Incompressible Gas-Liquid Two-Phase Flow
Two-phase flows are found in a large number of industrial applications, such as oil wells, airlift pumps, boilers, contractors and reactors in chemical, biochemical and petrochemical industries. It has been known that they can provide several advantages during operation and maintenance such as high heat and mass transfer rates, compactness and low operating maintenance costs. However, the physics of two-phase flow are still not well understood due to complexity, although two-phase flows have been examined in many previous studies.
[Figure 1] Time evolution of a single bubble rising
Bursting Jet in Two Tandem Bubbles
When a bubble reaches close to a gas-liquid interface, a bursting of the bubble produces a high-speed jet and subsequent droplet. This phenomenon is important to decide interaction at the gas-liquid interface, such as transport of biological material, pathogens, and surfactants from the sea surface (Veron 2015), destruction of cells during cultivation in the bioreactor (Boulton-Stone & Blake 1993), and fizziness in a carbonated beverage (Ghabache et al. 2014). Due to its transversal impact across fields, many studies have dedicated to understanding physics behind a bursting of the bubble at the free surface with diverse phase combinations (Spiel 1995; Krishnan et al. 2017; Deike et al. 2018). However, the effect of nearby bubbles on the bursting process has not been studied systematically even though most circumstances of a bubble bursting is observed under the presence of nearby bubbles.
[Figure 2] Time evolution of the liquid-gas interface during a single and two tandem bubble bursting
Heat Transfer with Bubble Condensation in Subcooled Flow
When a bubble nucleates and departs from a heat source within a subcooled flow, the bubble is condensed by subcooled liquid flow. To effectively control the heat removal, it is important to understand the bubble condensation that involves an interaction between the bubble and subcooled liquid flow. Although previous studies have examined condensation rate of condensing bubble with a change of system pressure and subcooled liquid temperature, the effects of the wall on the condensing bubble have not been studied despite the importance of the wall due to differences in flow patterns. In this study, we analyze the heat transfer characteristics of condensing bubble in the subcooled flow w/ and w/o the wall effects as the tube diameter and wall temperature vary.
[Figure 3] Temporal variation of the interface between the condensing bubble and liquid at ∆Tsub = 35 K