離心泵屬於流體機械的一種為三維複雜扭曲的流道，流體經過扭曲的流道時受到離心力的作用甩出去造成流場不穩定，更因回流與空蝕產生造成能量損失，而使葉輪效率降低。本研究的目的，即針對離心泵的葉片外型作流場分析，了解其物理現象，希望在未來的離心泵葉片設計時能有所貢獻。本文的離心泵係根據泵浦特有的無因次化參數「比速率」決定離心泵的流量、揚程及轉速。其葉片設計以「參數設計法」將葉片幾何參數化，再配合「歐拉理論」與「速度三角形」決定初始葉形的幾何參數值，為了使設計的葉形能夠被五軸加工機切削製造，故以「創成加工」來產生葉形輪廓線點資料，然後以CAD建構葉片的三維外型。初始葉形決定之後再以計算流體力學CFD模擬分析，最後導入最佳化方法試圖找出葉片的最佳化設計。最佳化部份是結合類神經網路與最佳化方法，其優點可以快速地搜尋到高效率的離心式葉片。最後結果指出本文的最佳葉形確實比初始葉形效率提昇百分之三十左右。

Centrifugal pump is one kind of turbomachinery. Because of centrifugal force causing, the flow field inside centrifugal impellers is unstable. Some special phenomena, such as separation and cavitation, have great effect on the loss inside the impellers. The purpose of this research is to analyze the flow field for different centrifugal impellers and to understand the physics in them. It is hoped that we can provide an efficient method for designing centrifugal pump impellers. In this research, the decision of flow rate, head and rotational speed is according to dimensionless “specific speed”. First, we choose 9 parameters of the impeller profiles according to “parametric impeller design method”. Second, we decide the 9 parametric values of the initial impeller profiles according to “Euler theory” and “velocity triangle”. Three, in order to assure the impeller profiles can be manufactured directly by five-axis machine tool, we adopt “generating machining” to establish the control data points of an impeller. The obtained data are used as the input data for CATIA CAD/CAM software to construct the three-dimensional CAD model. Finally, the computational fluid dynamics method (CFD) is then used to analyze the flow performance of the centrifugal impellers; besides, we also try to search the optimized impeller profiles. Increasing the efficiency is the main consideration in this research. A combination of “neural network” with “optimization method” is used to search high efficient centrifugal impellers. The result of this research is that the efficiency of optimized impellers is higher than initial impellers about 30%.

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