Experimental Detection of Transition on Wind Turbine Airfoils

A non-intrusive method for detection of laminar to turbulent boundary layer tran-sition, based on infrared thermography, was developed and implemented in the large low speed wind tunnel located at LM Glasfiber. The setup was tested on three different wind turbine blade airfoils at Reynolds numbers up to 6 millions. A comparison was made between the transition model of XFOIL and the measure-ments, showing that XFOIL predicts the transition point well, but in some isolated cases has a significant deviation from the measurements. An exact determination of the transition point is a key to correctly predict airfoil characteristics a wind tur-bine blades, and for development of high lift-to-drag airfoils. Key words: transition, airfoil, thermography