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首页> 外文期刊>Journal of Heat Transfer >Dynamic Spreading of a Droplet Impinging on Micro-Textured Surfaces
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Dynamic Spreading of a Droplet Impinging on Micro-Textured Surfaces

机译:液滴在微纹理表面上的动态扩散

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摘要

This study investigates the impact dynamics of a single water droplet impinging on micro-textured aluminum (Al 6061) surfaces fabricated by using a u-computer numerical control (u-CNC) milling machine. The textured surfaces are composed of micro-holes (diameter 125 urn, depth: 125 um) with different pitches between holes, resulting in different wettability conditions. We measured spreading diameters and dynamic apparent contact angles from images captured by a high-speed camera of 10,000 fps (HG-LE, Redlake), when water droplets of approximately 43 ul impinges on the surfaces with the impact velocity of 0.40 m/s. The contact diameter of an impinging droplet at the maximum spreading (D_m) decreases with smaller pitches between drilled holes due to an increase in hydrophobic surface characteristics. Also, the apparent dynamic contact angles at the maximum spreading (θ_m) increases with the increase in hole density due to the change in surface energy. In addition, this study suggests a modified equation to predict the maximum spreading diameter as follows: (We+12)(D_m/d_o)=8+(D_m/d_o)~3(4(We/√Re)-3ψ) where topography term is V=(cosθ_m(1-Φ_s+ Φ_s)(1-ω_s+ω_sr_scosθ_m-1; wetting state yield is ω_s=(D_w/D_m)~2 where D_w denotes Wenzel state region diameter, geometric parameters are texture area fraction (Φ_s=(πd2/4)l(s+d)~2) and texture roughness (r_s=1+(πdh_d)/(s+d)~2) where s, d and A_d are spacing, diameter, depth of holes, respectively. It has been found to be in good agreement with experimental results.
机译:本研究研究了使用u型计算机数控(u-CNC)铣床制造的单个水滴撞击在微织构铝(Al 6061)表面上的冲击动力学。带纹理的表面由微孔(直径125 um,深度:125 um)组成,孔之间的间距不同,从而导致不同的润湿条件。我们以10,000 fps的高速相机(HG-LE,Redlake)拍摄的图像(当大约43 ul的水滴以0.40 m / s的速度撞击表面时)测量了撒布直径和动态视在接触角。由于疏水表面特性的增加,在最大扩孔处(D_m)的撞击液滴的接触直径随着钻孔之间的间距变小而减小。另外,由于表面能的变化,最大扩展(θ_m)处的表观动态接触角随着空穴密度的增加而增加。另外,这项研究提出了一个修正的方程式来预测最大展布直径,如下所示:(We + 12)(D_m / d_o)= 8 +(D_m / d_o)〜3(4(We /√Re)-3ψ)其中形貌项为V =(cosθ_m(1-Φ_s+Φ_s)(1-ω_s+ω_sr_scosθ_m-1;润湿态屈服值为ω_s=(D_w / D_m)〜2,其中D_w表示Wenzel状态区域直径,几何参数为纹理区域分数( Φ_s=(πd2/ 4)l(s + d)〜2)和纹理粗糙度(r_s = 1 +(πdh_d)/(s + d)〜2)其中s,d和A_d是间距,直径,孔的深度已经发现它与实验结果非常吻合。

著录项

  • 来源
    《Journal of Heat Transfer》 |2011年第8期|p.080905.1|共1页
  • 作者单位

    Chung-Ang University, Seoul, Korea;

    Corresponding Author, Chung-Ang University, Seoul, Korea,Michigan Technological University, Houghton, MI USA;

    Michigan Technological University, Houghton, MI USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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