Experimental Investigation of Transition on a Plunging Airfoil

Abstract. Extensive tests were carried out on a section of a wind turbine blade. The eect of reduced frequency on the boundary layer transition point of the model oscillating in plunge has been investigated. The spatial-temporal progressions of the transition point and the state of the unsteady boundary layer were measured using multiple hot-lm sensors. The measurements showed that reduced frequency highly aects variations of the transition point and results in a hysteresis loop in the dynamic transition locations. The dominated frequencies of the boundary layer are found to be a function of the reduced frequency and mean angle of attack