| Project/Area Number |
15560175
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Thermal engineering
|
|---|
| Research Institution | Yokohama National University |
|---|
Principal Investigator |
UTAKA Yoshio Yokohama National University, Faculty of Engineering, Professor, 大学院・工学研究院, 教授 (50114856)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
SHIXUE Wang Yokohama National University, Faculty of Engineering, Assistant, 大学院・工学研究院, 助手 (60377091)
|
|---|
| Project Period (FY) |
2003 – 2004
|
| Project Status |
Completed (Fiscal Year 2004)
|
| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2003: ¥1,900,000 (Direct Cost: ¥1,900,000)
|
|---|
| Keywords | heat transfer / condensation / surface tension / surface tension instability / thin tube / water vapor |
|---|
| Research Abstract |
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.
|
