ISSN Online: 2377-424X
ISBN Print: 978-1-56700-474-8
ISBN Online: 978-1-56700-473-1
International Heat Transfer Conference 16
Method of the rupture film thickness measurement between approaching bubbles during coalescence process in water and ethanol pools
Abstrakt
Multiphase flow is prevalent in industrial processes, and its important applications include bubble columns and
heat exchange devices that employ phenomena with phase changes such as boiling. Despite intensive research
on bubble dynamics, detailed information on bubble coalescence remains unavailable. The objective of this
study was development of measurement technique to analysis on the characteristics of the liquid film in coalescence process and to show the quantitative change in liquid film thickness. To this end, a combined laser extinction and interferometric method was employed to measure the liquid thickness. The coalescence of twin bubbles that horizontally contact each other was studied in a constant-temperature system. The thickness variation and distribution of the liquid film between the twin bubbles was investigated. The experimental parameters were the supplied air flow rate, sample liquid, and transmitted laser position. Water and ethanol were used as the sample liquid. The bubble approach velocity and the close-contact duration of bubbles were
measured by analyzing the images captured at the same instant that the film thickness was measured. The spatial
resolution of the liquid film thickness distribution in the simultaneous measurement improved by approximately
ten times (approximately 6 ?m resolution) compared to the former laser extinction measurement. The measurement precision of liquid film thickness between bubbles was approximately ±0.12 μm for both water and ethanol.