An experimental analysis of the slug-induced vibration(SIV)of a flexible catenary riser with an aspect ratio of 130 is reported in this work.The vibration responses and internal slug flow details at different gas-liqu...An experimental analysis of the slug-induced vibration(SIV)of a flexible catenary riser with an aspect ratio of 130 is reported in this work.The vibration responses and internal slug flow details at different gas-liquid ratios(Q_(g)/Q_(l))and mixture velocities(vm)are non-intrusively and simultaneously captured by high-speed cameras.Both the in-plane and out-of-plane responses of the catenary riser are excited in all considered cases.The slug flow characteristics,including translational velocities,slug lengths,recurrence frequencies,and pressure variations,are analyzed and dis-cussed,as are the dynamic responses of the riser in terms of the amplitudes,space-varying frequency,and modal weight.The dominant modal response based on the root-mean-square amplitude profiles does not match that based on the dominant frequency.Three mode switching types are identified based on the RMS amplitude profiles and the dominant frequency.When vm is small,no mode switching(NMS)is observed in either the in-plane or out-of-plane responses.For mode switching I(MS I),the switching between the first and second modes in the in-plane response is induced by slug flow with different recurrence frequencies in cases of large Q_(g)/Q_(l).However,there is no mode switching in the out-of-plane response.The switching between the first and third modes for the in-plane response and the second and fourth modes for the out-of-plane response(MS II)occurs in cases of relatively high vm and low Q_(g)/Q_(l).展开更多
This study examines the slug-induced vibration(SIV)response and fatigue behavior of offshore risers subjected to internal slug flow.A structural model incorporating internal slug flow dynamics is developed using the A...This study examines the slug-induced vibration(SIV)response and fatigue behavior of offshore risers subjected to internal slug flow.A structural model incorporating internal slug flow dynamics is developed using the Absolute Nodal Coordinate Formulation(ANCF)and a spatial-temporal density variation equation to analyze how slug flow parameters affect the SIV response of risers.Structural displacement,stress,and fatigue responses are systematically evaluated to characterize the structural behavior under SIV conditions.Longer slugs induce more pronounced traveling wave characteristics,while shorter slugs facilitate a mixed traveling-standing wave mode.Moreover,higher slug frequencies lead to increased fatigue accumulation,especially over an extended touchdown zone,thereby compromising the structural integrity of the riser.The findings yield valuable insights into the dynamic interactions between slug flow and riser response.This research advances the understanding of SIV mechanisms and provides a theoretical foundation for fatigue assessment and structural optimization,contributing to the safe and efficient design of offshore risers in deepwater environments.展开更多
Hydrate phase transition may pose risks in pipeline blockage and severe challenges for offshore natural gas hydrate pro-duction.The present work involves the development of a multiphase gas-liquid-solid vertical slug ...Hydrate phase transition may pose risks in pipeline blockage and severe challenges for offshore natural gas hydrate pro-duction.The present work involves the development of a multiphase gas-liquid-solid vertical slug flow hydrodynamic model consi-dering hydrate phase transition kinetics with heat and mass transfer behaviors.The varying gas physical properties due to pressure and temperature variations are also introduced to evaluate vertical slug flow characteristics.The proposed model is used to carry out a series of numerical simulations to examine the interactions between hydrate phase transition and vertical slug flow hydrodynamics.Furthermore,the hydrate volumetric fractions under different pressure and temperature conditions are predicted.The results reveal that hydrate formation and gas expansion cause the mixture superficial velocity,and the gas and liquid fractions,void fraction in liq-uid slug,and unit length tend to decrease.The increase in outlet pressure leads to an increased hydrate formation rate,which not only increases the hydrate volumetric fraction along the pipe but also causes the upward shift of the hydrate phase transition critical point.展开更多
The liquid slug length distribution is crucial for designing the downstream processing system with mul-tiphase pipeline. Experiments were conducted in a 133m long horizontal test loop. The measurements were per-formed...The liquid slug length distribution is crucial for designing the downstream processing system with mul-tiphase pipeline. Experiments were conducted in a 133m long horizontal test loop. The measurements were per-formed by conductivity probes to determine the liquid slug length distribution. The data covered both the slug and plug flow regimes. From experimental results, the mean liquid slug lengths were relatively insensitive to gas and liquid flow rates in the higher mixture velocity range. But in the lower mixture velocity range, the mean liquid slug length decreased and then increased with mixture velocity. It shows that the development length of slug flow was longer than x/D=1157. A slug tracking model was adapted to study the evolution of liquid slug length distribution in a horizontal pipeline. In the present model, the wake effect of elongated bubble and the pressure drop due to accel-eration are taken into account and random slug lengths are introduced at the entrance. The results of the model are compared with the measured slug length distributions of slug flow regime. It shows that the predicted mean and maximum slug lengths are in agreement with the experimental data at x/D=1157 and the form of the slug length distributions is also predicted well by the model.展开更多
Slug initiation and subsequem evolution along a 5.0 cm ID, 16m long horizomal pipe are experimentally studied. The transient characteristics of interfacial structures are described by using simultaneous measuremeres o...Slug initiation and subsequem evolution along a 5.0 cm ID, 16m long horizomal pipe are experimentally studied. The transient characteristics of interfacial structures are described by using simultaneous measuremeres of the liquid height at multiple locations along the pipe. Various effects of superficial gas and liquid velocities and pressure oscillation on the slug initiation and evolution along the pipe are illustrated. It is found that the slug is initiated by a deterministic orocess with reolenishmem and deoletion of liquid near the inlet for the superficial gas velocity USG〈3.0m·s^-1 and by a stochastic process with wave coalescence along the pipe for USG〉3.0m·s^-1.The evolution of the slugs is strongly attected by superhclal gas and liquid veloclties for USG〈3.0m·s^-1 but weakly affected by the superficial gas velocity for USG〉3.0 m·s . The suppression of pressure oscillation at the pipe inlet significantly delays the onset of slugging, with slugs forming postponed further downstream. The slug frequency at the outlet is, however, not affected by the variation in the pressure oscillation.展开更多
目的研究血管内皮生长因子C(VEGF-C)促子宫颈癌细胞侵袭能力的影响,探讨Slug在其中的作用及相关信号转导途径。方法体外培养宫颈癌细胞株Si Ha细胞,观察VEGF-C对ERK1/2磷酸化及Slug蛋白表达的影响;转染Slug si RNA后,采用transwell侵袭...目的研究血管内皮生长因子C(VEGF-C)促子宫颈癌细胞侵袭能力的影响,探讨Slug在其中的作用及相关信号转导途径。方法体外培养宫颈癌细胞株Si Ha细胞,观察VEGF-C对ERK1/2磷酸化及Slug蛋白表达的影响;转染Slug si RNA后,采用transwell侵袭小室法观察其对宫颈癌细胞株增殖和侵袭的影响。结果 VEGF-C(100 ng/m L)处理Si Ha细胞12、24、48 h后,均能促进Slug蛋白表达,其表达幅度分别为(162.4±6.8)%、(202.8±9.4)%、(236.6±15.5)%,与对照组比较,差异均有统计学意义(P<0.05)。同时,VEGF-C处理后可促进ERK1/2蛋白磷酸化,表达幅度分别为(162.6±20.4)%、(197.8±25.6)%、(152.3±14.6)%,与对照组比较,差异均有统计学意义(P<0.05)。转染ERK1/2 si RNA可显著抑制VEGF-C促Slug表达的效应。Si Ha细胞转染特异性Slug si RNA 48 h后,VEGF-C促细胞侵袭的能力明显减弱。结论 VEGF-C可能通过激活ERK1/2,上调Slug蛋白表达,促进宫颈癌侵袭能力及其恶性进展。展开更多
目的:研究Slug与食管癌侵袭转移间的关系及其调控机制。方法:分别将构建好的pc DNA 3.1-Slug和miR-140通过Lip 2000转染到Eca-109中,以pc DNA 3.1和Lip 2000空转作为对照组,显微镜下观察转染前后细胞的形态变化,检测细胞中E-钙黏素、N-...目的:研究Slug与食管癌侵袭转移间的关系及其调控机制。方法:分别将构建好的pc DNA 3.1-Slug和miR-140通过Lip 2000转染到Eca-109中,以pc DNA 3.1和Lip 2000空转作为对照组,显微镜下观察转染前后细胞的形态变化,检测细胞中E-钙黏素、N-钙黏蛋白和波形蛋白的表达情况变化,另外使用穿透小室法检测细胞的侵袭能力在转染前后的变化情况。结果:转染pc DNA 3.1-Slug和miR-140到Eca-109中后细胞变得细长。转染pc DNA 3.1-Slug的Eca-109中E-钙黏素表达下调,N-钙黏蛋白和波形蛋白表达上调,细胞穿透基质胶的数量明显增多。转染miR-140的Eca-109中E-钙黏素表达上调,N-钙黏蛋白和波形蛋白表达下调,细胞穿透基质胶的数量明显减少。在食管癌细胞中miR-140和Slug的表达呈负相关(r=-0.96)。结论:转录因子Slug能够提高食管癌上皮细胞的间质转化能力和侵袭能力,而miR-140是通过调控Slug来调节食管癌细胞侵袭性的。展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.52301338)the Sichuan Science and Technology Program(Grant No.2024NSFSC0968).
文摘An experimental analysis of the slug-induced vibration(SIV)of a flexible catenary riser with an aspect ratio of 130 is reported in this work.The vibration responses and internal slug flow details at different gas-liquid ratios(Q_(g)/Q_(l))and mixture velocities(vm)are non-intrusively and simultaneously captured by high-speed cameras.Both the in-plane and out-of-plane responses of the catenary riser are excited in all considered cases.The slug flow characteristics,including translational velocities,slug lengths,recurrence frequencies,and pressure variations,are analyzed and dis-cussed,as are the dynamic responses of the riser in terms of the amplitudes,space-varying frequency,and modal weight.The dominant modal response based on the root-mean-square amplitude profiles does not match that based on the dominant frequency.Three mode switching types are identified based on the RMS amplitude profiles and the dominant frequency.When vm is small,no mode switching(NMS)is observed in either the in-plane or out-of-plane responses.For mode switching I(MS I),the switching between the first and second modes in the in-plane response is induced by slug flow with different recurrence frequencies in cases of large Q_(g)/Q_(l).However,there is no mode switching in the out-of-plane response.The switching between the first and third modes for the in-plane response and the second and fourth modes for the out-of-plane response(MS II)occurs in cases of relatively high vm and low Q_(g)/Q_(l).
基金financially supported by the National Natural Science Foundation of China(Grant No.52222111)the Science Foundation of China University of Petroleum,Beijing(Grant No.2462025SZBH002)。
文摘This study examines the slug-induced vibration(SIV)response and fatigue behavior of offshore risers subjected to internal slug flow.A structural model incorporating internal slug flow dynamics is developed using the Absolute Nodal Coordinate Formulation(ANCF)and a spatial-temporal density variation equation to analyze how slug flow parameters affect the SIV response of risers.Structural displacement,stress,and fatigue responses are systematically evaluated to characterize the structural behavior under SIV conditions.Longer slugs induce more pronounced traveling wave characteristics,while shorter slugs facilitate a mixed traveling-standing wave mode.Moreover,higher slug frequencies lead to increased fatigue accumulation,especially over an extended touchdown zone,thereby compromising the structural integrity of the riser.The findings yield valuable insights into the dynamic interactions between slug flow and riser response.This research advances the understanding of SIV mechanisms and provides a theoretical foundation for fatigue assessment and structural optimization,contributing to the safe and efficient design of offshore risers in deepwater environments.
基金supported by the National Natural Science Foundation of China(No.52301355)the Natu-ral Science Foundation of Qingdao Municipality(No.23-2-1-108-zyyd-jch)the China University of Petroleum(East China)Independent Innovation Research Project(Science and Engineering)-Leading Talent Cultivation Fund(No.24CX07001A).
文摘Hydrate phase transition may pose risks in pipeline blockage and severe challenges for offshore natural gas hydrate pro-duction.The present work involves the development of a multiphase gas-liquid-solid vertical slug flow hydrodynamic model consi-dering hydrate phase transition kinetics with heat and mass transfer behaviors.The varying gas physical properties due to pressure and temperature variations are also introduced to evaluate vertical slug flow characteristics.The proposed model is used to carry out a series of numerical simulations to examine the interactions between hydrate phase transition and vertical slug flow hydrodynamics.Furthermore,the hydrate volumetric fractions under different pressure and temperature conditions are predicted.The results reveal that hydrate formation and gas expansion cause the mixture superficial velocity,and the gas and liquid fractions,void fraction in liq-uid slug,and unit length tend to decrease.The increase in outlet pressure leads to an increased hydrate formation rate,which not only increases the hydrate volumetric fraction along the pipe but also causes the upward shift of the hydrate phase transition critical point.
基金Supported by the National Natural Science Foundation of China (No.50536020 and 50323001).
文摘The liquid slug length distribution is crucial for designing the downstream processing system with mul-tiphase pipeline. Experiments were conducted in a 133m long horizontal test loop. The measurements were per-formed by conductivity probes to determine the liquid slug length distribution. The data covered both the slug and plug flow regimes. From experimental results, the mean liquid slug lengths were relatively insensitive to gas and liquid flow rates in the higher mixture velocity range. But in the lower mixture velocity range, the mean liquid slug length decreased and then increased with mixture velocity. It shows that the development length of slug flow was longer than x/D=1157. A slug tracking model was adapted to study the evolution of liquid slug length distribution in a horizontal pipeline. In the present model, the wake effect of elongated bubble and the pressure drop due to accel-eration are taken into account and random slug lengths are introduced at the entrance. The results of the model are compared with the measured slug length distributions of slug flow regime. It shows that the predicted mean and maximum slug lengths are in agreement with the experimental data at x/D=1157 and the form of the slug length distributions is also predicted well by the model.
基金Supported by the National Natural Science Foundation of China （50521604） and the State Key Development Program for Basic Research of China （2007CB029804）.
文摘Slug initiation and subsequem evolution along a 5.0 cm ID, 16m long horizomal pipe are experimentally studied. The transient characteristics of interfacial structures are described by using simultaneous measuremeres of the liquid height at multiple locations along the pipe. Various effects of superficial gas and liquid velocities and pressure oscillation on the slug initiation and evolution along the pipe are illustrated. It is found that the slug is initiated by a deterministic orocess with reolenishmem and deoletion of liquid near the inlet for the superficial gas velocity USG〈3.0m·s^-1 and by a stochastic process with wave coalescence along the pipe for USG〉3.0m·s^-1.The evolution of the slugs is strongly attected by superhclal gas and liquid veloclties for USG〈3.0m·s^-1 but weakly affected by the superficial gas velocity for USG〉3.0 m·s . The suppression of pressure oscillation at the pipe inlet significantly delays the onset of slugging, with slugs forming postponed further downstream. The slug frequency at the outlet is, however, not affected by the variation in the pressure oscillation.
文摘目的:研究Slug与食管癌侵袭转移间的关系及其调控机制。方法:分别将构建好的pc DNA 3.1-Slug和miR-140通过Lip 2000转染到Eca-109中,以pc DNA 3.1和Lip 2000空转作为对照组,显微镜下观察转染前后细胞的形态变化,检测细胞中E-钙黏素、N-钙黏蛋白和波形蛋白的表达情况变化,另外使用穿透小室法检测细胞的侵袭能力在转染前后的变化情况。结果:转染pc DNA 3.1-Slug和miR-140到Eca-109中后细胞变得细长。转染pc DNA 3.1-Slug的Eca-109中E-钙黏素表达下调,N-钙黏蛋白和波形蛋白表达上调,细胞穿透基质胶的数量明显增多。转染miR-140的Eca-109中E-钙黏素表达上调,N-钙黏蛋白和波形蛋白表达下调,细胞穿透基质胶的数量明显减少。在食管癌细胞中miR-140和Slug的表达呈负相关(r=-0.96)。结论:转录因子Slug能够提高食管癌上皮细胞的间质转化能力和侵袭能力,而miR-140是通过调控Slug来调节食管癌细胞侵袭性的。
