針對軸流風扇系統其性能曲線與聲學特性之數值模擬研究

全密閉式風扇冷卻馬達廣泛應用於工業界，為了達成提高馬達致冷效果以及符合國家工廠噪音管制標準之目的，風扇冷卻系統氣動和聲學特性研究成為重要的研究課題。本研究主要使用計算流體力學軟體ANSYS Fluent內建之多重參考座標系統和滑移網格進行旋轉流場模擬。我們首先建立一數值風洞模型，針對Multi-Wing軸流式風扇採用傳統方法和下游流阻法兩種邊界條件進行風扇性能曲線的量測驗證。模擬結果和實驗數據相比，傳統方法最大誤差可達65.8%，而下游流阻法的結果較為精準，最大誤差僅8.72%。接著使用多重參考座標系統的擬穩態結果作為初始解代入滑移網格計算，誤差也皆小於5%，驗證了本研究之數值風洞是可行的。研究的後半段採用數值風洞計算包含安全網目、風扇、風罩和擋板的全密閉式風扇冷卻系統之系統性能曲線和聲場，安全網目以多孔隙材料簡化。我們嘗試四種幾何策略改善原始系統的性能，研究結果顯示幾何策略可大幅提升系統流量，但是由於後方斜流道和流體的交互作用產生多餘的聲源，和原始系統相比亦會造成少量噪音的產生。關鍵字：全密閉式風扇冷卻馬達、多重座標參考系統、滑移網格、風扇性能曲線、流道設計、下游流阻法

關鍵字

全密閉式風扇冷卻馬達；多重座標參考系統；滑移網格；風扇性能曲線；流道設計；下游流阻法

並列摘要

Totally-Enclosed-Fan-Cooled (TEFC) motor is extensively utilized in modern industry. To reach the purposes of improving the motor cooling effect and according with the factory noise control standard, the research of aerodynamic and acoustic characteristics of the fan cooling system become important issues. In this study, we mainly use the computational fluid dynamics software, ANSYS Fluent and its build-in rotating model, Multiple Reference Frame (MRF) and sliding mesh (SM) models to simulate the swirling flow. We first construct a numerical wind tunnel which is conducted by two boundary conditions, the conventional method and the Downstream Flow Resistance (DFR) method, calculate the flow field of the Multi-Wing axial fan and verify the fan performance measurement. In comparison to the experimental data, the maximum error of the conventional method result is up to 65.8% and the DFR method result becomes more accurate and its maximum error is reduced to 8.72%. We then compute the transient result which begins from the quasi-steady initial solution by the sliding mesh model, and the errors are all less than 5%. These results verify that the numerical wind tunnel is feasible. In the last half of this research, we apply the previous numerical wind tunnel to compute the system performance curve and the acoustic field of the fan cooling system including the safety mesh, fan, shroud, and plate. The safety mesh is simplified by the porous zone. We try four strategies to modify the geometry of the system on the purposes of improving the volume flow rate and reducing the noise of the original system. The results show that the modified system has the ability to improve the system volume flow rate obviously, but the system noise also increases a little due to the interaction between the deflected pathway and the fluid in comparison to the original system. Keywords: Totally-Enclosed-Fan-Cooled motor, Multiple Reference Frame, Sliding mesh, Fan performance curve, Downstream flow resistance method

並列關鍵字

Totally-Enclosed-Fan-Cooled motor ； Multiple Reference Frame ； Sliding mesh ； Fan performance curve ； Downstream flow resistance method

參考文獻

[1] AMCA Standard 210-99 Laboratory Methods of Testing Fans for Certified Aerodynamic Performance Rating.

[2] M. J. Lighthill, “On Sound Generated Aerodynamically. I. General Theory”, Proceedings of the Royal Society, London. Series A, Vol. 211, No. 1107, 564-587, (1952).

[3] N. Curle, “The Influence of Solid Boundaries upon Aerodynamic Sound”, Proceedings of the Royal Society, London. Series A, Vol. 231, No. 1187, 505-514, (1955).

[4] E. Ffowcs Williams and D. L. Hawkings, “Sound Generation by Turbulence and Surfaces in Arbitrary Motion”, Proceedings of the Royal Society, London. Series A, Vol. 264, No. 1151, 321-342, (1969).

[8] Michael Norton and Denis Karczub, Fundamentals of Noise and Vibration Analysis for Engineers, 178-179.

國際替代計量

針對軸流風扇系統其性能曲線與聲學特性之數值模擬研究

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