波浪结构超疏水表面对液滴聚并弹跳的影响

doi:10.11949/0438-1157.20220680

摘要/Abstract

摘要：

液滴自发聚并在自然和工业中广泛存在，如何高效去除聚并液滴是强化滴状冷凝换热、防结冰等的重要环节。采用数值模拟方法研究了不同半径比液滴在超疏水平壁面和超疏水波浪形壁面上的聚并起跳行为。研究发现，在平壁面上聚并的液滴水平速度与竖直速度差1～2个数量级，液滴的水平方向位移小，聚并后难以有效去除；在波浪形壁面上，由于液桥撞击在斜面上，产生较大的水平分力，聚并后其水平速度保持与竖直速度在同一数量级，水平位移显著增大；并且波浪结构对液滴弹跳过程影响显著，随波浪高宽比的增大液滴水平位移增大且弹跳高度减小，有效促进了液滴的水平运动，且当高宽比为0.21时，促进作用接近峰值。研究结果为聚并液滴的有效去除提供了新参考。

关键词: 液滴弹跳, 两相流, 界面张力, 超疏水表面, 数值模拟, 水平运动

Abstract:

Spontaneous coalescence of droplets is widespread in nature and industry. How to efficiently remove coalesced droplets is an important part of strengthening droplet condensation heat transfer and preventing icing. In this paper, the coalescence-induced droplet jumping with different radius ratios on superhydrophobic horizontal wall and superhydrophobic wavy wall is studied by numerical simulation. The horizontal and vertical velocities of the droplets coalescing on the flat wall surface differ by 1—2 orders of magnitude, the horizontal displacement of the droplets is small, so it's difficult to remove them effectively after coalescing. However, on the wavy wall surface, because the liquid bridge impinges on the inclined surface, the droplet is subjected to a large horizontal component force, and the horizontal velocity of the droplet remains at the same order of magnitude as the vertical velocity after coalescence, and the horizontal displacement increases significantly. Moreover, the wave structure has a significant effect. With the increase of the wave aspect ratio, the horizontal displacement of the droplet increases and the bounce height decreases, which can effectively promote the horizontal movement of the droplet. When the aspect ratio is 0.21, the promotion effect is close to the peak value. The findings provide a new reference for the efficient removal of coalesced droplets.

Key words: droplets jumping, two-phase flow, interfacial tension, superhydrophobic surface, numerical simulation, horizontal motion

中图分类号:

TQ 028.8

李英杰, 李奇侠, 王宏, 朱恂, 陈蓉, 廖强, 丁玉栋. 波浪结构超疏水表面对液滴聚并弹跳的影响[J]. 化工学报, 2022, 73(10): 4345-4354.

Yingjie LI, Qixia LI, Hong WANG, Xun ZHU, Rong CHEN, Qiang LIAO, Yudong DING. Influence of wavy-structured superhydrophobic surfaces on coalescence-induced droplet jumping[J]. CIESC Journal, 2022, 73(10): 4345-4354.

图/表 14

图1 几何模型及边界条件

Fig.1 Geometric model and boundary conditions

图2 表面张力模型验证

Fig.2 Verification of surface tension model

图3 液滴聚并弹跳的模拟与实验形态对比

Fig.3 Comparison of simulated jumping after droplet coalescence with experimental result

图4 液滴质量分数随时间的变化

Fig.4 The droplet mass ratio change with time

图5 n=0.8时液滴无量纲速度随无量纲时间的变化

Fig.5 Time evolution of droplet's dimensionless velocity with n=0.8

图6 不同半径比液滴聚并形态演化

Fig.6 The morphology of coalescence droplet at different radius ratios

图7 水平分速度云图及流线图

Fig.7 Horizontal velocity field cloud and streamline

图8 不同半径比下聚并液滴的无量纲速度与水平位移

Fig.8 The dimensionless velocity and horizontal displacement of coalescence droplet at different droplets radius ratios

图9 波浪壁面上液滴聚并形态变化

Fig.9 The morphology change of coalescence droplet on wavy wall

图10 波浪形壁面上聚并液滴的无量纲速度变化

Fig.10 The dimensional velocity change of coalescence droplet on wavy wall

图11 水平位移差和竖直位移差随波浪结构的变化

Fig.11 Horizontal displacement difference and vertical displacement difference vary with wave structure

图12 不同半径比下液滴在两种壁面上U*和Δx对比

Fig.12 The comparison of U* and Δx of coalescence droplet at different wall and radius ratio

图13 波浪形壁面无量纲速度变化

Fig.13 The dimensionless velocity change of coalescence droplet on wavy wall

图14 液滴撞击波浪壁面位置

Fig.14 The position droplet hit the wavy wall

参考文献 33

1	Miljkovic N, Enright R, Nam Y, et al. Jumping-droplet-enhanced condensation on scalable superhydrophobic nanostructured surfaces[J]. Nano Letters, 2013, 13(1): 179-187.
2	Rykaczewski K, Paxson A T, Anand S, et al. Multimode multidrop serial coalescence effects during condensation on hierarchical superhydrophobic surfaces[J]. Langmuir: the ACS Journal of Surfaces and Colloids, 2013, 29(3): 881-891.
3	Miljkovic N, Wang E N. Condensation heat transfer on superhydrophobic surfaces[J]. MRS Bulletin, 2013, 38(5): 397-406.
4	Wisdom K M, Watson J A, Qu X P, et al. Self-cleaning of superhydrophobic surfaces by self-propelled jumping condensate[J]. PNAS, 2013, 110(20): 7992-7997.
5	Tian Y, Wang H, Deng Q Y, et al. Dynamic behaviors and charge characteristics of droplet in a vertical electric field before bouncing[J]. Experimental Thermal and Fluid Science, 2020, 119: 110213.
6	Watson G S, Gellender M, Watson J A. Self-propulsion of dew drops on lotus leaves: a potential mechanism for self cleaning[J]. Biofouling, 2014, 30(4): 427-434.
7	Zhang K X, Li Z, Maxey M, et al. Self-cleaning of hydrophobic rough surfaces by coalescence-induced wetting transition[J]. Langmuir: the ACS Journal of Surfaces and Colloids, 2019, 35(6): 2431-2442.
8	Boreyko J B, Collier C P. Delayed frost growth on jumping-drop superhydrophobic surfaces[J]. ACS Nano, 2013, 7(2): 1618-1627.
9	Zhang Q L, He M, Chen J, et al. Anti-icing surfaces based on enhanced self-propelled jumping of condensed water microdroplets[J]. Chemical Communications (Cambridge, England), 2013, 49(40): 4516-4518.
10	Chu F Q, Wu X M, Wang L L. Dynamic melting of freezing droplets on ultraslippery superhydrophobic surfaces[J]. ACS Applied Materials & Interfaces, 2017, 9(9): 8420-8425.
11	Yin C C, Wang T Y, Che Z Z, et al. Critical and optimal wall conditions for coalescence-induced droplet jumping on textured superhydrophobic surfaces[J]. Langmuir: the ACS Journal of Surfaces and Colloids, 2019, 35(49): 16201-16209.
12	Wang Y H, Ming P J. Dynamic and energy analysis of coalescence-induced self-propelled jumping of binary unequal-sized droplets[J]. Physics of Fluids, 2019, 31(12): 122108.
13	Nam Y, Kim H, Shin S. Energy and hydrodynamic analyses of coalescence-induced jumping droplets[J]. Applied Physics Letters, 2013, 103(16): 161601.
14	Enright R, Miljkovic N, Sprittles J, et al. How coalescing droplets jump[J]. ACS Nano, 2014, 8(10): 10352-10362.
15	Chen Y, Lian Y. Numerical investigation of coalescence-induced self-propelled behavior of droplets on non-wetting surfaces[J]. Physics of Fluids, 2018, 30(11): 112102.
16	Liu F J, Ghigliotti G, Feng J J, et al. Numerical simulations of self-propelled jumping upon drop coalescence on non-wetting surfaces[J]. Journal of Fluid Mechanics, 2014, 752: 39-65.
17	Zhao G L, Zou G S, Wang W G, et al. Rationally designed surface microstructural features for enhanced droplet jumping and anti-frosting performance[J]. Soft Matter, 2020, 16(18): 4462-4476.
18	Kim M K, Cha H, Birbarah P, et al. Enhanced jumping-droplet departure[J]. Langmuir: the ACS Journal of Surfaces and Colloids, 2015, 31(49): 13452-13466.
19	Moradi M, Rahimian M H, Chini S F. Coalescence-induced droplet detachment on low-adhesion surfaces: a three-phase system study[J]. Physical Review E, 2019, 99(6): 063102.
20	Xie F F, Lu G, Wang X D, et al. Coalescence-induced jumping of two unequal-sized nanodroplets[J]. Langmuir, 2018, 34(8): 2734-2740.
21	Liang Z, Keblinski P. Coalescence-induced jumping of nanoscale droplets on super-hydrophobic surfaces[J]. Applied Physics Letters, 2015, 107(14): 143105.
22	Wang K, Li R X, Liang Q Q, et al. Critical size ratio for coalescence-induced droplet jumping on superhydrophobic surfaces[J]. Applied Physics Letters, 2017, 111(6): 061603.
23	Cheng Y P, Xu J L, Sui Y. Numerical investigation of coalescence-induced droplet jumping on superhydrophobic surfaces for efficient dropwise condensation heat transfer[J]. International Journal of Heat and Mass Transfer, 2016, 95: 506-516.
24	Chu F Q, Yuan Z P, Zhang X, et al. Energy analysis of droplet jumping induced by multi-droplet coalescence: the influences of droplet number and droplet location[J]. International Journal of Heat and Mass Transfer, 2018, 121: 315-320.
25	Vahabi H, Wang W, Mabry J M, et al. Coalescence-induced jumping of droplets on superomniphobic surfaces with macrotexture[J]. Science Advances, 2018, 4(11): eaau3488.
26	Wang K, Liang Q Q, Jiang R, et al. Self-enhancement of droplet jumping velocity: the interaction of liquid bridge and surface texture[J]. RSC Advances, 2016, 6(101): 99314-99321.
27	Lu D Q, Zhao M R, Zhang H L, et al. Self-enhancement of coalescence-induced droplet jumping on superhydrophobic surfaces with an asymmetric V-groove[J]. Langmuir, 2020, 36(19): 5444-5453.
28	Wang X, Chen Z Q, Xu B. Coalescence-induced jumping of condensate droplets on microstructured surfaces with different gravitational fields by lattice Boltzmann method[J]. Computers & Fluids, 2019, 188: 60-69.
29	彭启, 贾力, 丁艺, 等. 受限微结构对低表面张力液滴合并弹跳的影响[J]. 化工学报, 2021, 72(4): 1920-1929.
	Peng Q, Jia L, Ding Y, et al. The effect of confined microstructures on the coalescence-induced droplet jumping with low surface tension[J]. CIESC Journal, 2021, 72(4): 1920-1929.
30	任辉, 王宏, 朱恂, 等. 润湿性图案表面上的液滴侧向弹跳行为[J]. 化工学报, 2021, 72(8): 4255-4266.
	Ren H, Wang H, Zhu X, et al. Lateral bouncing behavior of droplets on the wettability-patterned surface[J]. CIESC Journal, 2021, 72(8): 4255-4266.
31	Liu X L, Cheng P. 3D multiphase lattice Boltzmann simulations for morphological effects on self-propelled jumping of droplets on textured superhydrophobic surfaces[J]. International Communications in Heat and Mass Transfer, 2015, 64: 7-13.
32	Fakhari A, Bolster D. Diffuse interface modeling of three-phase contact line dynamics on curved boundaries: a lattice Boltzmann model for large density and viscosity ratios[J]. Journal of Computational Physics, 2017, 334: 620-638.
33	Yurkiv V, Yarin A L, Mashayek F. Modeling of droplet impact onto polarized and nonpolarized dielectric surfaces[J]. Langmuir: the ACS Journal of Surfaces and Colloids, 2018, 34(34): 10169-10180.

[1]	宋嘉豪, 王文. 斯特林发动机与高温热管耦合运行特性研究[J]. 化工学报, 2023, 74(S1): 287-294.
[2]	张思雨, 殷勇高, 贾鹏琦, 叶威. 双U型地埋管群跨季节蓄热特性研究[J]. 化工学报, 2023, 74(S1): 295-301.
[3]	肖明堃, 杨光, 黄永华, 吴静怡. 浸没孔液氧气泡动力学数值研究[J]. 化工学报, 2023, 74(S1): 87-95.
[4]	周绍华, 詹飞龙, 丁国良, 张浩, 邵艳坡, 刘艳涛, 郜哲明. 短管节流阀内流动噪声的实验研究及降噪措施[J]. 化工学报, 2023, 74(S1): 113-121.
[5]	叶展羽, 山訸, 徐震原. 用于太阳能蒸发的折纸式蒸发器性能仿真[J]. 化工学报, 2023, 74(S1): 132-140.
[6]	张义飞, 刘舫辰, 张双星, 杜文静. 超临界二氧化碳用印刷电路板式换热器性能分析[J]. 化工学报, 2023, 74(S1): 183-190.
[7]	王志国, 薛孟, 董芋双, 张田震, 秦晓凯, 韩强. 基于裂隙粗糙性表征方法的地热岩体热流耦合数值模拟与分析[J]. 化工学报, 2023, 74(S1): 223-234.
[8]	江河, 袁俊飞, 王林, 邢谷雨. 均流腔结构对微细通道内相变流动特性影响的实验研究[J]. 化工学报, 2023, 74(S1): 235-244.
[9]	温凯杰, 郭力, 夏诏杰, 陈建华. 一种耦合CFD与深度学习的气固快速模拟方法[J]. 化工学报, 2023, 74(9): 3775-3785.
[10]	王玉兵, 李杰, 詹宏波, 朱光亚, 张大林. R134a在菱形离散肋微小通道内的流动沸腾换热实验研究[J]. 化工学报, 2023, 74(9): 3797-3806.
[11]	何松, 刘乔迈, 谢广烁, 王斯民, 肖娟. 高浓度水煤浆管道气膜减阻两相流模拟及代理辅助优化[J]. 化工学报, 2023, 74(9): 3766-3774.
[12]	袁佳琦, 刘政, 黄锐, 张乐福, 贺登辉. 泡状入流条件下旋流泵能量转换特性研究[J]. 化工学报, 2023, 74(9): 3807-3820.
[13]	韩晨, 司徒友珉, 朱斌, 许建良, 郭晓镭, 刘海峰. 协同处理废液的多喷嘴粉煤气化炉内反应流动研究[J]. 化工学报, 2023, 74(8): 3266-3278.
[14]	高燕, 伍鹏, 尚超, 胡泽君, 陈晓东. 基于双流体喷嘴的磁性琼脂糖微球的制备及其蛋白吸附性能探究[J]. 化工学报, 2023, 74(8): 3457-3471.
[15]	程小松, 殷勇高, 车春文. 不同工质在溶液除湿真空再生系统中的性能对比[J]. 化工学报, 2023, 74(8): 3494-3501.