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
In order to reduce or avoid the fluctuations from interface breakup, a meandering microchannel with curved multi-bends(44 turns) is fabricated, and investigations of scaling bubble/slug length in Taylor flow in a rect...In order to reduce or avoid the fluctuations from interface breakup, a meandering microchannel with curved multi-bends(44 turns) is fabricated, and investigations of scaling bubble/slug length in Taylor flow in a rectangular meandering microchannel are systematically conducted. Based on considerable experimental data,quantitative analyses for the influences of two important characteristic times, liquid phase physical properties and aspect ratio are made on the prediction criteria for the bubble/slug length of Taylor flow in a meandering microchannel. A simple principle is suggested to predict the bubble formation period by using the information of Rayleigh time and capillary time for six gas–liquid systems with average deviation of 10.96%. Considering physical properties of the liquid phase and cross-section configuration of the rectangular mcirochannel,revised scaling laws for bubble length are established by introducing Ca, We, Re and W/h whether for the squeezing-driven or shearing-driven of bubble break. In addition, a simple principle in terms of Garstecki-type model and bubble formation period is set-up to predict slug lengths. A total of 107 sets of experimental data are correlated with the meandering microchannel and operating range: 0.001 b CaTPb 0.05, 0.06 b WeTPb 9.0,18 b ReTPb 460 using the bubble/slug length prediction equation from current work. The average deviation between the correlated data and the experimental data for bubble length and slug length is about 9.42% and9.95%, respectively.展开更多
Suitable microstructures required for semisolid casting were formed by using a vertical pipe.Different lengths of vertical pipe,slug dimensions and pouring time were used to investigate their influence on the microstr...Suitable microstructures required for semisolid casting were formed by using a vertical pipe.Different lengths of vertical pipe,slug dimensions and pouring time were used to investigate their influence on the microstructure of A356 alloy.The results indicate that at the same length of the vertical pipe,the morphology of the primary α(Al)gradually deteriorates by the enlargement in the slug size,but the deteriorating speed slows down with increasing pipe length.They also reveal that the increase in the pipe length improves the microstructure,whereas no further improvement appears when the pipe length reaches a certain value.The optimum length of the pipe obtained in the present work is 430 mm.The microstructure of larger slug poured at higher pouring temperature gets worse and it can be improved by moderately elongating pouring time.The relative mechanisms were also discussed.展开更多
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(21476037,21606034).
文摘In order to reduce or avoid the fluctuations from interface breakup, a meandering microchannel with curved multi-bends(44 turns) is fabricated, and investigations of scaling bubble/slug length in Taylor flow in a rectangular meandering microchannel are systematically conducted. Based on considerable experimental data,quantitative analyses for the influences of two important characteristic times, liquid phase physical properties and aspect ratio are made on the prediction criteria for the bubble/slug length of Taylor flow in a meandering microchannel. A simple principle is suggested to predict the bubble formation period by using the information of Rayleigh time and capillary time for six gas–liquid systems with average deviation of 10.96%. Considering physical properties of the liquid phase and cross-section configuration of the rectangular mcirochannel,revised scaling laws for bubble length are established by introducing Ca, We, Re and W/h whether for the squeezing-driven or shearing-driven of bubble break. In addition, a simple principle in terms of Garstecki-type model and bubble formation period is set-up to predict slug lengths. A total of 107 sets of experimental data are correlated with the meandering microchannel and operating range: 0.001 b CaTPb 0.05, 0.06 b WeTPb 9.0,18 b ReTPb 460 using the bubble/slug length prediction equation from current work. The average deviation between the correlated data and the experimental data for bubble length and slug length is about 9.42% and9.95%, respectively.
基金Supported by the National Natural Science Foundation of China （50476015） and National High Technology Research and Development Program of China （2006AA09Z333）.
基金Project(2006AA03Z115)supported by the National Hi-tech Research and Development Program of ChinaProject(2006CB605203)supported by the National Basic Research Program of ChinaProject(50374012)supported by the National Natural Science Foundation of China
文摘Suitable microstructures required for semisolid casting were formed by using a vertical pipe.Different lengths of vertical pipe,slug dimensions and pouring time were used to investigate their influence on the microstructure of A356 alloy.The results indicate that at the same length of the vertical pipe,the morphology of the primary α(Al)gradually deteriorates by the enlargement in the slug size,but the deteriorating speed slows down with increasing pipe length.They also reveal that the increase in the pipe length improves the microstructure,whereas no further improvement appears when the pipe length reaches a certain value.The optimum length of the pipe obtained in the present work is 430 mm.The microstructure of larger slug poured at higher pouring temperature gets worse and it can be improved by moderately elongating pouring time.The relative mechanisms were also discussed.
