矩形结构壁面上液膜流动特性的数值研究
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摘要
壁面结构是影响液膜传热传质特性的重要因素之一。采用数值模拟技术研究矩形结构壁面上的液膜流动特性,得到了液膜的自由液面分布及涡结构特性。结果表明:矩形结构宽度w=3.0mm时,液膜下自由液面位置最低。调整矩形结构宽度,液膜上、下自由液面位置呈现相反的变化趋势,但总体效果变化不明显。在改变矩形结构宽度的基础上,随着液相入口流速的增大,液膜上自由液面位置均急速上升,而且w=1.0mm与w=1.5mm时,液膜流动稳定性良好,而液膜下自由液面位置的变化无明显规律;此外,不同结构尺寸的矩形结构内均有近似对称的旋涡存在。不同的矩形结构宽度下,旋涡的大小和产生的位置不同,w=1.5mm时,矩形结构前端处出现小旋涡。
Wall structure is one of the important factors affecting the heat and mass transfer characteristics of liquid film.The flow characteristics of the liquid film on the wall of the rectangular structure were studied by numerical simulation technique,and the free liquid surface distribution and vortex structure characteristics of the liquid film were obtained.The results show that the free liquid surface position under the liquid film is the lowest when the width of the rectangular structure is set as w=3.0 mm.Adjusting the width of the rectangular structure,the position of the free liquid surface above and below the liquid film showed an opposite trend,but the overall effect did not change significantly.On the basis of changing the width of the rectangular structure,as the flow velocity of the liquid phase increases,the free liquid surface position on the liquid film rises sharply.When w=1.0 mm and w=1.5 mm,the flow stability of liquid film is good,and there is no obvious change in the position of the free liquid surface under the liquid film.In addition,there are approximately symmetrical vortices in the rectangular structure of different structural sizes.The size and position of the vortex are different under different width of rectangular structures.When w=1.5 mm,small vortices appear at the front end of the rectangular structure.
Wall structure is one of the important factors affecting the heat and mass transfer characteristics of liquid film.The flow characteristics of the liquid film on the wall of the rectangular structure were studied by numerical simulation technique,and the free liquid surface distribution and vortex structure characteristics of the liquid film were obtained.The results show that the free liquid surface position under the liquid film is the lowest when the width of the rectangular structure is set as w=3.0 mm.Adjusting the width of the rectangular structure,the position of the free liquid surface above and below the liquid film showed an opposite trend,but the overall effect did not change significantly.On the basis of changing the width of the rectangular structure,as the flow velocity of the liquid phase increases,the free liquid surface position on the liquid film rises sharply.When w=1.0 mm and w=1.5 mm,the flow stability of liquid film is good,and there is no obvious change in the position of the free liquid surface under the liquid film.In addition,there are approximately symmetrical vortices in the rectangular structure of different structural sizes.The size and position of the vortex are different under different width of rectangular structures.When w=1.5 mm,small vortices appear at the front end of the rectangular structure.
引文
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[15]ZHAO L,CERRO R.Experimental characterization of viscous films flows over complex surface International[J].International Journal of Multiphase Flow,1992,18(4):495-516.
[2]卢川,段日强,姜胜耀.下降液膜流动不稳定性实验研究[J].清华大学学报(自然科学版),2008,48(9):107-109.LU Chuan,DUAN Riqiang,JIANG Shengyao.Experimental study on flow instability of liquid film[J].Journal of Tsinghua University(Science and Technology),2008,48(9):107-109.(in Chinese)
[3]宋建,胡珀,韦胜杰,等.竖直平板水膜表面波演化行为实验研究[J].原子能科学技术,2012,46(7):804-808.SONG Jian,HU Bo,WEI Shengjie,et al.Experimental study on surface-wave evolution behavior of water film falling down vertical plate[J].Atomic Energy Science and Technology,2012,46(7):804-808.(in Chinese)
[4]黄娜,周云龙,李洪伟,等.竖直热壁冷却下降液膜瞬变传热及相界面波动[J].中国电机工程学报,2017,37(6):1731-1739.HUANG Na,ZHOU Yunlong,LI Hongwei,et al.Transient heat transfer and phase interface wave of falling liquid film when cooling vertical heated surface[J].Proceedings of the CSEE,2017,37(6):1731-1739.(in Chinese)
[5]于意奇,杨燕华,程旭,等.降膜流动行为的数值模拟研究[J].原子能科学技术,2012,46(10):1207-1211.YU Yiqi,YANG Yanhua,CHENG Xu,et al.Numerical simulation on falling film behavior[J].Atomic Energy Science and Technology,2012,46(10):1207-1211.(in Chinese)
[6]ALBERT C,MARSCHALL H,BOTHE D.Direct numerical simulation of interfacial mass transfer into falling films[J].International Journal of Heat and Mass Transfer,2014,69:343-357.
[7]MIN J K,PARK I S.Numerical study for laminar wavy motions of liquid film flow on vertical wall[J].International Journal of Heat and Mass Transfer,2011,54(15/16):3256-3266.
[8]李相鹏,陈冰冰,高增梁.规整填料表面液膜流动特性的数值模拟[J].化工学报,2013,64(6):1925-1933.LI Xiangpeng,CHEN Bingbing,GAO Zengliang.Numerical simulation on hydraulic characteristics of liquid film on structured packing surface[J].CIESC Journal,2013,64(6):1925-1933.(in Chinese)
[9]ZHAO Linlin,DING Yudong,ZHU Xun,et al.Numerical simulation of liquid film spreading performance under different wall properties[J].Atomic Energy Science and Technology,2017,51(5):865-871.
[10]宋朝匣.非平整基底上液膜流动涡的生成及演化特性研究[D].保定:华北电力大学,2016.SONG Zhaoxia.Investigation on the generation and evolution characteristics of vortex as liquid film flows on uneven walls[D].Baoding:North China Electric Power University,2016.(in Chinese)
[11]朱永欣.非平整基底上液膜流动的数值模拟研究[D].保定:华北电力大学,2014.ZHU Yongxin.Numerical simulation of liquid film flows on uneven walls[D].Baoding:North China E-lectric Power University,2014.(in Chinese)
[12]李振涛,黄佰朋,郝木明,等.周向斜面台阶螺旋槽液膜密封流体动压性能[J].化工学报,2017,68(5):2016-2026.LI Zhentao,HUANG Baipeng,HAO Muming,et al.Hydrodynamic performance of liquid film seals in circumferential beveled-step spiral grooves[J].CIESCJournal,2017,68(5):2016-2026.(in Chinese)
[13]周云龙,常赫.小曲率蛇形微通道弯头处弹状流流动及传质特性的数值研究[J].化工学报,2017,68(1):97-103.ZHOU Yunlong,CHANG He.Numerical simulation on gas-liquid flow and mass transfer in curve part of serpentine micro-channel with small curvature[J].CI-ESC Journal,,2017,68(1):97-103.(in Chinese)
[14]程友良,杨星辉,韩富强.正弦波形填料基底上液膜的研究及热经济性分析[J].动力工程学报,2015,35(3):230-236.CHENG Youliang,YANG Xinghui,HAN Fuqiang.Study of liquid film flowing on the packing with sine wave form and related thermal economic analysis[J].Journal of Chinese Society of Power Engineering,2015,35(3):230-236.(in Chinese)
[15]ZHAO L,CERRO R.Experimental characterization of viscous films flows over complex surface International[J].International Journal of Multiphase Flow,1992,18(4):495-516.