Aerodynamics of gliding flight in common swifts
Aerodynamics of gliding flight in common swifts
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DOI：
10.1242/jeb.050609
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发表时间：
2011-02-01
影响因子：
2.8
通讯作者：
Hedenstrom, A.
中科院分区：
文献类型：
--
作者：
Henningsson, P.;Hedenstrom, A.
普通雨燕(Apus apus L.)的滑翔飞行性能和尾流拓扑结构在风洞中以7到11米的速度进行了检验。S(-1)。隧道被倾斜，以模拟不同下沉速度下的下降飞行。这只雨燕在速度范围内改变了它的翼展、翼面和尾展。翼展随速度呈线性减小，而尾展则呈非线性减小。对于每种空速，都找到了最小滑动角。相应的下沉速度与空速呈曲线关系，最小下沉速度在8.1m S(-1)，最佳滑行速度在9.4m S(-1)。计算了不同空速和倾角组合下的升阻比，各速度的最大值与空速呈曲线关系，当空速为9.5m时，S(-1)的最大值为12.5.用立体数字粒子图像测速仪(DPIV)在横向平面上对尾迹进行采样。尾迹的主要结构是一对尾翼尖涡和一对尾涡。测量了它们的循环，并建立了一个模型，显示了良好的重量支持。寄生虫阻力是根据在身体后面的尾流中测量的尾迹缺陷来估计的。在空速范围内，寄生虫的阻力系数在0.30到0.22之间。计算了诱导阻力，并将其用于估算剖面阻力系数，发现该系数与之前在哈里斯鹰上测得的结果相同。
Gliding flight performance and wake topology of a common swift (Apus apus L.) were examined in a wind tunnel at speeds between 7 and 11. m. s(-1). The tunnel was tilted to simulate descending flight at different sink speeds. The swift varied its wingspan, wing area and tail span over the speed range. Wingspan decreased linearly with speed, whereas tail span decreased in a non-linear manner. For each airspeed, the minimum glide angle was found. The corresponding sink speeds showed a curvilinear relationship with airspeed, with a minimum sink speed at 8.1 m s(-1) and a speed of best glide at 9.4 m s(-1). Lift-to-drag ratio was calculated for each airspeed and tilt angle combinations and the maximum for each speed showed a curvilinear relationship with airspeed, with a maximum of 12.5 at an airspeed of 9.5 m s(-1). Wake was sampled in the transverse plane using stereo digital particle image velocimetry (DPIV). The main structures of the wake were a pair of trailing wingtip vortices and a pair of trailing tail vortices. Circulation of these was measured and a model was constructed that showed good weight support. Parasite drag was estimated from the wake defect measured in the wake behind the body. Parasite drag coefficient ranged from 0.30 to 0.22 over the range of airspeeds. Induced drag was calculated and used to estimate profile drag coefficient, which was found to be in the same range as that previously measured on a Harris' hawk.