Aerodynamics of flapping wings in forward flight

前飞时扑动机翼的空气动力学

• 批准号: 456038422
• 负责人: Dr.-Ing. Jong-Seob Han
• 金额: --
• 依托单位: Lehrstuhl für Aerodynamik und Strömungsmechanik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/456038422?language=en
• 关键词: Aerodynamics; flapping; wings; forward; flight

Flying insects are capable of both long-term hovering and high-degree of maneuvering with flapping wings. There have been a lot of studies on the flapping wings and their flight mechanics, bringing on a great improvement in the development of biomimetic drones. Nonetheless, it is still hard to say that the techniques accomplished so far are sufficient to describe the flapping-wing systems overall. Accordingly, the biomimetic drone development also has not jumped over a certain level. One notable issue in the recent trends in flapping-wing aerodynamics is that most studies still strongly confine own scopes to the hovering flight, despite the fact that staying particular point in space is very rare for most flying insects (they usually fly with a certain preferred – energy optimum – flight speed). The studies on the LEV also have heavily relied on the hovering state where a body stays at a fixed point and the wings move along the horizontal stroke plane without freestream. The advance ratio, which is also one primary element governing the LEV behavior, has been regarded as zero in these studies. Two distinctive kinematic features of flying insects in forward flight, i.e., the inclined and shifted-back stroke plane, which can significantly change the spanwise flow thereby impacting the LEV, have not yet been sufficiently investigated either. Few studies trying to reveal the effect of advance ratio had barely managed to report superficial things, because they relied on simplified motion profiles and marginally extended conditions from that in hover. A lack of such knowledge about forward flight brings on long-term stagnancy in aerodynamic model development. All the studies on flight dynamics are only able to cover near-hover maneuvers.With this program, this applicant proposes a thorough investigation on the aerodynamics of flapping wings in forward flight. The LEV characteristics on low-aspect-ratio flat plates at various kinematic and fluidic configurations in a fixed freestream will be explored in detail, and a novel aerodynamic model, which can encompass the LEV characteristics with respect to the advance ratio, aspect ratio, sweptback angle, and the angle of inclination of the stroke plane thereby being expandable to various flight modes, will be established. The flight stability analysis by using the aerodynamic model and morphological data of an example insect will also follow. This will give us better insights on the stability and controllability in forward flight.

飞行的昆虫既能长时间盘旋，又能通过拍动翅膀进行高度机动。人们对扑翼及其飞行力学进行了大量的研究，为仿生无人机的发展带来了很大的进步。尽管如此，仍然很难说到目前为止所完成的技术足以描述整个扑翼系统。因此，仿生无人机的发展还没有跨越一定的台阶。在扑翼空气动力学的最新趋势中，一个值得注意的问题是大多数研究仍然强烈地将自己的范围限制在悬停飞行中，尽管对于大多数飞行昆虫来说，在空间中停留特定点是非常罕见的（它们通常以一定的优选能量最佳飞行速度飞行）。对LEV的研究也严重依赖于悬停状态，其中身体停留在一个固定的点上，而机翼沿着水平行程平面移动而没有自由飞行。在这些研究中，前进比也是控制LEV行为的主要因素之一，被认为是零。飞行昆虫向前飞行的两个明显的运动学特征，即，倾斜的和向后移动的冲程平面也没有得到充分的研究，该冲程平面可以显著地改变展向流动，从而影响LEV。很少有研究试图揭示前进比的影响，几乎没有设法报告表面的东西，因为他们依赖于简化的运动剖面和略微扩展的条件，从悬停。对前向飞行缺乏这样的认识，导致了空气动力学模型发展的长期停滞。所有关于飞行动力学的研究都只能涵盖近悬停机动，通过本项目，申请人提出对扑翼前飞的空气动力学进行深入研究。本文将详细研究在固定自由高度上，不同运动学和流体学构型下，低展弦比平板上的LEV特性，并建立一种新的气动模型，该模型可以包含LEV在前进比、展弦比、后掠角和冲程平面倾角等方面的特性，从而可以扩展到各种飞行模式。此外，还将利用一个昆虫实例的空气动力学模型和形态学数据进行飞行稳定性分析。这将使我们更好地了解前飞的稳定性和可控性。