Chokes are one of the most important components of downhole flow-control equipment. The particle erosion mathematical model, which considers particle-particle interaction, was established and used to simulate solid pa...Chokes are one of the most important components of downhole flow-control equipment. The particle erosion mathematical model, which considers particle-particle interaction, was established and used to simulate solid particle movement as well as particle erosion characteristics of the solid-liquid two-phase flow in a choke. The corresponding erosion reduction approach by setting ribs on the inner wall of the choke was advanced. This mathematical model includes three parts： the flow field simulation of the continuous carrier fluid by an Eulerian approach, the particle interaction simulation using the discrete particle hard sphere model by a Lagrangian approach and calculation of erosion rate using semiempirical correlations. The results show that particles accumulated in a narrow region from inlet to outlet of the choke and the dominating factor affecting particle motion is the fluid drag force. As a result, the optimization of rib geometrical parameters indicates that good anti-erosion performance can be achieved by four ribs, each of them with a height （H） of 3 mm and a width （B） of 5 mm equaling the interval between ribs （L）.展开更多
This paper is concerned with a remedy for interface smearing,which is usable when fixed (i.e. non moving and so non conforming) grids are employed. It is simple to employ and has been found to be rather effective. T...This paper is concerned with a remedy for interface smearing,which is usable when fixed (i.e. non moving and so non conforming) grids are employed. It is simple to employ and has been found to be rather effective. The paper explains its principle, describes how it has been implemented and presents some results obtained with its assistance. The results are compared both with those of earlier methods of interface motion calculation and with experimental data.展开更多
An investigation on phase distribution in air-water two-phase flow in horizontal circular channel was conducted by using the double-sensor resistivity probe.The variations of phase distribution with variations of gas ...An investigation on phase distribution in air-water two-phase flow in horizontal circular channel was conducted by using the double-sensor resistivity probe.The variations of phase distribution with variations of gas and liquid volumetric fluxes were analyzed and the present data were compared with some of other researcher’s data and existing models. It was found there exists more complicated phase distribution pattern in horizontal flow system than in vertical flow. The radial local void fraction profiles are similar at the same measurement angle with various gas and liquid flow rates. However, an asymmetric profile can be observed at a given slice of the pipe cross-section.展开更多
A new model of particle yield stress including cohesive strength is proposed,which considers the friction and cohesive strength between particles.A calculation method for the fluidization process of liquid–solid two-...A new model of particle yield stress including cohesive strength is proposed,which considers the friction and cohesive strength between particles.A calculation method for the fluidization process of liquid–solid two-phase flow in compact packing state is given,and the simulation and experimental studies of fluidization process are carried out by taking the sand–water two-phase flow in the jet dredging system as an example,and the calculation method is verified.展开更多
Aim To develop a hydrodynamic model on the void fraction in liquid slugs for gas liquid slug flow in vertical tubes. Methods Developing the model by considering the gas exchange between the Taylor bubble and the fo...Aim To develop a hydrodynamic model on the void fraction in liquid slugs for gas liquid slug flow in vertical tubes. Methods Developing the model by considering the gas exchange between the Taylor bubble and the following liquid slug. Results Some experimental data are obtained to check the model. In comparison with previous published results, the predictions from this model are better and in good agreement with the experimental data. The error is within ±20%. Conclusion The proposed model can correctly predict the void fraction in liquid slugs for gas liquid two phase slug flow in vertical tubes.展开更多
The two-phase flow models are commonly used in industrial applications, such as nuclear, power, chemical-process, oil-and-gas, cryogenics, bio-medical, micro-technology and so on. This is a survey paper on the study o...The two-phase flow models are commonly used in industrial applications, such as nuclear, power, chemical-process, oil-and-gas, cryogenics, bio-medical, micro-technology and so on. This is a survey paper on the study of compressible nonconservative two-fluid model, drift-flux model and viscous liquid-gas two-phase flow model. We give the research developments of these three two-phase flow models, respectively. In the last part, we give some open problems about the above models.展开更多
Flow patterns in upstream and downstream straight tubes of sudden-changed areas in a horizontal straight pipe were experimentally examined. Both sudden-expansion cross-section (SECS) and sudden-contraction cross-secti...Flow patterns in upstream and downstream straight tubes of sudden-changed areas in a horizontal straight pipe were experimentally examined. Both sudden-expansion cross-section (SECS) and sudden-contraction cross-section (SCCS) were investigated. The flow pattern maps upstream and downstream were delineated and compared with those in straight tubes with uniform cross-sections. The effects of the SECS and SCCS on flow patterns were discussed and analyzed. Furthermore, flow pattern transition mechanisms resulting in occurrences of different flow patterns were simply discussed and some transition criteria for the flow pattern transitions were deduced by using the non-dimensionlized analysis method.展开更多
为探究双组元空间发动机内自燃推进剂喷雾、燃烧和传热特性,首先对现有MMH/N_(2)O_(4)(甲基肼/四氧化二氮)详细燃烧反应机理进行适当简化,提出适用于三维模拟的MMH/N_(2)O_(4)化学反应动力学模型,并在不同工况下对简化机理的准确性进行...为探究双组元空间发动机内自燃推进剂喷雾、燃烧和传热特性,首先对现有MMH/N_(2)O_(4)(甲基肼/四氧化二氮)详细燃烧反应机理进行适当简化,提出适用于三维模拟的MMH/N_(2)O_(4)化学反应动力学模型,并在不同工况下对简化机理的准确性进行了验证;随后,采用流体体积(volume of fluid,VOF)模型对空间发动机内MMH/N_(2)O_(4)射流撞击雾化过程进行了非稳态模拟,并重点分析了直流互击作用下扇形液膜的形成和演变规律;基于以上化学反应机理及液雾分布模拟结果,在欧拉-拉格朗日体系下构建了离散液滴初始分布,并结合部分搅拌反应器湍流燃烧模型,开展了空间发动机内MMH/N_(2)O_(4)喷雾燃烧及流固耦合传热过程的模拟研究.结果表明,空间发动机内推进剂湍流喷射雾化燃烧过程对壁面冷却液膜的形成和发展具有重要影响,冷却液膜主要出现在燃烧室直线段,在高温燃气与固体域之间建立了一个明显的温度缓冲层,从而实现对发动机壁温的保护.展开更多
基金supported by the Fund of Innovation Research Group of National Natural Science Foundation of China (Grant NO.5052160450323001)Major Program of National Natural Science Foundation of China (Grant No.50536020)
文摘Chokes are one of the most important components of downhole flow-control equipment. The particle erosion mathematical model, which considers particle-particle interaction, was established and used to simulate solid particle movement as well as particle erosion characteristics of the solid-liquid two-phase flow in a choke. The corresponding erosion reduction approach by setting ribs on the inner wall of the choke was advanced. This mathematical model includes three parts： the flow field simulation of the continuous carrier fluid by an Eulerian approach, the particle interaction simulation using the discrete particle hard sphere model by a Lagrangian approach and calculation of erosion rate using semiempirical correlations. The results show that particles accumulated in a narrow region from inlet to outlet of the choke and the dominating factor affecting particle motion is the fluid drag force. As a result, the optimization of rib geometrical parameters indicates that good anti-erosion performance can be achieved by four ribs, each of them with a height （H） of 3 mm and a width （B） of 5 mm equaling the interval between ribs （L）.
文摘This paper is concerned with a remedy for interface smearing,which is usable when fixed (i.e. non moving and so non conforming) grids are employed. It is simple to employ and has been found to be rather effective. The paper explains its principle, describes how it has been implemented and presents some results obtained with its assistance. The results are compared both with those of earlier methods of interface motion calculation and with experimental data.
文摘An investigation on phase distribution in air-water two-phase flow in horizontal circular channel was conducted by using the double-sensor resistivity probe.The variations of phase distribution with variations of gas and liquid volumetric fluxes were analyzed and the present data were compared with some of other researcher’s data and existing models. It was found there exists more complicated phase distribution pattern in horizontal flow system than in vertical flow. The radial local void fraction profiles are similar at the same measurement angle with various gas and liquid flow rates. However, an asymmetric profile can be observed at a given slice of the pipe cross-section.
基金Project supported by the National Natural Science Foundation of China(Grant No.11772046)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.51705342)
文摘A new model of particle yield stress including cohesive strength is proposed,which considers the friction and cohesive strength between particles.A calculation method for the fluidization process of liquid–solid two-phase flow in compact packing state is given,and the simulation and experimental studies of fluidization process are carried out by taking the sand–water two-phase flow in the jet dredging system as an example,and the calculation method is verified.
文摘Aim To develop a hydrodynamic model on the void fraction in liquid slugs for gas liquid slug flow in vertical tubes. Methods Developing the model by considering the gas exchange between the Taylor bubble and the following liquid slug. Results Some experimental data are obtained to check the model. In comparison with previous published results, the predictions from this model are better and in good agreement with the experimental data. The error is within ±20%. Conclusion The proposed model can correctly predict the void fraction in liquid slugs for gas liquid two phase slug flow in vertical tubes.
基金supported by the National Natural Science Foundation of China(11722104,11671150)supported by the National Natural Science Foundation of China(11571280,11331005)+3 种基金supported by the National Natural Science Foundation of China(11331005,11771150)by GDUPS(2016)the Fundamental Research Funds for the Central Universities of China(D2172260)FANEDD No.201315
文摘The two-phase flow models are commonly used in industrial applications, such as nuclear, power, chemical-process, oil-and-gas, cryogenics, bio-medical, micro-technology and so on. This is a survey paper on the study of compressible nonconservative two-fluid model, drift-flux model and viscous liquid-gas two-phase flow model. We give the research developments of these three two-phase flow models, respectively. In the last part, we give some open problems about the above models.
基金the National Natural Science Foundation (No.59995460)
文摘Flow patterns in upstream and downstream straight tubes of sudden-changed areas in a horizontal straight pipe were experimentally examined. Both sudden-expansion cross-section (SECS) and sudden-contraction cross-section (SCCS) were investigated. The flow pattern maps upstream and downstream were delineated and compared with those in straight tubes with uniform cross-sections. The effects of the SECS and SCCS on flow patterns were discussed and analyzed. Furthermore, flow pattern transition mechanisms resulting in occurrences of different flow patterns were simply discussed and some transition criteria for the flow pattern transitions were deduced by using the non-dimensionlized analysis method.
文摘为探究双组元空间发动机内自燃推进剂喷雾、燃烧和传热特性,首先对现有MMH/N_(2)O_(4)(甲基肼/四氧化二氮)详细燃烧反应机理进行适当简化,提出适用于三维模拟的MMH/N_(2)O_(4)化学反应动力学模型,并在不同工况下对简化机理的准确性进行了验证;随后,采用流体体积(volume of fluid,VOF)模型对空间发动机内MMH/N_(2)O_(4)射流撞击雾化过程进行了非稳态模拟,并重点分析了直流互击作用下扇形液膜的形成和演变规律;基于以上化学反应机理及液雾分布模拟结果,在欧拉-拉格朗日体系下构建了离散液滴初始分布,并结合部分搅拌反应器湍流燃烧模型,开展了空间发动机内MMH/N_(2)O_(4)喷雾燃烧及流固耦合传热过程的模拟研究.结果表明,空间发动机内推进剂湍流喷射雾化燃烧过程对壁面冷却液膜的形成和发展具有重要影响,冷却液膜主要出现在燃烧室直线段,在高温燃气与固体域之间建立了一个明显的温度缓冲层,从而实现对发动机壁温的保护.
