凹槽結構管道微混合器流場分析

Abstract

兩種流體的混合在許多的微流體系統中是必要的過程，由於微流道的尺寸非常小，因此流體以層流方式流動，混合過程是以分子擴散方式進行，為了在合理的時間內達成有效的混合，必須控制流體使使兩流體界面增加，藉此才能降低擴散路徑，加強分子擴散行為以完成整個混合過程。具凹槽結構之微管道可產生二次流場，其可延展並且折疊流體介面，降低流體間之擴散路徑。在本文中，討論幾何外型參數對直型溝槽混合器混合性能的影響，並比較人字形混合器及具傾斜阻塊混合器之混合效率，數值計算結果顯示，溝槽較深的溝槽及較寬的溝槽有較佳的混合效果，雙傾斜溝槽比單傾斜溝槽有更佳的混合品質，於SHM管道中置入傾斜阻塊，可藉由影響流場型態及產生橫向質傳效應方式提升混合效率，因此，在有限的尺寸下，OBSHM概念應可提供微混合器設計有用的資訊

Two-fluids mixing is an essential processes in many microfluidics systems, Due to the small dimensions of the micro channels, the flow is predominantly laminar and mixing is limited by molecular diffusion. In order to efficiently mix in a reasonable time, fluids must be controlled to increase the interfacial area between the fluids so that the diffusion path is decreased to enhance the molecular diffusion in mixing processes. micro channels with grooved structure can create the secondary flow which stretched and folded material line to reduce the diffusion path between fluid streams. in the thesis, a study of the influence of various geometrical parameters of straight ridges micromixer on mixing performance is reported, then, comparing the efficiency between the staggered herringbone micromixer(SHM) and new type micromixer which we call OBSHM. The results indicate that a large groove depth and width has better performance then others. the mixing quality of microchannls with double grooved structure is superior to the the single structure, the oblique blocks placed in the SHM can improve mixing efficiency by affecting the flow pattern and alter the flow to create lateral mass transport, therefore, in the limits of dimensions, the ideal of OBSHM can provide useful information in the design of micomixers.