The power generated by horizontal axis and vertical axis wind turbines is strongly dependent on the aerodynamic performance of the turbine. This includes the lift and drag forces generated by the individual blades and interactions between them in a rotating configuration; as well the aerodynamic effects of the turbine structure and the terrain. To maximize the efficiency of wind turbines, experimental and computation analysis of the blade and system is normally needed. This research is part of larger efforts at Michigan State University to develop a sustainable low speed wind energy systems and is focused on the aerodynamic modeling of vertical and horizontal axis wind turbines. The main objective is to better understand the effects of various parameters on the performance of these turbines. A computational model was developed as part of this research for studying the aerodynamics of vertical axis turbines. The model is refined via experimental data and other computational results available in literature. A parametric study was conducted with this model. The effects of parameters like the tip speed ratio, airfoil shape/type, Reynolds number are investigated in detail. The aerodynamics of variable pitch vertical axis wind turbines is also studied. Our results indicate that a significant improvement in aerodynamic efficiency of vertical axis turbines is possible by variable pitching.
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