Active Load Control of a Wind Turbine Airfoil Using Microtabs

Abstract

The dynamic response of an airfoil to microtab deployment has been studied in the University of California, Davis Aeronautical Wind Tunnel. Static tests were conducted at a Reynolds number of , whereas dynamic testing examined deploying microtabs under steady conditions and during simulated wind gusts. Experimental results are compared with two-dimensional Reynolds-averaged Navier–Stokes computational results generated using OVERFLOW2. Microtabs with a height equal to 1% of the airfoil chord are seen to produce a rapid change in the sectional lift coefficient sufficient to compensate for a 12% change in the freestream airspeed. The effect of tab deployment was modeled using a linear equation that related the lift force to the difference in surface pressure at 15% chord. The resulting function provided a usable approximation to the lift force during tab activation. Two modes of tab activation are examined: simultaneous deployment of all tabs along the airfoil span and sequential deployment of individual segments. The latter mode allowed the timing of tab activation to be matched more closely to the changing airspeed.