor blade thickness and camber on the performance of a 5kW scale Vertical Axis Wind Turbine (VAWT). Validation is provided by reference to experimental data for a pitching aerofoil with dynamic stall phenomenon. The performance of the turbine is mapped out for a variety of different tip speed ratios and detailed investigations are presented to determine how and most importantly why the turbine performance varies with thickness and camber as it does. The rotor blades chosen were the NACA0012, NACA0022, NACA5522 and LS0421. The turbine rotor has a diameter of with a blade chord length of . Over the range of tip speed ratios examined, the NACA0012 profile performed with the highest overall performance (CP) of 50% at . Slightly cambering aerofoils (such as the LS0421) can improve the overall performance of the VAWT whereas a camber of 5% (NACA5522) results in unfavourable performance. Of the cambered blades tested, the LS0421 performs the best with maximum CP of 0.40 at . A camber along the blade path causes the blades to generate higher values of torque in both the upwind and the downwind regions. It was also determined that inverted cambered profiles produce power mostly in the upwind region.