Tip speed dependent vortical structures in the wake of a model wind turbine at high Reynolds numbers

The wake a of a model horizontal-axis wind turbine was studied at a Reynolds number of 4 million across a range of tip speed ratios of 4<λ<7. To achieve Reynolds numbers higher than most existing turbine wake studies, the High Reynolds number Test Facility (HRTF) was used, which uses pressurized air, up to 230 bar, as the working fluid. Hot-wire anemometry was used to acquire velocity measurements, but through the use of the nano-scale thermal anemometry probe (NSTAP), spatial and temporal filtering was avoided. Downstream distances of 0.77