高芳,郑佳宜,李准,余延顺.复合梯度楔形表面上液滴自输运特性的数值研究[J].表面技术,2022,51(11):405-411, 422.
GAO Fang,ZHENG Jia-yi,LI Zhun,YU Yan-shun.Numerical Study on Droplet Self-transport on Composite Gradient Wedge-shaped Surface[J].Surface Technology,2022,51(11):405-411, 422
复合梯度楔形表面上液滴自输运特性的数值研究
Numerical Study on Droplet Self-transport on Composite Gradient Wedge-shaped Surface
  
DOI:10.16490/j.cnki.issn.1001-3660.2022.11.038
中文关键词:  润湿梯度  界面张力  楔形  自输运  两相流  数值模拟
英文关键词:wettability gradient  interfacial tension  wedge-shape  self-transport  two-phase flow  numerical simulation
基金项目:国家自然科学基金项目(51706101)
作者单位
高芳 南京理工大学 电子设备热控制工信部重点实验室,南京 210094 
郑佳宜 南京理工大学 电子设备热控制工信部重点实验室,南京 210094 
李准 南京理工大学 电子设备热控制工信部重点实验室,南京 210094 
余延顺 南京理工大学 电子设备热控制工信部重点实验室,南京 210094 
AuthorInstitution
GAO Fang MIIT Key Laboratory of Thermal Control of Electronic Equipment, Nanjing University of Science and Technology, Nanjing 210094, China 
ZHENG Jia-yi MIIT Key Laboratory of Thermal Control of Electronic Equipment, Nanjing University of Science and Technology, Nanjing 210094, China 
LI Zhun MIIT Key Laboratory of Thermal Control of Electronic Equipment, Nanjing University of Science and Technology, Nanjing 210094, China 
YU Yan-shun MIIT Key Laboratory of Thermal Control of Electronic Equipment, Nanjing University of Science and Technology, Nanjing 210094, China 
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中文摘要:
      目的 提高表面液滴的自输运速率。方法 在表面引入润湿梯度和楔形形状,基于VOF模型(流体体积模型)对表面液滴运动进行数值研究,并建立一种适用于润湿梯度和楔形图案联合的模型,分析润湿梯度和楔形角度对液滴位移的影响。结果 润湿梯度越大,液滴受不平衡的表面张力越大,液滴移动速度越快。润湿梯度为15 (°)/mm表面上液滴的平均速度比10、5 (°)/mm润湿梯度的表面分别快42.3%和130%。楔角越大,加速阶段的液滴移动速度越快,但会越早失去驱动力而停止移动,而楔角越小,液滴移动位移越大。液滴在40°楔角表面最先停止运动,在20°楔角表面位移比30°和40°楔角表面分别远10.3%和32.3%。联合润湿梯度和楔形图案后,15 (°)/mm表面上的液滴在20°、30°、40°和20°楔角表面上的液滴在15、10 (°)/mm下均能运动到计算模型出口,且15 (°)/mm、40°楔角表面液滴的平均速度达到292 mm/s,比单一梯度表面增长37.7%,比单一楔形图案表面(20°)增长175.5%。结论 通过调节润湿梯度和楔形角度,可有效控制液滴移动速度。联合润湿梯度和楔形图案的复合梯度楔形表面能同时减小润湿性范围瓶颈和楔形形状制约,提高表面液滴的移动速度和距离。研究结果将有助于设计高效的液滴输运功能表面,并可将其扩展到冷凝装置、微流体装置和药物检测等领域。
英文摘要:
      The control of droplets on heat transfer surfaces is crucial to the overall energy efficiency of the system, and self-transport of droplets can be controlled by surface wettability modification. Influenced by natural surfaces in nature, many scholars have introduced wetting gradients and wedge patterns to drive droplets to move on surfaces. Although the surface of the wetting gradient can realize the self-transportation of droplets, the bottleneck of the wettability range greatly limits the moving distance of the droplets. Droplet transport on the surface of the wedge pattern is restricted by the shape of the wedge, and larger wedge tip size is required for long-distance transport. This paper aimsto study the directional self-transport of droplets and further improve the self-transport rate of droplets, in addition to introducing wettability gradient and wedge-shape, and the two were combined on the surface. Based on the VOF (volume fluid model)model, a model suitable for the combination of wettability gradient and wedge-shape pattern is used to analyze the effects of wettability gradient and wedge angle on the droplet displacement by numerical simulation. The results show that the moving speed of the droplet can be effectively controlled by adjusting the wetting gradient and wedge angle. The unbalanced surface tension of the droplets increases with the wetting gradient, leading to higher moving velocities. The average velocity of the droplets on the surface with a wettability gradient of 15 (°)/mm was 42.3% and 130% faster than that on the surfaces of 10 (°)/mm and 5 (°)/mm. For larger wedge angle, although the speed of droplet was higher during the acceleration phase, it would stop earlier due to the loss of the driving force.The smaller wedge angle, the greater the displacement of the droplet. The droplet firstlystopped moving on the surface of 40° wedge angle, and the displacement on the surface of 20° wedge angle was 10.3% and 32.3% farther than that on the surface of 30° and 40° wedge angle, respectively. Due to the combination of the wettability gradient and wedge-shape on the composite gradient wedge-shaped surface, under the combined action of the unbalanced surface tension and the driving force formed by the wedge angle, the droplet moves faster and further on the composite gradient wedge surface. After combined wetting gradient and wedge pattern, droplets on 20° wedge angle surface at 15 (°)/mm and 10 (°)/mmcan move to the exit of the calculation model, and the average velocity of the droplet on the surface with 15 (°)/mm and 40° wedge angle reaches 292 mm/s, which is 37.7% higher than that of the single gradient surface and 175.5% higher than that of the single wedge pattern surface (20°).The composite gradient wedge-shaped surface that combined the wettability gradient and the wedge pattern can simultaneously reduce the bottleneck of the wettability range and the wedge shape restriction and improve the moving speed and distance of the droplets. The research results will help design efficient droplet transport functional surfaces and extend the fields of condensing devices, microfluidic devices, and drug detection.
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