無閥門微幫浦及脈衝流場混合器的數值研究

Abstract

本文利用CFDRC軟體作為分析工具，尋求以不對稱擋體作流體導向（簡稱O型）的無閥門微幫浦與脈衝流場混合器之設計。此一幫浦的特色為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，在壓電薄膜上下游各裝置一梯形擋體作流體導向裝置；而脈衝流場混合器則是利用入口流體速度差與梯形擋體破壞流體介面，藉以增強混合。對於O型無閥門微幫浦，本文討論各種幾何條件及工作參數，得到流道中的最小截面寬對流場的影響，較擋體導角曲率半徑的影響為大；而破壞擋體構形會對淨流量造成影響，若破壞的體積愈大，改變的流量值愈多；而改變幫浦吸入與排出過程的時間比，會影響其淨流量大小，並且流量改變幅度與工作頻率有關。在脈衝流場混合器方面，首先我們模擬文獻中的微混合器，以驗證我們計算的正確性。本文並探討了多種的二維直管流狀況，得到在流道中放置擋體，脈衝流場提升混合效應的幅度最大，且注入狀態若為ABA排列（指流體A沿流到兩壁注入，另一流體B由流道中央注入），對於混合效果更為良好。我們也探討雷諾數Re與史卓荷數St對脈衝流場混合器之影響，得知在雷諾數小於5，脈衝流場混合器的混合效應相當良好，而當Re=0.5有一個最佳值，並且得到最適合脈衝流場混合器的操作頻率參數為St=19.2。

We use the CFDRC software to do the research about the

valveless micro-pump which is by means of asymmetric

obstacles to control the direction and the volume flow

rate of the flow. The design can be taken as a mechanical

valveless micro-pump driven by a piezo film. We also

study about the mixer using time pulsing flows. We

illustrate the technique by studying mixing in a simple

channel which contains obstacles as well as physically

mixing two aqueous reagents.

After analyzing the results, We can obtain some

conclusions. If we change the size of the narrowest part

of the channel, it will has a greater effect for the

volume flow rate of the flow than if we change the

curvature of the angle of the obstacle. It can improve the

volume flow rate of the flow by means of changing the

ratio of time for puming mode and suction mode of the

pump. We also disscuss mixing effeciency about several

different 2D flow. We get the fact that time pulsing flows

with a obstacle have a great improvement about the mixing

effeciency. Furthermore, we changed Reynolds number and

Strohul number to observe the mixing efficiency. We get

the best mixing contion for the mixer is Re=0.5 and

St=19.2.