| Summary: | 碩士 === 國防大學理工學院 === 造船及海洋工程碩士班 === 99 === In this study, we apply particle image velocimetry (PIV) and dye injection techniques to observe and measure the characteristic of flow vorticity influenced by the gaps of cylinders and the wall effect. In order to provide meaningful parameters for heat exchanger design, we also use the methodology of DOE to find out the optimum combination of factors among the gaps of cylinders, cylinder-to-wall gaps, and Reynolds numbers. The experiments were conducted in a circulating water channel with 22mm diameter cylinders arranged side by side. Three conditions were chosen to these three dimensionless factors as the levels. The data of flow velocity were acquired by Insight 5.0, then analyzed vorticity field by Tecplot 10. On seeking optimum parameter design, we first have used Taguchi method to conduct static analysis and found that Reynolds number is the most critical factor； then deal with dynamic analysis to find out the better combination of the cylinders gaps and cylinder-to-wall gaps. Proceeding to the next step, in order to look precisely for the best combination of parametric levels, we have succeeded in getting a non-linear function model by using artificial neural network with a training set resulted from the data of orthogonal arrays. Finally, the best parameter design of global optimization is obtained by way of a genetic algorithm to the model of neural network.
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