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.

在垂直排列的细管的湿外表面上观察和测量了蒸汽冷凝现象。冷凝水模式受冷凝水的表面张力的影响，由于薄管上的表面张力不稳定性，冷凝水表面的波浪形形状出现。虽然观察到具有1.0毫米外径的管的光滑凝结物表面，但观察到直径为0.5 mm的管道，厚度为1.0 mm，但观察到具有不均匀厚度的波浪形。波浪形形状变得明显，管道直径降低。尽管低冷凝速率下不稳定性的波长几乎与雷利（Rayleigh）在游离液体喷气机上获得的分析获得的波长相吻合，但它们会随着凝结速率和轴向长度的增加而增加。纤维液的精确测量，使用电影分析，通过厚度液体驼峰形成了薄冷凝物膜厚度的精确测量。同样，通过使用VOF方法将液体厚度的测量结果与数值分析进行了比较。在这些结果的基础上，研究了在细管外表面形成的凝结物的特征。

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.

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.

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 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