悬停飞行过程中扭曲翼和平直扑翼效率的实验对比研究。

Phan Hoang Vu, Truong Quang Tri, Park Hoon Cheol

Artificial Muscle Research Center, Konkuk University, Seoul, Republic of Korea. Department of Advanced Technology Fusion, Konkuk University, Seoul, Republic of Korea.

Bioinspir Biomim. 2017 Apr 19;12(3):036009. doi: 10.1088/1748-3190/aa65e6.

This work presents a parametric study to find a proper wing configuration for achieving economical flight using unsteady blade element theory, which is based on the 3D kinematics of a flapping wing. Power loading was first considered as a performance parameter for the study. The power loadings at each wing section along the wingspan were obtained for various geometric angles of attack (AoAs) by calculating the ratios of the vertical forces generated and the power consumed by that particular wing section. The results revealed that the power loading of a negatively twisted wing could be higher than the power loading that a flat wing can have; the power loading of the negatively twisted wing was approximately 5.9% higher. Given the relatively low average geometric AoA (α ≈ 44° and α ≈ 25°), the vertical force produced by the twisted wing for the highest power loading was approximately 24.4% less than that produced by the twisted wing for the strongest vertical force. Therefore, for a given wing geometry and flapping amplitude, a flapping-wing micro air vehicle required a 13.5% increase in flapping frequency to generate the same strongest cycle-average vertical force while saving about 24.3% power. However, when force/power and force/power ratios were considered as performance indices, the twisted wings for the highest force/power (α ≈ 43° and α ≈ 30°) and force/power (α ≈ 43° and α ≈ 36°) required only 6.5% and 4% increases in flapping frequency and consumed 26.2% and 25.3% less power, respectively. Thus, it is preferable to use a flapping wing operating at a high frequency using the geometric AoAs for the highest power loading, force/power ratio, and force/power ratio over a flapping wing operating at a low frequency using a high geometric AoA with the strongest vertical force. Additionally, by considering both aerodynamic and inertial forces, this study obtained average geometric AoAs in the range of 30° to 40°, which are similar to those of a typical hovering insect's wings. Therefore, the operation of an aerodynamically uneconomical, high AoA in a hovering insect's wings during flight is explainable.

这项工作进行了一项参数研究，以使用基于扑翼三维运动学的非定常叶片元理论找到一种实现经济飞行的合适机翼配置。功率载荷首先被视为该研究的一个性能参数。通过计算特定机翼截面产生的垂直力与消耗的功率之比，获得了沿翼展各机翼截面在不同几何攻角（AoA）下的功率载荷。结果表明，负扭转机翼的功率载荷可能高于平机翼的功率载荷；负扭转机翼的功率载荷大约高5.9%。鉴于平均几何攻角相对较低（α≈44°和α≈25°），对于最高功率载荷，扭转机翼产生的垂直力比产生最强垂直力时的扭转机翼产生的垂直力大约小24.4%。因此，对于给定的机翼几何形状和扑动幅度，扑翼微型飞行器需要将扑动频率提高13.5%才能产生相同的最强循环平均垂直力，同时节省约24.3%的功率。然而，当将力/功率和力/功率比视为性能指标时，对于最高力/功率（α≈43°和α≈30°）和力/功率（α≈43°和α≈36°）的扭转机翼，扑动频率仅需分别提高6.5%和4%，且功率消耗分别减少26.2%和25.3%。因此，对于最高功率载荷、力/功率比和力/功率比，使用在高几何攻角下以高频率运行的扑翼比使用在高几何攻角下以低频率运行且具有最强垂直力的扑翼更可取。此外，通过同时考虑气动力和惯性力，本研究获得了30°至40°范围内的平均几何攻角，这与典型悬停昆虫翅膀的攻角相似。因此，飞行过程中悬停昆虫翅膀的高攻角在空气动力学上不经济的运行情况是可以解释的。