Sierpinski亲/疏水分形图案表面气泡分布及强化换热研究  

Study on the Bubble Distribution and Heat Transfer Enhancement on Sierpinski Hydrophobic/Hydrophilic Fractal Pattern

作　　者：于婷 王雅 齐宝金[1,2] 魏进家 YU Ting;WANG Ya;QI Baojin;WEI Jinjia(School of Chemical Engineering and Technology,Xi'an Jiaotong University,Xi'an 710049,China;Xi'an Jiaotong University Suzhou Institute,Suzhou,Jiangsu 215123,China)

机构地区：[1]西安交通大学化学工程与技术学院,西安710049 [2]西安交通大学苏州研究院,江苏苏州215123

出　　处：《西安交通大学学报》2019年第5期100-108,共9页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(51776168);江苏省自然科学基金资助项目(BK20171236)

摘　　要：针对芯片散热表面热流具有典型的中心高四周低的非均匀分布特征,设计制备了具有三阶Sierpinski地毯曲线分形特点的亲疏水交错润湿铜表面,并通过实验观测了气泡在典型的亲/疏水分形表面的动力学特性。结果表明,气泡会首先在预设的高阶疏水点处成核、生长,并呈现典型的分形特征,实现了初始气泡成核位置的可控分布;之后,相互邻近的疏水点上的气泡开始克服能垒而发生合并,同时伴随着高阶疏水区域的气泡向中央低阶区域的定向移动、合并过程,最终在中心一阶疏水区域形成大气泡。相比于光滑及疏水点阵表面,Sierpinski亲/疏水交错润湿表面不仅能够有效降低液体起始沸腾温度,提高沸腾换热的临界热流密度,而且可以规划气泡的成核点及移动、合并方向,进而实现气泡空间分布与加热壁面热流密度分布的协同一致。因此,具有Sierpinski分形特性的亲/疏水交错润湿表面进一步提高了沸腾换热性能。The heat dissipation of chip, which releases much more heat from its center than from the marginal area, shows a typical non-uniform distribution feature. Based on this, a non-uniform wetting copper surface with fractal features of three-order Sierpinski carpet was designed, and then the dynamic behaviors of the bubble on the surface with typical hydrophobic/hydrophilic fractal pattern were observed experimentally. The results showed that small bubbles would first nucleate and grow at the preset high-order hydrophobic points, and their distribution presented typical fractal feature, which indicates that the controllable distribution of the initial bubble nucleation sites is achieved. Subsequently, the neighboring bubbles at the hydrophobic points began to merge with each other after overcoming the energy barrier. Directional migration of small bubbles from the high-order hydrophobic region to central low-order region could also be observed simultaneously. A large bubble was finally formed in the central first-order hydrophobic region after bubbles coalescence. Compared with smooth and hydrophobic point array surfaces, the fractal non-uniform wetting surface can reduce the onset boiling temperature effectively, and increase the critical heat flux density of boiling heat transfer. More importantly, the nucleation sites of the bubbles and their moving and merging processes on the fractal pattern surface can be designed and planned in advance, so the distribution of the bubbles can keep consistent with the heat flux on heating surface. Therefore, this non-uniform wetting surface with Sierpinski fractal pattern can further improve the boiling heat transfer performance.

关 键 词：分形图案 亲/疏水 气泡分布 池沸腾 

分 类 号：TK124[动力工程及工程热物理—工程热物理]