Aerodynamic characteristics of unsteady gap flow in a bristled wing
Aerodynamic characteristics of unsteady gap flow in a bristled wing
复制标题
DOI：
10.1063/1.5030693
复制
发表时间：
2018-07-01
影响因子：
4.6
通讯作者：
Kim, Daegyoum
中科院分区：
文献类型：
--
作者：
Lee, Seung Hun;Lahooti, Mohsen;Kim, Daegyoum
微型飞虫有一个独特的翅膀结构，由一个中心框架和几个刚毛组成。对于昆虫生活的低雷诺数状态，刚毛翼利用剪切层的强粘性扩散产生的间隙内的虚拟流体屏障来克服其形态限制。考虑到这种机翼的非定常扑动，采用宽雷诺数范围的二维刚毛翼模型对间隙流形成的气动特性进行了数值研究。在刚毛间隙内，减速阶段停止涡的发展及其对在同一边缘产生的已有涡消灭的影响取决于雷诺数，这导致即使雷诺数变化很小，在冲程反转时涡度分布也会发生显著变化。随着雷诺数的减小，间隙流对机翼运动的响应更快，并且其模式不会明显偏离机翼的运动学。在低雷诺数和高雷诺数时，还观察到作用在每个刚毛上的气动力行为的显著差异。对于刚毛产生的气动力，在高雷诺数下，由于相对于机翼的强间隙流，每个刚毛的行为是独立的，并且产生相似的力。同时，在低雷诺数下，每个刚毛在相对位置上受到的力不同，表明存在通过虚拟流体屏障的刚毛集体相互作用。AIP出版社出版。
A micro-scale flying insect has a unique wing configuration consisting of a central frame and several bristles. For the low-Reynolds-number regime in which the insect lives, the bristled wing utilizes a virtual fluid barrier inside gaps produced by strong viscous diffusion of shear layers to overcome its morphological limitations. Considering the unsteady flapping motion of such a wing, the aerodynamic characteristics of gap flow formation are investigated numerically using a two-dimensional bristled wing model for a wide range of Reynolds numbers. Inside a gap between bristles, the development of a stopping vortex during the deceleration phase and its effect on the extinction of an existing vortex generated at the same edge are dependent on the Reynolds number, which leads to a significant change in vorticity distribution at stroke reversal even with just a small change in the Reynolds number. As the Reynolds number decreases, the gap flow responds more rapidly to wing motion, and its pattern does not deviate significantly from the kinematics of the wing. A noticeable difference is also observed in the behavior of the aerodynamic force acting on each bristle at low and high Reynolds numbers. With regard to aerodynamic force generation by the bristles, each bristle behaves independently and produces similar force because of strong gap flows relative to the wing at high Reynolds numbers. Meanwhile, at low Reynolds numbers, each bristle experiences a different force depending on its relative position, which indicates the existence of collective interaction of bristles through a virtual fluid barrier. Published by AIP Publishing.