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.

对垂直排列的细圆管外表面湿蒸汽凝结现象进行了观察和测量。凝结水的表面张力影响凝结水的流动模式，由于表面张力的不稳定性，凝结水表面出现了波纹状。对于外径为1.0 mm的管，观察到厚度均匀的光滑冷凝表面，而对于直径为0.5 mm的管，观察到厚度不均匀的波浪形状。随着管径的减小，波纹状变得明显。尽管低冷凝率下不稳定性的波长与Rayleigh对自由液体射流的分析结果几乎一致，但它们随着冷凝率和距顶部轴向长度的增加而增加。此外，采用运动图像分析技术精确测量厚液丘之间形成的薄冷凝膜厚度。同时，将液体厚度的测量结果与VOF法的数值分析结果进行了比较，并在此基础上研究了细圆管外表面凝结水的特性。

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