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On a swept vertical tailplane with infinite span tangential blowing over the shoulder of a deflected rudder is applied. For large rudder deflection angles the flow on the rudder is separated without blowing. A numerical study is conducted with the aim to increase the side force coefficient. This could for example be required during takeoff if the engine on one side fails, necessitating the compensation of a large yawing moment. If this criterion is critical for the sizing of the vertical tailplane, active flow control like tangential blowing could help to reduce the size of the vertical tailplane and thus save weight and fuel. With a continuous slot it is demonstrated that the separation on the rudder can be reduced or avoided. It is shown that by using discrete slots this can be achieved with a smaller momentum coefficient. To analyze the effects of the discrete slots and their jets on each other and their effectivity with regard to the gain in side force coefficient a parameter study is conducted. The number of slots as well as the size of the slots in spanwise direction is varied and the impact of jet velocity changes is also studied. In comparing the results for a constant increase in side force and constant slot size in spanwise direction the configuration with the smaller number of slots but a higher jet velocity proved to be the most effective one.

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A numerical study was carried out to assess the interference effects between the wake of a transport aircraft and several generic cargo bodies during the early stage of an airdrop scenario. DLR carried out extensive wind tunnel airdrop investigations between 2006 and 2012. Based on the experimental data and preceding numerical simulations distinct positions of the trajectory being subject to strong interference effects were statically reproduced. The flow field around the bodies was experimentally investigated using stereoscopic Particle Image Velocimetry and compared to steady and unsteady Reynoldsaveraged Navier-Stokes (RANS) computations. The latter were carried out using the unstructured DLR TAU code. The primary focus is to assess the suitability, accuracy and the limitations of RANS methods in such challenging flow conditions. Therefore, the influence of several turbulence models was investigated and compared to experimental field velocity data. In addition, an exemplary unsteady RANS simulation was conducted to highlight the differences to the steady approach. Although deviations in the wake of the bodies were observed, the qualitative agreement between the steady simulations and experiment was very good. Quantitatively, however, the steady approach leaves room for further improvements. The gap to the experimental data could partially be reduced in applying unsteady RANS methods.