入口角度及壁面性质对蛇形微通道内弹状流流动特性影响的格子Boltzmann模拟
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摘要
在Y型汇流的矩形截面蛇形微通道内,采用格子Boltzmann方法对不同壁面性质的蛇形微通道内弹状流流动进行了数值计算。首先以空气和水为工作流体对气液两相流动进行模拟研究并通过实验进行验证。通过验证实验后,模拟计算了气相速度,Y型夹角和壁面性质对气泡长度的影响,以及Y型夹角对微通道内弹状流压降和流动阻力的影响;探讨了粗糙度与壁面润湿性对流动阻力的影响;同时,针对蛇形微通道弯管部分,分析了角度和壁面性质对弹状流流动的影响。通过计算,发现当壁面接触角及Y型夹角为90?时,气泡长度最大;当直微通道为亲水性光滑壁面,回转弯道为粗糙度较大的疏水壁面时,Po数较小。
Lattice Boltzmann simulation was adopted to study Taylor flow in Y-junction convergence coil. Simulation of gas-liquid two-phase flow(with air and water as working media) was carried out in serpentine microchannels with rectangular cross section, and experimental studies were used to verify the simulation results. Effects of gas phase velocity, Y angle and wall properties on bubble length, and effects of Y type angle on flow pressure drop and flow resistance were simulated. Effects of roughness and wall surface wettability on flow resistance were also discussed. Effects of angle and wall surface property on flow were analyzed to evaluate the curved section of the microchannel. The results show that the bubble length reaches to maximum when the wall contact angle and Y type are 90 degrees. When the straight microchannel is composed of hydrophilic smooth wall and the curved section is hydrophobic with higher roughness, the Po number becomes smaller.
Lattice Boltzmann simulation was adopted to study Taylor flow in Y-junction convergence coil. Simulation of gas-liquid two-phase flow(with air and water as working media) was carried out in serpentine microchannels with rectangular cross section, and experimental studies were used to verify the simulation results. Effects of gas phase velocity, Y angle and wall properties on bubble length, and effects of Y type angle on flow pressure drop and flow resistance were simulated. Effects of roughness and wall surface wettability on flow resistance were also discussed. Effects of angle and wall surface property on flow were analyzed to evaluate the curved section of the microchannel. The results show that the bubble length reaches to maximum when the wall contact angle and Y type are 90 degrees. When the straight microchannel is composed of hydrophilic smooth wall and the curved section is hydrophobic with higher roughness, the Po number becomes smaller.
引文
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[5]Wu P Y,Little W A.Measurement of the heat transfer characteristics of gas flow in fine channel heat exchangers used for microminiature refrigerators[J].Cryogenics,1984,24(8):415-420.
[6]Mala G M,Li D.Flow characteristics of water in mirotubes[J].Heat Mass Transfer,1999,20(2):142-148.
[7]Zhu X Y,Zhu L,Chen H J,et al.Fabrication of multi-scale micro-lens arrays on hydrophobic surfaces using a drop-on-demand droplet generator[J].Optics and Laser Technology,2015,66(8):156-165.
[8]Ma M,Hill R M.Superhydrophobic surfaces[J].Current Opinion in Colloid Interface Science,2006,11(4):193-202.
[9]Wu Y,Gao S.Development of free adjustable function generator for drop-on-demand droplets generation[C]//Adv.Future Comput.Control Syst.,Berlin Herdelberg:Springer,2012:477-481.
[10]Chen W C,Wu T J,Wu W J.Fabrication of inkjet-printed SU-8 photoresist microlens using hydrophilic confinement[J].Journal of Micromechanics and Microengineering,2013,23(6):65008-65015.
[11]Kim J Y.Pfeiffer K.Voigt A.Directly fabricated multi-scale microlens arrays on a hydrophobic flat surface by a simple ink-jet printing technique[J].Journal of Materials Chemistry,2012,22(7):3053-3058.
[12]LIU Qian(刘谦),ZHANG Song-hong(张颂红).Gas-liquid two phase flow patterns and boundaries in a rectangular microchannel(矩形微通道内气液两相流型及其转换边界的实验研究)[J].Journal of Chemical Engineering of Chinese Universities(高校化学工程学报),2011,25(6):916-922.
[13]Van S V,Kreutzer M T,Kleijn C R.mu-PIV study of the formation of segmented flow in microluidic T-junctions[J].Chemical Engineering Science,2007,62(24):7505-7514.
[14]Dai L,Cai W F,Xin F.Numerical study on bubble formation of a gas-liquid flow in a T-junction mcrochannel[J].Chemical Engineering&Technology,2009,32(12):1984-1991.
[15]Fries D,von Rohr P R.Impact of inlet design on mass transfer in gas-liquid rectangular micrchannels[J].Microfluidics and Nanofluidics,2009,6(1):27-35.
[16]Tan J,Du L,Xu J H.Surfacant-free microdsipersion process of gas in organic solvents in microfluidic devices[J].AICh E Journal,2011,57(10):2647-2656.
[17]ZHOU Yun-long(周云龙),CHANG He(常赫).Numerical simulation on flow pattern of gas-liquid two-phase flow in serpentine micro-channel(蛇形微通道气液两相流型的数值研究)[J].Journal of Chemical Engineering of Chinese Universities(高校化学工程学报),2016,30(5):1067-1073.
[18]WANG Lin-lin(王琳琳),LI Guo-jun(李国君),TIAN Hui(田辉).Numerical simulation of gas-liquid two-phase flow in a T-junction microchannel(T型微通道内气液两相流数值模拟)[J].Journal of Xi’an Jiaotong University(西安交通大学学报),2011,45(9):65-69.
[19]Cassie A B D.Contact angles[J].Discussions of Faraday Society,1948,3(5):11-16.
[20]HU Guang(胡广),HU Gang-yi(胡刚义).Effects of roughness on gaseous flow characteristics in microchannels(粗糙度对微通道流动特性影响研究)[J].Ship Electronic Engineering(船舶电子工程),2015,35(8):57-60.
[21]Song M,Kim H Y,Kim K.Effects of hydrophilic/hydrophobic properties of gas flow channels on liquid water transport in a serpentine polymer electrolyte membrane fuel cell[J].International Journal of Hydrogen Energy,2014,39(34):19714-19721.