The Darrieus turbine, a vertical axis wind turbine, is used for electricity generation. However, its practical deployment is often limited by performance challenges. This study addresses these limitations by introducing a novel upstream deflector designed to enhance rotor efficiency. A two-dimensional computational fluid dynamics (CFD) approach is employed to simulate the flow field around seven different deflector configurations. The results demonstrate that all configurations significantly improve performance. Specifically, reducing the radial distance (d1) of the deflector enhances both the power coefficient (Cp). A maximum Cp of 0.656 was achieved, representing a twofold increase at a tip speed ratio (TSR) of 3. Likewise, reducing the deflector length (l) led to a 90.6% improvement. Finally, optimizing the deflector’s axial distance (d2) resulted in a peak Cp at TSR = 3.3, reflecting an 87.77% increase. These insights contribute to the advancement of sustainable power generation by guiding the development of more efficient Darrieus turbines.
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