Positive effect of a synthetic low-level jet on the mean power and momentum transport of a wind-turbine array

Nocturnal low-level jet (LLJ) is a distinctive phenomenon at the top of stable boundary layers. A low-level velocity peak results in attractive power resource for wind turbines. However, a maximum in the mean wind speed profile implies the co-existence of positive and negative mean shear in the vicinity of the peak. To gain better understanding of the impact of LLJ (e.g., positive \& negative shear) on the performance of a scaled-down power plant, with similar LLJ profile in the atmosphere were performed using particle imaging velocimetry (PIV). The results from single turbine and $3\times2$ turbines array in the positive and negative shear regions of the synthetic LLJ were compared to canonic turbulent boundary layer. For both positive and negative shear cases a 12\% increase in power generation in the $2^{nd}$ row were observed in comparison to the unstable boundary layer condition. In addition, the role of energy entrainment induced by the positive and negative shear of the LLJ and the contribution to the vertical transport of momentum and kinetic energy across the turbine array are explored in depth.