題 目：利用入口脈動流之主動式微混合器研究
研究生：黎康熙
指導教授：潘大知

本研究以計算流體力學為工具，探討入口脈動流與微混合器結構參數對混合效果的影響。本研究採用T型管為基本混合器元件，在其出口管道加上混合腔，並於兩個入口流體流速加上具180°相差的週期性脈動流。研究結果顯示，若入口流速不具週期性脈動，則兩流體之混合界面將沿出口管道軸向延伸，兩液體的混合主要靠流體分子在管徑方向的擴散運動造成。若在入口流場加入具180°相差的週期性脈動，可使二入口的待混流體以交錯方式進入混合器，使得兩流體間之混合界面在管徑方向產生拉伸擴大的效果，讓混合界面面積擴大，增加混合效率。在出口管道加上的混合腔具有擴散段(diffuser)效果，使流體減速，並使管徑方向的混合界面進一步拉伸擴大，加強混合效率。研究結果也顯示，入口脈動的振幅及頻率之最佳選擇與混合器的幾何參數及混合流體的黏滯係數，擴散係數都相關，並非定值。

Subject：A Study of Active Micro-Mixer Based on Pulsating Inlet Flows
Student：Kaung-Hsi Li
Advisor：Dartzi Pan
This work adopts Computational Fluid Dynamics (CFD) as a research tool to discuss the effects of the geometric parameters of the micro-mixer and the frequency and the amplitude of the pulsating inlet flows on the mixing efficiency. The basic elements of the mixer are a T-tube and a mixing chamber added along the outlet passage of the T-tube. The two pulsating inlet flows have a phase difference of 180°. The research results indicate that, without the inlet flow pulsation, the interface between two fluids basically extends steadily along the axis of the outlet passage. The mixing effect is solely due to the molecular diffusion in the direction normal to the passage axis. With the addition of two out-of-phase inlet pulsations, however the two fluids are forced to enter the outlet passage alternatively such that the interface between two fluids are stretched and elongated in the direction normal to the passage axis. The elongation of interface area increases the mixing efficiency effectively. The inlet region of the added mixing chamber works as a diffuser which slows down the fluid velocity and further elongates the interface area and ultimately increases the mixing efficiency. The research results also indicate that the optimal choices of the amplitude and frequency of the pulsating inlet flows are not constant but depend on the geometry of the micro-mixer and the viscosity and the diffusivity of the two mixing fluids.

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