Experimental investigation of turbulent wakes generated by wind turbine models in a large boundary layer wind tunnel

Velocity profiles were measured in the wake of two wake generator models in the University of New Hampshire (UNH) Flow Physics Facility. Mean horizontal and vertical velocity profiles were measured with a pitot tube behind a 51\% open area porous disk up to 50 diameters downstream. The disk wake is shown to elongate in the vertical direction and shift downward as it evolves downstream. Streamwise and azimuthal velocity profiles were measured in the wake a of a 1 m diameter scale model wind turbine to 20 diameters downstream. The azimuthal velocity profile shifts horizontally with downstream distance but still adheres to a $W \sim x^{-1} \sim U_o^{3/2}$ similarity scale at select downstream locations; where $W$ is mean azimuthal velocity, $x$ is downstream distance, and $U_o$ is the wake centerline velocity deficit $U_o = {U_{\infty} - U_{cl}}$. Both disk and wind turbine wakes exhibit the classical high-Reynolds number scaling for axisymmetric turbulent wakes, where the mean velocity deficit decays as $U_o \sim x^{-2/3}$ and the wake grows as $\delta^* \sim x^{1/3}$ where $\delta^*$ is the wake displacement thickness.