A Study on the Surface Tension Effect on Condensation Phenomena on the Thin Vertical Tubes

表面张力对细立管冷凝现象的影响研究

• 批准号: 15560175
• 负责人: UTAKA Yoshio
• 金额: $ 2.37万
• 依托单位: Yokohama National University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560175/
• 关键词: heat transfer; condensation; surface tension; surface tension instability; thin tube; water vapor

Observation and measurement of steam condensation phenomena on the wetted outer surface of thin tubes arranged vertically were conducted. The condensate modes were affected by surface tension of the condensate, and the wavy shape of the condensate surface appeared due to surface tension instability on the thin tubes. While smooth condensate surface of uniform thickness was observed for tubes having an outer diameter of 1.0 mm, a wavy shape with non-uniform thickness was observed for tubes of 0.5 mm in diameter. The wavy shape became distinct with a decrease in tube diameter. Although the wavelengths of the instability at low condensation rates almost coincided with those obtained from analysis on free liquid jet by Rayleigh, they increased with increases in the condensation rate and axial length from the top.Furthermore, the precise measurement of thin condensate film thickness formed between the thick liquid humps by using the motion picture analysis. Also, the measuring results of liquid thickness were compared with the numerical analysis by using VOF method.On the basis of those results, the characteristics of condensate formed on the outer surface of thin tubes were investigated.

对垂直排列的细管润湿外表面的蒸汽凝结现象进行了观察和测量。凝结水模态受凝结水表面张力的影响，由于细管表面张力不稳定，导致凝结水表面出现波状形状。对于外径为1.0mm的管，观察到厚度均匀的光滑冷凝表面，而对于直径0.5mm的管，观察到厚度不均匀的波状形状。随着管直径的减小，波浪形状变得明显。尽管低凝结率下的不稳定性波长几乎与瑞利对自由液体射流分析获得的波长一致，但它们随着凝结率和顶部轴向长度的增加而增加。此外，通过运动图像分析精确测量了厚液体驼峰之间形成的薄凝结膜厚度。并将液体厚度的测量结果与VOF法的数值分析进行了比较。在此基础上，研究了细管外表面形成的冷凝水的特性。

项目成果

宇高義郎, 根上智幸, 園田英之: "鉛直細管外面における水蒸気の凝縮現象の観測"日本機械学会論文集(B編). (掲載決定). (2004)

Yoshiro Utaka、Tomoyuki Negami、Hideyuki Sonoda：“垂直管外表面水蒸气凝结现象的观察”日本机械工程学会论文集（B 版）（2004 年出版）。

An Investigation of Condensation Phenomena on Vertical Thin Tubes

垂直薄管上凝结现象的研究

• 发表时间: 2004
• 期刊: Proc.Third Int.Conf.on Heat Transfer, Fluid Mechanics and Thermodynamics (Cd-Rom)
• 作者: Utaka;Y.;Negami;T.;Sonoda;H.
• 通讯作者: H.

鉛直細管外面における水蒸気の凝縮現象の観測

立管外表面水蒸气凝结现象观察

• 发表时间: 2004
• 期刊: 日本機械学会論文集(B編) 70・690
• 作者: 宇高義郎;根上智幸;園田英之
• 通讯作者: 園田英之

An Investigation of Condenasation Phenomena on Vertical Thin Tubes

垂直薄管上凝结现象的研究

• 发表时间: 2004
• 期刊: Proc.Third Int.Conf.on Heat Transfer, Fluid Mechanics and Thermodynamics (CD-Rom)
• 作者: Utaka;Y.;Negami;T.;Sonoda;H.
• 通讯作者: H.

An Invstigation of Condenasation Phenomena on Vertical Thin Tubes

垂直薄管上凝结现象的研究

• 发表时间: 2004
• 期刊: Proc.Third Int.Conf.on Heat Transfer, Fluid Mechanics and Thermodynamics (CD-ROM)
• 作者: Utaka;Y.;Nagami;T.;Sonoda;H
• 通讯作者: H