本文選題：微混合器 + 循環(huán)回流��； 參考：《江蘇大學》2017年碩士論文

【摘要】：作為微流控芯片的重要結(jié)構(gòu)單元和微機電系統(tǒng)的前處理裝置,微混合器伴隨著微流控芯片和微機電系統(tǒng)的發(fā)展而興起。根據(jù)有無增加額外動力源,微混合器可分為主動式和被動式兩大類;相比較而言,被動式微混合器由于不需要添加額外動力源,因而具有結(jié)構(gòu)簡單、加工方便、易于集成、且不會影響有機流體的生化活性和理化性質(zhì)等優(yōu)點,使其在化學合成、生化分析、生物測量技術(shù)、藥物控制釋放等領(lǐng)域有著廣闊的應用前景。為了克服微混合器混合過程中,中心面附近的流體混合效率比較高,而靠近壁面附近的流體混合效率比較低的缺點,本文設(shè)計出一種利用高速射流原理來實現(xiàn)高效回流的循環(huán)被動式微混合器,其具有結(jié)構(gòu)簡單,容易產(chǎn)生回流且回流率高,混合效率高等諸多優(yōu)點。該微混合器主要利用高速射流對混合區(qū)流體的卷吸、摻混作用,使循環(huán)通道中產(chǎn)生回流,從而實現(xiàn)邊界層附近混合效率較低流體的多次循環(huán)混合。本文通過ANSYS CFX數(shù)值模擬的方法,研究了不同結(jié)構(gòu)參數(shù)和流體參數(shù)對微混合器混合性能的影響;同時,通過設(shè)計微流體混合實驗,研究了微混合器的實際混合效果,并將實驗結(jié)果和模擬結(jié)果進行了對比。數(shù)值模擬結(jié)果表明,射流強度越大,流體粘度越小,微混合器的回流率和混合效率就越高,而且縮小射流噴嘴寬度L,或適當降低微混合器高度H均可有效提高射流強度;而當射流強度達到一定程度時,射流跡線會在混合區(qū)產(chǎn)生偏轉(zhuǎn),從而導致兩個循環(huán)通道中混合流體的回流量相差較大,這種不對稱的循環(huán)回流使得混合區(qū)流體分子間的碰撞更為劇烈,混沌對流強度更強,此時通常能實現(xiàn)很高的混合效率;當Re15時,微混合器的最大回流率已超過22%,混合效率則超過95%。根據(jù)實驗結(jié)果與數(shù)值模擬結(jié)果的對比,可以發(fā)現(xiàn):微流體混合實驗的實驗結(jié)果與數(shù)值模擬結(jié)果保持了良好的一致性,從而證明了本文采用的數(shù)值模擬方法的準確性和可靠性;這也說明,本文所設(shè)計的微混合器具有很好的實際應用價值。
[Abstract]:As an important structure unit of microfluidic chip and pre-processing device of micro-electromechanical system, micro-mixer has been developed with the development of microfluidic chip and micro-electromechanical system. Based on the availability of additional power sources, micromixers can be divided into active and passive types; by comparison, passive micromixers have simple structures, easy processing and easy integration because they do not require additional power sources. It will not affect the biochemical activity and physicochemical properties of organic fluid, which makes it have a broad application prospect in the fields of chemical synthesis, biochemical analysis, biological measurement technology, drug release control and so on. In order to overcome the disadvantage of high mixing efficiency near the center surface and low mixing efficiency near the wall in the mixing process of the micro mixer, In this paper, a kind of circulating passive micro mixer with high efficiency is designed by using the principle of high speed jet. It has many advantages, such as simple structure, easy to produce reflux and high reflux rate, high mixing efficiency and so on. The micro mixer mainly uses the high speed jet to absorb and mix the fluid in the mixing zone, so that the reflux is produced in the circulation channel, so that the mixing efficiency near the boundary layer is low. In this paper, the influence of different structure parameters and fluid parameters on the mixing performance of the micro mixer is studied by means of ANSYS CFX numerical simulation, and the actual mixing effect of the micro mixer is studied by designing the micro fluid mixing experiment. The experimental results are compared with the simulation results. The numerical simulation results show that the greater the jet strength and the lower the fluid viscosity, the higher the reflux rate and mixing efficiency of the micro mixer, and reducing the jet nozzle width L or reducing the height H of the micro mixer can effectively increase the jet strength. However, when the jet intensity reaches a certain degree, the jet trace will deflect in the mixing zone, resulting in a large difference in the reflux of the mixed fluid in the two circulation channels. This asymmetric circumfluence makes the collision between molecules in the mixing region more intense and chaotic convection more intense, which usually achieves a high mixing efficiency; when Re15, The maximum reflux rate of the micro mixer is over 22 and the mixing efficiency is over 95. According to the comparison between the experimental results and the numerical simulation results, it can be found that the experimental results of the micro-fluid mixing experiment are in good agreement with the numerical simulation results, which proves the accuracy and reliability of the numerical simulation method used in this paper. It also shows that the micro mixer designed in this paper has good practical application value.
【學位授予單位】：江蘇大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TH-39;TN492

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