Wake reduction in horizontal axis wind turbine: A review of advancements in techniques

Renewable energy systems have experienced exponential growth toward producing zero-carbon energy. In this context, wind turbines continue to play a significant role. To extract maximum power, wind turbines are installed in array-like formation in wind farms. This arrangement though beneficial, also leads to detrimental wind-wakes effects. The wakes reduce wind speed and induce undesirable turbulence of flow field in downstream direction. To address this issue, several innovative techniques have been proposed. This paper surveys the best methods by classifying these into passive and active techniques. The passive techniques affect the wake flow by modifying only the geometrical or operating characteristics of wind turbines such as adjustment of forward and backward sweeps, etc. The active techniques use additional surfaces/devices for wake handling such as vortex generators, leading edge protuberances, dual-rotors, and cross-axis wind turbines etc. Additionally, this paper also reviews various wake measurement methods and recommends the best suited technique.