LARGE-EDDY SIMULATION OF FLOW PAST A FULL-SPAN TRAILING-EDGE FLAP

Large-eddy simulations of flow (M=0.2, Re-c=1x10(6)) past a full-span flap at two angles-of attack are performed in an effort to understand the flow unsteadiness and noise generation mechanisms. Two types of acoustic waves are categorized. They are: (I) high-frequency acoustic waves radiated from the suction surface of the main wing, and (II) high-frequency acoustic waves radiated from the trailing edge of the main wing and the flap. Increasing the angle-of-attack does not change the noise components. The radiation of the high-frequency acoustic waves from the suction surfaces is related to a transition/reattachment mechanism. The trailing-edge noise is generated because of the successive vortex forming and shedding in the main-wing and flap wake. Its generation has less dependence on the status (turbulent or laminar) of the incoming boundary layer developing on the two sides of the trailing edge.