以田口法優化帶翅種子翼翅幾何外形對氣動力影響之研究

本論文目的在於開發氣動力性能更好的仿生葉片。藉由使用田口法分析帶翅種子翼翅幾何外形對氣動力之影響，找出氣動力特性之最佳因子組合。本研究探討六項不同因子：風速、攻角、翼片厚度、翼片長寬比、翼片後掠角以及翼片弧度對氣動力特性的影響。本文使用二維雷射掃描描繪出翼翅之輪廓，並利用直交表的因子組合，建立出三維仿生葉片模型，匯入至ANSYS Fluent中進行求解，分析流場情況，計算出升力係數、阻力係數以及升阻比，並使用變異數分析找出各因子效應與重要性。對於升阻比因子影響之顯著性依序排列為攻角、弧度、後掠角、長寬比、風速及厚度。本文利用最佳因子組合建立最佳化翼型後，再次使用ANSYS Fluent進行求解，計算出最佳化翼型氣動力特性。最佳化翼型最高升阻比與仿生青楓葉片最高升阻比兩者之間差距，而與號基底葉片差距，顯示最佳化後之翼型氣動力特性優於尚未最佳化之翼型。在流場的分析中，速度向量在攻角越大時速度梯度越明顯，攻角大於時上翼面流場開始產生迴流影響升阻比的表現。

關鍵字

帶翅種子翼翅；田口法；直交表； ANSYS Fluent ；最佳化

並列摘要

The purpose of this thesis is to develop bionic blades with better aerodynamic performance. By using Taguchi method to study the influence of wing geometric contour of the maple samara on aerodynamic performance, and the best combination of factors. Six different factors affecting the aerodynamic characteristics are discussed: wind speed, angle of attack, blade thickness, blade aspect ratio, blade sweep angle, and camber of blade. In the study, a two-dimensional laser is used to scan and draw the contour of the samara, and a three-dimensional bionic blade model is established by using the factor combination of the orthogonal array. The setup of the computational domain is imported into ANSYS Fluent to solve the flow fields, the lift coefficient, drag coefficient and the lift to drag ratio, and uses ANOVA to find out the effect and importance of each factor. The importance for the lift to drag ratio are, in the order of effectiveness, angle of attack, blade camber, blade sweep angle, blade aspect ratio, wind speed and blade thickness. The optimal combination of factors is used to establish an optimized bionic blade, and then using ANSYS Fluent to solve the flow field to obtain the aerodynamic characteristics of the optimized blade. The enhancement of the highest lift to drag ratio is increasing 28% of the optimized bionic blade than the bionic green maple blade, and 23% higher than the base blade. The aerodynamic characteristics of the optimized blade are better than the non-optimized blades. In the flow field analysis, the velocity vector diagrams show larger velocity gradients while the angle of attack is larger, and there is a recirculating flow, which will affect the aerodynamic performance, on the top surface of the blade when the angle of attack is higher than degrees.