馬達噪音的來源可分為機械噪音、電磁噪音、以及氣動噪音。對高轉速馬達而言，氣動噪音為主要的噪音源，本研究對三相交流馬達進行探討，透過計算氣動聲學(Computational Aeroacoustics, CAA)進行數值模擬，再與實驗量測結果進行比較驗證，旨在建立一套可用來預測馬達氣動噪音的分析模型。
首先在無響室內對馬達進行噪音頻譜的量測，藉由使用不同控制因子對馬達進行多組實驗，交互比對量測結果，可以歸納出氣動噪音的聲源是由風扇所主導。另一方面，數值模擬的計算分為流場與聲場兩大部份，首先使用ANSYS Fluent計算流場，得到風扇的聲源強度資料，接著再使用邊界元素法計算其聲學響應。最後將數值模擬的結果與實驗數據比較，得到相當良好的結果，證明往後在進行馬達設計時，此計算模式可作為降低噪音的一項利器。

The source of motor noise can be from mechanical, electro-magnetic, and aerodynamic. For high speed motor, the noise is dominated by aeroacoustics. In this thesis, we discussed with a three-phase induction motor. The noise is simulated by numerical method of computational aeroacoustics (CAA), then compare with experiment result for validation. The purpose of this research is to develop an analysis model to predict motor noise that generated by aeroacoustics.
In order to obtain motor noise spectral, we perform experiment for the noise measurement at anechoic chamber. Also design a series of different variable factor in the experiment. By analysising measurement data for each cases, we can find that fan is the major sound source of aeroacoustics. In addition, simulation procedure has two parts, one is in fluid field, and another is in acoustic field. We use ANSYS Fluent to calculate fluid field in advance to obtain sound source of fan. And then the sound source we obtained will use boundary element method to calculate acoustic response for the receivers. Finally, we compare simulation result with experiment data, the consequence of comparison is very well. Proves that this calculation model is useful and provide motor designer a tool to proceed noise reduction in further design.

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