Surfactant effects on single bubble motion and bubbly flow structure

2010 ◽  
Author(s):  
Yoshiyuki Tagawa ◽  
Toshiyuki Ogasawara ◽  
Shu Takagi ◽  
Yoichiro Matsumoto ◽  
Liejin Guo ◽  
...  
Keyword(s):  
Flow Structure ◽  
Bubbly Flow ◽  
Single Bubble ◽  
Bubble Motion ◽  
Surfactant Effects

scholarly journals PIV-Based Acoustic Pressure Measurements of a Single Bubble near the Elastic Boundary

Micromachines ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 637
Author(s):  
Qidong Yu ◽  
Zhicheng Xu ◽  
Jing Zhao ◽  
Mindi Zhang ◽  
Xiaojian Ma
Keyword(s):  
Flow Structure ◽  
Acoustic Pressure ◽  
Transient Flow ◽  
Single Bubble ◽  
Rigid Boundary ◽  
Inverted Cone ◽  
Migration Direction ◽  
Elastic Boundary ◽  
Image Velocimetry ◽  
Spark Bubble

The objective of this paper was to investigate acoustic pressure waves and the transient flow structure emitted from the single bubble near an elastic boundary based on the particle image velocimetry (PIV). A combination of an electric-spark bubble generator and PIV were used to measure the temporal bubble shapes, transient flow structure, as well as the mid-span deflection of an elastic boundary. Results are presented for three different initial positions near an elastic boundary, which were compared with results obtained using a rigid boundary. A formula relating velocity and pressure was proposed to calculate the acoustic pressure contours surrounding a bubble based on the velocity field of the transient flow structure obtained using PIV. The results show the bubbles near the elastic boundary presented a “mushroom” bubble and an inverted cone bubble. Based on the PIV-measured acoustic pressure contours, a significant pressure difference is found between the elastic boundary and the underside of the bubble, which contributed to the formation of the “mushroom” bubble and inverted cone bubble. Furthermore, the bubbles had opposite migration direction near rigid and elastic boundaries, respectively. In detail, the bubble was repelled away from the elastic boundary and the bubble was attracted by the rigid boundary. The resultant force made up of a Bjerknes force and buoyancy force dominated the migration direction of the bubble.

Two-Phase Bubbly Flow Structure in Large-Diameter Vertical Pipes

2008 ◽  
Vol 81 (2) ◽  
pp. 205-211 ◽  
Author(s):  
Mamdouh Shoukri ◽  
Ibrahim Hassan ◽  
Ihab Gerges
Keyword(s):  
Flow Structure ◽  
Bubbly Flow ◽  
Large Diameter ◽  
Two Phase

Shear-Induced Lift Force on a Single Bubble in Surfactant Solutions

2007 ◽  
Author(s):  
Masato Fukuta ◽  
Shu Takagi ◽  
Yoichiro Matsumoto
Keyword(s):  
Lift Force ◽  
Marangoni Effect ◽  
Surface Concentration ◽  
Bubble Surface ◽  
Single Bubble ◽  
Bubble Motion ◽  
Surfactant Solutions ◽  
Cap Model ◽  
Desorption Rate Constant ◽  
The Asymmetry

In this paper, single bubble motion in surfactant solutions is discussed. We focus on the change of the shear-induced lift force acting on a bubble when the bubble surface is contaminated by surfactant adsorption which leads the Marangoni effect. With the increase of Langmuir number corresponding to the decrease of desorption rate constant of surfactant, the lift force on a spherical bubble decreases from that on a clean bubble to near zero value. This reduction is related significantly to the asymmetry of pressure distribution on surface. Comparing the present result with our previous simulation using the stagnant cap model, the lift force of this study is larger than that of the stagnant cap model. This is because in a shear flow, the surface concentration distributes asymmetrically, and the asymmetry of the surface pressure produced by the shear appears stronger than that of the stagnant cap model.

Development of Prediction Technology of Two-Phase Flow Dynamics Under Earthquake Acceleration — (5) Measurement of Bubble Deformation Near Wall Under Structure Vibration

2012 ◽  
Author(s):  
Kousuke Mizuno ◽  
Akiko Kaneko ◽  
Hideaki Monji ◽  
Yutaka Abe ◽  
Hiroyuki Yoshida ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Flow Structure ◽  
Test Section ◽  
High Speed ◽  
Bubbly Flow ◽  
Oscillation Amplitude ◽  
Reactor Core ◽  
Two Phase ◽  
Piv Measurement ◽  
Structure Vibration

In a nuclear power plant, one of the important issues is evaluation of the safety of reactor core and its pipes when an earthquake occurs. Many researchers have conducted studies on constructions of plants. Consequently, there is some knowledge about earthquake-resisting designs. However the influence of an earthquake vibration on thermal fluid inside a nuclear reactor plant is not fully understood. Especially, there are little knowledge how coolant in a core response when large earthquake acceleration is added. Some studies about the response of fluid to the vibration were carried out. And it is supposed that the void fraction or the power of core is fluctuated with the oscillation by the experiments and numerical analysis. However detailed mechanism about a kinetic response of gas and liquid phases is not enough investigated, therefore the aim of this study is to clarify the influence of vibration of construction on bubbly flow structure. In order to investigate it, we visualize changing of bubbly flow structure in pipeline on which sine wave is applied. Bubbly flow is produced with injecting gas into liquid flow through a horizontally circular pipe. In order to vibrate the test section, the oscillating table is used. The frequency of vibration added from the table is from 1.0 Hz to 10 Hz and acceleration is from 0.4 G to 1 G (1 G = 9.8 m/s2). The test section and a high speed video camera are fixed on the table. Thus the relative velocity between the camera and the test section is ignored. In the visualization experiment, the PIV measurement is conducted. Then the motion of bubbles, for example the shape, the positions and the velocity are measured with observation. In addition, by varying added oscillation amplitude, frequency and flow rate of the fluids, the correlation between these parameters and bubble motion was evaluated. It was clarified that the behavior of liquid phase and bubble through horizontal circular pipes was affected by an oscillation. When structure vibration affects the flow, two main mechanisms are supposed. One is the addition of body force of the oscillation acceleration to liquid phase and bubble, and the other is the velocity oscillation of the test section and the effect of the boundary layer of the pipe wall. It was also found that when the added oscillation frequency and amplitude was changed, the degree of the fluctuation of liquid phase and bubble motions were changed.

Effects of inlet condition on flow structure of bubbly flow in a rectangular column

2013 ◽  
Vol 104 ◽  
pp. 166-176 ◽  
Author(s):  
Mohd. Hatta bin Mohd. Akbar ◽  
Kosuke Hayashi ◽  
Dirk Lucas ◽  
Akio Tomiyama
Keyword(s):  
Flow Structure ◽  
Bubbly Flow ◽  
Inlet Condition

Single bubble motion in horizontal circular channel

2017 ◽  
Vol 2017.92 (0) ◽  
pp. P021
Author(s):  
Yusuke DEGUCHI ◽  
Ryo KURIMOTO ◽  
Hisato MINAGAWA ◽  
Takahiro YASUDA
Keyword(s):  
Single Bubble ◽  
Bubble Motion ◽  
Circular Channel

Development of Prediction Technology of Two-Phase Flow Dynamics Under Earthquake Acceleration: (12) Bubble Motion Along the Flow in Structure Vibration

2014 ◽  
Author(s):  
Yuki Kato ◽  
Rie Arai ◽  
Akiko Kaneko ◽  
Hideaki Monji ◽  
Yutaka Abe ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Velocity Field ◽  
Test Section ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubbly Flow ◽  
Experimental Results ◽  
Phase Flow ◽  
Bubble Motion ◽  
Two Phase

In a nuclear power plant, one of the important issues is an evaluation of the safety of the reactor core and its pipes when an earthquake occurs. Many researchers have conducted studies on constructions of plants. Consequently, there is some knowledge about earthquake-resisting designs. However the influence of an earthquake vibration on thermal fluid inside a nuclear reactor plant is not fully understood. Especially, there is little knowledge how coolant in a core response when large earthquake acceleration is added. Some studies about the response of fluid to the vibration were carried out. And it is supposed that the void fraction and/or the power of core are fluctuated with the oscillation by the experiments and numerical analysis. However the detailed mechanism about a kinetic response of gas and liquid phases is not enough investigated, therefore the aim of this study is to clarify the influence of vibration of construction on bubbly flow behavior. In order to investigate the influence of vibration of construction on bubbly flow behavior, we visualized bubbly flow in pipeline on which sine wave was applied. In a test section, bubbly flow was produced by injecting gas into liquid flow through a horizontal circular pipe. In order to vibrate the test section, an oscillating table was used. The frequency and acceleration of vibration added from the oscillating table was from 1.0 Hz to 10 Hz and . 0.4 G (1 G=9.8 m/s2) at each frequency. The test section and a high speed video camera were fixed on the oscillating table. Thus the relative velocity between the camera and the test section was ignored. PIV measurement was also conducted to investigate interaction between bubble motion and surround in flow structure. Liquid pressure was also measured at upstream and downstream of the test section. The effects of oscillation on bubbly flow were quantitatively evaluated by these pressure measurements and the velocity field. In the results, it was observed that the difference of bubble motion by changing oscillation frequency. Moreover it was suggested that the bubble deformation is correlated with the fluctuation of liquid velocity field around the bubble and the pressure gradient in the flow area. In addition, these experimental results were compared with numerical simulation by a detailed two-phase flow simulation code with an advanced interface tracking method, TPFIT. Numerical simulation was qualitatively agreed with experimental results.

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