臺灣博碩士論文加值系統

為嘗試改善線流扇流場的噪音特性，本實驗設計在轉子與舌部間三個位置上置入粗細兩種圓管，在固定風道與轉子下，冀以造成原流場中偏心渦元現象的改變，以達成噪音降低之效果。利用葉片頻率單音相關實驗所得之結果，以及音場頻譜分析所獲得之精神聲學上的響度、銳度、純音調及悅音值等四個指標，來綜合判斷噪音改善之效果，並佐以風扇性能測試以確定置入圓管之動作是否造成風扇性能之下降。
根據實驗結果可發現，不論圓管粗細，置於線流扇流場舌部內側位置，對抑制第一階葉片頻率單音有明顯效果，且將所得結果計算精神聲學指標也發現銳度的明顯下降，進而造成悅音值上升，證明可為一有效的噪音改善手段，由風扇性能測試結果亦可確定置入實驗所採用之圓管管徑並未因此造成風扇性能下降，故可視為一種合理之減噪過程。至於舌部及舌部外側兩個位置則沒有上述效果。

In order to improve the noise characteristic in the flow field of the tangential fan , the present study tries to change the eccentric vortex shedding by inserting cylinders at three different position between the tongue and the rotor. The results obtained from blade passing tone experiment and the four indices of Psychoacoustic principle were used to judge the effect of the noise improvement . The fan performance test was conducted to ensure that the inserted cylinders would not cause any opposite effect.
The results showed that the cylinder placed at the inner side would decline the 1st blade passing tone and effectively reduce sharpness without deprivation of the fan performance of fan . However, the two cylinders that were placed at two other positions had almost no effectiveness. Therefore, inserting cylinder in an adequate location between the tongue and rotor was proved to be an efficient way in noise reduction.

中文摘要Ⅰ
英文摘要Ⅱ
目錄Ⅲ
附表目錄Ⅵ
附圖目錄Ⅶ
符號說明Ⅹ
希臘字母ⅩⅢ
第一章 導論1
第二章 文獻回顧5
第三章 實驗原理11
3.1葉片頻率單音11
3.2聲音品質13
3.2.1響度14
3.2.2銳度16
3.2.3純音調17
3.2.4悅音值20
3.3風扇性能測試21
3.4線流扇基本送風原理22
3.5風機定律23
第四章 實驗設備與方法25
4.1 測試線流扇與附件26
4.1.1 測試線流扇26
4.1.2 圓管27
4.2 噪音測試設備27
4.2.1 麥克風28
4.2.2 頻譜分析儀28
4.2.3 無回響室29
4.2.4 噪音測試規範29
4.3 風扇性能測試設備30
4.3.1 壓力測試設備32
4.3.2 風扇轉子轉速量測設備33
4.3.3 風量量測設備與方法34
4.3.4 幾何尺寸量測法34
4.3.5 送風機性能測試標準與壓力測試定義35
第五章 結果與討論37
5.1 圓管對葉片頻率單音音壓之影響38
5.1.1 圓管對各階葉片頻率單音音壓值之影響38
5.1.2 圓管對機械常數 與頻率分佈函數 之影響
40
5.1.3 圓管對頻率頻率響應函數 影響42
5.2 圓管對流場聲音品質之影響43
5.2.1 圓管對流場噪音頻譜之影響44
5.2.2 圓管對響度之影響45
5.2.3 圓管對銳度之影響46
5.2.4 圓管對純音調之影響47
5.2.5 圓管對悅音值之影響48
5.3 圓管對風扇性能之影響49
5.3.1 風扇性能與轉速之關係50
5.3.2 風扇性能與圓管位置之關係51
第六章 結論與建議54
6.1 結論54
6.2 建議55
參考文獻56
附表59
附圖61
附錄一 不準度分析97
附錄二 聲音品質參數計算說明98

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