仿生撲翼之二維流場與受力量測

Abstract

本研究藉由模型實驗方法來探討仿生懸停撲翼下的簡化二維流場，針對文獻上所敘述的非定常流體力學機制做一番討論，不僅利用PTV技術觀察撲翼拍動所產生的流場，還同時對翼板所受到的力做量測。對於拍動中各項參數的改變做一系列的探討，包括攻角、轉速、拍動時機等，並利用得到的受力變化，配合流場，做觀察比對，希望能找出流場與力產生的關係。轉動時機對整體的升力表現有很大的關係，拍動模式從advanced mode接近symmetrical mode升力的表現很好，尤其對於『wake capture』部分的提供，而delayed mode則相反。上下拍的攻角對整體平均升力的大小的關係有相當的影響，卻沒有拍動模式影響的那麼大，一般而言，在50°∼60°左右，得到的平均升力最大，攻角再更大，升力產生越少。轉動時的角速度對於升力表現略有影響，能提供更多的升力，但對整體升阻比並沒有提升太多。本研究將有助於仿生的非定常流體力學機制以及未來數值模擬成果的比對做更深入的探討。

This research discusses the biological modelling in hovering flights by the model experiment method for two-dimensional simplified flow field, and narrates some mechanisms in non-steady flow in literatures to make discussion. This experiment not only uses the PTV technology to observe the flow field which produces by the wing plate, but also measures the force on the wing plate at the same time. Regarding each parameter change to make a series of discussions, and it is included the angle of attack, the rotational speed, the flap opportunity and so on. Then, to compare the force with flow field finds the relations between the flow field and force. 1. In the result, the timing of rotation has great effect on the lift performance. For three kinematics conditions, advanced and symmetrical rotations produce more lift force than delayed rotation, especially when the wake capture happened. 2. The angle of attack in upstroke and downstroke is also an important parameter in flapping process, and the results indicate the best lift performance at 50°~60° angle of attack. 3. Angular velocity in rotation affects a little bit on lift performance. Faster speed not only provides more lift force, but also supplies more drag force. This research will help to proof the mechanisms in non-steady flow and to compare with the result of numerical analysis in future.