Simultaneous Image Measurement of Unsteady Flying due to Interaction

利用PIV和两台高速CCD摄像机组成的MOFIA系统，同时测量了小圆盘在水中的下落运动及其周围的水速度场。用PIV测量了圆盘周围的速度场。荧光示踪粒子用于分离YAG激光的波长和CCD相机拍摄的图像的光的波长。利用两台高速摄像机的图像重建了圆盘的三维运动。以直径10mm的盘为标准。其密度和厚度分别为1000 ~ 7800 kg/m^3和0.07 ~ 1 mm。象限板和方形板也进行了研究。实验结果表明，圆盘的运动受其密度和厚度的影响。运动由二维之字形运动转变为随圆盘密度的螺旋运动。在高密度圆盘的情况下，观察到混沌运动，特别是三维的“之”字形运动和空翻运动。以圆盘象限模型为模型的机翼（半径20 mm，厚度0.3 mm）为研究对象，利用MOFIA分析了机翼与周围气流的相互作用。在机翼拍打下，观察到旋涡的产生、旋涡脱落和翅膀拍打引起的吸力或推力流动。并对白菜蝴蝶翅面形状进行了测量。

The motion of small thin disk falling down in water and its surrounding water velocity field were measured simultaneously by using the MOFIA system, which is composed by PIV and two high speed CCD cameras. The velocity field around disk was measured by PIV. The fluorescent tracer particles were used to separate its wavelength from both that of YAG laser and those of lights for images taken by the CCD cameras. The three dimensional motion of disk was reconstructed using the images of two high-speed cameras.Disks of 10 mm diameter were used as standard in the study. Their density and thickness were 1000 to 7800 kg/m^3 and 0.07 to 1 mm, respectively. Quadrantal and square plates were also investigated. The experimental results show that the motion of disk was affected by its density and thickness. The motion changed from two-dimensional zig-zag motion to spiral motion with density of disk. In the case of a high density disk, a chaotic motion, especially a three-dimensional zig-zag motion with somersault was observed.Using a wing (radius 20 mm and thickness 0.3 mm) modeled by quadrant of disk, the interaction between the wing and surrounding flow was investigated by use of MOFIA. With flapping-down of the wing, vortex generation, vortex shedding, and suction or pushing flow due to flapping of wings were observed. The shape of wing surface of a cabbage butterfly was also measured.