Active flow control for leading-edge vortex configurations

三角翼构型周围流动的特点是形成大尺度的前缘涡，与附着层和分离层、层流层和湍流剪切层相连。这些流动结构与大范围尺度上的不稳定性有关，并包含非线性相互作用。从气动的角度来看，影响特征涡流动不稳定性，即与卷起的剪切层和涡爆有关的不稳定性，是非常有趣的，因为有可能增加这种配置的性能以及飞行包线边界的稳定性。在这里，采用分段、前缘主动襟翼元件的周期性振荡和利用前缘斜槽的脉冲吹气来操纵和控制涡流。驱动频率与流动不稳定机制的频率相关。该研究是针对先前研究计划（BR 1511/1）中使用的通用三角翼几何结构进行的，该研究具有大型实验和数值数据库。该数据库包括部分发展、完全发展和破裂前缘涡的情况，取决于几何固定或自由的主分离和攻角。流动控制的目的是在大迎角（失速和后失速）状态下提高气动效率和纵向和横向稳定性，并通过减轻非定常气动载荷来减少结构动载荷。

The flow around delta wing configurations is characterized by the formation of large-scale leading edge vortices, linked to attached and separated, laminar and turbulentshear layers. These flow structures are associated with unsteadiness over a broad range of scales and comprise non-linear interaction. From an aerodynamic point of view, influencing the characteristic vortex flow instabilities, namely those related to the rolling up shear layer and to vortex burtsing, is of great interest due to the possibility of increasing the performance of such configurations as well as the stability at the borders of the flight envelope. Here, periodic oscillations of sectional, leading-edge active flap elements and pulsed blowing using slanted slots near the leading edge are used to manipulate and control the vortex flow. Actuation frequencies are correlated to the frequencies of the flow instability mechanisms. The investigations are conducted for a generic delta wing geometry used in a previous research program (BR 1511/1) featuring a large experimental and numerical data base. This data base comprises the case of partly developed, fully developed and burst leading-edge vortices depending geometrically fixed or free primary separation and angle of attack. Flow control is aimed to increase the aerodynamic efficiency and longitudinal and lateral stability in the high angle-of-attack regime (stall and post-stall regime) and to reduce structural dynamic loads by alleviating unsteady aerodynamic loads.