臺灣博碩士論文加值系統

風扇葉片外型在製造後與原設計不符，則將影響風扇的特性曲線的表現。因此，本文主要針對風扇葉片外型在製造前後之差異性，探討差異產生原因，並嘗試利用以葉片幾何外型為參數，分析各參數對特性曲線之影響，更進一步達到修正特性曲線之目的。
風扇葉型製造後之尺寸差異分析，首先使用逆向工程系統對葉片成品之誤差進行研究，結果發現誤差主要發生於葉片之前後緣部份，此部分誤差之原因係由於葉片塑膠射出時之熱量無法平衡所導致。而葉片之尺寸差異直接的將影響到葉片之特性曲線，因此針對製造前後之葉片特性曲線部份，分別以風洞實驗與計算流體力學方法進行比較，結果發現由於前後緣角度尺寸之差異將廣泛的影響特性曲線之表現，影響程度在風量與風壓方面均約為15%左右。
進一步修正幾何外型造成特性曲線之偏差，研究使用以葉型的角度、厚度與外形等九個參數的葉型設計之數值模型，利用計算流體力學方法分別討論各參數對風扇特性曲線的影響，並在了解各參數之影響後，修正前後緣角度型並以計算流體力學方法驗證，結果發現與原始逆向模型相比，最大風量提升約7％、中段處提升約13.44％以及最大風壓處提升約5.26％。
本研究分析結果得知，風扇變形主要是在葉型前後緣呈現上揚，進而減小沖角與偏移角等，而對特性曲線的最大風壓造成下降，為了補正幾何偏差影響的特性曲線變化，可利用相關參數的特性加以修正。

The blade profile has a strong effect on the performance curve in axial fan design. However, since the blade is plastic injected, the profile will be altered in the manufacturing process. In this study, the dimension differences of the blade and its effect on the performance curve will be investigated. Dimensions compensation will also be inspected to correct the performance curve variation.

In the objective of the dimensions differences, a 3D reversed engineering approach is used. Results show that the deviation is mostly located in the leading and trailing edge of the blade. These errors are due to the thermal imbalance in the mold cavity.

The dimension differences of the blade profile change the performance curve of the fan. Both wind tunnel experimental and computational fluid dynamics approaches are employed to study this variation. It is shown that the dimension differences can change the air flow rate and pressure approximately 15%.


The variation of performance curve is then compensated by offsetting the blade geometry. Numerical results prove that by changing the inlet angle, outlet angle and the installment angle, the air flow rate can be raised about 7-14% and the air pressure can be lifted about 5%.

摘要 I
ABSTRACT II
誌謝 IV
目錄 V
表目錄 VII
一、 緒論 1
1-1前言 1
1-2文獻回顧 3
1-2-1風扇設計 3
1-2-2逆向工程 5
1-3研究動機與目的 8
二、 風扇基本參數介紹 9
2-1 風扇結構簡介 9
2-1-1 驅動馬達 9
2-1-2 葉片實體 9
2-1-3 外框 11
2-2特性曲線 12
2-3計算流體力學 13
三、 設備與實驗規劃 14
3-1逆向檢測與模型重建 14
3-2風洞與量測 14
3-3基本假設與簡化的風扇模型 15
3-4網格系統 16
3-5流體分析與葉型建立 16
3-5-1計算流體力學操作之流程 16
3-5-2葉型建立 17
四、 結果與討論 18
4-1製造前後的差異 18
4-2特性曲線的差異 19
4-2-1 8015之特性曲線比較 19
4-2-2 8020之特性曲線比較 20
4-2-3 8025之特性曲線比較 21
4-3葉型參數之影響 22
4-3-1葉型定義 22
4-3-2沖角對風扇特性曲線的影響 24
4-3-3葉片入口角對風扇特性曲線的影響 25
4-3-4 葉片安裝角對風扇特性曲線的影響 26
4-3-5偏移角對風扇特性曲線的影響 27
4-3-6葉片出口角對風扇特性曲線的影響 28
4-3-7 前緣厚度對風扇性能的影響 29
4-3-8後緣厚度對風扇特性曲線的影響 30
4-3-9前緣外形對風扇特性曲線的影響 31
4-3-10後緣外形對風扇特性曲線的影響 32
4-4 修正模型與分析 33
五、結論 35
5-1未來研究的方向 36

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