微液滴撞击微结构疏水表面的实验研究
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摘要
液滴撞击固体表面是自然界中最常见的物理现象之一,宏观液滴与微液滴的撞击过程因有较强的传热传质性能而被广泛地应用于工农业等领域。通过微液滴产生装置产生微液滴,利用高速数码摄像系统记录下液滴撞击表面的过程,最后通过程序处理液滴动态过程图,分析了表面微结构对液滴最大铺展系数以及振动过程的影响规律。实验结果表明:最大铺展系数随液滴撞击速度的增大而增大,受表面微结构的形貌特征影响较小;将液滴撞击表面后的振动过程等效为单自由度的阻尼弹簧系统,发现表面微结构对于液滴振动阻尼系数有影响,但是对于弹性常数的影响不大。
The droplet impacting solid surface is the most common physical phenomenon in the natural world and the impacting process of macro-droplet and micro-droplet is widely used in the industrial and agricultural fields due to its strong heat-transfer character. The experiment analyzes the influence laws of surface micro-structure on maximum spreading coefficient and vibration process by generating micro-droplet with micro-droplet generator, recording the process of droplet impacting the surface with high-speed digital camera and processing the dynamic process diagram with programs. The experiment result indicates that the maximum spreading coefficient increases along with the increase of droplet impacting speed and is less affected by the shape characteristics of surface micro-structure, if the vibration process after droplet impacting the surface is equivalent to the single-degree-of-freedom spring-damper system, it can be found that the surface micro-structure has an influence on the damping coefficient of droplet vibration but not on the elastic constant.
The droplet impacting solid surface is the most common physical phenomenon in the natural world and the impacting process of macro-droplet and micro-droplet is widely used in the industrial and agricultural fields due to its strong heat-transfer character. The experiment analyzes the influence laws of surface micro-structure on maximum spreading coefficient and vibration process by generating micro-droplet with micro-droplet generator, recording the process of droplet impacting the surface with high-speed digital camera and processing the dynamic process diagram with programs. The experiment result indicates that the maximum spreading coefficient increases along with the increase of droplet impacting speed and is less affected by the shape characteristics of surface micro-structure, if the vibration process after droplet impacting the surface is equivalent to the single-degree-of-freedom spring-damper system, it can be found that the surface micro-structure has an influence on the damping coefficient of droplet vibration but not on the elastic constant.
引文
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[ 2 ] Van der Bos A,Van der Meulen M J,Driessen T,et al.Velocity Profile inside Piezoacoustic Inkjet Droplets in Flight:Comparison between Experiment and Numerical Simulation[J].Phys Rev Appl,2014,1(1):14004(1-9).
[ 3 ] 钟香梅.典型靶标作物叶表面对农药液滴吸附特性的研究[D].长春:吉林大学,2015.
[ 4 ] Van Dam D B,Le Clerc C.Experimental Study of the Impact of an Ink-jet Printed Droplet on a Solid Substrate[J].Physics of Fluids,2004,16(9):3403-3414.
[ 5 ] Clanet C,Beguin C,Richard D,et al.Maximal Deformation of an Impacting Drop[J].Journal of Fluid Mechanics,2004,517:199-208.
[ 6 ] Bartolo D,Josserand C,Bonn D.Retraction Dynamics of Aqueous Drops Upon Impact on Non-wetting Surfaces[J].Journal of Fluid Mechanics,2005,545:329-338.
[ 7 ] Eggers J,Tontelos M A,Josserand C,et al.Drop Dynamics after Impact on a Solid Wall:Theory and Simulations[J].Physics of Fluids,2010,22(6):062101(1-13).
[ 8 ] Pasandideh-Fard M,Qiao Y M,Chandra S,et al.Capillary Effects During Droplet Impact on a Solid Surface[J].Physics of Fluids,1996,8(3):650-659.
[ 9 ] Ukiwe C,Kwok D Y.On the Maximum Spreading Diameter of Impacting Droplets on Well-prepared Solid Surfaces[J].Langmuir,2005,21(2):666-673.
[10] 李西营,高丽,刘勇,等.超疏水表面上液滴撞击动力学的研究[J].广州化工,2011,39(22):39-41,51.
[11] Laan N,de Bruin K G,Bartolo D,et al.Maximum Diameter of Impacting Liquid Droplets[J].Phys Rev Appl,2014,2(4):044018(1-7).
[12] Lee J B,Laan N,De Bruin K G,et al.Universal Rescaling of Drop Impact on Smooth and Rough Surfaces[J].Journal of Fluid Mechanics,2016,786:R4(1-11).
[13] Vaikuntanathan V,Sivakumar D.Maximum Spreading of Liquid Drops Impacting on Groove-Textured Surfaces:Effect of Surface Texture[J].Langmuir,2016,32(10):2399-2409.
[14] Zhao B Y,Wang X,Zhang K,et al.Impact of Viscous Droplets on Superamphiphobic Surfaces[J].Langmuir,2017,33(1):144-151.
[15] Lin S J,Zhao B Y,Zou S,et al.Impact of Viscous Droplets on Different Wettable Surfaces:Impact Phenomena,the Maximum Spreading Factor,Spreading Time and Post-impact Oscillation[J].Journal of Colloid and Interface Science,2018,516:86-97.
[16] Manglik R M,Jog M A,Gande S K,et al.Damped Harmonic System Modeling of Post-impact Drop-spread Dynamics on a Hydrophobic Surface[J].Physics of Fluids,2013,25(8):082112(1-15).
[17] Lafuma A,Quere D.Superhydrophobic States[J].Nat Mater,2003,2(7):457-460.
[18] Tsai P C,Lammertink R G H,Wessling M,et al.Evaporation-Triggered Wetting Transition for Water Droplets upon Hydrophobic Microstructures[J].Phys Rev Lett,2010,104(11):116102(1-4).
[19] Richard D,Clanet C,Quere D.Surface Phenomena-contact Time of a Bouncing Drop[J].Nature,2002,417(6891):811-811.
[20] 赵亚溥.表面与界面物理力学[M].北京:科学出版社,2012.
[21] Chen L Q,Bonaccurso E,Deng P G,et al.Droplet Impact on Soft Viscoelastic Surfaces[J].Physical Review E,2016,94(6):063117(1-9).
[22] Wang F J,Fang T G.Post-impact Drop Vibration on a Hydrophilic Surface[J].Experimental Thermal and Fluid Science,2018,98:420-428.