本文選題：潤(rùn)濕性　切入點(diǎn)：超疏水　出處：《大連海事大學(xué)》2015年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：微流體系統(tǒng)作為微機(jī)電系統(tǒng)的一個(gè)重要分支,在生物醫(yī)學(xué)、化學(xué)工程等領(lǐng)域具有廣泛應(yīng)用。隨著微流體技術(shù)的發(fā)展,液體在微通道中流動(dòng)的阻力特性成為研究的熱點(diǎn)。微通道壁面的潤(rùn)濕性在很多情況下影響流體的流動(dòng),超疏水表面通過(guò)降低材料表面自由能,來(lái)減小微通道中固液之間的吸附作用,使得流體在壁面處發(fā)生速度滑移,從而減小界面阻力。本文從實(shí)驗(yàn)測(cè)試和數(shù)值模擬兩個(gè)方面研究了表面潤(rùn)濕性對(duì)微通道中流體流動(dòng)的影響。采用Micro-PIV微觀(guān)粒子成像測(cè)速技術(shù)對(duì)由四種不同潤(rùn)濕特性的壁面兩兩組合的微通道進(jìn)行流場(chǎng)測(cè)試,研究了壁面滑移速度與壁面潤(rùn)濕性之間的關(guān)系。結(jié)果表明,隨著壁面疏水性的提高,壁面處的滑移速度增大；對(duì)于兩側(cè)壁面疏水性不同的微通道,最大速度位置偏向疏水性較強(qiáng)的一側(cè)。在不同入口壓力條件下,利用高速攝像系統(tǒng)記錄空泡在由不同潤(rùn)濕性的硅表面組成的通道中的運(yùn)動(dòng)過(guò)程,研究了壁面潤(rùn)濕性對(duì)空泡在壁面處動(dòng)態(tài)接觸角的影響。研究發(fā)現(xiàn),空泡動(dòng)態(tài)接觸角隨著壁面疏水性的增強(qiáng)而增大,且一側(cè)壁面疏水性的增強(qiáng)有助于提高另一側(cè)壁面疏水性對(duì)動(dòng)態(tài)接觸角影響的敏感度。當(dāng)入口壓力小于40 kPa時(shí),壁面潤(rùn)濕性對(duì)空泡動(dòng)態(tài)接觸角的影響占主導(dǎo)作用；入口壓力大于等于40 kPa時(shí),壁面潤(rùn)濕性作用減弱,壓力成為主要影響因素。采用計(jì)算流體動(dòng)力學(xué)對(duì)微通道的流場(chǎng)分布以及空泡運(yùn)動(dòng)形狀進(jìn)行了數(shù)值模擬,分析了空泡動(dòng)態(tài)接觸角、滑移速度以及壁面潤(rùn)濕性之間的關(guān)系。分析表明,流場(chǎng)速度決定了空泡頭部的形狀,且空泡在壁面處的動(dòng)態(tài)接觸角與滑移速度存在明確的對(duì)應(yīng)關(guān)系,用動(dòng)態(tài)接觸角可以有效地表征壁面滑移。
[Abstract]:As an important branch of MEMS, microfluidic system is widely used in biomedicine, chemical engineering and so on. The resistance characteristics of liquid flowing in microchannels have become a hot topic. The wettability of microchannel wall affects the flow of fluid in many cases, and the superhydrophobic surface decreases the free energy of the material surface. To reduce the adsorption between solid and liquid in the microchannel, and make the fluid slip at the wall, In this paper, the effect of surface wettability on fluid flow in microchannels was studied from two aspects: experimental test and numerical simulation. The effects of Micro-PIV microparticle imaging velocimetry on the wetting properties of four different wetting properties were studied. The flow field of microchannels with pairwise combination on the wall is measured. The relationship between wall slip velocity and wall wettability is studied. The results show that the slip velocity increases with the increase of wall hydrophobicity, and for microchannels with different wall hydrophobicity, The maximum velocity position is in favor of the hydrophobic side. Under different inlet pressures, a high-speed camera system is used to record the motion of the cavitation in a channel composed of different wettable silicon surfaces. The effect of wall wettability on the dynamic contact angle of cavitation was studied. It was found that the dynamic contact angle of cavitation increased with the increase of hydrophobicity. The enhancement of hydrophobicity of one wall can improve the sensitivity of the hydrophobicity of the other side to the dynamic contact angle. When the inlet pressure is less than 40 kPa, the influence of wall wettability on the dynamic contact angle of cavitation is dominant. When the inlet pressure is greater than 40 kPa, the wettability of the wall becomes weaker, and the pressure becomes the main factor. The flow field distribution and the cavitation motion shape of the microchannel are numerically simulated by computational fluid dynamics (CFD). The dynamic contact angle, slip velocity and wall wettability of cavitation are analyzed. It is shown that the velocity of the flow field determines the shape of the cavitation head, and the dynamic contact angle of the cavitation at the wall has a clear relationship with the slip velocity. The wall slip can be effectively characterized by the dynamic contact angle.
【學(xué)位授予單位】：大連海事大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TH-39;TN304.12

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本文編號(hào)：1622487