In this work, a 2D aero-servo-elastic model of an airfoil section with 3 degrees of freedom (DOF) based on the 2D CFD solver EllipSys2D to calculate the aerodynamic forces is utilized to calculate the load reduction potential of an airfoil equipped with an adaptive trailing edge flap (ATEF) and subjected to a turbulent inflow signal.
The employed airfoil model corresponds to a successfully tested prototype airfoil where piezoelectric actuators were used for the flapping. In the present investigation two possible control methods for the flap are compared in their ability to reduce the fluctuating normal forces on the airfoil due to a 4 s turbulent inflow signal and the best location of the measurement point for the respective control input is determined. While Control 1 uses the measurements of a Pitot tube mounted in front of the leading edge (LE) as input, Control 2 uses the pressure difference between the pressure and suction side of the airfoil measured at a certain chord position.
Control 1 achieves its maximum load reduction of RStd(Fy) = 76.7% for the shortest Pitot tube of the test, i.e. a Pitot tube with a length of 0.05% of the chord length. Control 2 shows the highest load reduction of RStd(Fy) = 77.7% when the pressure difference is measured at a chord position of approximately 15%. Copyright © 2010 John Wiley & Sons, Ltd.