微流道中以不對稱擋體作流場導向的研究

Abstract

摘 要 本文利用CFDRC軟體作為分析工具，研究在以往復振動機制驅動的微流道流動中，以不對稱擋體作為導流及流量控制之可行性。流場基本條件為三維度非穩態的單一種流體，假設為不可壓縮流，且忽略重力、磁力、溫度場等影響。此研究及設計可視為一項機械式無閥門微幫浦，而此一幫浦的特色為可直接建構在矩形截面的直微流道上，以壓電薄膜作為一驅動源，在壓電薄膜上或下游裝置一梯形擋體（不對稱障礙體）作流體導向裝置。模擬此幫浦前，我們先模擬文獻中漸張/漸縮管式的微幫浦及相關實驗結果，以驗證計算的正確性；並作了完整的格點測試。本文探討了眾多尺寸及操作參數狀況，得到擋體斜邊小角度時，流量為正（擋體側邊與流道壁間隙漸增的方向為正），而加大擋體角度將導致淨流量下降，甚至達到負流量（流向相反）的情況。此外，擋體配置位置在壓電薄膜左、右也有不同的淨流量。模擬的結果顯示，我們可藉由調整壓電薄膜振幅及工作頻率，達到調整幫浦流量甚至流向的效果。另外我們也分析了所設計的幫浦其內各阻力貢獻，得到小角度淨流量的發生主要來自於擋體與流道間的剪應力對流道所產生阻力差異，而大角度淨流量主要來自於擋體的形狀阻力效應。以上對於微流道中流場導向的研究結果，對於提升幫浦的工作效率及適用性有參考價值，以利作為生醫方面用途或將來的各種應用。

Abstract We use the CFDRC software to do the research about the reciprocating mechanism to drive the flow in the micro-channel. The main idea of the thesis is to use the asymmetric obstacle which controls the directions of the flow and the volume flow rate. The design can be taken as a mechanics valveless micro-pump driven by a piezo film. We discuss different sizes which are the angles and the different positions of the obstacle and operated parameters which are the working frequencies and the amplitudes of the piezo in the micro-pump. After analyzing the results, there are some conclusions. The larger angles of the obstacle, the less volume flow rate. However, the volume flow rate may be negative in some cases. We can change different the working frequencies and the amplitudes of the piezo to control the directions of the flow and the volume flow rate. In a word, the results can provide the appropriate designs to promote the working efficiency of the micro-pump and it can also apply to biologic medical aspect and other driven applications.