On the fluid-structure interaction of flexible membrane wings for MAVs in and out of ground-effect
On the fluid-structure interaction of flexible membrane wings for MAVs in and out of ground-effect
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DOI：
10.1016/j.jfluidstructs.2016.12.001
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发表时间：
2017-04-01
影响因子：
3.6
通讯作者：
Ganapathisubramani, B.
中科院分区：
文献类型：
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作者：
Bleischwitz, R.;de Kat, R.;Ganapathisubramani, B.
风洞实验在雷诺数 Re=56,000 下进行，测量刚性平板和柔性膜翼从自由飞行到地面效应条件的情况。称重传感器测量、数字图像相关和粒子图像测速被应用于高速，以解决时间同步升力、阻力和俯仰振荡以及膜和流动动力学的问题。对流动振荡应用适当的正交分解以确定其时空演化。负载、膜运动和流动动力学相互关联，以研究它们潜在的耦合物理现象。当机翼处于地面效应时，膜翼的静态拱度和动态膜振荡能力被发现是有益的，其中高度的下降迫使过早的前缘涡旋脱落和阻力增加。膜翼的动态运动有助于利用前缘的涡流脱落动力学，确保机翼上表面上的时间平均重新附着流，从而进一步增强升力。膜翼在峰值升力条件下表现出无滞后的流体膜耦合。在失速后条件下，发现膜滞后于流动动力学，标志着直接流固耦合的结束。
Wind tunnel experiments are conducted at a Reynolds number of Re=56,000, measuring rigid flat-plates and flexible membrane wings from free-flight into ground-effect conditions. Load cell measurements, digital image correlation and particle image velocimetry are applied in highspeed to resolve time-synchronised lift, drag and pitch oscillations simultaneously with membrane and flow dynamics. Proper orthogonal decomposition is applied on flow oscillations to determine their spatiotemporal evolution. Loads, membrane motions and flow dynamics are correlated to each other to investigate their underlying coupling physics. A membrane wing's ability of static cambering and dynamic membrane oscillations are found to be beneficial when the wing is in ground-effect, where the descent in height forces premature leading-edge vortex shedding and drag increase. The dynamic motions of membrane wings help to exploit vortex shedding dynamics from the leading-edge that ensures time-averaged reattached flow over the wing upper surface, resulting in further lift enhancement. Membrane wings show lag-free fluid membrane coupling at peak-lift conditions. In post-stall conditions, the membrane is found to lag the flow dynamics, signalling the end of direct fluid-structure coupling.