Microstructure of the flow field around a bubble in counter-current bubbly flow

Suzuki, Yumiko; Nakagawa, Masamichi; Aritomi, Masanori; Murakawa, Hideki; Kikura, Hiroshige; Mori, M.

doi:10.1016/s0894-1777(02)00130-9

Cited by 26 publications

(18 citation statements)

References 8 publications

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“…Extension of UVP measurements to bubbly two-phase flow was first reported by Suzuki et al (28) . Their method is based on detection of the local maximum velocity in each instant profile to identify the bubble interface in a counter-current vertical two-phase flow.…”

Section: Introductionmentioning

confidence: 92%

Turbulent Bubbly Channel Flow Investigated by Ultrasound Velocity Profiler

Murai

Fujii

Tasaka

et al. 2006

JFST

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Ultrasound velocity profiler (UVP) is applied to measurements of a horizontal turbulent bubbly channel flow to ascertain the mechanism of bubble-induced frictional drag reduction. Typical parameter regimes of the target flow are Re number of 0.6-6.0 x10 4 , void fraction of 0-3%, and bubble diameter of 10-50mm.Since the UVP system only outputs velocity profiles on an ultrasound beam inside a liquid phase, a signal processing method for raw velocity data is proposed and used to detect the bubble interface. A conditional averaged liquid phase velocity profile that excludes gas phase data, has shown for the first time the structure of a turbulent boundary layer altered by large buoyant bubbles sliding along the channel wall.

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Section: Introductionmentioning

confidence: 92%

Turbulent Bubbly Channel Flow Investigated by Ultrasound Velocity Profiler

Murai

Fujii

Tasaka

et al. 2006

JFST

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“…Since ultrasonic pulses are reflected by liquid-gas interfaces, the measured velocity profile must be divided into gas and liquid velocity information. By adopting the UVP for bubbly-flow measurements, the liquid velocity information can be calculated using a statistical method (Suzuki et al, 2002;Murakawa et al, 2003a). The first step in dividing the velocity information is to obtain the probability density function (PDF) from all measured instantaneous velocities at each measuring position.…”

Section: Effect Of Measuring Volumementioning

confidence: 99%

“…Suzuki et al (2002) measured the liquid structures around bubbles using UVP. Furthermore, Murakawa et al (2003a) investigated the liquid flow structures in bubbly flows.…”

Section: Introductionmentioning

confidence: 99%

Velocity Profile Measurements in Bubbly Flow Using Multi-Wave Ultrasound Technique

Kikura

Murakawa

Aritomi

2009

Chemical Engineering Communications

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Velocity profile measurements in bubbly flows have been performed by using the ultrasonic velocity profile technique, which can measure velocity distributions along a measuring line. To obtain the liquid and gas velocity distributions simultaneously, a new technique for separating liquid and gas velocity data is developed. The technique employs a unique ultrasonic transducer (TDX) referred to as a multi-wave transducer. The multi-wave TDX consists of two kinds of ultrasonic piezoelectric elements that are concentrically set and have different resonant frequencies. The central element of 3 mm diameter has a basic frequency of 8 MHz for liquid-phase measurements, and the outer element has a basic frequency of 2 MHz for bubble-phase measurements in two-phase bubbly flows. The multi-wave TDX can emit the two ultrasonic frequencies independently. First, the multi-wave TDX is used together with an ultrasonic velocity profiler (UVP) based on the ultrasonic pulse repetition method. The effects due to volume, liquid velocity, and bubble rising velocity measurements are obtained by the UVP in two-phase bubbly flows. However, the velocity distribution of bubbles measured by the UVP includes errors induced by tracer particles suspended in the liquid. The ultrasonic velocity profile technique requires tracer particles as ultrasonic reflectors. Then to improve the accuracy of the bubble rising velocity distribution, the ultrasound time domain correlation (UTDC) method is applied. Comparing the intensities of echo signals from 2 MHz and 8 MHz ultrasounds, bubble and liquid velocity distributions were obtained. The velocity distributions measured by the UTDC are in good agreement with those measured by the UVP. This technique can be utilized for many industrial applications.

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“…[28][29][30] Generally speaking, gas bubbles passing the ultrasound beam can be considered as ideal reflectors. Measured velocity profiles in the center of the bubble plume contain both the gas and the liquid phase velocity.…”

Section: ½1mentioning

confidence: 99%

The Impact of a Vertically Travelling Magnetic Field on the Flow in a Cylindrical Liquid Metal Bubble Plume

Zhang

Eckert

Gerbeth

2009

Metall Mater Trans B

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This article describes laboratory experiments for the investigations of flow structures and related transport processes in liquid metal bubbly flows under the influence of a traveling magnetic field (TMF). The melt flow is driven by central gas injection into a cylindrical container filled with the low-melting-point alloy GaInSn. The velocity fields of both the liquid and the gaseous phase were measured nonintrusively using the ultrasound Doppler method. Depending on the traveling direction of the magnetic field, the TMF mainly imposes either a concurrent flow or counterflow with respect to the original bubble-driven circulation. In general, the application of a downward TMF significantly increases the liquid velocity all over the fluid volume. An upward TMF gives rise to the more complex structures of the velocity field resulting in alternately arranged upstream and downstream regions. Both the upward and downward TMF promote the occurrence of nonsteady motions with distinct velocity fluctuations leading to an intensification of related transport processes in the melt and providing the perspective of enhanced mixing efficiencies.

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Microstructure of the flow field around a bubble in counter-current bubbly flow

Cited by 26 publications

References 8 publications

Turbulent Bubbly Channel Flow Investigated by Ultrasound Velocity Profiler

Turbulent Bubbly Channel Flow Investigated by Ultrasound Velocity Profiler

Velocity Profile Measurements in Bubbly Flow Using Multi-Wave Ultrasound Technique

The Impact of a Vertically Travelling Magnetic Field on the Flow in a Cylindrical Liquid Metal Bubble Plume

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