During the exploitation of offshore oil and gas,it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system.The flow pattern and pressure ...During the exploitation of offshore oil and gas,it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system.The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m.It is found that severe slugging can be divided into three severe slugging regimes：regime I at low gas and liquid flow rates with large pressure fluctuation,intermittent flow of liquid and gas in the riser,and apparent cutoff of liquid phase,regime II at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff,regime III at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow.The results indicate that severe slugging still occurs when the declination angle of pipeline is 0,and there are mainly two kinds of regimes：regime I and regime II.As the angle increases,the formation ranges of regime I and regime III increase slightly while that of regime II is not affected.With the increase of gas superficial velocity and liquid superficial velocity,the pressure fluctuation at the bottom of riser increases initially and then decreases.The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and II.展开更多
Due to the special structure of offshore multiphase pipes, it is easy for severe slugging to occur in the riser at low gas-liquid velocity. Violent pressure fluctuations and dramatic changes of flow rate are the main ...Due to the special structure of offshore multiphase pipes, it is easy for severe slugging to occur in the riser at low gas-liquid velocity. Violent pressure fluctuations and dramatic changes of flow rate are the main characteristics of severe slugging, leading to the risk of serious damage. In this paper, the separator control is adopted to accurately control the separator liquid level and pressure under severe slugging flow conditions. This indicates that the separator liquid level control alone does not have a significant impact on the upstream flow, but it is beneficial for normal operation and pressure control of the separator. As the separator pressure increases, the peak pressure in the riser apparently diminishes, and the amplitude of pressure fluctuation gradually decreases, which means that severe slugging is inhibited. During the slug blowing out, the gas/liquid slipping in the riser intensifies. The long gas plug quickly flows through the riser, and then tends to morph into short and slowly flowing gas bubbles. The elimination effect of the pressure control strategy on severe slugging is related to the relative rate of the superficial gas/liquid flow.展开更多
Severe slugging can occur in a pipeline-riser system at relatively low liquid and gas flow rates during gas-oil transportation, possibly causing unexpected damage to the production facilities. Experiments with air and...Severe slugging can occur in a pipeline-riser system at relatively low liquid and gas flow rates during gas-oil transportation, possibly causing unexpected damage to the production facilities. Experiments with air and water are conducted in a horizontal and downward inclined pipeline followed by a catenary riser in order to investigate the mechanism and characteristics of severe slugging. A theoretical model is introduced to compare with the experiments. The results show that the formation mechanism of severe slugging in a catenary riser is different from that in a vertical riser due to the riser geometry and five flow patterns are obtained and analyzed. A gas-liquid mixture slug stage is observed at the beginning of one cycle of severe slugging, which is seldom noticed in previous studies. Based on both experiments and computations, the time period and variation of pressure amplitude of severe slugging are found closely related to the superficial gas velocity, implying that the gas velocity significantly influences the flow patterns in our experiments. Moreover, good agreements between the experimental data and the numerical results are shown in the stability curve and flow regime map, which can be a possible reference for design in an offshore oil-production system.展开更多
A mathematical model is presented to study the main characteristics of severe slugging in a downward inclined pipeline followed by a catenary riser. In this model, both simplified transient model and phase distributio...A mathematical model is presented to study the main characteristics of severe slugging in a downward inclined pipeline followed by a catenary riser. In this model, both simplified transient model and phase distribution model are included so that the flow characteristics of each stage for severe slugging can be accurately reproduced, especially for blowout stage. The results show that the flow features of severe slugging can be simulated by the proposed mathematical model. A good agreement between the experimental data and the numerical results is observed. The model can predict the transient fluctuation of many respects, such as the superficial gas velocity at the bottom of the riser and the average velocity at the outlet of the riser.展开更多
Accurate prediction of the frictional pressure drop is important for the design and operation of subsea oil and gas transporting system considering the length of the pipeline. The applicability of the correlations to ...Accurate prediction of the frictional pressure drop is important for the design and operation of subsea oil and gas transporting system considering the length of the pipeline. The applicability of the correlations to pipeline-riser flow needs evaluation since the flow condition in pipeline-riser is quite different from the original data where they were derived from. In the present study, a comprehensive evaluation of 24prevailing correlation in predicting frictional pressure drop is carried out based on experimentally measured data of air-water and air-oil two-phase flows in pipeline-riser. Experiments are performed in a system having different configuration of pipeline-riser with the inclination of the downcomer varied from-2°to-5°to investigated the effect of the elbow on the frictional pressure drop in the riser. The inlet gas velocity ranges from 0.03 to 6.2 m/s, and liquid velocity varies from 0.02 to 1.3 m/s. A total of885 experimental data points including 782 on air-water flows and 103 on air-oil flows are obtained and used to access the prediction ability of the correlations. Comparison of the predicted results with the measured data indicate that a majority of the investigated correlations under-predict the pressure drop on severe slugging. The result of this study highlights the requirement of new method considering the effect of pipe layout on the frictional pressure drop.展开更多
目的观察β-catenin/Slug信号特异性抑制剂FH535与EMT的关系,探讨LPCAT1在调节子宫颈癌细胞侵袭、转移和生长中的作用。方法采用sh-NC和sh-LPCAT1转染Hela细胞,利用载体(Vector)组和LPCAT1过表达质粒转染SiHa细胞,将SiHa细胞分为对照组(...目的观察β-catenin/Slug信号特异性抑制剂FH535与EMT的关系,探讨LPCAT1在调节子宫颈癌细胞侵袭、转移和生长中的作用。方法采用sh-NC和sh-LPCAT1转染Hela细胞,利用载体(Vector)组和LPCAT1过表达质粒转染SiHa细胞,将SiHa细胞分为对照组(Con)、LPCAT1组、LPCAT1+FH535组和FH535组。运用CCK-8法和集落形成试验检测子宫颈癌细胞的增殖。通过伤口愈合试验和Transwell实验检测子宫颈癌细胞的转移、侵袭能力。应用Western blot分析细胞中LPCAT1、β-catenin/Slug信号通路和EMT相关蛋白的表达。结果与Vector组相比,LPCAT1组SiHa细胞的活力、集落数、迁移和侵袭细胞数均显著增加(P<0.05);与sh-NC组相比,sh-LPCAT1组Hela细胞的活力、集落数、迁移和侵袭细胞数均显著降低(P<0.05)。与LPCAT1组相比,LPCAT1+FH535组SiHa细胞中Wnt4(1.18±0.05 vs 0.80±0.06)、β-catenin(1.05±0.08 vs 0.77±0.05)、Slug(1.13±0.06 vs 0.28±0.02)、Cyclin D1(0.99±0.06 vs 0.44±0.02)、N-cadherin(0.91±0.07 vs 0.46±0.03)和vimentin(0.95±0.06 vs 0.49±0.03)表达降低(P<0.05),E-cadherin(0.44±0.03 vs 0.58±0.03)表达增加(P<0.05)。此外,与LPCAT1组相比,LPCAT1+FH535组SiHa细胞的集落数(224±15 vs 146±11)、迁移数(85±3 vs 51±4)和侵袭数(166±10 vs 90±5)均降低(P<0.05)。结论LPCAT1表达增加可能通过激活β-catenin/Slug信号通路促进子宫颈癌的转移和进展,LPCAT1的靶向治疗有望提高子宫颈癌患者的预后。展开更多
The supercritical-water fluidized bed(SCWFB)is a reactor for coal and biomass gasification without pollutant emission.We carried out a series of experiments in a SCWFB,and a dual-capacitance probe measurement system w...The supercritical-water fluidized bed(SCWFB)is a reactor for coal and biomass gasification without pollutant emission.We carried out a series of experiments in a SCWFB,and a dual-capacitance probe measurement system was applied to measure the hydrodynamics of slugs,such as the slug frequency,chord length,and rising velocity.Four groups of Geldart-B particles with different mean diameters were fluidized by supercritical water with a system pressure of 20-27MPa and at 410-570℃.The minimum slugging Reynolds number increases logarithmically with Archimedes number and a predicting correlation of the minimum slugging fluidization velocity in the SCWFB is presented:Rems=32908.84 ln(Ar^0.55+260376.65)-410361.90.The relative error of the above correlation was within ±15% and the averaged relative error was 7.5%.The effect of operating conditions on the minimum slugging fluidization velocity is discussed.This research provides useful guidance for scaling-up design and for determining the optimum range of operating conditions in the SCWFB.展开更多
In 2023, the world economy was generally sluggish, and recovery remained weak. Under the pretext of “derisking,” the United States(US)-led West has generalized economic security and engaged in punitive, exclusive, a...In 2023, the world economy was generally sluggish, and recovery remained weak. Under the pretext of “derisking,” the United States(US)-led West has generalized economic security and engaged in punitive, exclusive, and collectivized economic protectionism. Developing countries are struggling.展开更多
Slugging represents one of the major regimes in fluidization,which occurs in small diameter beds with large bed height-to-diameter ratio or in large diameter beds with internals that resemble multiple small diameter f...Slugging represents one of the major regimes in fluidization,which occurs in small diameter beds with large bed height-to-diameter ratio or in large diameter beds with internals that resemble multiple small diameter fluidized beds.Slug types include round-nosed slug,wall slug and square nosed slug.Studies of the slugs have been mainly focused on round-nosed or wall slugs known as half slug.typically occurring in Geldart group A particle fuidization.The square-nosed slug typically occurring for Geldart group D particles appears to be regarded as simple in its structure.The Electrical Capacitance Volume Tomogra phy(ECVT)imaging of the square-nosed slugging phenomena conducted in this study reveals otherwise.That is the structure of the square nosed slug is,in fact,complex,particularly with respect to its dynamic variation in fluidization.More broadly.this study examines experimentally the hydrodynamic character-istics of the square-nosed fluidization regime.Specifically,simultaneous measurements from multiple ECVT sensors provide non-inv asive,continuous,3.dimensional imaging of the entire flow region of the slugging bed and hence enabling the dynamic characterization of the evolution of the slugs.The analysis of the 3D images reconstructed for real time gas-solid volume fraction profile of the slugging fluidized bed indicates that there are three different zones.namely.the bottom fluidization zone,the gas slug zone,and the solid slug zone,co-existing in the bed.The three zones present different hydrodynamic characteristics during the slug evolution.It is found that varying the gas velocity of the slugging bed mainly varies the maximum length of the gas slug zone,while it only has a minor effect on the lengths of the bottom fluidization zone and solid slug zone.It also has an insignificant efect on the solid volume fraction of the three zones.展开更多
The hydrodynamic study of the liquid film around Taylor bubbles in slug flow has great significance for understanding parallel flow and interaction between Taylor bubbles.The prediction models for liquid film thicknes...The hydrodynamic study of the liquid film around Taylor bubbles in slug flow has great significance for understanding parallel flow and interaction between Taylor bubbles.The prediction models for liquid film thickness mainly focus on stagnant flow,and some of them remain inaccurate performance.However,in the industrial process,the slug flow essentially is co-current flow.Therefore,in this paper,the liquid film thickness is studied by theoretical analysis and experimental methods under two conditions of stagnant and co-current flow.Firstly,under the condition of stagnant flow,the present work is based on Batchelor's theory,and modifies Batchelor's liquid film thickness model,which effectively improves its prediction accuracy.Under the condition of co-current flow,the prediction model of average liquid film thickness in slug flow is established by force and motion analysis.Taylor bubble length is introduced into the model as an important parameter.Dynamic experiments were carried out in the pipe with an inner diameter of 20 mm.The liquid film thickness,Taylor bubble velocity and length were measured by distributed ultrasonic sensor and intrusive cross-correlation conductivity sensor.Comparing the predicted value of the model with the measured results,the relative error is controlled within 10%.展开更多
Large vertical pipes are key structures connecting subsea wells to offshore platforms.However,existing studies mainly focus on small vertical pipes.In a vertical acrylic pipe with 80 mm inner diameter and 11 m height,...Large vertical pipes are key structures connecting subsea wells to offshore platforms.However,existing studies mainly focus on small vertical pipes.In a vertical acrylic pipe with 80 mm inner diameter and 11 m height,a high-speed camera was used to visually research the influences of pipe diameters,liquid properties and inlet effect on air-water co-flow characteristic.Different flow regime maps of vertical pipes(diameters are in the range of 50e189 mm)were compared and the critical gas velocity of the transition boundary from bubble to slug flow tended to increase with the increase of diameters at D≥80 mm.Drift-flux models were established in different flow regimes and liquid properties have a significant effect on drift coefficients of bubble flow and slug flow(void fraction a≤0.4).The influence of inlet turbulent effect on the gas-liquid interface distribution gradually weakened and disappeared from the pipe base to 85D,where the flow was fully developed.Slug frequency has a trend of increase first and then decrease with the gas Weber numbers increasing at low liquid superficial velocities(J_(L)≤0.31 m/s).And on the basis of this law,a new slug frequency correlation was proposed.It was found that there was an exponential relationship between the ratio of lengths of Taylor bubble to slug and the void fraction.展开更多
Gastropods,a mollusk class including slugs and snails,represent an extraordinarily diverse and ecologically significant group of organisms featuring the largest class of invertebrates.They can be classified as aquatic...Gastropods,a mollusk class including slugs and snails,represent an extraordinarily diverse and ecologically significant group of organisms featuring the largest class of invertebrates.They can be classified as aquatic and terrestrial animals having coiled shells,although some species have reduced or absent shells.Their unique body structure includes a muscular foot for locomotion,a visceral mass containing essential organs,and a distinct head region with sensory organs such as tentacles and eyes.They are used to secrete a complex mixture of glycoproteins,enzymes,peptides,mucus and other bioactive compounds,namely slime,which represents a tool to allow locomotion,protection,and interaction within different habitats.The biological activities of the slime have attracted considerable interest due to their diverse and potentially valuable properties ranging from defense mechanisms to potential therapeutic applications in wound healing,antimicrobial therapy,management of inflammation,and neurological disorders.This review aims at exploring the beneficial effects of snail and slug slime focusing,in particular,on the improvement of the biological processes underlying them.Continued exploration of the intricate components of these slimy secretions promises to discover new bioactive molecules with diverse applications in various scientific and industrial fields.展开更多
基金Supported by the National High Technology Research and Development Program of China(2006AA09Z302)
文摘During the exploitation of offshore oil and gas,it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system.The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m.It is found that severe slugging can be divided into three severe slugging regimes：regime I at low gas and liquid flow rates with large pressure fluctuation,intermittent flow of liquid and gas in the riser,and apparent cutoff of liquid phase,regime II at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff,regime III at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow.The results indicate that severe slugging still occurs when the declination angle of pipeline is 0,and there are mainly two kinds of regimes：regime I and regime II.As the angle increases,the formation ranges of regime I and regime III increase slightly while that of regime II is not affected.With the increase of gas superficial velocity and liquid superficial velocity,the pressure fluctuation at the bottom of riser increases initially and then decreases.The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and II.
文摘Due to the special structure of offshore multiphase pipes, it is easy for severe slugging to occur in the riser at low gas-liquid velocity. Violent pressure fluctuations and dramatic changes of flow rate are the main characteristics of severe slugging, leading to the risk of serious damage. In this paper, the separator control is adopted to accurately control the separator liquid level and pressure under severe slugging flow conditions. This indicates that the separator liquid level control alone does not have a significant impact on the upstream flow, but it is beneficial for normal operation and pressure control of the separator. As the separator pressure increases, the peak pressure in the riser apparently diminishes, and the amplitude of pressure fluctuation gradually decreases, which means that severe slugging is inhibited. During the slug blowing out, the gas/liquid slipping in the riser intensifies. The long gas plug quickly flows through the riser, and then tends to morph into short and slowly flowing gas bubbles. The elimination effect of the pressure control strategy on severe slugging is related to the relative rate of the superficial gas/liquid flow.
基金financially supported by the National Natural Science Foundation of China(Grant No.11272211)the National Program on Key Basic Research Project of China(973 Program,Grant No.2015CB251203)
文摘Severe slugging can occur in a pipeline-riser system at relatively low liquid and gas flow rates during gas-oil transportation, possibly causing unexpected damage to the production facilities. Experiments with air and water are conducted in a horizontal and downward inclined pipeline followed by a catenary riser in order to investigate the mechanism and characteristics of severe slugging. A theoretical model is introduced to compare with the experiments. The results show that the formation mechanism of severe slugging in a catenary riser is different from that in a vertical riser due to the riser geometry and five flow patterns are obtained and analyzed. A gas-liquid mixture slug stage is observed at the beginning of one cycle of severe slugging, which is seldom noticed in previous studies. Based on both experiments and computations, the time period and variation of pressure amplitude of severe slugging are found closely related to the superficial gas velocity, implying that the gas velocity significantly influences the flow patterns in our experiments. Moreover, good agreements between the experimental data and the numerical results are shown in the stability curve and flow regime map, which can be a possible reference for design in an offshore oil-production system.
基金financially supported by the National Natural Science Foundation of China(Grant No.51979257)the Key Research and Development Program of Shandong Province(Grant No.2018GHY115045)
文摘A mathematical model is presented to study the main characteristics of severe slugging in a downward inclined pipeline followed by a catenary riser. In this model, both simplified transient model and phase distribution model are included so that the flow characteristics of each stage for severe slugging can be accurately reproduced, especially for blowout stage. The results show that the flow features of severe slugging can be simulated by the proposed mathematical model. A good agreement between the experimental data and the numerical results is observed. The model can predict the transient fluctuation of many respects, such as the superficial gas velocity at the bottom of the riser and the average velocity at the outlet of the riser.
基金the support of the Opening Fund of State Key Laboratory of Multiphase Flow in Power Engineering(SKLMF-KF-2102)。
文摘Accurate prediction of the frictional pressure drop is important for the design and operation of subsea oil and gas transporting system considering the length of the pipeline. The applicability of the correlations to pipeline-riser flow needs evaluation since the flow condition in pipeline-riser is quite different from the original data where they were derived from. In the present study, a comprehensive evaluation of 24prevailing correlation in predicting frictional pressure drop is carried out based on experimentally measured data of air-water and air-oil two-phase flows in pipeline-riser. Experiments are performed in a system having different configuration of pipeline-riser with the inclination of the downcomer varied from-2°to-5°to investigated the effect of the elbow on the frictional pressure drop in the riser. The inlet gas velocity ranges from 0.03 to 6.2 m/s, and liquid velocity varies from 0.02 to 1.3 m/s. A total of885 experimental data points including 782 on air-water flows and 103 on air-oil flows are obtained and used to access the prediction ability of the correlations. Comparison of the predicted results with the measured data indicate that a majority of the investigated correlations under-predict the pressure drop on severe slugging. The result of this study highlights the requirement of new method considering the effect of pipe layout on the frictional pressure drop.
文摘目的观察β-catenin/Slug信号特异性抑制剂FH535与EMT的关系,探讨LPCAT1在调节子宫颈癌细胞侵袭、转移和生长中的作用。方法采用sh-NC和sh-LPCAT1转染Hela细胞,利用载体(Vector)组和LPCAT1过表达质粒转染SiHa细胞,将SiHa细胞分为对照组(Con)、LPCAT1组、LPCAT1+FH535组和FH535组。运用CCK-8法和集落形成试验检测子宫颈癌细胞的增殖。通过伤口愈合试验和Transwell实验检测子宫颈癌细胞的转移、侵袭能力。应用Western blot分析细胞中LPCAT1、β-catenin/Slug信号通路和EMT相关蛋白的表达。结果与Vector组相比,LPCAT1组SiHa细胞的活力、集落数、迁移和侵袭细胞数均显著增加(P<0.05);与sh-NC组相比,sh-LPCAT1组Hela细胞的活力、集落数、迁移和侵袭细胞数均显著降低(P<0.05)。与LPCAT1组相比,LPCAT1+FH535组SiHa细胞中Wnt4(1.18±0.05 vs 0.80±0.06)、β-catenin(1.05±0.08 vs 0.77±0.05)、Slug(1.13±0.06 vs 0.28±0.02)、Cyclin D1(0.99±0.06 vs 0.44±0.02)、N-cadherin(0.91±0.07 vs 0.46±0.03)和vimentin(0.95±0.06 vs 0.49±0.03)表达降低(P<0.05),E-cadherin(0.44±0.03 vs 0.58±0.03)表达增加(P<0.05)。此外,与LPCAT1组相比,LPCAT1+FH535组SiHa细胞的集落数(224±15 vs 146±11)、迁移数(85±3 vs 51±4)和侵袭数(166±10 vs 90±5)均降低(P<0.05)。结论LPCAT1表达增加可能通过激活β-catenin/Slug信号通路促进子宫颈癌的转移和进展,LPCAT1的靶向治疗有望提高子宫颈癌患者的预后。
基金supported financially by the China National Funds for Distinguished Young Scientists(No.51925602)National Natural Science Foundation of China(No.91634109 and No.51676158)the National Key Research and Development Program of China(2016YFB0600102).
文摘The supercritical-water fluidized bed(SCWFB)is a reactor for coal and biomass gasification without pollutant emission.We carried out a series of experiments in a SCWFB,and a dual-capacitance probe measurement system was applied to measure the hydrodynamics of slugs,such as the slug frequency,chord length,and rising velocity.Four groups of Geldart-B particles with different mean diameters were fluidized by supercritical water with a system pressure of 20-27MPa and at 410-570℃.The minimum slugging Reynolds number increases logarithmically with Archimedes number and a predicting correlation of the minimum slugging fluidization velocity in the SCWFB is presented:Rems=32908.84 ln(Ar^0.55+260376.65)-410361.90.The relative error of the above correlation was within ±15% and the averaged relative error was 7.5%.The effect of operating conditions on the minimum slugging fluidization velocity is discussed.This research provides useful guidance for scaling-up design and for determining the optimum range of operating conditions in the SCWFB.
文摘In 2023, the world economy was generally sluggish, and recovery remained weak. Under the pretext of “derisking,” the United States(US)-led West has generalized economic security and engaged in punitive, exclusive, and collectivized economic protectionism. Developing countries are struggling.
文摘Slugging represents one of the major regimes in fluidization,which occurs in small diameter beds with large bed height-to-diameter ratio or in large diameter beds with internals that resemble multiple small diameter fluidized beds.Slug types include round-nosed slug,wall slug and square nosed slug.Studies of the slugs have been mainly focused on round-nosed or wall slugs known as half slug.typically occurring in Geldart group A particle fuidization.The square-nosed slug typically occurring for Geldart group D particles appears to be regarded as simple in its structure.The Electrical Capacitance Volume Tomogra phy(ECVT)imaging of the square-nosed slugging phenomena conducted in this study reveals otherwise.That is the structure of the square nosed slug is,in fact,complex,particularly with respect to its dynamic variation in fluidization.More broadly.this study examines experimentally the hydrodynamic character-istics of the square-nosed fluidization regime.Specifically,simultaneous measurements from multiple ECVT sensors provide non-inv asive,continuous,3.dimensional imaging of the entire flow region of the slugging bed and hence enabling the dynamic characterization of the evolution of the slugs.The analysis of the 3D images reconstructed for real time gas-solid volume fraction profile of the slugging fluidized bed indicates that there are three different zones.namely.the bottom fluidization zone,the gas slug zone,and the solid slug zone,co-existing in the bed.The three zones present different hydrodynamic characteristics during the slug evolution.It is found that varying the gas velocity of the slugging bed mainly varies the maximum length of the gas slug zone,while it only has a minor effect on the lengths of the bottom fluidization zone and solid slug zone.It also has an insignificant efect on the solid volume fraction of the three zones.
基金supported by National Natural Science Foundation of China(42074142,51527805)。
文摘The hydrodynamic study of the liquid film around Taylor bubbles in slug flow has great significance for understanding parallel flow and interaction between Taylor bubbles.The prediction models for liquid film thickness mainly focus on stagnant flow,and some of them remain inaccurate performance.However,in the industrial process,the slug flow essentially is co-current flow.Therefore,in this paper,the liquid film thickness is studied by theoretical analysis and experimental methods under two conditions of stagnant and co-current flow.Firstly,under the condition of stagnant flow,the present work is based on Batchelor's theory,and modifies Batchelor's liquid film thickness model,which effectively improves its prediction accuracy.Under the condition of co-current flow,the prediction model of average liquid film thickness in slug flow is established by force and motion analysis.Taylor bubble length is introduced into the model as an important parameter.Dynamic experiments were carried out in the pipe with an inner diameter of 20 mm.The liquid film thickness,Taylor bubble velocity and length were measured by distributed ultrasonic sensor and intrusive cross-correlation conductivity sensor.Comparing the predicted value of the model with the measured results,the relative error is controlled within 10%.
基金supported by the National Natural Science Foundation of China(No.51888103,No.52076175).
文摘Large vertical pipes are key structures connecting subsea wells to offshore platforms.However,existing studies mainly focus on small vertical pipes.In a vertical acrylic pipe with 80 mm inner diameter and 11 m height,a high-speed camera was used to visually research the influences of pipe diameters,liquid properties and inlet effect on air-water co-flow characteristic.Different flow regime maps of vertical pipes(diameters are in the range of 50e189 mm)were compared and the critical gas velocity of the transition boundary from bubble to slug flow tended to increase with the increase of diameters at D≥80 mm.Drift-flux models were established in different flow regimes and liquid properties have a significant effect on drift coefficients of bubble flow and slug flow(void fraction a≤0.4).The influence of inlet turbulent effect on the gas-liquid interface distribution gradually weakened and disappeared from the pipe base to 85D,where the flow was fully developed.Slug frequency has a trend of increase first and then decrease with the gas Weber numbers increasing at low liquid superficial velocities(J_(L)≤0.31 m/s).And on the basis of this law,a new slug frequency correlation was proposed.It was found that there was an exponential relationship between the ratio of lengths of Taylor bubble to slug and the void fraction.
基金FAR 2020,2021 Cataldi,FAR 2020,2021 Zara and also supported by MUR National Innovation Ecosystem-Recovery and Resilience Plan(PNRR)Italy。
文摘Gastropods,a mollusk class including slugs and snails,represent an extraordinarily diverse and ecologically significant group of organisms featuring the largest class of invertebrates.They can be classified as aquatic and terrestrial animals having coiled shells,although some species have reduced or absent shells.Their unique body structure includes a muscular foot for locomotion,a visceral mass containing essential organs,and a distinct head region with sensory organs such as tentacles and eyes.They are used to secrete a complex mixture of glycoproteins,enzymes,peptides,mucus and other bioactive compounds,namely slime,which represents a tool to allow locomotion,protection,and interaction within different habitats.The biological activities of the slime have attracted considerable interest due to their diverse and potentially valuable properties ranging from defense mechanisms to potential therapeutic applications in wound healing,antimicrobial therapy,management of inflammation,and neurological disorders.This review aims at exploring the beneficial effects of snail and slug slime focusing,in particular,on the improvement of the biological processes underlying them.Continued exploration of the intricate components of these slimy secretions promises to discover new bioactive molecules with diverse applications in various scientific and industrial fields.
