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Journal of Hydrodynamics 2009年第5期21卷 591-599页

作者： FU Ying-jie WEI Ying-jie ZHANG Jia-zhong School of Astronautics Harbin Institute of Technology Harbin 150001 China

To predict the thrust of bubbly water ramjet with a converging-diverging nozzle, the physical processes occurring in the diffuser, mixing chamber and nozzle were analyzed. The mathematical models were constructed separately under the restrictions of certain assumptions. The bubbly nozzle flow was examined using a two-fluid model and accomplished by specifying the water velocity distribution in the nozzle. The numerical analysis of flow field in the nozzle shows that the Mach number at the throat is 1.009, near unity, and supersonic bubble flow appears behind the throat. There is greater thrust produced by bubbly water ramjet, compared with single-phase air ramjets. Subsequently, the influences of vessel velocity, air mass flow rate, inlet area Ai, area ratio （i.e., mixing chamber to inlet area Am/Ai）, and initial bubble radius on the thrust were emphatically investigated. Results indicate that the thrust increases with the increase of air mass flow rate, inlet area and the area ratio, and the decrease of initial bubble radius. However, the thrust weakly depends on the vessel velocity. These analytical and numerical results are useful for further investigation of bubbly water ramjet engine.

关键词： bubbly water ramjet converging-diverging nozzle bubbly flow ramjet thrust numerical simulation

Measurement of two-phase velocities in bubble flows using laser Doppler velocimetry

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Journal of Hydrodynamics 2022年第6期34卷 1134-1144页

作者： Ling-xin Zhang Xin-sheng Cheng Han Tu Qi Gao Xue-ming Shao Xiang-Wei Liao Liang Zhao Department of Engineering Mechanics Zhejiang UniversityHangzhou310027China Iron and Steel Research Institutes of Ansteel Group Corporation Anshan114009China State Key Laboratory of Metal Material for Marine Equipment and Application Anshan114009China

The measurement of two-phase velocities in bubble flows using laser Doppler velocimetry(LDV)is *** key to the problem is to differentiate the LDV signals from bubbles and tracers,based on which the two-phase velocities can be *** this study,two experiments are carried ***,the bubble-chain experiment is performed to investigate the optical response of bubble surface and the corresponding LDV *** optical response shows that the light received by the LDV detector is dominated by the reflection component,which is similar to specular reflection to some *** are three typical patterns of signals of large bubbles passing through the measurement volume,all of which are with high amplitude and ***,the upward-flow experiment is conducted to study the statistical characteristics of large bubbles as well as micro tracers and micro *** results show that the amplitude of signal of millimeter bubbles is about an order of magnitude larger than that of tracers or micro *** on this significant difference of the amplitude,we propose a phase discrimination method to distinguish two-phase *** capability of the proposed method is tested in a complex bubble flow,and its reliability is verified by bubble tracking velocimetry(BTV)technology.

关键词： laser Doppler velocimetry(LDV) bubbly flow phase discrimination bubble tracking velocimetry(BTV)

MEASUREMENT OF BUBBLE-BUBBLE INTERACTION DEPENDED ON REYNOLDS NUMBER USING STEREOSCOPIC BUBBLE-TRACKING TECHNIQUE

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Journal of Hydrodynamics 2005年第2期17卷 243-251页

作者： QUJian-wu MURAlYuichi YAMAMOTOFujio DepartmentofMechanicalEngineering UniversityofFukuiFukuiJapan／／CollegeofIndustrialEngineeringWenzhouUniversityWenzhou325035China DivisionofMechanicalScience SchoolofEngineeringHokkaidoUniversitySapporo.Japan FiberAmenityEngineeringCourse GraduateSchoolofEngineeringUniversityofFukuiFukuiJapan

Bubble-bubble interaction in free rising bubbly flows is experimentally investigated in the present study. The velocity vectors of the bubbles are measured by a stereoscopic bubble-tracking technique and then the relative velocity vectors of two nearest-neighbor bubbles are calculated with high statistical reliability. With the measurement data at Reynolds number ranging from 5 to 75, the vertical attraction and the horizontal repulsion are confirmed for Re30 have repulsive velocity bothin the horizontal and the vertical directions as those rise closely. Moreover, the three-dimensional structure of the bubble-bubble interaction is discussed with the data analysis of the interaction vector fields.

关键词： bubbly flow bubbly dynamics three-dimensional measurement PTV image processing

An Experimental Study of a Bubble-Driven Liquid Metal flow Under the Influence of a Rotating Magnetic Field

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Journal of Iron and Steel Research International 2012年第S1期19卷 505-508页

作者： VOGT Tobias ANDRUSZKIEWICZ Artur ECKERT Kerstin ODENBACH Stephan ECKERT Sven GERBETH Gunter Helmholtz-Zentrum Dresden-Rossendorf Dresden 01314Germany Technische Universitt Dresden Dresden 01069Germany

In this study we investigate the flow structure in a liquid metal cylinder while a bubble-driven flow is superposed with a rotating magnetic field(RMF).Argon gas is injected through a nozzle into a column of the eutectic alloy GalnSn. Without electromagnetic stirring the bubble plume in the centre region of the cylindrical vessel produces a recirculation with high velocities near the free surface while the fluid velocities in the bottom region remain rather *** measurements revealed the potential of the RMF to control both the amplitude of the meridional flow and the bubble distribution and to provide an effective mixing in the whole fluid *** periodic flow patterns were observed in a certain parameter range with respect to variations of the magnetic field strength and the gas flow rate.

关键词： bubbly flow rotating magnetic field electromagnetic stirring mixing

On Measurement Property of Vortex flowmeter in bubbly Two-Phase flows

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On Measurement Property of Vortex Flowmeter in Bubbly Two-Ph...

Numerical Modeling and Analysis of Gas Entrainment for the Ventilated Cavity in Vertical Pipe

The 5th International Symposium on Measurement Techniques for Multiphase flows(5th ISMTMF)

作者： Zhiqiang Sun~* Hongjian Zhang~* Yinjie Xiang~* Department of Control Science and Engineering,Zhejiang University,Hangzhou 310027,Zhejiang,China School of Energy Science and Engineering,Central South University,Changsha 410083,Hunan,China

The measurement behavior of vortex flowmeter was examined under the condition of bubbly two-phase flows, in which the Reynolds number of the two-phase mixture was 4.63×10-23.45×10 with volume void fraction up to 30%.Regular Karman vortex shedding was found,but its stability was strongly influenced by the introduction of gas- phase *** frequency of the bubbly vortex shedding was in approximately linear proportion to the two-phase Reynolds number,whereas the volume void fraction has little impact on the *** findings provide a possibility of using a vortex flowmeter for bubbly two-phase flow measurement.

关键词： gas-liquid two-phase flow bubbly flow vortex flowmeter vortex frequency flow measurement

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Chinese Journal of Chemical Engineering 2014年第3期22卷 252-260页

作者：向敏江振宇张为华屠基元 Collage of Aerospace Science and Engineering National University of Defense Technology Institute of Nuclear and New Energy Technology Tsinghua University School of Aerospace Mechanical and Manufacturing Engineering RMITUniversity

A semi-empirical gas entrainment model was proposed for the ventilated cavity in vertical pipe, based on which, a complete numerical scheme was established by coupling with the Eulerian-Eulerian two-fluid model to predict the multiscale flow field created by ventilated cavity. Model predictions were validated against experimental measurements on void fraction and bubble size distributions. Simulations were carried out to explore the effect of ventilation rate and inlet turbulence intensity on the macroscale cavity shape and the bubbly flow downstream of the ventilated cavity. As the ventilation rate increasing, a reverse trend was observed for the void fraction and bub-ble size distributions. It is concluded that the average void fraction in the pipe flow region is determined by the vo-lumetric ratio between liquid and gas. However, the bubble size evolution is dominated by the breakage effect induced by turbulence in the vortex region. Furthermore, simulations were conducted to analyze geometric scale effect based upon Froude similitude. The results imply that the velocity distributions were properly scaled. Slight scale effect was seen for the void fraction caused by faster dispersion of bubbles in the larger size model. The comparatively greater bubble size was predicted in the smaller model, implying significant scale effects in terms of tur-bulence and surface tension effect. It reveals that empirical correlations valid in wide range are required for the extrapolation from small-size laboratory models.

关键词： ventilated cavity gas entrainment bubbly flow simulation

EXPERIMENTAL STUDY OF VOID FRACTION IN A DYNAMIC WAVE SCRUBBER

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EXPERIMENTAL STUDY OF VOID FRACTION IN A DYNAMIC WAVE SCRUBB...