Comparative Study of Two-Bladed Upwind and Downwind Turbines Using the NREL Reference Wind Turbine

Two-bladed wind turbines offer the potential for a lower cost of energy compared with three-bladed rotor turbines. This investigation was conducted to quantify the differences between the loads of upwind and downwind two-bladed wind turbines operating under random wind conditions. This paper focuses on a comparison of maximum and average loads that can cause first excursion failure, and loads that can cause fatigue failure. In this study, upwind and downwind turbines with two bladed rotors are compared. The NREL 5MW reference wind turbine was used as a baseline design and was modified as necessary to design a two bladed upwind wind turbine. The tower shadow effect was considered for the downwind turbine. The IEC61400-3 standard load cases were used to define the loading conditions for the wind turbine simulations. The computed load effects generally showed that the downwind configuration had lower load effects. Moreover, fatigue damage was lower for the two-bladed downwind turbine compared to the upwind turbine.