| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 90 === 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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