現今室內空調機的設計漸漸趨向分離化設計，亦即將較占空間與較吵雜的壓縮機獨立安裝在室外，因此消費者必將更為重視室內機的送風與靜音性能，橫流式風扇也因為構造簡單輕巧與低噪音的特性而廣為室內機與其他空調送風設施(HVAC)所使用。一般而言橫流扇的運轉噪音並不算大，但是在夜深人靜時某些特別突出的單頻噪音卻顯得極度惱人，因此本研究嘗試以不同之葉輪扭轉角設計來改善橫流扇之尖銳單頻噪音，並經由實驗方法來驗證其可行性。本研究分兩階段將煙線切面組合為三維視流流場觀測，冀望藉此克服前人慣用的二維雷射切面僅能觀測單一橫斷面之盲點；另外在舌端上不同的軸向量測點上擷取其壓力頻譜，進行量測點位置與噪音頻譜之間的相干性分析，最後再以能夠模擬人耳聽覺特性的聲學人偶錄製出風口的噪音頻譜加以分析。結果在流場中成功地觀察到葉輪扭轉角所造成的軸向流線分歧現象；聲場分析方面，應用葉輪扭轉角的確有降低葉片通過頻率音壓峰值之效果，而葉輪軸向的壓力頻譜相干性變差也是此現象的有利佐證。綜合聲場與流場之實驗數據進行分析。結果顯示，適當的扭轉角設計可抑制葉片通過頻率而有效降低整體噪音量。

This paper concentrates on the improvement of operating noises of a cross-flow fan using different rotor-skewed angles. Also, analysis of the differences between performances, flow patterns, and noise spectrum were studied. Especially, this study overcame the blind sight of LDV and PTV with two configurations of flow visualization. The 3-D flow differences of RSA design were confirmed by images of streamlines. Finally, the experimental results summarized that the design of RSA-5 had the optimal noise reduction effect. Although RSA-10 still had better noise reduction effect than RSA-0, unfortunately, it excited some undesired noises about 2-5kHz. For compromise between performance and sound pressure level, RSA-5 is the most suitable design in this study.

中文摘要 i
英文摘要 ii
誌謝 iii
目錄 iv
圖目錄 vi
第一章　緒論…………………………………………………………...1
1.1 研究動機…………………………………………………………..1
1.2 橫流式風扇之構造與流場簡介………………………………..…2
1.3 橫流式風扇運轉噪音之分類…………………………….……….3
1.4 研究目的與方法…………………………….…………………….4
第二章 文獻回顧…………………….…………………………………5
2.1 橫流式風扇構造之演進.………………………………………….5
2.2 流場分析…………………………………………………………..6
2.2.1 流場幾何設計與性能分析….………………………………...6
2.2.2 流場量測與可視化技術….…………………………………...8
2.3 聲場分析………………………………………….……………….9
2.3.1 風扇內部流場誘發噪音機制探討.…………………………...9
2.3.2 結構振動噪音…………………….…………………………...12
2.3.3 降低風扇噪音之有效策略…...……………………………...12
第三章　實驗設計…………………………………………………….…14
3.1　實驗平台……………………………………….………………….15
3.1.1 葉輪扭轉角之設計…………………………………………....15
3.1.2 透明壓克力觀測模型………………………………………....17
3.1.3 驅動馬達與調速裝置………………………………………....19
3.2 流場方面之實驗設備與方法………….………………………….21
3.2.1 流場觀測……………………………………………………....21
3.2.2 舌端壓力擾動量測…………………………………………....23
3.2.3 葉輪內緣全壓量測…………………………………………....25
3.3 出風口噪音量測…………………………………………………..27
3.3.1 量測環境……………………………………………………....27
3.3.2 量測設備及方法……………………………………………....27
3.4 量測誤差與不確定度分析………………………………………..30
第四章 結果與討論……………………………..………………………32
4.1 流場解析…………………………………………………………..32
4.1.1 流場觀測……………………………………………………....32
4.1.2 舌端壓力擾動之相干性分析………………………………....48
4.1.3 葉輪內緣之全壓分佈………………………………………....53
4.2 出風口聲場解析…………………………………………………..57
第五章　結論與未來展望……………………………………………….62
5.1 結論………………………………….……...……………………62
5.2 未來展望………………………………….……………………….63
參考文獻………………………………………………………………….64
作者簡介………………………………………………………………….67

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