During the landing approach the feathers on the upper surface of bird wings tend to pop up, which can be interpreted as a biological high-lift device. Experimental studies of Meyer and Bechert, 1998, show that feather-like movable flaps on the upper surface of a laminar airfoil can increase lift and reduce drag at high angles of attack. For a better understanding, the effect of self-activated movable flaps is investigated by a numerical simulation of an airfoil with flap at different angles. Similar to the experiments, the numerical study considers an HQ17 airfoil at Re = 106.
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HQ17 airfoil with movable flap (Re=106)
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