Separation Control by Self-Activated Movable Flaps
Separation control is also an important issue in the physiology of birdflight. In this paper the adaption of the separation control mechanism by bird feathers to the requirements of engineering applications is described in detail. Self-activated movable flaps similar to artificial bird feathers represent a high-lift system enhancing the maximum lift of airfoils. Their effect on the unsteady flow around a two-dimensional airfoil configuration is investigatd by a joint numerical and experimental
... l and experimental study. First, attention is paid to the automatic opening and closing mechanism of the flap. Following this, its beneficial effect on the lift is investigated for varying incidences and flap configurations. In-depth analysis of experimental and numerical results provides a detailed description of the important phenomena and the effect of self-adjusting flaps on the flow around the airfoil. In the second part of this paper, a contribution to verification of the applicability of Unsteady Reynolds-averaged (URANS) approaches using statistical turbulence models for unsteady flows with special respect to the occuring turbulent time-scales is given for which comparison to the results of a hybrid simulation based on URANS and Large-Eddy-Simulation (LES) is made. Finally, flight experiments using an aircraft with movable flaps fitted on its laminar wing are described.