振荡热管内两相流界面形态数值模拟研究

发布时间：2018-01-04 02:46

本文关键词：振荡热管内两相流界面形态数值模拟研究　出处：《南昌大学》2015年硕士论文　论文类型：学位论文

【摘要】：作为一种新型高效的传热元件,振荡热管以其结构简单、传热性能优良、成本低廉、适应性强等优点,受到了国内外学者极大的关注,在电子元件散热、空气调节、余热回收等领域得到了广泛应用,并具有极大的开发潜力。振荡热管工作时,管内压力温度波动极为复杂,促使管内表现出复杂的两相流动,流型的形成及转变在很大程度上影响着振荡热管的工作性能,所以对管内两相流界面形态的研究具有重要意义。毛细管作为振荡热管的基本元件,采用毛细管模型对振荡热管内两相流动进行研究是一种切实可行且新颖独特的途径。针对柱塞流、气泡脉动及其变形破裂等振荡热管中非常普遍的流型,基于毛细管几何模型,耦合VOF模型和CSF表面张力模型,采用ANSYS FLUENT14.0求解器进行计算分析。首先借助毛细T形管结构产生稳定柱塞流,探究T形管内柱塞流形成机理,得到柱塞长度与支管半径的关系,为管内柱塞流动深入研究提供参考。随后对毛细管内气泡运动变形进行模拟,通过与其他学者的实验结果及LBM模拟结果对比,一致性较好,模型准确性得到验证。研究不同Re数、We数、Ca数情况下毛细管内气泡的变形破裂规律,以及脉动压力驱动下的振荡变形规律。在毛细管内气泡破裂临界毛细值会随气泡直径增加而增加,压力脉动导致流体流动脉动以及界面波加剧,致使流动紊乱程度增加。随着振荡热管管径的微型化,管内多个独立气液界面的相互作用在很大程度上影响着界面的运动,引入界面追踪法(Front-Tracking Method,FTM),借助其精确追踪界面的优点,运用MATLAB软件计算处理,以管内两个液滴自由下落为例,初步探索了管内多个气液界面间的耦合作用。数值分析不同Re数、Eo数和液滴初始中心距情况下液滴的运动变形情况。在初始中心距较小(L/D=2)时,液滴在下落过程中变形是不对称的,并且会相互排斥,在Re数较大和Eo数较大时,这种现象更加明显;而初始中心距较大的液滴运动特性主要由Re数和Eo数决定。这些研究为FTM方法在振荡热管两相流研究上的应用提供参考。
[Abstract]:As a new type of high efficient heat transfer component, oscillating heat pipe with its simple structure, high heat transfer performance, low cost, strong adaptability etc, by domestic and foreign scholars of great concern, in the air conditioning cooling, electronic components, field of heat recovery has been widely used, and has great development potential. The oscillation the heat pipe, pipe pressure temperature fluctuation is very complex, the tube exhibits complex two-phase flow, formation and change of flow pattern affects the working performance of an oscillating heat pipe to a great extent, so the research on the interface morphology of two-phase flow in pipe is of great significance. As the basic element of capillary oscillating heat pipe the model of capillary flow in oscillating heat pipe flow is a feasible and unique way to research on plunger flow, bubble deformation and rupture of oscillating heat pipe is very common in the The flow pattern, capillary geometry model based on coupling model of VOF and CSF surface tension model, using ANSYS solver of FLUENT14.0 were calculated and analyzed. First by capillary T tube structure to generate stable slug flow, exploring the T - shaped pipe plunger flow mechanism, piston length and branch pipe radius relationship, provide reference for further study on the tube in the plunger flow. Then the bubble movement in capillary deformation is simulated by experimental results with other scholars and the LBM simulation results have good consistency, accuracy of the model was verified. The study of different Re number, We number, Ca number of bubbles in the capillary deformation under the condition of deformation and rupture of oscillation driven by fluctuating pressure the critical rupture value. Capillary increases with the increase of bubble diameter bubbles in the capillary, resulting in fluid flow pulsation and pressure pulsation of interface wave intensified, resulting in the flow disturbance process The degree of increase. With the miniaturization of the oscillating heat pipe, the interaction of multiple independent gas-liquid interface tube affects the interface movement to a great extent, the introduction of the interface tracking method (Front-Tracking Method FTM), with its advantages of accurate tracking interface, calculating and processing using MATLAB software, the tube two drops free fall as an example, a preliminary exploration of the coupling between a gas-liquid interface inside the tube. The numerical analysis of different Re number, Eo number and the initial droplet center distance of droplet motion and deformation. In the initial center distance is smaller (L/D=2), the droplet in the falling process of deformation is asymmetrical, and will repel each other, in a large number of Re and the Eo number is large, this phenomenon is more obvious; and the movement characteristics of liquid droplet from the larger initial center is mainly composed of Re and Eo number decision. These studies for the FTM method in the application of oscillating heat pipe two-phase flow on. Test.

【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK172.4

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