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multiphase flow and Wear in the Cutting Head of Ultra-high Pressure Abrasive Water Jet

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Chinese Journal of Mechanical Engineering 2009年第5期22卷 729-734页

作者： YANG Minguan WANG Yuli KANG Can YU Feng School of Energy and Power Engineering Jiangsu University Zhenjiang 212013 China

Abrasive water jet cutting technology is widely applied in the materials processing today and attracts great attention from scholars, but many phenomena concerned are not well understood, especially in the internal jet flow of the cutting head at the condition of ultra-high pressure. The multiphase flow in the cutting head is numerically simulated to study the abrasive motion mechanism and wear inside the cutting head at the pressure beyond 300 MPa. Visible predictions of the particles trajectories and wear rate in the cutting head are presented. The influences of the abrasive physical properties, size of the jewel orifice and the operating pressure on the trajectories are discussed. Based on the simulation, a wear experiment is carried out under the corresponding pressures. The simulation and experimental results show that the flow in the mixing chamber is composed of the jet core zone and the disturbance zone, both affect the particles trajectories. The mixing efficiency drops with the increase of the abrasive granularity. The abrasive density determines the response of particles to the effects of different flow zones, the abrasive with medium density gives the best general performance. Increasing the operating pressure or using the jewel with a smaller orifice improves the coherency of p articles trajectories but increases the wear rate of the jewel holder at the same time. Walls of the jewel holder, the entrance of the mixing chamber and the convergence part of the mixing tube are subject to wear out. The computational and experimental results give a qualitative consistency which proves that this numerical method can provide a reliable and visible cognition of the flow characteristics of ultra-high pressure abrasive water jet. The investigation is benefit for improving the machining properties of water jet cutting systems and the optimization design of the cutting head.

关键词： abrasive water jet cutting head multiphase flow wear

multiphase flow model developed for simulating gas hydrate transport in horizontal pipe

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Applied Mathematics and Mechanics(English Edition) 2016年第9期37卷 1193-1202页

作者： Shuai TANG Caixi LIU Yuhong DONG Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University

The hydrate formation or dissociation in deep subsea flow lines is a challenging problem in oil and gas transport systems. The study of multiphase flows is complex while necessary due to the phase changes （i.e., liquid, solid, and gas） that occur with increasing the temperature and decreasing the pressure. A one-dimensional multiphase flow model coupled with a transient hydrate kinetic model is developed to study the characteristics of the multiphase flows for the hydrates formed by the phase changes in the pipes. The multiphase flow model is derived from a multi-fluid model, while has been widely used in modelling multiphase flows. The heat convection between the fluid and the ambient through the pipe wall is considered in the energy balance equation. The developed multiphase flow model is used to simulate the procedure of the hydrate transport. The results show that the formation of the hydrates can cause hold-up oscillations of water and gas.

关键词： multiphase flow hydrate slug flow phase change

A new interacting capillary bundle model on the multiphase flow in micropores of tight rocks

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Petroleum Science 2024年第2期21卷 1099-1112页

作者： Wen-Quan Deng Tian-Bo Liang Wen-Zhong Wang Hao Liu Jun-Lin Wu Fu-Jian Zhou National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China

Surfactants are widely used in the fracturing fluid to enhance the imbibition and thus the oil recovery rate. However, current numerical models cannot capture the physics behind capillary imbibition during the wettability alteration by surfactants. Although the interacting capillary bundle(ICB) model shows potential in characterizing imbibition rates in different pores during wettability alteration, the existing ICB models neglect the influence of wettability and viscosity ratio on the imbibition behavior, making it difficult to accurately describe the oil-water imbibition behavior within the porous media. In this work,a new ICB mathematical model is established by introducing pressure balance without assuming the position of the leading front to comprehensively describe the imbibition behavior in a porous medium under different conditions, including gas-liquid spontaneous imbibition and oil-water *** the pore size distribution of a tight rock is known, this new model can predict the changes of water saturation during the displacement process in the tight rock, and also determine the imbibition rate in pores of different sizes. The water saturation profiles obtained from the new model are validated against the waterflooding simulation results from the CMG, while the imbibition rates calculated by the model are validated against the experimental observations of gas-liquid spontaneous imbibition. The good match above indicates the newly proposed model can show the water saturation profile at a macroscopic scale while capture the underlying physics of the multiphase flow in a porous medium at a microscopic scale. Simulation results obtained from this model indicate that both wettability and viscosity ratio can affect the sequence of fluid imbibition into pores of different sizes during the multiphase flow, where less-viscous wetting fluid is preferentially imbibed into larger pores while more-viscous wetting fluid tends to be imbibed into smaller pores. Fur

关键词： Imbibition multiphase flow Tight rock Interacting capillary bundle model Wettability

Exact solutions to drift-flux multiphase flow models through Lie group symmetry analysis

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Applied Mathematics and Mechanics(English Edition) 2015年第8期36卷 1105-1112页

作者： B.BIRA T.R.SEKHAR Department of Mathematics National Institute of Science and Technology Department of Mathematics Indian Institute of Technology Kharagpur

In the present paper, Lie group symmetry method is used to obtain some exact solutions for a hyperbolic system of partial differential equations （PDEs）, which governs an isothermal no-slip drift-flux model for multiphase flow problem. Those sym- metries are used for the governing system of equations to obtain infinitesimal transforma- tions, which consequently reduces the governing system of PDEs to a system of ODEs. Further, the solutions of the system of ODEs which in turn produces some exact solutions for the PDEs are presented. Finally, the evolutionary behavior of weak discontinuity is discussed.

关键词： multiphase flow drift-flux models Lie group analysis exact solution weakdiscontinuity

Numerical simulation study on multiphase flow pattern of hydrate slurry

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Petroleum Science 2023年第6期20卷 3897-3917页

作者： Xiao-Fang Lv Feng Chen Jie Zhang Yang Liu Qian-Li Ma Hui Du Chuan-Shuo Wang Shi-Dong Zhou Bo-Hui Shi Shang-Fei Song Jing Gong Jiangsu Key Laboratory of Oil and Gas Storage&Transportation Technology Changzhou UniversityChangzhou213016JiangsuChina China Petroleum&Chemical Corporation Northwest Oilfield Branch Petroleum Engineering Technology Research InstituteUrumqi830011XinjiangChina Sinopec Shengli Oilﬁeld Company Dongying257001ShandongChina National Engineering Laboratory for Pipeline Safety/MOE Key Laboratory of Petroleum Engineering China University of Petroleum-Beijing102249BeijingChina

The research on the multiphase flow characteristics of hydrate slurry is the key to implementing the risk prevention and control technology of hydrate slurry in deep-water oil and gas mixed transportation *** paper established a geometric model based on the high-pressure hydrate slurry experimental *** model was used to carry out simulation research on the flow characteristics of gas-liquid-solid three-phase *** specific research is as follows:Firstly,the effects of factors such as slurry flow velocity,hydrate particle density,hydrate particle size,and hydrate volume fraction on the stratified smooth flow were specifically *** test obtained particle size has the most influence on the particle concentration *** slurry flow velocity is gradually increased based on stratified smooth *** flow patterns were observed and their characteristics were ***,increasing the slurry velocity to 2 m/s could achieve the slurry flow pattern of partial hydrate in the pipeline transition from stratified smooth flow to wavy *** the flow rate increases to 3 m/s,a violent wave forms throughout the entire *** on wave flow,as the velocity increased to 4 m/s,and the flow pattern changed to slug *** the particle concentration was below 10%,the increase of the concentration would aggravate the slug flow trend;if the particle concentration was above 10%,the increase of the concentration would weaken the slug flow trend,the increase of particle density and liquid viscosity would weaken the tendency of slug *** relationship between the pressure drop gradients of several different flow patterns is:slug flow>wave flow>stratified smooth flow.

关键词： Hydrate slurry Numerical simulation multiphase flow flow field distribution flow pattern transition

Numerical simulation on the multiphase flow and reoxidation of the molten steel in a two-strand tundish during ladle change

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1540-1553页

作者： Jingcheng Wang Zhentong Liu Wei Chen Hongliang Chen Lifeng Zhang School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China School of Materials Science and Engineering Tianjin UniversityTianjin 300350China School of Mechanical and Materials Engineering North China University of TechnologyBeijing 100144China

A 3D mathematical model was proposed to investigate the molten steel–slag–air multiphase flow in a two-strand slab continuous casting(CC)tundish during ladle *** study focused on the exposure of the molten steel and the subsequent reoxidation *** exposure of the molten steel was calculated using the coupled realizable k–εmodel and volume of fluid(VOF)*** diffusion of dissolved oxygen was determined by solving the user-defined scalar(UDS)***,the user-defined function(UDF)was used to describe the source term in the UDS equation and determine the oxidation rate and oxidation *** effect of the refilling speed on the molten steel exposure and dissolved oxygen content was also *** the refilling speed during ladle change reduced the refilling time and the exposure duration of the molten ***,the elevated refilling speed enlarged the slag eyes and increased the average dissolved oxygen content within the tundish,thereby exacerbating the reoxidation *** addition,the time required for the molten steel with a high dissolved oxygen content to exit the tundish varied with the refilling *** the inlet speed was 3.0 m·s^(-1)during ladle change,the molten steel with a high dissolved oxygen content exited the outlet in a short period,reaching a maximum dissolved oxygen content of 0.000525wt%.Conversely,when the inlet speed was 1.8 m·s^(-1),the maximum dissolved oxygen content was 0.000382wt%.The refilling speed during the ladle change process must be appropriately decreased to minimize reoxidation effects and enhance the steel product quality.

关键词： tundish ladle change reoxidation multiphase flow numerical simulation

Uncertainty analysis of flow rate measurement for multiphase flow using CFD

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Acta Mechanica Sinica 2015年第5期31卷 698-707页

作者： Joon-Hyung Kim Uk-Hee Jung Sung Kim Joon-Yong Yoon Young-Seok Choi Department of Mechanical Design Engineering Hanyang University Thermal & Fluid System R&BD Group Korea Institute of Industrial Technology Energy System Engineering University of Science and Technology

The venturi meter has an advantage in its use,because it can measure flow without being much affected by the type of the measured fluid or flow ***,it has excellent versatility and is being widely applied in many *** flow of a liquid containing air is a representative example of a multiphase flow and exhibits complex flow *** particular,the greater the gas volume fraction（GVF）,the more inhomogeneous the flow *** a result,using a venturi meter to measure the rate of a flow that has a high GVF generates an *** this study,the cause of the error occurred in measuring the flow rate for the multiphase flow when using the venturi meter for analysis by *** ensure the reliability of this study,the accuracy of the multiphase flow models for numerical analysis was verified through comparison between the calculated results of numerical analysis and the experimental *** a result,the Grace model,which is a multiphase flow model established by an experiment with water and air,was confirmed to have the highest ***,the characteristics of the internal flow Held about the multiphase flow analysis result generated by applying the Grace model were analyzed to find the cause of the uncertainty occurring when measuring the flow rate of the multiphase flow using the venturi meter.A phase separation phenomenon occurred due to a density difference of water and air inside the venturi,and flow inhomogeneity happened according to the flow velocity difference of each *** was confirmed that this flow inhomogeneity increased as the GVF increased due to the uncertainty of the flow measurement.

关键词： multiphase flow Measurement Numerical analysis Venturi meter Gas volume fraction(GVF) Uncertainty multiphase flow model Grace model

The simulation of multiphase flow field in implantable blood pump and analysis of hemolytic capability

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Journal of Hydrodynamics 2013年第4期25卷 606-615页

作者：李铁岩叶亮洪方文刘登成范慧敏刘中民 Department of Cardiac Surgery Shanghai East Hospital Affiliated to Tongji University China Ship Scientific Research Center

The numerical simulation of the axial flow impeller blood pump NIVADIII is carried out by using a CFD multiphase flow model. The hydrodynamic performance of the pump and the flow field in the pump are analyzed, and the shear stress distribution is obtained. A hemolytic prediction model based on the shear stress is built based on the calculation results, and it can be used for qua- ntitative predictions of the hemolytic behavior of a blood pump. Hemolysis tests in vitro were performed 6 times with fresh bovine blood. At each time, the flow of the pump NIVADIII is 5 L/min and the outflow tract pressure is 100 mmHg. According to the tests, the plasma free hemoglobin （FHB） content and the hematocrit （HCT） are measured after 0 s, 0.5 s, 1 s, 1.5 s 4 s. At the end of each experiment Normal Index of Hemolysis （NIH） of NIVADIII is calculated. The average of NIH is 0.0055 g/100L, almost identi- cal with that obtained from the hemolytic prediction model. This method can be applied in the selection stage of a blood pump.

关键词： blood pump multiphase flow numerical simulation hemolytic

A semi-analytical rate-transient analysis model for light oil reservoirs exhibiting reservoir heterogeneity and multiphase flow

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Petroleum Science 2023年第1期20卷 309-321页

作者： Jin-Chang Li Bin Yuan Christopher R.Clarkson Jian-Quan Tian Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580ShandongPR China School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongPR China Department of Geoscience University of CalgaryABT2L2N5Canada

Rate-transient analysis(RTA)has been widely applied to extract estimates of reservoir/hydraulic fracture ***,the majority of RTA techniques can lead to misdiagnosis of reservoir/fracture information when the reservoir exhibits reservoir heterogeneity and multiphase flow *** work proposes a practical-yet-rigorous method to decouple the effects of reservoir heterogeneity and multiphase flow during TLF,and improve the evaluation of reservoir/fracture properties.A new,general,semi-analytical model is proposed that explicitly accounts for multiphase flow,fractalbased reservoir heterogeneity,anomalous diffusion,and pressure-dependent fluid *** is achieved by introducing a new Boltzmann-type transformation,the exponent of which includes reservoir heterogeneity and anomalous *** order to decouple the effects of reservoir heterogeneity and multiphase flow during TLF,the modified Boltzmann variable allows the conversion of three partial differential equations(PDE's)(i.e.,oil,gas and water diffusion equations)into ordinary differential equations(ODE's)that are easily solved using the Runge-Kutta(RK)method.A modified time-power-law plot is also proposed to estimate the reservoir and fracture properties,recognizing that the classical square-root-of-time-plot is no longer valid when various reservoir complexities are exhibited *** the slope of the straight line on the modified time-power-law plot,the linear flow parameter can be estimated with more ***,because of the new Boltzmann-type transformation,reservoir and fracture properties can be derived more efficiently without the need for defining complex pseudo-variable *** the new semi-analytical model,the effects of multiphase flow,reservoir heterogeneity and anomalous diffusion on rate-decline behavior are *** the case of approximately constant flowing pressure,multiphase flow impacts initial oil rate,which is a funct

关键词： Transient linear flow multiphase flow Reservoir heterogeneity Unconventional reservoirs