The Effect of Fluid Properties on the Evolution of a Long Bubble in a Circular Tube
| Autor: | Ching-Chuan Chang, 張清泉 |
|---|---|
| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 This study investigated the properties of long bubbles penetrating silicone oil and volatile organic compounds (VOCs) in a circular tube. In this experiment, the volume rate of the injection of gas was controlled by using a mass flow controller (MFC). The profile and the evolution of the bubble were observed and compared for various volume flow rates of the injection gas. The evolution images of bubbles were captured by a high-speed camera in this study. The average velocity of the bubble was obtained from the bubble displacement divided by the time difference between two frames. The diameters of bubbles were obtained from the image processing method. The fractional converge (m) of the liquid and the hollow ratio (λ) of the bubbles were estimated by the diameters of bubbles. The Capillary number (Ca) and Reynolds number (Re) were calculated by the velocity of bubbles. The experimental results showed that the bubble velocity got faster as the silicone oil viscosity increases under a constant gas flow. For silicone oil with constant viscosity, as the gas flow rate got higher, then Ca and Re were also larger; however, λ was smaller. As the VOCs filled in circular tube, the velocity of bubble had changed, a specific transient response occurred. The transient shape was defined mushroom bubbles. As the evaporation rate of VOCs ≧1, mushroom bubbles were expected to occur as the Reynolds number (Re) reached a certain region. As the VOCs evaporation rate ＜1, the mushroom bubble phenomenon did not occur, regardless how the Re values had changed. When the Re values for acetone, methyl alcohol and butyl acetate were between 4381~4430, 2460~2490 and 1940~1980, respectively, the transient response phenomenon occurred. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|