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Stochastic formulation of particle kinetics in wall-bounded two-phase flows

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Science China(Technological Sciences) 2014年第10期57卷 2001-2011页

作者： MA HongBo FU XuDong State Key Laboratory of Hydroscience and Engineering Department of Hydraulic Engineering Tsinghua University

This paper presents a generalized framework of stochastic modeling for particle kinetics in wall-bounded *** modified a reflected Brownian motion process and straightforwardly obtained a Kramers equation for particle probability density function(PDF).After the wall effects were accounted for as a drift from zero in the mean displacement and suppression in the diffusivity of a particle,an analytical solution was worked out for *** distinguishable mechanisms were identified to affect the profile of particle probability distribution:external forces,turbophoresis effect,and wall-drift *** proposed formulation covers the Huang et al.(2009)model of a wall that produces electrostatic repulsion force and van der Waals force,as well as Monte-Carlo solutions for the Peter and Barenbrug(2002)model under a variety of relaxation ***,it successfully reproduces the two patterns of particle concentration profiles observed in experiments of sediment-laden open-channel *** strength of the wall-drift effect was found to be connected with the interaction frequency between particle and *** exploration of the relationship among flow turbulence,particle inertia,and particle concentration is worthwhile.

关键词： stochastic formulation Kramers equation reflected Brownian motion wall-bounded flow two-phase flow concentration profile

twophase flow OF HIGHLY CONCENTRATED SLURRY IN A PIPELINE

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Journal of Hydrodynamics 2004年第3期16卷 325-331页

作者： NIFu-sheng ZHAOLi-juan MATOUSEKV. VLASBLOMW.J. ZWARTBOLA. FacultyofMechanicalandElectricalEngineering HohaiUniversityChangzhou213022China SectionofDredgingTechnology DelftUniversityofTechnologyTheNetherlands

Hydraulic transport of sand is one of the key processes in river, lake,harbor and waterway dredging engineering. Understanding the flow resistance, solid distribution,flow stratification, transport economy, etc. , in the two-phase flow of sand-water mixture through apipeline is crucial to the design and operation of power drives of a dredger, and to theconstruction of a dredging project. This paper presents the intensive laboratory experimental dataand physical and numerical analyses on the highly concentrated slurry flow under an extended largerange of slurry mean velocities for three narrow-graded sands of different sizes. The investigationindicates that the solids concentration and particle size strongly affect the slurry flowcharacteristics.

关键词： two-phase flow hydraulic transport laboratory experiment modeling

THE SETTING UP OF THE EQUATIONS FOR two-phase flowS BY THE KINETIC THEORY METHOD

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Acta Mechanica Sinica 1986年第3期2卷 220-231页

作者： Liu Dayou(Institute of Mechanics,Academia Sinica) 中科院力学所，100080

The fundamental equations for two-phase flows are deduced from the Boltzmann’*** collision terms are treated with a method similar to what is used in the classical kinetictheory for handling the transport properties of dense *** is shown that collision pressure andcollision thermal flux exist in gas-particle flows in addition to the general partial pressure and partialthermal *** physical natures are quite different from those of the general partial pressure andpartial thermal *** applicability of the binary collision assumption and the molecular chaosassumption to gas-particle flows is also ***,the equations for two-phase flowsobtained by the method of the kinetic theory are compared with those obtained by averagecontinuum models and by the model of particle *** results from the kinetic theory showclearly the physical significance of various parameters and clarify some confusing concepts.

关键词： two-phase flow kinetic theory collision term in Boltzmann’s equation collision pressure

Application of D-S Evidence Theory in flow Regime Identification of two-phase Horizontal Pipe flow

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Application of D-S Evidence Theory in Flow Regime Identifica...

Experimental study on dynamic behavior of mechanically pumped two-phase loop with a novel accumulator in simulated space environment

第二十七届中国控制会议

作者： Zhang Fusheng,Dong Feng Tianjin Key Laboratory of Process Measurement and Control School of Electrical Engineering and Automation,Tianjin University,Tianjin 300072,P.R.China

Identification of two-phase flow regimes is deadly required in many industrial processes and is difficult to perform ***-sensor data fusion has been applied to the recognition of flow regimes of air/water flow in horizontal pipe.A specific fusion process architecture based on Dasarathy fusion model is introduced,and D-S evidence theory is adopted on the decision fusion *** fusion data is provided by dual-plane electrical resistance tomography system in which each plane works as a single ***-correlation technique is used to match the data from the two electrode *** is shown that this flow regime recognition method in which multi-sensor fusion is adopted is an approval strategy.

关键词： two-phase flow flow Regime Identification Electrical Resistance Tomography D-S evidence theory Cross-Correlation Technique

来源： cnki会议评论

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Chinese Journal of Aeronautics 2022年第12期35卷 102-116页

作者： Qingliang MENG Tao ZHANG Feng YU Yu ZHAO Zhenming ZHAO Zhenhua ZHOU Beijing Institute of Space Mechanics and Electricity Beijing 100094China Beijing Key Laboratory of Advanced Optical Remote Sensing Technology Beijing 100094China College of Energy and Mechanical Engineering Shanghai University of Electric PowerShanghai 200090China

Mechanically pumped two-phase loop(MPTL)which is a prominent two-phase heat transfer technology presents a promising prospect in thermal control for space ***,transient behavior of MPTL caused by phase-change and heat sources load-on/off in simulated space environment is rarely *** the present study,one MPTL setup was designed and constructed,and experimentally ***,a novel two-phase thermally-controlled accumulator integrated with passive cooling measure and three capillary structures was designed as the temperature-control *** behavior of the start-up,temperature control,and temperature adjustment were monitored;meanwhile,thermodynamic behavior within the proposed accumulator,the operating behavior as well as the heat and mass transfer behavior between the main loop and the accumulator were *** results show that the fluid management function of the capillary structures for the novel accumulator is *** working point of the MPTL system can be adjusted by changing the temperature control point of the accumulator and it is little influenced by external heat flux and heat sources on/***-drop oscillations which are manifested as fluctuations of temperature and pressure can be observed after phase changing due to the compressible volume within the accumulator and the negative-slope portion of the internal pressure.

关键词： Heat and mass transfer Mechanically pumped twophase loop(MPTL) Pressure drop fluctuation Thermal control two-phase flow

A USM-Θ two-phase turbulence model for simulating dense gas-particle flows

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Acta Mechanica Sinica 2005年第3期21卷 228-234页

作者： Yong Yu Lixing Zhou Baoguo Wang Feipeng Cai Department of Engineering Mechanics Tsinghua University Beijing 100084 China School of Mechanico-Electrical Engineering Beijing Institute of Technology Beijing 100081 China Institute of Chemical Engineering University of Petroleum Beijing 102249 China

A second-order moment two-phase turbulence model for simulating dense gas-particle flows （USM-Θ model）, combining the unified second-order moment twophase turbulence model for dilute gas-particle flows with the kinetic theory of particle collision, is proposed. The interaction between gas and particle turbulence is simulated using the transport equation of two-phase velocity correlation with a two-time-scale dissipation closure. The proposed model is applied to simulate dense gas-particle flows in a horizontal channel and a downer. Simulation results and their comparison with experimental results show that the model accounting for both anisotropic particle turbulence and particle-particle collision is obviously better than models accounting for only particle turbulence or only particle-particle collision. The USM-Θ model is also better than the k-ε-kp-Θ model and the k-ε-kp-εp-Θ model in that the first model can simulate the redistribution of anisotropic particle Reynolds stress components due to inter-particle collision, whereas the second and third models cannot.

关键词： Turbulence two-phase flow Second-ordermoment model

two-phase air-water flows: Scale effects in physical modeling

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Journal of Hydrodynamics 2014年第2期26卷 291-298页

作者： PFISTER Michael CHANSON Hubert Ecole Polytechnique Fédérale de Lausanne (EPFL) Laboratory of Hydraulic Constructions (LCH) The University of Queensland School of Civil Engineering

Physical modeling represents probably the oldest design tool in hydraulic engineering together with analytical approaches. In free surface flows, the similitude based upon a Froude similarity allows for a correct representation of the dominant forces, namely gravity and inertia. As a result fluid flow properties such as the capillary forces and the viscous forces might be incorrectly reproduced, affecting the air entrainment and transport capacity of a high-speed model flow. Small physical models operating under a Froude similitude systematically underestimate the air entrainment rate and air-water interfacial properties. To limit scale effects, minimal values of Reynolds or Weber number have to be respected. The present article summarizes the physical background of such limitations and their combination in terms of the Morton number. Based upon a literature review, the existing limits are presented and discussed, resulting in a series of more conservative recommendations in terms of air concentration scaling. For other air-water flow parameters, the selection of the criteria to assess scale effects is critical because some parameters （e.g., bubble sizes, turbulent scales） can be affected by scale effects, even in relatively large laboratory models.

关键词： air entrainment hydraulic structures physical modeling scale effects two-phase flow Morton number

Numerical method for simulating rarefaction shocks in the approximation of phase-flip hydrodynamics

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Applied Mathematics and Mechanics(English Edition) 2021年第6期42卷 871-884页

作者： M.M.BASKO Keldysh Institute of Applied Mathematics Russian Academy of SciencesMiusskaya Square 4Moscow 125047Russia

A finite-difference algorithm is proposed for numerical modeling of hydrodynamic flows with rarefaction shocks, in which the fluid undergoes a jump-like liquid-gas phase transition. This new type of flow discontinuity, unexplored so far in computational fluid dynamics, arises in the approximation of phase-flip(PF) hydrodynamics, where a highly dynamic fluid is allowed to reach the innermost limit of metastability at the spinodal, upon which an instantaneous relaxation to the full phase equilibrium(EQ) is assumed. A new element in the proposed method is artificial kinetics of the phase transition, represented by an artificial relaxation term in the energy equation for a "hidden"component of the internal energy, temporarily withdrawn from the fluid at the moment of the PF transition. When combined with an appropriate variant of artificial viscosity in the Lagrangian framework, the latter ensures convergence to exact discontinuous solutions, which is demonstrated with several test cases.

关键词： fluid dynamics with phase transitions two-phase flow rarefaction shock Lagrangian scheme artificial viscosity artificial kinetics

Experimental study on prediction model of wet gas pressure drop across single-orifice plate in horizontal pipes in the low gas phase Froude number region

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Chinese Journal of Chemical Engineering 2022年第6期35卷 63-72页

作者： Youfang Ma Youfu Ma Junfu Lyu Weiye Liu Shanghai Key Laboratory of Multiphase flow and Heat Transfer in Power Engineering School of Energy and Power EngineeringUniversity of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China

The pressure drop prediction of wet gas across single-orifice plate in horizontal pipes had been solved satisfactorily under an annular-mist flow in the upstream of orifice ***,this pressure drop prediction is still not clearly determined when the upstream is in an intermittent flow or stratified flow,which is corresponding to a region of low FrG(gas phase Froude number)in the flow pattern map of wet *** this study,the wet gas pressure drop across a single-orifice plate was experimentally investigated in the low FrG *** the experiment,the flow pattern transition in the downstream of single-orifice plates,as well as the effects of FrG and FrL(liquid phase Froude number)on UG(gas phase multiplier),were determined and compared when the upstream is in the flow pattern transition and the stratified flow region,*** performances were examined on the available pressure drop *** was found that no model could be capable of jointly predicting the wet gas pressure drop in the low FrG region with an acceptable *** a new method of correlating FrG and FrL simultaneously,new correlations were proposed for the low FrG *** which the modified Chisholm model shows the best prediction accuracies,with the prediction deviations of UG being within 7%and 3%when the upstream is in flow pattern transition and stratified flow region,respectively.

关键词： Gas-liquid flow two-phase flow Wet gas Orifice plate Pressure drop Model