Wake measurements behind a horizontal-axis 50 kW wind turbine

Abstract

This paper presents some results on the wake of a full-scale 50 kW wind turbine located in Näsudden peninsula. Gotland Island, Sweden. It is found that the wind velocity deficit, $\text{Δ}\text{u}$, and turbulence intensity, $\text{δ}{}_{\mathrm{<mtext>u</mtext>}}\text{/}\text{u}$, take greater values at the center of the wake than its boundaries. Also the temperature structure parameter, $\text{C}{}_{\mathrm{<mtext>T</mtext>}}{}^2$, takes higher values at the centre of the wake than its edges, A 2-D $\text{δ}{}_{\mathrm{<mtext>u</mtext>}}\text{/}\text{u}$ plot shows two maxima (the third is missing because of lack of measurements) and a minimum at the expected positions in the wake. The $\text{u-}\text{component}$ power spectra levels seem to be higher at the high frequencies around the central parts of the wake while at its boundaries they are higher at the lower frequency portion of the spectrum. All results agree with theory and other experimental findings.