本研究開發並測試出一套新的方法，即是利用泡膜觀察拍翼流場。此研究是基於泡膜干涉之概念，其中不同厚度的泡膜將呈現出不同色彩。10cm翼展拍翼機在泡膜中作動，並且以一台彩色CCD捕捉泡膜色彩變化圖案。將影像送入MATLAB來生成每個像素的RGB值，並且對應標準泡膜厚度色卡之厚度。MATLAB求解器也被用來求解Poisson方程的Neumann邊界條件問題，最終獲得了速度勢與拍翼流場的流線圖。 This thesis presents a 2D quasi-steady flow simulation of a 10 cm wingspan flapping wing with given moving boundary fed from stereo-photography measurement. This trajectory work used the softwares Surfer and Gambit to slice a 2D quarter-span cross section from the 3D trajectory by stereo photography. It’s then regarded as a 2D moving boundary for the quasi-steady CFD simulation by ANSYS/Fluent. The upwind direction changing of the flapping flow field has also been novelly considered herein. The computed time-varying outputs include the 2D flow fields and the corresponding lift coefficient. The one cycle history of lift coefficient subjected to 40 Hz flapping shows the qualitative similarity to the corresponding wind tunnel data and PVDF on-site measurement data.
A novel method utilizing bubble film to observe the flapping flow field has been also developed and tested in this thesis. This work is based on the concept of thin film interference where bubble film of different thickness exhibits different chromatic appearance. Herein, the bubble film was subjected to the flow field of a 10 cm wingspan flapping wing, and a color CCD camera was used to capture the chromatic patterns on the bubble film. The captured photograph was fed into MATLAB to generate RGB values per pixel and corresponding thickness values based on the standard color card for bubble thickness. The commercial finite difference solver in MATLAB was also used to solve the Neumann boundary value problem of Poisson equation to obtain the velocity potential field and the corresponding stream line pattern of the flapping flow field. Some technical difficulties were addressed finally.