臺灣博碩士論文加值系統

大葉桃花心木種子構造十分簡單堅固，利用自轉來降低下降速度傳播種子，且受損後仍可以自動旋轉。本論文主要是研究桃花心木種子的相關特性，分析相關參數趨勢與相關空氣力學特性之結果。本研究以桃花心木種子進行觀測實驗，以影片計算相關數據取得趨勢與參數數據，使用FLUENT模擬計算，最後使用乾冰的白色煙霧觀察種子穩態旋轉的流場變化來驗證。
分析結果桃花心木種子的穩態旋轉發現，其旋轉平均轉速805 rpm，下降速度1.2 m/sec，傾斜角29.9 度；分析其趨勢可知1.面積單位重量越重，降落速度與轉速越快2.種子的表面積越大，越慢進入旋轉高程，並且轉速越慢3.重量越重，下降速度越高，越慢進入穩態旋轉軌跡4.種子長度越長，轉速越慢5.寬度越寬，轉速越慢，越慢進入穩態旋轉。桃花心木種子的翼面截斷與破損的動作分析得知，破損是否對進入穩態旋轉軌跡高度有明顯影響，翼長越短越慢轉為穩態旋轉，但是轉速越快。利用FLUENT模擬桃花心木種子旋轉分析的流場分析中，可以看到漩渦中心向後偏移，將旋轉種子前緣翼面被渦漩吸引朝上，翼尾部朝下，如飛機升空時的機翼狀態，以此產生浮力減緩下降速度。

The structure of Swietenia macrophylla seed is simple and sturdy. It uses rotation to reduce the descending speed for seed spreading and can still rotate automatically after being partially damaged. This thesis studies the related aerodynamic characteristics by both experiments and simulation.
The results showed that steady rotation of the Swietenia macrophylla seeds has an average rotational speed of 805 rpm, a descending speed of 1.2 m/sec, and a tilt angle of 29.9 degrees. Moreover, seeds of heavier weight will have faster landing speed and rotational speeds. A larger the surface area of the seed will lead to slower rotation speed; a longer seed length results in a slower rotational speed. Also, a wider width will have a slower speed and slower steady state rotation. Shortening the seed length has a significant effect on the height of the steady-state rotation trajectory. The shorter the wing length, the slower the rotation to the steady state rotation, but the faster the rotation speed. In the flow field finite element analysis, we can see that the center of the vortex shifts backwards, and the leading edge of the rotating seed is curing upwards, and the tail of the wing is facing downwards. The state of the wing, thereby generating lift to slow down the rate of descend.

摘要 I
Extended Abstract II
目錄 IX
圖目錄 XI
表目錄 XII
第一章 緒論 1
1.1前言 1
1.2研究動機 2
第二章 文獻回顧 3
2.1 自旋種子 3
2.2 自旋種子氣動力學 4
第三章 理論基礎 7
3.1 FLUENT升阻力計算公式 7
第四章 實驗設計 9
4.1 實驗規劃 9
4.2 檢測儀器與軟體 10
4.3 種子翼片樣品 11
4.4 截短種子翼片實驗 13
4.5 模擬分析設定 15
4.6 流場實驗設計 20
第五章 結果分析 21
5.1 實驗結果 21
5.2 比對分析 27
5.3 截斷分析 34
5.4 FLUENT 模擬與流場實際觀測 36
第六章 結論與建議 41
6.1 結論 41
6.2 建議 42
參考文獻 43

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