Active Flow Control with an Oscillating Dropped-Hinge Flap

高升力系统将飞行包线扩展到低空速，并实现短起飞和着陆距离。为了进一步提高传统高扬程系统的性能，人们正在研究主动流量控制系统。本项目研究的主动流动控制方法可以抑制流动的分离，这在工业大学和TUM联合项目的初步工作中用数值方法证明了这一点。为了实现主动流量控制，将高扬程结构的垂下铰链襟翼设置为围绕铰链点的谐波振荡运动。垂铰襟翼振荡对升力系数的影响很大程度上取决于其振荡频率。因此，在我们自己的初步工作中，主动流影响的效果只在一定的频率范围内表现出来。确定了振荡间隙大小对间隙流动的影响以及壁面附近边界层上振荡襟翼表面的影响。为了更好地理解这些影响，通过跟踪扰流片的振动频率和振幅来改变振荡间隙宽度，进行了数值和实验研究。参数研究将用于确定在大范围的迎角和襟翼角范围内，振荡下垂铰链襟翼主动流量控制的潜力。此外，还将通过数值研究来考虑雷诺数的影响。

High-lift systems extend the flight envelope to low airspeeds and enable short take-off and landing distances. In order to further improve the performance of classical high-lift systems, active flow control systems are being investigated. The method for active flow control investigated in this project can suppress the separation of the flow, as was shown in preliminary work within a joint project between RWTH and TUM using numerical methods. To achieve active flow control, a dropped-hinge flap of an high-lift configuration is set into harmonic oscillating movement around the hinge point. The influence of an oscillating dropped-hinge flap on the lift coefficient strongly depends on the oscillation frequency. Thus, in our own preliminary work, the effect of the active flow influence was only shown in a certain frequency range. Effects of the oscillating gap size on the gap flow and of the oscillating flap surface on the boundary layer near the wall were identified as influencing variables. In order to better understand these effects, numerical and experimental studies are carried out to vary the oscillating gap width by tracking the spoiler on the one hand and the oscillation frequency and amplitude on the other. Parameter studies will be used to determine the potential for active flow control with an oscillating dropped-hinge flap over a wide range of angles of attack and flap angles. In addition, the influence of the Reynolds number will be considered by means of numerical studies.