TRPIV experimental study of the effect of superhydrophobic surface on the coherent structure of turbulent boundary layer
-
摘要: 湍流边界层中的相干结构是壁面摩擦阻力的主要来源。通过研究超疏水壁面对相干结构的影响，揭示其减阻机理。利用高时间分辨率粒子图像测速技术（TRPIV），分别对流速为0.165m/s的亲水壁面和超疏水壁面平板湍流边界层进行测量，得到了2种壁面瞬时速度矢量场的大样本时间序列。通过对比分析2种壁面的平均速度剖面和湍流度，得到了5.39%的减阻效果。通过二维空间两点相关函数的方法定义并提取相干结构，对比得到超疏水壁面能够有效减小相干结构流向尺度的结论。进一步采用λci准则对发卡涡头进行识别，并以此为条件事件对其周围的脉动速度分布情况进行线性随机估计。结果表明：超疏水壁面能够有效削弱单个发卡涡头的强度，并且能够影响其周围发卡涡包结构的组织形式，整体减弱涡包下方近壁区低速流体质点的流向脉动，从而有效减小壁面摩擦阻力。Abstract: The existence of coherent structures in the turbulent boundary layer contributes greatly to the skin friction. The investigation of the influence of the superhydrophobic wall on the coherent structure is of great significance in revealing the drag reduction mechanism. The instantaneous velocity vector fields of turbulent boundary layers over hydrophilic and superhydrophobic surfaces were measured using time-resolved Particle Image Velocimetry (TRPIV) at the free-coming velocity of 0.165m/s. The mean velocity profiles and turbulence intensity profiles of the two types of surfaces were compared. And the drag reduction rate of 5.39% was obtained. The coherent structure is extracted by the two-point correlation function. By contrast, it is found that the superhydrophobic surface can effectively reduce the streamwise scale of the coherent structure. And the λci criterion is employed to identify the hairpin vortex head as the conditional event. The linear stochastic estimation of the fluctuating velocity field around the conditional event is performed. The results show that the superhydrophobic surface can effectively weaken the strength of the single hairpin vortex head at the center of the conditional event, and can affect the surrounding hairpin vortex package structures. At the same time, the fluctuating velocity of the flow under the vortex package in the near wall region is weakened as a whole, and thus the skin friction is effectively reduced.
-
Key words:
- drag reduction /
- superhydrophobic surface /
- TRPIV /
- two point correlation /
- linear stochastic estimation
-
表 1 基本湍流减阻参数
Table 1. Basic turbulent drag reduction parameters
Parameters Hydrophilic surfaces Superhydrophobic surfaces uτ/(m·s-1) 0.008192 0.007968 Reτ 627 631 τω/(kg·m-1·s-2) 0.066975 0.063362 Cf 0.005099 0.004574 η － 5.39% 
下载: 导出CSV
-
[1] Bhushan B, Jung Y C, Koch K. Micro-, nano- and hierarchical structures for superhydrophobicity, self-cleaning and low adhesion[J]. Philosophical Transactions of the Royal Society A:Mathematical, Physical and Engineering Sciences, 2009, 367(1894):1631-1672. doi: 10.1098/rsta.2009.0014 [2] Barthlott W, Neinhuis C. Purity of the sacred lotus, or escape from contamination in biological surfaces[J]. Planta, 1997, 202(1):1-8. doi: 10.1007/s004250050096 [3] 高雪峰, 江雷.天然超疏水生物表面研究的新进展[J].物理, 2006, 35(7):559-564. doi: 10.3321/j.issn:0379-4148.2006.07.008Gao X F, Jiang L. Recent studies of natural superhydophobic bio-surfaces[J]. Physics, 2006, 35(7):559-564. doi: 10.3321/j.issn:0379-4148.2006.07.008 [4] Neinhuis C, Barthlott W. Characterization and distribution of water-repellent, self-cleaning plant surfaces[J]. Annals of Botany, 1997, 79(6):667-677. doi: 10.1006/anbo.1997.0400 [5] 王庆军, 陈庆民.超疏水表面的制备技术及其应用[J].高分子材料科学与工程, 2005, 21(2):6-10. doi: 10.3321/j.issn:1000-7555.2005.02.002Wang Q J, Chen Q M. Recent Research advances in manufacturing super hydrophobic membrane and applications[J]. Polymer Materials Science and Engineering, 2005, 21(2):6-10. doi: 10.3321/j.issn:1000-7555.2005.02.002 [6] 李杰, 张会臣.超疏水表面制备技术的研究进展[J].润滑与密封, 2011, 36(1):107-111. doi: 10.3969/j.issn.0254-0150.2011.01.028Li J, Zhang H C. Research progress in superhydrophobic surface preparation technology[J]. Lubrication Engineering, 2011, 36(1):107-111. doi: 10.3969/j.issn.0254-0150.2011.01.028 [7] 余斌, 吴学忠, 肖定邦.仿生超疏水表面技术及其军事应用[J].国防科技, 2015, 36(5):42-45. http://d.old.wanfangdata.com.cn/Periodical/gfkj201505009Yu B, Wu X Z, Xiao D B. The bionic superhydrophobic surface technology and its military application[J]. National Defense Science and Technology, 2015, 36(5):42-45. http://d.old.wanfangdata.com.cn/Periodical/gfkj201505009 [8] Daniello R J, Waterhouse N E. Rothstein J P. Drag reduction in turbulent flows over superhydrophobic surfaces[J]. Physics of Fluids, 2009, 21(8):085103. doi: 10.1063/1.3207885 [9] Min T, Kim J. Effects of hydrophobic surface on skin-friction drag[J]. Physics of Fluids, 2004, 16(7):L55-L58. doi: 10.1063/1.1755723 [10] Park H, Park H, Kim J. A numerical study of the effects of superhydrophobic surface on skin-friction drag in turbulent channel flow[J]. Physics of Fluids, 2013, 25(11):110815. doi: 10.1063/1.4819144 [11] Bidkar R A, Leblanc L, Kulkarni A J, et al. Skin-friction drag reduction in the turbulent regime using random-textured hydrophobic surfaces[J]. Physics of Fluids, 2014, 26(8):085108. doi: 10.1063/1.4892902 [12] Busse A, Sandham N D. Influence of an anisotropic slip-length boundary condition on turbulent channel flow[J]. Physics of Fluids, 2012, 24(5):055111. doi: 10.1063/1.4719780 [13] Park H, Sun G Y, Kim C J. Superhydrophobic turbulent drag reduction as a function of surface grating parameters[J]. Journal of Fluid Mechanics, 2014, 747:722-734. doi: 10.1017/jfm.2014.151 [14] 宋保维, 任峰, 胡海豹, 等.表面张力对超疏水微结构表面减阻的影响[J].物理学报, 2014, 63(5):054708.Song B W, Ren F, Hu H B, et al. Drag reduction on micro-structured hydrophobic surfaces due to surface tension effect[J]. Acta Physica Sinica, 2014, 63(5):054708. [15] 吕鹏宇, 薛亚辉, 段慧玲.超疏水材料表面液-气界面的稳定性及演化规律[J].力学进展, 2016, 46(1):179-225. http://d.old.wanfangdata.com.cn/Periodical/lxjz201601004Lyu P Y, Xue Y H, Duan H L. Stability and evolution of liquid-gas interfaces on superhydrophobic surfaces[J]. Advance in Mechanics, 2016, 46(1):179-225. http://d.old.wanfangdata.com.cn/Periodical/lxjz201601004 [16] Tian H P, Zhang J X, Jiang N, et al. Effect of hierarchical structured superhydrophobic surfaces on coherent structures in turbulent channel flow[J]. Experimental Thermal and Fluid Science, 2015, 69:27-37. doi: 10.1016/j.expthermflusci.2015.07.018 [17] Tian H P, Zhang J X, Wang E D, et al. Experimental investigation on drag reduction in turbulent boundary layer over superhydrophobic surface by TRPIV[J]. Theoretical and Applied Mechanics Letters, 2015, 5(1):45-49. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=lxkb-e201501011 [18] 王二丹, 田海平, 张静娴, 等.超疏水壁面湍流边界层减阻机理的TRPIV实验[J].航空动力学报, 2016, 31(12):2870-2877. http://d.old.wanfangdata.com.cn/Periodical/hkdlxb201612008Wang E D, Tian H P, Zhang J X, et al. TRPIV experimental investigation of drag-reduction mechanism in turbulent boundary layer over superhydrophobic surfaces[J]. Journal of Aerospace Power, 2016, 31(12):2870-2877. http://d.old.wanfangdata.com.cn/Periodical/hkdlxb201612008 [19] 苏健, 田海平, 姜楠.逆向涡对超疏水壁面减阻影响的TRPIV实验研究[J].力学学报, 2016, 48(5):1033-1039. http://d.old.wanfangdata.com.cn/Periodical/lxxb201605002Su J, Tian H P, Jiang N. TRPIV experimental investigation of the effect of retrograde vortex on drag-reduction mechanism over superhydrophobic surfaces[J]. Chinese Journal of Theore-tical and Applied Mechanics, 2016, 48(5):1033-1039. http://d.old.wanfangdata.com.cn/Periodical/lxxb201605002 [20] Robinson S K. Coherent motions in the turbulent boundary layer[J]. Annual review of Fluid Mechanics, 1991, 23:601-639. doi: 10.1146/annurev.fl.23.010191.003125 [21] Zhou J, Adrian R J, Balachandar S, et al. Mechanisms for generating coherent packets of hairpin vortices in channel flow[J]. Journal of Fluid Mechanics, 1999, 387:353-396. doi: 10.1017/S002211209900467X [22] Adrian R J, Meinhart C D, Tomkins C D. Vortex organization in the outer region of the turbulent boundary layer[J]. Journal of Fluid Mechanics, 2000, 422:1-54. doi: 10.1017/S0022112000001580 [23] Adrian R J. Hairpin vortex organization in wall turbulence[J]. Physics of Fluids, 2007, 19(4):041301. doi: 10.1063/1.2717527 [24] Kang Y D, Choi K S, Chun H H. Direct intervention of hairpin structures for turbulent boundary-layer control[J]. Physics of Fluids, 2008, 20(10):101517. doi: 10.1063/1.3006346 [25] Kim K, Adrian R J, Balachandar S, et al. Dynamics of hairpin vortices and polymer-induced turbulent drag reduction[J]. Physical Review Letters, 2008, 100(13):134504. doi: 10.1103/PhysRevLett.100.134504 [26] 许春晓.壁湍流相干结构和减阻控制机理[J].力学进展, 2015, 45(1):201504. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=lxjz201501004Xu C X. Coherent structure and drag-reduction mechanism in wall turbulence[J]. Advance in Mechanics, 2015, 45(1):201504. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=lxjz201501004 [27] 卢思, 姚朝晖, 郝鹏飞, 等.具有微纳结构超疏水表面的槽道减阻特性研究[J].中国科学:物理学力学天文学, 2010, 40(7):916-942. http://d.old.wanfangdata.com.cn/Conference/7373351 [28] 卢思, 姚朝晖, 郝鹏飞, 等.微纳米超疏水表面的制作与特性研究[C]//中国力学大会2011暨钱学森诞辰100周年纪念大会论文集. 2011. [29] 樊星, 姜楠.用平均速度剖面法测量壁湍流摩擦阻力[J].力学与实践, 2005, 27(1):28-30. doi: 10.3969/j.issn.1000-0879.2005.01.007Fan X, Jiang N. Skin friction measurement in turbulent boundary layer by mean velocity profile method[J]. Mechanics in Engineering, 2005, 27(1):28-30. doi: 10.3969/j.issn.1000-0879.2005.01.007 [30] Ganapathisubramani B, Hutchins N, Hambleton W T, et al. Investigation of large-scale coherence in a turbulent boundary layer using two-point correlations[J]. Journal of Fluid Mechanics, 2005, 524:57-80. doi: 10.1017/S0022112004002277 [31] Adrian R J, Moin P, Moser R D. Stochastic estimation of conditional eddies in turbulent channel flow[C]//Proc of the Studying Turbulence Using Numerical Simulation Databases. 1987. [32] Adrian R J. Stochasticestimation of conditional structure:a review[J]. Applied Scientific Research, 1994, 53(3-4):291-303. doi: 10.1007/BF00849106 [33] Christensen K T, Adrian R J. Statistical evidence of hairpin vortex packets in wall turbulence[J]. Journal of Fluid Mechanics, 2001, 431:433-443. doi: 10.1017/S0022112001003512 [34] Chakraborty P, Balachandar S, Adrian R J. On the relationships between local vortex identification schemes[J]. Journal of Fluid Mechanics, 2005, 535:189-214. doi: 10.1017/S0022112005004726 [35] Chong M S, Perry A E, Cantwell B J. A general classification of three-dimensional flow fields[J]. Physics of Fluids A:Fluid Dynamics, 1990, 2(5):765-777. doi: 10.1063/1.857730 [36] 王鑫, 李山, 唐湛棋, 等.沟槽对湍流边界层中展向涡影响的实验研究[J].实验流体力学, 2018, 32(1):55-63. http://www.syltlx.com/CN/abstract/abstract11080.shtmlWang X, Li S, Tang Z Q, et al. An experimental study on riblet-induced spanwise vortices in turbulent boundary layers[J]. Journal of Experiments in Fluid Mechanics, 2018, 32(1):55-63. http://www.syltlx.com/CN/abstract/abstract11080.shtml [37] Tang Z Q, Wu Y H, Jia Y X, et al. PIV measurements of a turbulent boundary layer perturbed by a wall-mounted transverse circular cylinder element[J]. Flow, Turbulence and Combustion, 2018, 100(2):365-389. doi: 10.1007/s10494-017-9852-8 [38] Deng S C, Pan C, Wang J J, et al. On the spatial organization of hairpin packets in a turbulent boundary layer at low-to-moderate Reynolds number[J]. Journal of Fluid Mechanics, 2018, 844:635-668. doi: 10.1017/jfm.2018.160 -
点击查看大图
图(6) / 表(1)
计量
- 文章访问数: 250
- HTML全文浏览量: 132
- PDF下载量: 12
- 被引次数: 0
