1. The vortex oscillation will cause a fluctuating slat slot throughflow component which in turn will generate a corresponding unsteadiness of the slat leading-edge stagnation point and thus superimpose an unsteady flow component on the complete slat flow field. Propagation times for disturbances originating from the cove vortex and travelling with the speed of sound around the slat contour are affected by the distribution of local flow velocitiesnottoofarfromtheslatsurface.Roughapproximations result in time scales which would correspond to frequenciesontheorderof2kHz.Themostpronounced level peak (at f2) in Fig.15 indeed is located close to thisvalue(i.e.1960Hz)andalsotwoharmonicsarevisible. From the spectrum in Fig. 15 it seems that f2isrelatedtof1throughanintegerfactorof4,whichmightbe an indication for a possible feedback phenomenon.
2. AIAA/CEAS 2002-2604, 2002. [3] Wild, J. "Numerical Optimization of Two-Dimen
3. sional High-Lift Configurations Solving Navier-Stokes Equations", DLR-FB-2001-11, Braunsch