本文選題：氣泡生成 + 流變性質(zhì)��； 參考：《沈陽航空航天大學(xué)》2017年碩士論文

【摘要】：非牛頓流體中氣泡運動在實際過程中廣泛存在,如:能源、化工、環(huán)境、復(fù)合材料加工等領(lǐng)域。對流體中氣泡運動的深入研究,將有助于生物反應(yīng)器、鼓泡塔等過程設(shè)備進行優(yōu)化設(shè)計。本文主要研究剪切變稀流體中的單氣泡的生成行為,粘彈性流體中單氣泡上升過程中的軌跡和以及非牛頓流體中雙氣泡之間相互作用的數(shù)值模擬。本文采用高速攝像儀對單氣泡在剪切變稀流體中生成過程進行了研究,并與甘油水溶液(牛頓流體)中的氣泡生成過程進行了對比,討論了剪切變稀流體的流變性、噴嘴的孔徑和氣體流速對氣泡在生成過程中的體積及縱橫比的影響。結(jié)果表明:氣泡的形成時間和分離體積隨著流體的粘度增加而增大。氣泡的縱橫比在氣泡生成階段是比較復(fù)雜,在氣泡生成初期縱橫比速度隨著流體粘度的增大而增大,在氣泡生成后期,氣泡長徑比的增長速率則隨剪切程度的增大而增大。然而,氣泡分離體積、瞬時體積、生成時間隨著噴嘴直徑和氣體流速的增加而增大,相反,氣泡的縱橫比隨著噴嘴直徑和氣體流速的增加而減小。為了研究粘彈性流體中穩(wěn)定上升的氣泡運動軌跡,主要對穩(wěn)定上升的氣泡在三種不同濃度的粘彈性流體(聚丙烯酰胺-PAA溶液)中運動軌跡進行了實驗研究。結(jié)果發(fā)現(xiàn)氣泡的上升軌跡主要分為兩種:直線型和螺旋型。氣泡運動軌跡變化與氣泡的形狀及流體的濃度有關(guān),氣泡形變越大,軌跡越易由直線型轉(zhuǎn)變?yōu)槁菪�。軌跡的不穩(wěn)定還與溶液的粘彈性剪切變稀流體的流變性質(zhì)有關(guān),隨著溶液濃度的增加,氣泡運動軌跡由螺旋形轉(zhuǎn)變?yōu)橹本�型。通過螺徑螺距比r/L表示螺旋線的彎曲程度,得到隨著Re的增大,螺徑螺距比也越來越大,最終逐漸趨向穩(wěn)定。通過二維VOF方法模擬氣泡尺寸、間距、溶液濃度對雙氣泡之間的相互作用的影響,研究中發(fā)現(xiàn):在線模擬過程中,先行氣泡和跟隨氣泡之間的相互作用與兩氣泡之間的中心間距有關(guān),無因次變量距離S*越小,先行氣泡和跟隨氣泡聚并成為為一個大氣泡的時間越短。當(dāng)無因次變量距離S*增大到一定程度時,兩氣泡之間始終不會發(fā)生聚并,最終會以各自不同的速度上升。無因次變量距離S*與溶液濃度有關(guān),隨著溶液濃度越大,無因次變量距離S*也越大,先行氣泡與跟隨氣泡速度之比不斷減小,直至先行氣泡和跟隨氣泡速度之比為1時,跟隨氣泡不受先行氣泡的尾流影響。水平相互作用模擬過程中,氣泡的相互作用與氣泡之間的間距有關(guān),隨著氣泡之間距離增大,氣泡之間的相互作用由相互吸引變?yōu)橄嗷ヅ懦�。兩水平氣泡越�?氣泡之間的臨界距離越小。在相同的初始距離下,氣泡越小,氣泡越容易發(fā)生相互作用聚并為一個大氣泡。流體濃度越高,兩氣泡之間發(fā)生聚并的臨界距離就越小。
[Abstract]:Bubble motion in non-Newtonian fluids is widely used in practical processes, such as energy, chemical engineering, environment, composite material processing and so on. The study of bubble motion in fluid will be helpful to optimize the design of bioreactor and bubbling tower. This paper mainly studies the formation behavior of single bubble in shear thinning fluid, the trajectory of single bubble rising in viscoelastic fluid and the numerical simulation of the interaction between two bubbles in non-Newtonian fluid. In this paper, the formation process of single bubble in shear-thinning fluid is studied by using a high-speed camera, and compared with that in glycerol aqueous solution (Newtonian fluid), and the rheology of shear-thinning fluid is discussed. The influence of nozzle aperture and gas velocity on the volume and aspect ratio of bubble formation. The results show that the bubble formation time and separation volume increase with the increase of fluid viscosity. The aspect ratio of bubbles is more complex in the bubble formation stage. In the initial stage of bubble formation, the velocity of aspect ratio increases with the increase of fluid viscosity, and at the later stage of bubble formation, the growth rate of bubble aspect ratio increases with the increase of shear degree. However, the bubble separation volume, instantaneous volume and formation time increase with the increase of nozzle diameter and gas velocity. On the contrary, the aspect ratio of bubble decreases with the increase of nozzle diameter and gas velocity. In order to study the trajectory of bubbles rising stably in viscoelastic fluids, the trajectory of bubbles rising stably in three different concentrations of viscoelastic fluids (polyacrylamide PAA solution) was studied experimentally. The results show that the rising trajectory of bubbles is mainly divided into two types: linear and spiral. The change of bubble trajectory is related to the shape of bubble and the concentration of fluid. The larger the bubble deformation, the easier it is to change the trajectory from linear to spiral. The instability of the trajectory is also related to the rheological properties of the viscoelastic shear-thinning fluid. With the increase of the concentration of the solution, the trajectory of the bubble changes from a spiral to a linear one. The ratio of screw diameter to pitch r / L indicates the bending degree of helical line. It is shown that with the increase of re, the ratio of screw diameter to pitch becomes larger and larger, and eventually tends to be stable. The effects of bubble size, spacing and solution concentration on the interaction between two bubbles were simulated by two-dimensional VOF method. The interaction between the first bubble and the follower bubble is related to the central distance between the two bubbles. The smaller the dimensionless variable distance S *, the shorter the time for the leading bubble and the following bubble to gather and become a large bubble. When the distance of dimensionless variable S * increases to a certain extent, there will always be no coalescence between the two bubbles, which will eventually rise at different speeds. The distance of dimensionless variable S * is related to the concentration of the solution. With the increase of the concentration of the solution, the distance of the dimensionless variable S * increases, and the ratio of the leading bubble to the velocity of the following bubble decreases continuously until the ratio of the leading bubble to the velocity of the following bubble is 1. The following bubble is not affected by the wake of the leading bubble. In the process of horizontal interaction simulation, the interaction of bubbles is related to the distance between bubbles. With the increase of the distance between bubbles, the interaction between bubbles changes from mutual attraction to mutual repulsion. The larger the two horizontal bubbles, the smaller the critical distance between the bubbles. At the same initial distance, the smaller the bubble is, the easier it is for the bubble to interact and converge into a large bubble. The higher the fluid concentration, the smaller the critical distance between the two bubbles.
【學(xué)位授予單位】：沈陽航空航天大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O373

【相似文獻】

相關(guān)期刊論文 前10條

1 唐永剛;;三維氣泡運動的數(shù)值模擬[J];南通航運職業(yè)技術(shù)學(xué)院學(xué)報;2011年03期

2 張紅;丁述理;徐博會;任曉慧;;超聲空化氣泡運動的數(shù)值模擬[J];河北工程大學(xué)學(xué)報(自然科學(xué)版);2013年04期

3 董瑞;;奇妙的氣泡運動[J];物理教學(xué)探討;2009年05期

4 劉二平;付英杰;郝劉倉;蘇浩;李建東;;波浪中氣泡運動的數(shù)值模擬[J];艦船科學(xué)技術(shù);2012年05期

5 張淑君;吳錘結(jié);王惠民;;界面模擬方法在氣泡運動領(lǐng)域的應(yīng)用述評[J];河海大學(xué)學(xué)報(自然科學(xué)版);2006年06期

6 李維仲;趙大勇;陳貴軍;;豎直流道寬度對氣泡運動行為影響的數(shù)值模擬[J];計算力學(xué)學(xué)報;2006年02期

7 武博;郝宗睿;陳濤;吳大轉(zhuǎn);;水下氣泡運動的數(shù)值模擬[J];中國科技論文在線;2010年08期

8 黃世鴻,B.Vonnegut;進入密度不連續(xù)層的氣泡運動的初步實驗?zāi)M[J];氣象科學(xué);1988年02期

9 張文娟;安宇;;兩氣泡相互繞圈運動的理論研究[J];聲學(xué)技術(shù);2013年S1期

10 徐玲君;陳剛;邵建斌;薛陽;;單個氣泡靜水中上升特性的數(shù)值模擬[J];沈陽農(nóng)業(yè)大學(xué)學(xué)報;2012年03期

相關(guān)會議論文 前7條

1 高建成;劉趙淼;;熔融金屬中氣泡運動數(shù)值模擬分析[A];北京力學(xué)會第14屆學(xué)術(shù)年會論文集[C];2008年

2 宋禹林;譚思超;付學(xué)寬;;晃蕩對氣泡上升運動影響的數(shù)值研究[A];中國核學(xué)會核能動力分會2013年學(xué)術(shù)研討會論文集[C];2013年

3 聞仲卿;張凌新;邵雪明;;多泡相互作用對氣泡潰滅的影響[A];第七屆全國流體力學(xué)學(xué)術(shù)會議論文摘要集[C];2012年

4 張文娟;安宇;;兩氣泡相互繞圈運動的理論研究[A];中國聲學(xué)學(xué)會第十屆青年學(xué)術(shù)會議論文集[C];2013年

5 邵雪明;張凌新;聞仲卿;王文鳳;劉蘭;;泡群運動數(shù)值模擬及宏觀特性分析[A];中國力學(xué)大會——2013論文摘要集[C];2013年

6 楊超;陳杰;張麗;毛在砂;;剪切變稀流體中氣泡運動和溶解的數(shù)值模擬[A];中國力學(xué)大會——2013論文摘要集[C];2013年

7 朱琳;田振夫;王燕;;用Level-Set方法模擬氣泡在水中運動的過程[A];第七屆全國水動力學(xué)學(xué)術(shù)會議暨第十九屆全國水動力學(xué)研討會文集（上冊）[C];2005年

相關(guān)博士學(xué)位論文 前1條

1 王詩平;水中結(jié)構(gòu)物附近爆炸氣泡運動特性研究[D];哈爾濱工程大學(xué);2011年

相關(guān)碩士學(xué)位論文 前3條

1 許玲麗;單氣泡運動特性分析及曳力模型修正[D];中國礦業(yè)大學(xué);2015年

2 徐雙;非牛頓流體中氣泡運動特性的研究[D];沈陽航空航天大學(xué);2017年

3 李建東;船用氣泡藥劑發(fā)射落點分析及氣泡運動研究[D];天津大學(xué);2012年

，

本文編號：2061287