| 题名 | 液态泡沫强制渗流实验研究及控制机制分析 |
| 作者 | 黄晋 |
| 学位类别 | 硕士 |
| 答辩日期 | 2007-06-05 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 过程工程研究所 |
| 导师 | 孙其诚 |
| 关键词 | 液态泡沫 二维渗流 光检测技术 控制机制协调 |
| 其他题名 | Experimental study on liquid foam drainage and analysis of dominant mechanisms |
| 学位专业 | 化学工程 |
| 中文摘要 | 液态泡沫（liquid foam）是极高气含率的密集气液体系，是典型的复杂系统，广泛存在于化工、石油等工业过程中。泡沫强制渗流（forced drainage）是指以恒定流率输入的液体在重力与毛细管力以及粘滞力的共同作用下，在气泡间隙内的流动过程，是影响泡沫稳定的主要因素之一；渗流波传播规律以及泡沫液体分率的空间分布和时间演变规律不仅是国际理论和应用力学领域中近年来的活跃点，更能为化工、石油等相关领域中的泡沫稳定性控制等提供理论指导。 本工作实验中使用的表面活性剂溶液由去离子水、“金鱼”牌洗涤剂和食用色素按照40:1:10的体积比配制而成，通过注射针头注入氮气生成泡沫。我们首先完善了用色素显示泡沫中液体流动的方法，通过一维强制渗流实验确定了液体分率与光透射率的关系。我们发现泡沫柏拉图通道内的液体流动符合泊肃叶流动，能量耗散主要发生在柏拉图通道边界上。从控制机制协调的角度我们对泡沫渗流过程中的气泡表面能和流动耗散能进行了理论推导，分析了在渗流过程中这两种能量之间的相互关系。我们发现粘性耗散受液体分率变化的影响很大而表面能很小；当液体分率从0.01增加至约0.14时，粘性耗散能增加了近30倍，而表面能仅减小约14％；基于Kelvin cell结构随液体分率演变的准静态假设，我们还分析了表面能和粘性耗散的动态演化规律。 我们模拟了大小为12 cm×14 cm×3 mm的Hele-Shaw cell内两维液态泡沫在8种重力加速度下单点输入强制渗流，发现在竖直和水平方向的渗流波传播位置与时间的关系很好的符合幂函数形式。 我们实验研究了二维双点输入强制渗流过程中渗流波的传播规律。发现双点输入渗流与单点输入渗流过程明显不同，两股渗流波的运动相互影响。实验发现两输入点中间的泡沫内的渗流波以恒定速度传播，且这个恒定的传播速度与输入点间距成反比；而单个输入点下方渗流波的传播距离与时间满足幂率关系。 本论文提出从控制机制协调的角度来分析渗流过程；改进的显示微流动的实验方法简便易行，且精度高；本文所得结论将有助于丰富泡沫渗流力学理论和复杂系统协调理论。 |
| 英文摘要 | Liquid foam is a dense packing of gas bubbles in a small amount of surfactant solution, which is a typical complex system. Liquid foam has a broad application in chemical engineering and petroleum industries. Forced drainage is one of major mechanisms causing liquid foam evolution. It refers to the flow of constantly input liquid through the network of interstitial channels between bubbles in foams under actions of gravity, capillarity and viscous force. The research on how drainage wave propagates and how liquids distribute in foams is not only a central aspect in the physics of foams, but also can throw valuable light on the stability control of foams used widely in chemical and petroleum processes. The foam solution in our work was made of pure water and ordinary washing up detergent (gold-fish) and dark red food dye with a ratio of 40:1:10 in volume. The foam was then produced by blowing gas through a syringe needle into the foam solution. After the film rupture and bubble coarsening were carefully slowed down, forced foam drainages in one dimension were studied by using the improved light scattering technique. The light transmission ratio was found not to be reciprocal of liquid fraction as similar with the transmission probability in diffuse-transmission spectroscopy technique, but of a relationship. We found that the drainage in our experiments was consistent with traditional ones based on Poiseuille-type flow assumption in Plateau borders, that is, the Plateau borders have rigid boundaries and the flow dissipation mainly comes from Plateau borders but not vertexes. Also, the compromise between the minimization tendencies of viscous dissipation and surface energy in the process of foam drainage was analyzed. We found that liquid fraction had influence on both viscous energy and surface energy, while the affection on the former one was greater. We also found that when liquid fraction increased from 0.01 to about 0.14, the viscous energy will increase almost 30 times, but the surface energy only deceased by 14%. Then the evolution of the two kinds of energy at local area of foam was predicted based on the quasi-static assumption of Kelvin cell structure evolution along with liquid fraction variation. Previous experiments, theory and computation predominantly concerned drainage in only one dimension. We have extended this by performing forced drainage experiments in two dimensions. We did simulations of 2D forced foam drainage with single narrow input in a Hele Shaw cell under 8 different gravities. The spread of liquid both vertical and horizontal was recorded over time. Positions of drainage wave fronts in both directions with time were found to be well described in the power law form, and the exponents were and respectively. We also conducted 2D forced foam drainage with two narrow inputs. We found that foam drainage with two inputs was very different with traditional single input one. The two inputs liquid will interact with each other. It was found that along the vertical direction down the center of the two nozzles, the spreading speed was nearly constant for a fixed separation, and changed inversely with the separation distance of the two inputs. While along the vertical direction beneath one nozzle, the liquid spreading was well described by power law with exponents greater than that of individual drainage. And as the separation distance increased 6 times, the speed increased only about 14%. The analysis of liquid foam drainage from the aspect of compromise between dominant mechanisms was an effective idea; the improved technique for measuring liquid fraction was shown to be effective and simple; the major conclusion we have had in this thesis, therefore, may enrich both the theory of liquid foam drainage as well as the compromise mechanism theory of complex systems. |
| 语种 | 中文 |
| 公开日期 | 2013-09-13 |
| 页码 | 81 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1163]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 黄晋. 液态泡沫强制渗流实验研究及控制机制分析[D]. 过程工程研究所. 中国科学院过程工程研究所. 2007. |
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