Oil–water two-phase flow patterns in a horizontal pipe are analyzed with a 16-electrode electrical resistance tomography(ERT) system. The measurement data of the ERT are treated as a multivariate time-series, thus th...Oil–water two-phase flow patterns in a horizontal pipe are analyzed with a 16-electrode electrical resistance tomography(ERT) system. The measurement data of the ERT are treated as a multivariate time-series, thus the information extracted from each electrode represents the local phase distribution and fraction change at that location. The multivariate maximum Lyapunov exponent(MMLE) is extracted from the 16-dimension time-series to demonstrate the change of flow pattern versus the superficial velocity ratio of oil to water. The correlation dimension of the multivariate time-series is further introduced to jointly characterize and finally separate the flow patterns with MMLE. The change of flow patterns with superficial oil velocity at different water superficial velocities is studied with MMLE and correlation dimension, respectively, and the flow pattern transition can also be characterized with these two features. The proposed MMLE and correlation dimension map could effectively separate the flow patterns, thus is an effective tool for flow pattern identification and transition analysis.展开更多
Bends are widely used in pipelines carrying single-and two-phase fluids in both ground and space applications.In particular,they play more important role in space applications due to the extreme spatial constraints.In...Bends are widely used in pipelines carrying single-and two-phase fluids in both ground and space applications.In particular,they play more important role in space applications due to the extreme spatial constraints.In the present study,a set of experimental data of two-phase flow patterns and their transitions in a 90°bend with inner diameter of 12.7 mm and curvature radius of 76.5 mm at microgravity conditions are reported.Gas and liquid superficial velocities are found to range from (1.0～23.6)m/s for gas and(0.09～0.5)m/s for liquid,respectively.Three major flow patterns, namely slug,slug-annular transitional,and annular flows,are observed in this study.Focusing on the differences between flow patterns in bends and their counterparts in straight pipes,detailed analyses of their characteristics are made.The transitions between adjoining flow patterns are found to be more or less the same as those in straight pipes,and can be predicted using Weber number models satisfactorily. The reasons for such agreement are carefully examined.展开更多
In this companion paper, flow patterns in the upstream and downstream tubes of a sudden-expansion cross-section (SECS) in a vertical straight pipe were presented. The effect of SECS on flow patterns upstream and down...In this companion paper, flow patterns in the upstream and downstream tubes of a sudden-expansion cross-section (SECS) in a vertical straight pipe were presented. The effect of SECS on flow patterns upstream and downstream was analyzed by comparing with flow patterns in uniform cross-section vertical tubes. It is found the effect is great. There exist great instabilities of two-phase flow in the neighboring areas of the SECS both downstream and upstream.展开更多
In this work, flow pattern and mass transfer of liquid-liquid two-phase flow in a wire-embedded concentric microchannel are studied using toluene-water system. Droplet flow, slug flow, oval flow and annular flow are o...In this work, flow pattern and mass transfer of liquid-liquid two-phase flow in a wire-embedded concentric microchannel are studied using toluene-water system. Droplet flow, slug flow, oval flow and annular flow are observed in the wire-embedded concentric microchannel. The effects of embedded wires and physical properties on flow patterns are investigated. The embedded wire insert is conducive to the formation of annular flow. The flow pattern distribution regions are distinguished by the Caaq(capillary number)±We_(org)(Weber number) flow pattern map. When Weorg<0.001, slug flow is the main flow pattern, and when Weorg>0.1, annular flow is the main flow pattern. Oval flow and droplet flow are between We_(org)= 0.001-0.1, and oval flow is transformed into droplet flow with the increase of Caaq. The effect of flow rate, phase ratio, initial acetic acid concentration, insert shape and flow patterns on mass transfers are studied. Mass transfer process is enhanced under annular flow conditions, the volumetric mass transfer coefficient is up to 0.36 s^(-1) because of the high interfacial area and interface renewal rate of annular flow.展开更多
Flow patterns upstream and downstream of a sudden-contraction cross-section in a vertical straight pipe were presented. By comparing with flow patterns in uniform cross-section vertical tubes, the effect of the sudde...Flow patterns upstream and downstream of a sudden-contraction cross-section in a vertical straight pipe were presented. By comparing with flow patterns in uniform cross-section vertical tubes, the effect of the sudden change in pipe diameter on flow patterns was analyzed. Flow pattern transition mechanisms were discussed and transition criteria for flow pattern transitions were deduced accordingly using the dimensional analysis.展开更多
During horizontal well drilling,the interaction between drilling fluid and cuttings entering the annulus generates diverse flow patterns.These solid-liquid two-phase flow patterns must be accurately predicted to optim...During horizontal well drilling,the interaction between drilling fluid and cuttings entering the annulus generates diverse flow patterns.These solid-liquid two-phase flow patterns must be accurately predicted to optimize the determination of hydraulic parameters and improve the efficiency of cuttings transport.Accordingly,this study identified flow patterns and conducted transition experiments under different inclination angles using a visualized wellbore annulus apparatus(120 mm outer diameter/73 mm inner diameter).Through direct visual observations,four primary flow patterns were systematically classified on the basis of the solid-liquid two-phase flow behaviors identified in the experiments:stable bed(SB),sand wave(SW),sand dune(SD),and bed load(BL)flows.The experimental data were then used to construct flow pattern maps with solid/liquid phases as axes,after which the transition boundaries between different flow patterns were established.The morphological characteristics and transition mechanisms of SB,SW,SD,and BL flows were systematically analyzed to develop three predictive models of the fluid dynamics principles governing these flow patterns’transitions:(1)A transition boundary model of SB and SW flows was established using Kelvin-Helmholtz stability,for which a stability analysis of solid-liquid two-phase flow in deviated and horizontal annuli was carried out.(2)A transition boundary model of SW and SD flows was constructed through an analysis of the geometric features of sand waves in the annuli,with the critical ratio of the average height of a cuttings bed to its height after erosion being 0.45.(3)A traditional critical velocity model was refined by adjusting the von Karman constant to account for the effect of solid volume concentration,yielding a boundary model for the transition of SW or SD flow into BL flow.All the models were experimentally validated.Finally,we integrated the models to develop a unified method for identifying and classifying the patterns typifying solid-liquid two-phase flow in deviated and horizontal annuli.展开更多
The gas-liquid two-phase swirl flow can increase the gas-liquid two-phase contact area and enhance the heat and mass transfer efficiency between gas and liquid.The swirl flow has important practical application value ...The gas-liquid two-phase swirl flow can increase the gas-liquid two-phase contact area and enhance the heat and mass transfer efficiency between gas and liquid.The swirl flow has important practical application value for promoting gas hydrate formation and ensuring the flow safe of natural gas hydrate slurry.The experimental section was made of plexiglass pipe and the experimental medium was air and water.The flow pattern of the gas-liquid two-phase swirl flow in the horizontal pipe was divided,according to a high-definition camera and the overall characteristics of the gas-liquid interface.The flow pattern map of the gas-liquid two-phase swirl flow in a horizontal pipe was studied.The influence of the flow velocity and vane parameters on pressure drop was investigated.Two types of gas-liquid two-phase swirl flow pressure drop models was established.The homogeneous-phase and split-phase pressure drop models have good prediction on swirl bubble flow,swirl dispersed flow,swirl annular flow and swirl stratified flow,and the predictive error band is not more than 20%.展开更多
The amount of waste heat in a space facility became larger, because of increase in the space platform size and its power consumption. It requires development of high-performance space thermal management systems handli...The amount of waste heat in a space facility became larger, because of increase in the space platform size and its power consumption. It requires development of high-performance space thermal management systems handling a large amount of waste. Boiling two-phase flow could become powerful means for this system because a boiling and condensation system is one of the most efficient modes of heat transfer due to phase change （liquid-vapor）. However, gravity effects on boiling two-phase flow phenomena and the corresponding heat transfer characteristics are not clear. Therefore, we prepare the experiments of boiling two-phase flow utilizing a long-term microgravity environment onboard a Japanese Experimental Module ＂KIBO＂ in the International Space Station （ISS） as one of the JAXA official projects. In this paper, recent progress of the preparation for the project is reported.展开更多
The flow patterns and their transitions of oil-water two-phase flow in horizontal pipes were studied. The experiments were conducted in two kinds of horizontal tubes, made of plexiglas pipe and stainless steel pipe wi...The flow patterns and their transitions of oil-water two-phase flow in horizontal pipes were studied. The experiments were conducted in two kinds of horizontal tubes, made of plexiglas pipe and stainless steel pipe with 40 mm ID respectively. No. 46 mechanical oil and tap water were used as working fluids. The superflcial velocity ranges of oil and water were: 0.04-1.2m·s-1 and 0.04-2.2m·s-1, respectively. The flow patterns were identified by visualization and by transient fluctuation signals of differential pressure drop. The flow patterns were defined according to the relative distribution of oil and water phases in the pipes. Flow pattern maps were obtained for both pipelines. In addition, semi-theoretical transition criteria for the flow patterns were proposed, and the proposed transitional criteria are in reasonable agreement with available data in liquid-liquid systems.展开更多
This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil–water two-phase flow. The finite element method is used to calculate the sensitivity...This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil–water two-phase flow. The finite element method is used to calculate the sensitivity field of the sensor in a pipe with 20 mm inner diameter and the effect of sensor geometry on the distribution of sensitivity field is presented. Then, a horizontal oil–water two-phase flow experiment is carried out to measure the response of the double helix capacitance sensor, in which a novel method is proposed to calibrate the liquid holdup based on three pairs of parallel-wire capacitance probes. The performance of the sensor is analyzed in terms of the flow structures detected by mini-conductance array probes.展开更多
A new method of nonlinear analysis is established by combining phase space reconstruction and data reduction sub-frequency band wavelet. This method is applied to two types of chaotic dynamic systems(Lorenz and Rssler...A new method of nonlinear analysis is established by combining phase space reconstruction and data reduction sub-frequency band wavelet. This method is applied to two types of chaotic dynamic systems(Lorenz and Rssler) to examine the anti-noise ability for complex systems. Results show that the nonlinear dynamic system analysis method resists noise and reveals the internal dynamics of a weak signal from noise pollution. On this basis, the vertical upward gas–liquid two-phase flow in a 2 mm × 0.81 mm small rectangular channel is investigated. The frequency and energy distributions of the main oscillation mode are revealed by analyzing the time–frequency spectra of the pressure signals of different flow patterns. The positive power spectral density of singular-value frequency entropy and the damping ratio are extracted to characterize the evolution of flow patterns and achieve accurate recognition of different vertical upward gas–liquid flow patterns(bubbly flow:100%, slug flow: 92%, churn flow: 96%, annular flow: 100%). The proposed analysis method will enrich the dynamics theory of multi-phase flow in small channel.展开更多
Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typica...Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typically governed by gravity, viscous and capillary forces, these factors lead invasive fluids to occupy pore space irregularly and incompletely. Previous studies have demonstrated capillary numbers,describing the viscous and capillary forces, to quantificationally induce evolution of invasion patterns.While the evolution mechanisms of invasive patterns have not been deeply elucidated under the constant capillary number and three variable parameters including velocity, viscosity, and interfacial tension.Our research employs two horizontal visualization systems and a two-phase laminar flow simulation to investigate the tendency of invasive pattern transition by various parameters at the pore scale. We showed that increasing invasive viscosity or reducing interfacial tension in a homogeneous pore space significantly enhanced sweep efficiency, under constant capillary number. Additionally, in the fingering crossover pattern, the region near the inlet was prone to capillary fingering with multi-directional invasion, while the viscous fingering with unidirectional invasion was more susceptible occurred in the region near the outlet. Furthermore, increasing invasive viscosity or decreasing invasive velocity and interfacial tension promoted the extension of viscous fingering from the outlet to the inlet, presenting that the subsequent invasive fluid flows toward the outlet. In the case of invasive trunk along a unidirectional path, the invasive flow increased exponentially closer to the outlet, resulting in a significant decrease in the width of the invasive interface. Our work holds promising applications for optimizing invasive patterns in heterogeneous porous media.展开更多
We generate a directed weighted complex network by a method based on Markov transition probability to represent an experimental two-phase flow. We first systematically carry out gas-liquid two-phase flow experiments f...We generate a directed weighted complex network by a method based on Markov transition probability to represent an experimental two-phase flow. We first systematically carry out gas-liquid two-phase flow experiments for measuring the time series of flow signals. Then we construct directed weighted complex networks from various time series in terms of a network generation method based on Markov transition probability. We find that the generated network inherits the main features of the time series in the network structure. In particular, the networks from time series with different dynamics exhibit distinct topological properties. Finally, we construct two-phase flow directed weighted networks from experimental signals and associate the dynamic behavior of gas-liquid two-phase flow with the topological statistics of the generated networks. The results suggest that the topological statistics of two-phase flow networks allow quantitative characterization of the dynamic flow behavior in the transitions among different gas-liquid flow patterns.展开更多
In order to eliminate mal-distribution and ensure the side arm to produce desirable gas quality a special distributor is proposed. The experimental distributor mainly consists of a straight through section,a gas extra...In order to eliminate mal-distribution and ensure the side arm to produce desirable gas quality a special distributor is proposed. The experimental distributor mainly consists of a straight through section,a gas extraction line,a liquid extraction line and a side arm branch. A gas orifice and a liquid orifice are mounted at the gas and liquid extraction line respectively to control the outlet gas quality. The diameter of the liquid orifice was set to 2. 50 mm and three gas orifices with different size( dG= 2. 65,5. 00,10. 00 mm) were tested. The experiments were carried out at an air-water two-phase flow loop. The gas superficial velocity ranged from 6. 0 to 20. 0 m /s and the liquid superficial velocity was in the range of 0. 02- 0. 18 m /s. Flow patterns such as wave flow,slug flow and annular flow were observed. The gas quality of the side arm branch was found mainly determined by the flow area ratio of the gas orifice to the liquid orifice and independent of gas and liquid superficial velocity,flow patterns and extraction flux.展开更多
Two-phase flow distributions in the merged pipe distributor have still remained mal-uniformity problem and the causes have not clearly discovered yet. Therefore, the enhancement study is needed, absolutely. The experi...Two-phase flow distributions in the merged pipe distributor have still remained mal-uniformity problem and the causes have not clearly discovered yet. Therefore, the enhancement study is needed, absolutely. The experimental was carried out upon the distributor constructed by acrylics resembling merged triple pipe, 8 mm in diameter of inlet channel and two set 5 mm in diameter of each outlet channel, set horizontally sideways. Three flow patterns were fed, i.e., bubble, slug and stratified flow, observed via high speed video camera. The pressure distribution was measured by series of U-tube water gauge manometer. The flow patterns, phase distribution and pressure drop were analyzed by CFD software, validated by experimental data and compared by existing correlation, analytically. The experiment is extended by modeling, in order to vary three inclinations of distributor： horizontally, 45° and vertically up-ward as well as to vary three outlet channel lengths with length ratio lc/dc： 3.2, 10 and 70. It was revealed that the two-phase flow distribution tends to be mal-uniform and to transform to different flow pattern in outlet channels. These are promoted by different： outlet channel length, feeding two-phase flow pattern in inlet distributor and inclination angle. The changing of flow pattern is driven by fluctuating velocity in both upper and lower outlet channel.展开更多
The upward multiphase cross flow and heat transfer in the vertical tube may occur in oil production and chemical facilities. In this study, the local flow patterns of an upward gas-water two phase cross flow in a vert...The upward multiphase cross flow and heat transfer in the vertical tube may occur in oil production and chemical facilities. In this study, the local flow patterns of an upward gas-water two phase cross flow in a vertical tube with a horizontal rod have been investigated with an optical probe and the digital high speed video system. The local flow patterns are defined as the bubble, slug, churn and annular flow patterns. Optical probe signals are ana- lyzed in terms of probability density function, and it is proved that the local flow patterns can be recognized by this method. The transition mechanisms between the different flow patterns have been analyzed and the corresponding transitional models are proposed. Finally, local flow pattern maps of the upward gas-water two-phase flow in the vertical tube with a horizontal rod are constructed.展开更多
Gas–liquid two-phase flow abounds in industrial processes and facilities. Identification of its flow pattern plays an essential role in the field of multiphase flow measurement. A bluff body was introduced in this s...Gas–liquid two-phase flow abounds in industrial processes and facilities. Identification of its flow pattern plays an essential role in the field of multiphase flow measurement. A bluff body was introduced in this study to recognize gas–liquid flow patterns by inducing fluid oscillation that enlarged differences between each flow pattern. Experiments with air–water mixtures were carried out in horizontal pipelines at ambient temperature and atmospheric pressure. Differential pressure signals from the bluff-body wake were obtained in bubble, bubble/plug transitional, plug, slug, and annular flows. Utilizing the adaptive ensemble empirical mode decomposition method and the Hilbert transform, the time–frequency entropy S of the differential pressure signals was obtained. By combining S and other flow parameters, such as the volumetric void fraction β, the dryness x, the ratio of density φ and the modified fluid coefficient ψ, a new flow pattern map was constructed which adopted S（1–x）φ and （1–β）ψ as the vertical and horizontal coordinates, respectively. The overall rate of classification of the map was verified to be 92.9% by the experimental data. It provides an effective and simple solution to the gas–liquid flow pattern identification problems.展开更多
Flow patterns of liquid-gas two-phase flow were experimentally investigated. The experiments were carried out in both vertical and horizontal capillary tubes having inner diameters of 1,60 mm, The working liquid was t...Flow patterns of liquid-gas two-phase flow were experimentally investigated. The experiments were carried out in both vertical and horizontal capillary tubes having inner diameters of 1,60 mm, The working liquid was the mixture of water and Sodium Dodecyl Benzoyl Sulfate （SDBS）. The working gas was Nitrogen. For the water/SDBS mixture-gas flow in the vertical capillary tube, flow-pattern transitions occurred at lower flow velocities than those for the water-gas flow in the same tube. For the water/SDBS mixture-gas flow in the horizontal capillary tube, surface tension had little effect on the bubbly-intermittent transition and had only slight effect on the plug-slug and slug-annular transitions. However, surface tension had significant effect on the wavy stratified flow regime. The wavy stratified flow regime of water/SDBS mixture-gas flow expanded compared with that of water-gas.展开更多
The heat transfer of hydrocarbon refrigerant across tube bundles have been widely used in refrigeration.Three-dimensional simulation model using volume of fluid(VOF) was presented to study the effects of tube shapes o...The heat transfer of hydrocarbon refrigerant across tube bundles have been widely used in refrigeration.Three-dimensional simulation model using volume of fluid(VOF) was presented to study the effects of tube shapes on flow pattern, film thickness and heat transfer of n-pentane across tube bundles, including circle, ellipse-shaped, egg-shaped and cam-shaped tube bundles. Simulation results agree well with experimental data in the literature. The liquid film thickness of sheet flow and heat transfer for different tube shapes were obtained numerically. The flow pattern transition occurs lower vapor quality for ellipse-shaped tube than other tube shapes. For sheet flow, the liquid film on circle tube and ellipseshaped tube is symmetrically distributed along the circumferential direction. However, the liquid film on egg-shaped tube at circumferential angles(θ) = 15°–60° is thicker than θ = 135°–165°. The liquid film on cam tube at θ = 15°–60° is slightly thinner than θ = 135°–165°. The liquid film thickness varies from thinner to thicker for ellipse-shaped, cam-shaped, egg-shape and circle within θ = 15°–60°. The effect of tube shape is insignificant on thin liquid film thickness. Ellipse-shaped tube has largest heat transfer coefficient for sheet flow. In practical engineering, the tube shape could be designed as ellipse to promote heat transfer.展开更多
The upward multiphase cross flow and heat transfer in the vertical tube may occur in oil production and chemical facilities. In this study, the local flow patterns of an upward gas-water two phase cross flow in a vert...The upward multiphase cross flow and heat transfer in the vertical tube may occur in oil production and chemical facilities. In this study, the local flow patterns of an upward gas-water two phase cross flow in a vertical tube with a horizontal rod have been investigated with an optical probe and the digital high speed video system. The local flow patterns are defined as the bubble, slug, churn and annular flow patterns. Optical probe signals are ana- lyzed in terms of probability density function, and it is proved that the local flow patterns can be recognized by this method. The transition mechanisms between the different flow patterns have been analyzed and the corresponding transitional models are proposed. Finally, local flow pattern maps of the upward gas-water two-phase flow in the vertical tube with a horizontal rod are constructed.展开更多
基金Projects(61227006,61473206) supported by the National Natural Science Foundation of ChinaProject(13TXSYJC40200) supported by Science and Technology Innovation of Tianjin,China
文摘Oil–water two-phase flow patterns in a horizontal pipe are analyzed with a 16-electrode electrical resistance tomography(ERT) system. The measurement data of the ERT are treated as a multivariate time-series, thus the information extracted from each electrode represents the local phase distribution and fraction change at that location. The multivariate maximum Lyapunov exponent(MMLE) is extracted from the 16-dimension time-series to demonstrate the change of flow pattern versus the superficial velocity ratio of oil to water. The correlation dimension of the multivariate time-series is further introduced to jointly characterize and finally separate the flow patterns with MMLE. The change of flow patterns with superficial oil velocity at different water superficial velocities is studied with MMLE and correlation dimension, respectively, and the flow pattern transition can also be characterized with these two features. The proposed MMLE and correlation dimension map could effectively separate the flow patterns, thus is an effective tool for flow pattern identification and transition analysis.
基金The project supported by the Canadian Space Agency (CSA) and the visiting scholar program of the Chinese Academy of Sciences (CAS)
文摘Bends are widely used in pipelines carrying single-and two-phase fluids in both ground and space applications.In particular,they play more important role in space applications due to the extreme spatial constraints.In the present study,a set of experimental data of two-phase flow patterns and their transitions in a 90°bend with inner diameter of 12.7 mm and curvature radius of 76.5 mm at microgravity conditions are reported.Gas and liquid superficial velocities are found to range from (1.0～23.6)m/s for gas and(0.09～0.5)m/s for liquid,respectively.Three major flow patterns, namely slug,slug-annular transitional,and annular flows,are observed in this study.Focusing on the differences between flow patterns in bends and their counterparts in straight pipes,detailed analyses of their characteristics are made.The transitions between adjoining flow patterns are found to be more or less the same as those in straight pipes,and can be predicted using Weber number models satisfactorily. The reasons for such agreement are carefully examined.
基金the National Natural Science Foundation of China (No. 59236130).
文摘In this companion paper, flow patterns in the upstream and downstream tubes of a sudden-expansion cross-section (SECS) in a vertical straight pipe were presented. The effect of SECS on flow patterns upstream and downstream was analyzed by comparing with flow patterns in uniform cross-section vertical tubes. It is found the effect is great. There exist great instabilities of two-phase flow in the neighboring areas of the SECS both downstream and upstream.
基金the National Natural Science Foundation of China (21776180, 22108177)the open project of the Key Laboratory of Fine Chemical Application Technology of Luzhou (HYJH-2102-A)。
文摘In this work, flow pattern and mass transfer of liquid-liquid two-phase flow in a wire-embedded concentric microchannel are studied using toluene-water system. Droplet flow, slug flow, oval flow and annular flow are observed in the wire-embedded concentric microchannel. The effects of embedded wires and physical properties on flow patterns are investigated. The embedded wire insert is conducive to the formation of annular flow. The flow pattern distribution regions are distinguished by the Caaq(capillary number)±We_(org)(Weber number) flow pattern map. When Weorg<0.001, slug flow is the main flow pattern, and when Weorg>0.1, annular flow is the main flow pattern. Oval flow and droplet flow are between We_(org)= 0.001-0.1, and oval flow is transformed into droplet flow with the increase of Caaq. The effect of flow rate, phase ratio, initial acetic acid concentration, insert shape and flow patterns on mass transfers are studied. Mass transfer process is enhanced under annular flow conditions, the volumetric mass transfer coefficient is up to 0.36 s^(-1) because of the high interfacial area and interface renewal rate of annular flow.
基金the National Natrual Science Foundation of China (No. 59236130).
文摘Flow patterns upstream and downstream of a sudden-contraction cross-section in a vertical straight pipe were presented. By comparing with flow patterns in uniform cross-section vertical tubes, the effect of the sudden change in pipe diameter on flow patterns was analyzed. Flow pattern transition mechanisms were discussed and transition criteria for flow pattern transitions were deduced accordingly using the dimensional analysis.
基金sponsored by the National Natural Science Foundation of China(Nos.52174002&52204008)the Heilongjiang Provincial Natural Science Foundation of China(No.LH2022E020).
文摘During horizontal well drilling,the interaction between drilling fluid and cuttings entering the annulus generates diverse flow patterns.These solid-liquid two-phase flow patterns must be accurately predicted to optimize the determination of hydraulic parameters and improve the efficiency of cuttings transport.Accordingly,this study identified flow patterns and conducted transition experiments under different inclination angles using a visualized wellbore annulus apparatus(120 mm outer diameter/73 mm inner diameter).Through direct visual observations,four primary flow patterns were systematically classified on the basis of the solid-liquid two-phase flow behaviors identified in the experiments:stable bed(SB),sand wave(SW),sand dune(SD),and bed load(BL)flows.The experimental data were then used to construct flow pattern maps with solid/liquid phases as axes,after which the transition boundaries between different flow patterns were established.The morphological characteristics and transition mechanisms of SB,SW,SD,and BL flows were systematically analyzed to develop three predictive models of the fluid dynamics principles governing these flow patterns’transitions:(1)A transition boundary model of SB and SW flows was established using Kelvin-Helmholtz stability,for which a stability analysis of solid-liquid two-phase flow in deviated and horizontal annuli was carried out.(2)A transition boundary model of SW and SD flows was constructed through an analysis of the geometric features of sand waves in the annuli,with the critical ratio of the average height of a cuttings bed to its height after erosion being 0.45.(3)A traditional critical velocity model was refined by adjusting the von Karman constant to account for the effect of solid volume concentration,yielding a boundary model for the transition of SW or SD flow into BL flow.All the models were experimentally validated.Finally,we integrated the models to develop a unified method for identifying and classifying the patterns typifying solid-liquid two-phase flow in deviated and horizontal annuli.
基金Project(51574045)supported by the National Nature Science Foundation of China
文摘The gas-liquid two-phase swirl flow can increase the gas-liquid two-phase contact area and enhance the heat and mass transfer efficiency between gas and liquid.The swirl flow has important practical application value for promoting gas hydrate formation and ensuring the flow safe of natural gas hydrate slurry.The experimental section was made of plexiglass pipe and the experimental medium was air and water.The flow pattern of the gas-liquid two-phase swirl flow in the horizontal pipe was divided,according to a high-definition camera and the overall characteristics of the gas-liquid interface.The flow pattern map of the gas-liquid two-phase swirl flow in a horizontal pipe was studied.The influence of the flow velocity and vane parameters on pressure drop was investigated.Two types of gas-liquid two-phase swirl flow pressure drop models was established.The homogeneous-phase and split-phase pressure drop models have good prediction on swirl bubble flow,swirl dispersed flow,swirl annular flow and swirl stratified flow,and the predictive error band is not more than 20%.
文摘The amount of waste heat in a space facility became larger, because of increase in the space platform size and its power consumption. It requires development of high-performance space thermal management systems handling a large amount of waste. Boiling two-phase flow could become powerful means for this system because a boiling and condensation system is one of the most efficient modes of heat transfer due to phase change （liquid-vapor）. However, gravity effects on boiling two-phase flow phenomena and the corresponding heat transfer characteristics are not clear. Therefore, we prepare the experiments of boiling two-phase flow utilizing a long-term microgravity environment onboard a Japanese Experimental Module ＂KIBO＂ in the International Space Station （ISS） as one of the JAXA official projects. In this paper, recent progress of the preparation for the project is reported.
基金National Natural Science Foundation of China (No.59995462 and 10172069)
文摘The flow patterns and their transitions of oil-water two-phase flow in horizontal pipes were studied. The experiments were conducted in two kinds of horizontal tubes, made of plexiglas pipe and stainless steel pipe with 40 mm ID respectively. No. 46 mechanical oil and tap water were used as working fluids. The superflcial velocity ranges of oil and water were: 0.04-1.2m·s-1 and 0.04-2.2m·s-1, respectively. The flow patterns were identified by visualization and by transient fluctuation signals of differential pressure drop. The flow patterns were defined according to the relative distribution of oil and water phases in the pipes. Flow pattern maps were obtained for both pipelines. In addition, semi-theoretical transition criteria for the flow patterns were proposed, and the proposed transitional criteria are in reasonable agreement with available data in liquid-liquid systems.
基金Supported by the National Natural Science Foundation of China(50974095,41174109,61104148)the National Science and Technology Major Projects(2011ZX05020-006)
文摘This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil–water two-phase flow. The finite element method is used to calculate the sensitivity field of the sensor in a pipe with 20 mm inner diameter and the effect of sensor geometry on the distribution of sensitivity field is presented. Then, a horizontal oil–water two-phase flow experiment is carried out to measure the response of the double helix capacitance sensor, in which a novel method is proposed to calibrate the liquid holdup based on three pairs of parallel-wire capacitance probes. The performance of the sensor is analyzed in terms of the flow structures detected by mini-conductance array probes.
基金Supported by the National Natural Science Foundation of China(51406031)
文摘A new method of nonlinear analysis is established by combining phase space reconstruction and data reduction sub-frequency band wavelet. This method is applied to two types of chaotic dynamic systems(Lorenz and Rssler) to examine the anti-noise ability for complex systems. Results show that the nonlinear dynamic system analysis method resists noise and reveals the internal dynamics of a weak signal from noise pollution. On this basis, the vertical upward gas–liquid two-phase flow in a 2 mm × 0.81 mm small rectangular channel is investigated. The frequency and energy distributions of the main oscillation mode are revealed by analyzing the time–frequency spectra of the pressure signals of different flow patterns. The positive power spectral density of singular-value frequency entropy and the damping ratio are extracted to characterize the evolution of flow patterns and achieve accurate recognition of different vertical upward gas–liquid flow patterns(bubbly flow:100%, slug flow: 92%, churn flow: 96%, annular flow: 100%). The proposed analysis method will enrich the dynamics theory of multi-phase flow in small channel.
基金supported by the National Natural Science Foundation of China Joint Fund Project (Grant/Award Number: U20B6003)National Natural Science Foundation of China (Grant/Award Number: 52304054)。
文摘Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typically governed by gravity, viscous and capillary forces, these factors lead invasive fluids to occupy pore space irregularly and incompletely. Previous studies have demonstrated capillary numbers,describing the viscous and capillary forces, to quantificationally induce evolution of invasion patterns.While the evolution mechanisms of invasive patterns have not been deeply elucidated under the constant capillary number and three variable parameters including velocity, viscosity, and interfacial tension.Our research employs two horizontal visualization systems and a two-phase laminar flow simulation to investigate the tendency of invasive pattern transition by various parameters at the pore scale. We showed that increasing invasive viscosity or reducing interfacial tension in a homogeneous pore space significantly enhanced sweep efficiency, under constant capillary number. Additionally, in the fingering crossover pattern, the region near the inlet was prone to capillary fingering with multi-directional invasion, while the viscous fingering with unidirectional invasion was more susceptible occurred in the region near the outlet. Furthermore, increasing invasive viscosity or decreasing invasive velocity and interfacial tension promoted the extension of viscous fingering from the outlet to the inlet, presenting that the subsequent invasive fluid flows toward the outlet. In the case of invasive trunk along a unidirectional path, the invasive flow increased exponentially closer to the outlet, resulting in a significant decrease in the width of the invasive interface. Our work holds promising applications for optimizing invasive patterns in heterogeneous porous media.
基金Project supported by the National Natural Science Foundation of China ( Grant Nos. 61104148, 41174109, and 50974095)the National Science and Technology Major Project of the Ministry of Science and Technology of China (Grant No. 2011ZX05020-006)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20110032120088)
文摘We generate a directed weighted complex network by a method based on Markov transition probability to represent an experimental two-phase flow. We first systematically carry out gas-liquid two-phase flow experiments for measuring the time series of flow signals. Then we construct directed weighted complex networks from various time series in terms of a network generation method based on Markov transition probability. We find that the generated network inherits the main features of the time series in the network structure. In particular, the networks from time series with different dynamics exhibit distinct topological properties. Finally, we construct two-phase flow directed weighted networks from experimental signals and associate the dynamic behavior of gas-liquid two-phase flow with the topological statistics of the generated networks. The results suggest that the topological statistics of two-phase flow networks allow quantitative characterization of the dynamic flow behavior in the transitions among different gas-liquid flow patterns.
基金Sponsored by the National Natural Science Foundation of China (Grant No.51006123)the Fundamental Research Funds for the Central Universities (Grant No.14CX05028A)
文摘In order to eliminate mal-distribution and ensure the side arm to produce desirable gas quality a special distributor is proposed. The experimental distributor mainly consists of a straight through section,a gas extraction line,a liquid extraction line and a side arm branch. A gas orifice and a liquid orifice are mounted at the gas and liquid extraction line respectively to control the outlet gas quality. The diameter of the liquid orifice was set to 2. 50 mm and three gas orifices with different size( dG= 2. 65,5. 00,10. 00 mm) were tested. The experiments were carried out at an air-water two-phase flow loop. The gas superficial velocity ranged from 6. 0 to 20. 0 m /s and the liquid superficial velocity was in the range of 0. 02- 0. 18 m /s. Flow patterns such as wave flow,slug flow and annular flow were observed. The gas quality of the side arm branch was found mainly determined by the flow area ratio of the gas orifice to the liquid orifice and independent of gas and liquid superficial velocity,flow patterns and extraction flux.
文摘Two-phase flow distributions in the merged pipe distributor have still remained mal-uniformity problem and the causes have not clearly discovered yet. Therefore, the enhancement study is needed, absolutely. The experimental was carried out upon the distributor constructed by acrylics resembling merged triple pipe, 8 mm in diameter of inlet channel and two set 5 mm in diameter of each outlet channel, set horizontally sideways. Three flow patterns were fed, i.e., bubble, slug and stratified flow, observed via high speed video camera. The pressure distribution was measured by series of U-tube water gauge manometer. The flow patterns, phase distribution and pressure drop were analyzed by CFD software, validated by experimental data and compared by existing correlation, analytically. The experiment is extended by modeling, in order to vary three inclinations of distributor： horizontally, 45° and vertically up-ward as well as to vary three outlet channel lengths with length ratio lc/dc： 3.2, 10 and 70. It was revealed that the two-phase flow distribution tends to be mal-uniform and to transform to different flow pattern in outlet channels. These are promoted by different： outlet channel length, feeding two-phase flow pattern in inlet distributor and inclination angle. The changing of flow pattern is driven by fluctuating velocity in both upper and lower outlet channel.
文摘The upward multiphase cross flow and heat transfer in the vertical tube may occur in oil production and chemical facilities. In this study, the local flow patterns of an upward gas-water two phase cross flow in a vertical tube with a horizontal rod have been investigated with an optical probe and the digital high speed video system. The local flow patterns are defined as the bubble, slug, churn and annular flow patterns. Optical probe signals are ana- lyzed in terms of probability density function, and it is proved that the local flow patterns can be recognized by this method. The transition mechanisms between the different flow patterns have been analyzed and the corresponding transitional models are proposed. Finally, local flow pattern maps of the upward gas-water two-phase flow in the vertical tube with a horizontal rod are constructed.
基金Project(51576213)supported by the National Natural Science Foundation of ChinaProject(2015RS4015)supported by the Hunan Scientific Program,ChinaProject(2016zzts323)supported by the Innovation Project of Central South University,China
文摘Gas–liquid two-phase flow abounds in industrial processes and facilities. Identification of its flow pattern plays an essential role in the field of multiphase flow measurement. A bluff body was introduced in this study to recognize gas–liquid flow patterns by inducing fluid oscillation that enlarged differences between each flow pattern. Experiments with air–water mixtures were carried out in horizontal pipelines at ambient temperature and atmospheric pressure. Differential pressure signals from the bluff-body wake were obtained in bubble, bubble/plug transitional, plug, slug, and annular flows. Utilizing the adaptive ensemble empirical mode decomposition method and the Hilbert transform, the time–frequency entropy S of the differential pressure signals was obtained. By combining S and other flow parameters, such as the volumetric void fraction β, the dryness x, the ratio of density φ and the modified fluid coefficient ψ, a new flow pattern map was constructed which adopted S（1–x）φ and （1–β）ψ as the vertical and horizontal coordinates, respectively. The overall rate of classification of the map was verified to be 92.9% by the experimental data. It provides an effective and simple solution to the gas–liquid flow pattern identification problems.
基金supported by Key foundational research project of Science and Technology Bureau of Shanghai (Grant No. 04JC14049).
文摘Flow patterns of liquid-gas two-phase flow were experimentally investigated. The experiments were carried out in both vertical and horizontal capillary tubes having inner diameters of 1,60 mm, The working liquid was the mixture of water and Sodium Dodecyl Benzoyl Sulfate （SDBS）. The working gas was Nitrogen. For the water/SDBS mixture-gas flow in the vertical capillary tube, flow-pattern transitions occurred at lower flow velocities than those for the water-gas flow in the same tube. For the water/SDBS mixture-gas flow in the horizontal capillary tube, surface tension had little effect on the bubbly-intermittent transition and had only slight effect on the plug-slug and slug-annular transitions. However, surface tension had significant effect on the wavy stratified flow regime. The wavy stratified flow regime of water/SDBS mixture-gas flow expanded compared with that of water-gas.
基金supported by National Natural Science Foundation of China (52006242)National Natural Science Foundation of China (52192623)+1 种基金Science Foundation of China University of Petroleum,Beijing (ZX20200126)Science and technology program for strategic cooperation of CNPC–China University of Petroleum (ZLZX2020-05)。
文摘The heat transfer of hydrocarbon refrigerant across tube bundles have been widely used in refrigeration.Three-dimensional simulation model using volume of fluid(VOF) was presented to study the effects of tube shapes on flow pattern, film thickness and heat transfer of n-pentane across tube bundles, including circle, ellipse-shaped, egg-shaped and cam-shaped tube bundles. Simulation results agree well with experimental data in the literature. The liquid film thickness of sheet flow and heat transfer for different tube shapes were obtained numerically. The flow pattern transition occurs lower vapor quality for ellipse-shaped tube than other tube shapes. For sheet flow, the liquid film on circle tube and ellipseshaped tube is symmetrically distributed along the circumferential direction. However, the liquid film on egg-shaped tube at circumferential angles(θ) = 15°–60° is thicker than θ = 135°–165°. The liquid film on cam tube at θ = 15°–60° is slightly thinner than θ = 135°–165°. The liquid film thickness varies from thinner to thicker for ellipse-shaped, cam-shaped, egg-shape and circle within θ = 15°–60°. The effect of tube shape is insignificant on thin liquid film thickness. Ellipse-shaped tube has largest heat transfer coefficient for sheet flow. In practical engineering, the tube shape could be designed as ellipse to promote heat transfer.
基金Supported by the Special Funds for Major State Basic Research Program of China (973 Program, No.1999022308).
文摘The upward multiphase cross flow and heat transfer in the vertical tube may occur in oil production and chemical facilities. In this study, the local flow patterns of an upward gas-water two phase cross flow in a vertical tube with a horizontal rod have been investigated with an optical probe and the digital high speed video system. The local flow patterns are defined as the bubble, slug, churn and annular flow patterns. Optical probe signals are ana- lyzed in terms of probability density function, and it is proved that the local flow patterns can be recognized by this method. The transition mechanisms between the different flow patterns have been analyzed and the corresponding transitional models are proposed. Finally, local flow pattern maps of the upward gas-water two-phase flow in the vertical tube with a horizontal rod are constructed.
