Effect of turbulent length scale on a wind turbine aerofoil

Wind Energy represents the most technically advanced and diffused renewable resource. The lack of available sites for on-shore wind farms has spurred interest for unconventional locations, such as the urban environment. As production coincides with consumption, urban wind energy might reduce infrastructural costs associated to traditional sites. However, hardly few (if any) applications have so far succeeded in providing a reliable source of power output, fostering scepticism towards the whole wind energy sector. This might be attributed to the lack in understanding of the performance of wind turbines in the highly turbulent inflow present in the built environment. Therefore, a “back to basics” approach is needed to understand the effect of a turbulent inflow on the aerodynamic performance of wind turbine aerofoils. One particularly disguised issue is the effect of the integral length scale towards the negligibility of the effects of turbulence. A wind turbine aerofoil model with chord c is therefore tested in the wind tunnel under different turbulent inflows, where turbulence intensity (I) and integral length scale (LS), are varied independently. Unlike what it is stated in literature, results might suggest that an effect of turbulence is noticed even if LS>>c.