Bulk wing kinematics and wing deformations of free-flying dragonflies of the species Pachydiplax longipennis were measured in a controlled environment. Both upright and inverted straight flights were recorded and analyzed. The inverted dragonflies exhibited similar bulk kinematics to the upright specimens in the global frame, but wing deformations were generally consistent in the body-relative frame. The deformations primarily comprised camber during the body-relative downstroke and twist during the body-relative upstroke. Based on these data, models were developed to incorporate the measured kinematics and deformations into computational fluid dynamics simulations. Both isolated and tandem wings were simulated (rigid and deforming in each case), allowing the effects of deformations and wing-wing interactions to be examined independently. During the upstroke the addition of deformation reduced flow separation on the outboard sections of the wing, whereas the impact of the deformation during the downstroke was found to be dependent on the wing kinematics. The simulations of tandem wings indicated that they produce more force than isolated wings, but the wing deformations reduced the impact of this wing-wing interaction. The changes in average lift and thrust induced by the wing deformations were relatively minor and dependent on the flight orientation, but the aerodynamic efficiency of the deforming wings was significantly higher than that of the rigid wings for all examined cases, including the inverted flights for which the deformations were in the opposite (global) sense to the upright flights.

中文翻译：

---

蜻蜓的机翼变形对前飞过程中空气动力性能的影响。

在受控环境中测量了Pachydiplax longipennis物种自由飞行蜻蜓的体翼运动学和机翼变形。记录并分析直立和倒转的直线飞行。倒置的蜻蜓在整体框架中表现出与直立标本相似的整体运动学，但机翼变形在身体相对框架中通常是一致的。变形主要包括在相对身体向下冲程中的外倾和在相对身体向上冲程中的扭曲。基于这些数据，开发了将测量的运动学和变形纳入计算流体动力学模拟的模型。模拟了孤立的和串联的机翼（在每种情况下都是刚性的和变形的），从而可以独立检查变形和机翼-机翼相互作用的影响。在上冲程期间，变形的增加减小了机翼外侧部分上的流动分离，而发现在下冲程期间变形的影响取决于机翼运动学。串联机翼的仿真表明，它们比孤立机翼产生更大的力，但是机翼变形减小了这种机翼-机翼相互作用的影响。机翼变形引起的平均升力和推力变化相对较小，并取决于飞行方向，但在所有检查的情况下，包括反向飞行，变形机翼的空气动力学效率均明显高于刚性机翼。变形与直立飞行的方向相反（整体）。