In large wind farms, the wake behind the upstream wind turbine affects the performance of the downstream turbines which reduces the overall power output. The geometry of the wind turbine blades has significant effects on the mechanical efficiency of this process. Here, we suggest to utilize a bio-inspired blade based on the common swift wing. Common swift is known to be a long-distance flyer, able to stay aloft for long periods of time by maintaining high lift and low drag. We study the near wake flow characteristics of a horizontal turbine model with swept blades and its aerodynamic loads. These are compared with a straight-bladed turbine. The experiments were conducted in a water flume using particle image velocimetry (PIV) technique. Both blades were studied for four different speeds with freestream Reynolds numbers ranging from 23,000 to 41,000. Our results show that the near wake developed behind the swept-back blade was significantly different from the straight blade configuration. The near wake developed behind the swept-back blade exhibited relatively lower momentum loss and suppressed turbulent activity (mixing and production) compared to the straight blade. Comparing the aerodynamic characteristics, though the swept-back blade generated relatively less lift than the straight blade, the drag was relatively lower as well. Thus, the swept-back blade produced 2-3 times higher lift-to-drag ratio than the straight blade. Based on the observations, we suggest that, with improved design optimizations, using the swept-back configuration in wind turbine blades can positively help to improve the energy loss in downstream wind turbines in wind farms and can increase the overall energy efficiency.

This dataset was collected using PIV (particle image velocimetry), then it was processed using Insight 4G^TM global image acquisition, analysis and display software to obtain vector files.

In the file names 30Hz, 40Hz, 50Hz, 60Hz refers to 0.12m/s, 0.15m/s, 0.18m/s, 0.21m/s freestream velocity respectively.