中文摘要
本文的目的在建立一軸流風扇的設計流程，而此設計流程只要輸入風扇的設計條件，然後經由簡單的設定即可獲得符合需求的風扇，最後再將設計完成的風扇葉片輸出成三維幾何座標檔，然後藉由電腦輔助設計軟體讀取此幾何檔案，便能夠建構成風扇實體。在設計風扇之前，礙於現有的翼形氣動資料皆僅適用於高雷諾數，而且資料散亂不完整，因此本文藉由數值模擬計算建構一組適用於小型風扇的翼形氣動資料以供設計所需。設計風扇時首先將三維的軸流風扇沿徑向切割成數個二維平面，並分別設定截面的軸向速度與揚程分佈，經由求解速度三角形之後即可獲得所有截面的安裝角與攻角；最後在決定截面的翼形與弦長時，會利用理論推導所得的關係式計算合適與否，當所有截面都挑選完成後即完成設計。在本研究當中將設計所得的結果利用符合AMCA 210-99規範所設計的實驗設備進行驗證，實驗結果比設計目標還要大31％，雖然實驗結果顯示本文的設計方法較保守，但如何減少兩者之間的差距將是日後的研究方向。在本文中所有的計算與設定過程利用Visual Basic撰寫成為應用程式，如此一來便能夠大幅縮短風扇的設計流程，相信此風扇設計程式的完成，將能夠提供風扇的開發人員一套快速且可靠的工具。

Abstract
This research intends to establish a systematic design scheme for small axial-flow fans. First of all, a new low-Reynolds-number database for NACA airfoils is generated via CFD calculations to compensate the shortcoming caused by the present unsuitable airfoil database, which is only valid for high speed flow. The design procedure starts from dividing the 3D rotor blade into several 2D blade shapes uniformly distributed from hub to blade tip. With the assigned axial velocity and head distributions, the attack and setting angles for each 2D blade section can be decided via solving the velocity triangles within the framework of cascade theory. Later, by selecting the airfoil type and chord length, the checking process is performed iteratively to make sure the fulfillment of performance requirement. Thus, the complete rotor is furnished by combining the above 2D blade shapes. Consequently, with the inputs of operating conditions and few settings, this design software, coded by Visual Basic, can generate a fan configuration to meet the requirement and a CAD/CAM file for prototype fabrication. To validate this design tool, a 120mm×120mm×38mm fan is designed using this code and manufactured by the CNC machine to carry out the corresponding experimental verifications. To ensure a reliable outcome, the fan performance test is executed in the AMCA-210 chamber. The experimental and numerical result shows a higher pressure than design target by 31% and 33%, respectively. In conclusion, a conservative, systematic, and user-friendly design tool is established in this study. Hence, design engineer can achieve the required design for small axial-flow fans in a relatively short period and reliable way.

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