Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-5308
Y. Nishio, K. Niwa, T. Ogawa
Motion of liquid pouring from a beverage can is numerically studied. A liquid is poured from a can which is rotated at a prescribed angular speed. The flow is simulated by solving the unsteady three-dimensional Navier-Stokes equations. An experiment under the same condition is also carried out to validate the computational result. The result shows that, when the can is tipped, the liquid flows over the lid of the can and is once obstructed by the rim of the lid. The numerical result is in good agreement with the experimental result. The effect of condensation formed on a can surface is also considered. The effect of condensation is taken into account by adjusting a contact angle. The liquid pouring from a can trickles down along the can body. The computation reproduces these experimental observations.
{"title":"Numerical Simulation of a Pouring Flow From a Beverage Can","authors":"Y. Nishio, K. Niwa, T. Ogawa","doi":"10.1115/ajkfluids2019-5308","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5308","url":null,"abstract":"\u0000 Motion of liquid pouring from a beverage can is numerically studied. A liquid is poured from a can which is rotated at a prescribed angular speed. The flow is simulated by solving the unsteady three-dimensional Navier-Stokes equations. An experiment under the same condition is also carried out to validate the computational result. The result shows that, when the can is tipped, the liquid flows over the lid of the can and is once obstructed by the rim of the lid. The numerical result is in good agreement with the experimental result. The effect of condensation formed on a can surface is also considered. The effect of condensation is taken into account by adjusting a contact angle. The liquid pouring from a can trickles down along the can body. The computation reproduces these experimental observations.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"168 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128732328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4783
C. Youn, Kenjiro Saito, M. Furuya
In this research, in order to predict the dynamic characteristics of a regulating valve, a mathematical model is proposed for a pneumatic control valve using a smart valve positioner (AVP300), and the dynamic characteristics of the control valve were simulated. We modeled the components of the control valve (i.e., nozzle flapper, pilot valve, Auto/Manual (A/M) screw, bleed orifice, pneumatic actuator, gland packing, and pressure reducing valve), and simulated the dynamic characteristics using SimulationX, a one-dimensional analysis software. For the nozzle flapper, we proposed a model that considers the influence of fluid force due to pressure change as well as the influence of the change in effective area by measuring the displacement, pressure, and flow rate of the nozzle flapper. The diaphragm chamber, which operates the pilot valve of the positioner, was made of transparent acrylic. The displacement of the pilot valve was measured by a laser displacement sensor, and its movement against pressure change was clarified. The sonic speed conductance and critical pressure ratio of the A/M screw and bleed orifice were determined experimentally and reflected in the model. In the pneumatic actuator, the effective cross-section of the diaphragm was obtained from the change in pressure and displacement. The change in volume was calculated from the experiment using a fixed chamber. The friction force of gland packing was modeled using static and dynamic friction forces. The experiment on the dynamic characteristics of valve displacement was performed with the input signal of the valve displacement set from 20% to 80%. A comparison of the experimental results of the valve displacement and simulation results showed good agreement. The simulation in this study is considered effective in predicting the dynamic characteristics of the control valve.
{"title":"Simulation of Dynamic Characteristics of Pneumatic Control Valve With Smart Valve Positioner","authors":"C. Youn, Kenjiro Saito, M. Furuya","doi":"10.1115/ajkfluids2019-4783","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4783","url":null,"abstract":"\u0000 In this research, in order to predict the dynamic characteristics of a regulating valve, a mathematical model is proposed for a pneumatic control valve using a smart valve positioner (AVP300), and the dynamic characteristics of the control valve were simulated. We modeled the components of the control valve (i.e., nozzle flapper, pilot valve, Auto/Manual (A/M) screw, bleed orifice, pneumatic actuator, gland packing, and pressure reducing valve), and simulated the dynamic characteristics using SimulationX, a one-dimensional analysis software.\u0000 For the nozzle flapper, we proposed a model that considers the influence of fluid force due to pressure change as well as the influence of the change in effective area by measuring the displacement, pressure, and flow rate of the nozzle flapper. The diaphragm chamber, which operates the pilot valve of the positioner, was made of transparent acrylic. The displacement of the pilot valve was measured by a laser displacement sensor, and its movement against pressure change was clarified. The sonic speed conductance and critical pressure ratio of the A/M screw and bleed orifice were determined experimentally and reflected in the model. In the pneumatic actuator, the effective cross-section of the diaphragm was obtained from the change in pressure and displacement. The change in volume was calculated from the experiment using a fixed chamber. The friction force of gland packing was modeled using static and dynamic friction forces.\u0000 The experiment on the dynamic characteristics of valve displacement was performed with the input signal of the valve displacement set from 20% to 80%. A comparison of the experimental results of the valve displacement and simulation results showed good agreement. The simulation in this study is considered effective in predicting the dynamic characteristics of the control valve.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130903855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-5059
R. Huang, Xianwu Luo
When the marine vessels exceed the speed of 30 knots, it is preferred to adopt the waterjet propulsion method due to its high propulsive efficiency, good maneuverability, less vibration and good anti-cavitation performance. The efficiency of the waterjet pump is up to 90% with advanced modern design methods while 7∼9% of total power is lost in the intake duct. In this paper, the flow simulation in an intake duct has been conducted using the modified partially averaged Navier-Stokes method for better understanding of flow features inside the intake duct and instructing how to reduce the power loss at various ship speeds and inlet velocity ratio (IVR) with considering the hull boundary layer. The nonuniformity and perpendicularity at the impeller plane is applied to analyze the flow quality at the outlet plane of intake duct. The results indicate that the nonuniformity decreases while the perpendicularity increases with increasing IVR. Thus a large IVR together with a high ship speed would cause better outflows. Further analyses of the pressure along the ramp and cutwater depict that cavitation easily occurs at the upper side of the cutwater with a larger IVR. The hydraulic efficiency is seen to firstly increase and then decrease with an increase in IVR. The hydraulic efficiency of the intake duct is over 80% during IVR = 0.4∼1.2 with the maximum value of 92.19% at IVR = 0.6.
{"title":"Numerical Investigation of an Intake Duct for a Waterjet Propulsion System Using Modified Partially Averaged Navier-Stokes Method","authors":"R. Huang, Xianwu Luo","doi":"10.1115/ajkfluids2019-5059","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5059","url":null,"abstract":"\u0000 When the marine vessels exceed the speed of 30 knots, it is preferred to adopt the waterjet propulsion method due to its high propulsive efficiency, good maneuverability, less vibration and good anti-cavitation performance. The efficiency of the waterjet pump is up to 90% with advanced modern design methods while 7∼9% of total power is lost in the intake duct. In this paper, the flow simulation in an intake duct has been conducted using the modified partially averaged Navier-Stokes method for better understanding of flow features inside the intake duct and instructing how to reduce the power loss at various ship speeds and inlet velocity ratio (IVR) with considering the hull boundary layer. The nonuniformity and perpendicularity at the impeller plane is applied to analyze the flow quality at the outlet plane of intake duct. The results indicate that the nonuniformity decreases while the perpendicularity increases with increasing IVR. Thus a large IVR together with a high ship speed would cause better outflows. Further analyses of the pressure along the ramp and cutwater depict that cavitation easily occurs at the upper side of the cutwater with a larger IVR. The hydraulic efficiency is seen to firstly increase and then decrease with an increase in IVR. The hydraulic efficiency of the intake duct is over 80% during IVR = 0.4∼1.2 with the maximum value of 92.19% at IVR = 0.6.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"174 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122160542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4684
Hyunkyoo Cho, U. Shrestha, Young-Do Choi, Jungwan Park
Global sensitivity analysis (GSA) estimates influence of design variables in the entire design domain on performance measures. Hence, using GSA, important design variables could be found for an engineering application with high dimension which require computationally expensive analyses. Then, similar engineering applications could use selected variables to carry out design process with smaller dimension and affordable computational cost. In this study, GSA has been carried out for the performance measures in design of stay vane and casing of reaction hydraulic turbines. Global sensitivity index method is used for GSA because it can fully capture the effect of interaction between the design variables. For efficiency, genetic aggregation surrogate models are constructed using the responses of computational fluid dynamic (CFD) analysis. Global sensitivity indices for the performance measures of stay vane and casing have been evaluated using the surrogate models. It is found that less than three design variables among 12 are effective in the design process of stay vane and casing in reaction hydraulic turbines.
{"title":"Global Sensitivity Analysis for Stay Vane and Casing Design of Reaction Hydraulic Turbine","authors":"Hyunkyoo Cho, U. Shrestha, Young-Do Choi, Jungwan Park","doi":"10.1115/ajkfluids2019-4684","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4684","url":null,"abstract":"\u0000 Global sensitivity analysis (GSA) estimates influence of design variables in the entire design domain on performance measures. Hence, using GSA, important design variables could be found for an engineering application with high dimension which require computationally expensive analyses. Then, similar engineering applications could use selected variables to carry out design process with smaller dimension and affordable computational cost. In this study, GSA has been carried out for the performance measures in design of stay vane and casing of reaction hydraulic turbines. Global sensitivity index method is used for GSA because it can fully capture the effect of interaction between the design variables. For efficiency, genetic aggregation surrogate models are constructed using the responses of computational fluid dynamic (CFD) analysis. Global sensitivity indices for the performance measures of stay vane and casing have been evaluated using the surrogate models. It is found that less than three design variables among 12 are effective in the design process of stay vane and casing in reaction hydraulic turbines.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132529295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4935
H. Yagihashi, D. Nakata, Ryojiro Minato, Inaho Yoshikawa, K. Arimatsu, M. Uchiumi
This paper describes the ignition transients of a LOX/ethanol gas generator that is used for a gas generator cycle air turbo ramjet engine. It is essential to know the temperature history of the LOX injector manifold in order to determine the appropriate ignition sequence. Following a chill-down process, an inert gas purge is performed prior to ignition. Once the main valve is opened, liquid oxygen is discharged after a short period of discharging gaseous oxygen. The period of the gas discharge is a critical parameter for the success of the ignition that is affected by the injector temperature at the time that the valve opens. As a result of the experiments, the gas discharge period was found to be in the range of 0.5–1.0 second, whereas the injector temperature when the valve was opened ranged from 120–170 K under various experimental conditions.
{"title":"Experimental Study of Temperature and Phase Transition of Liquid Oxygen at Ignition in Impinging Injector of Gas Generator","authors":"H. Yagihashi, D. Nakata, Ryojiro Minato, Inaho Yoshikawa, K. Arimatsu, M. Uchiumi","doi":"10.1115/ajkfluids2019-4935","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4935","url":null,"abstract":"\u0000 This paper describes the ignition transients of a LOX/ethanol gas generator that is used for a gas generator cycle air turbo ramjet engine. It is essential to know the temperature history of the LOX injector manifold in order to determine the appropriate ignition sequence. Following a chill-down process, an inert gas purge is performed prior to ignition. Once the main valve is opened, liquid oxygen is discharged after a short period of discharging gaseous oxygen. The period of the gas discharge is a critical parameter for the success of the ignition that is affected by the injector temperature at the time that the valve opens. As a result of the experiments, the gas discharge period was found to be in the range of 0.5–1.0 second, whereas the injector temperature when the valve was opened ranged from 120–170 K under various experimental conditions.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"255 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132539791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4740
Yun Long, Cheng-zao Han, B. Ji, X. Long, Zhi-rong Zhang
In this paper, the unsteady cavitating turbulent flow around a marine propeller behind the hull is simulated by the k-ω SST turbulence model coupled with the Zwart cavitation model. Three systematic refined structured meshes around the hull and propeller have been generated to study the predicted cavitation patterns and pressure fluctuations. Numerical results indicate that the predicted transient cavitating flow behind the hull wake, including sheet cavitation and tip vortex cavitation, shows quasi-periodic feature and agrees fairly well with the available experimental data. The deviations of pressure fluctuations between experimental data and numerical results are much small. With mesh refining, the cavitation region and the magnitudes of the calculated pressure fluctuations increase, while the differences between two adjacent sets of grids become smaller. In addition, the uncertainty of the thrust coefficient obtained by Factor of Safety method is significantly small. Further, the interaction between the cavitation and the vortex by the relative vorticity transport equation is illustrated. Results show that the magnitude of stretching term is obviously larger than the other three terms, and the dilatation term and the baroclinic term both have an important influence on the generation of vortices.
{"title":"Numerical Simulation and Vorticity Analysis of Cavitating Flow Around a Marine Propeller Behind the Hull","authors":"Yun Long, Cheng-zao Han, B. Ji, X. Long, Zhi-rong Zhang","doi":"10.1115/ajkfluids2019-4740","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4740","url":null,"abstract":"\u0000 In this paper, the unsteady cavitating turbulent flow around a marine propeller behind the hull is simulated by the k-ω SST turbulence model coupled with the Zwart cavitation model. Three systematic refined structured meshes around the hull and propeller have been generated to study the predicted cavitation patterns and pressure fluctuations. Numerical results indicate that the predicted transient cavitating flow behind the hull wake, including sheet cavitation and tip vortex cavitation, shows quasi-periodic feature and agrees fairly well with the available experimental data. The deviations of pressure fluctuations between experimental data and numerical results are much small. With mesh refining, the cavitation region and the magnitudes of the calculated pressure fluctuations increase, while the differences between two adjacent sets of grids become smaller. In addition, the uncertainty of the thrust coefficient obtained by Factor of Safety method is significantly small. Further, the interaction between the cavitation and the vortex by the relative vorticity transport equation is illustrated. Results show that the magnitude of stretching term is obviously larger than the other three terms, and the dilatation term and the baroclinic term both have an important influence on the generation of vortices.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"71 14","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113970215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4901
K. Yousef, A. Hegazy, A. Engeda
This paper presents a Computational Fluid Dynamic (CFD) simulation for dry air/water-liquid and two-phase flow mixing in a vertical inverted U-tube using the mixture multiphase and turbulence models. This study is to investigate the flow behaviors and underlying some physical mechanisms encountered in dry air/water-liquid flow in the inverted U-tube. Water flows through the inverted U-tube while the dry air is entrained using the side-tube installed after the water flow downward. The inverted U-tube is tested at water mass flow rates of 2,4,6 and 8 kg/s, air mass flow rates, 0.000614–0.02292 kg/s, with dry air volume fractions 0.2–0.9. The obtained results are compared with the experimental data for model validation and the present CFD model is able to give an acceptable agreement. Also, the results show that, at water mass flow rate of 2 kg/s, there are vortices and turbulent intensity disturbances are noticed at the inverted U-tube higher part, which refers to an air entrainment occurrence from the side-tube. Theses disturbances starts to be stabilized at air mass flow rate around 0.00736 kg/s and air volume fraction, αa = 0.75. This means, if the air mass flow rate increases above this limit, the air entrainment may be blocked. On the other side, at water mass flow rate of 4 kg/s, there are little noticed disturbances until air mass flow rate of 0.00368 kg/s and αa = 0.43 and thereafter stabilized. After this point for water mass flow rate of 4 kg/s, increasing air mass flow rate may block the water flow and the whole inverted U-tube system possible stop flowing. Therefore, this study is able to estimate the required operational conditions and mass ratios for stable air entrainment process. Beyond these operational conditions, air entrainment may be blocked and the whole system discontinues its normal induced gravitational flow. In addition, this study proves that the inverted U-tube is able to generate a vacuum pressure up to 53.382 kPa based on the present geometrical configuration. This generated low-pressure by the inverted U-tube can be used for engineering applications which are working under vacuum and need continuous evacuating form the dry air and non-condensable gases. Furthermore, these findings motivate the utilizing of inverted U-tube for the air evacuation purposes for less power consuming in power plants.
{"title":"Mixing of Dry Air With Water-Liquid Flowing Through an Inverted U-Tube for Power Plant Condenser Applications","authors":"K. Yousef, A. Hegazy, A. Engeda","doi":"10.1115/ajkfluids2019-4901","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4901","url":null,"abstract":"\u0000 This paper presents a Computational Fluid Dynamic (CFD) simulation for dry air/water-liquid and two-phase flow mixing in a vertical inverted U-tube using the mixture multiphase and turbulence models. This study is to investigate the flow behaviors and underlying some physical mechanisms encountered in dry air/water-liquid flow in the inverted U-tube. Water flows through the inverted U-tube while the dry air is entrained using the side-tube installed after the water flow downward. The inverted U-tube is tested at water mass flow rates of 2,4,6 and 8 kg/s, air mass flow rates, 0.000614–0.02292 kg/s, with dry air volume fractions 0.2–0.9. The obtained results are compared with the experimental data for model validation and the present CFD model is able to give an acceptable agreement. Also, the results show that, at water mass flow rate of 2 kg/s, there are vortices and turbulent intensity disturbances are noticed at the inverted U-tube higher part, which refers to an air entrainment occurrence from the side-tube. Theses disturbances starts to be stabilized at air mass flow rate around 0.00736 kg/s and air volume fraction, αa = 0.75. This means, if the air mass flow rate increases above this limit, the air entrainment may be blocked. On the other side, at water mass flow rate of 4 kg/s, there are little noticed disturbances until air mass flow rate of 0.00368 kg/s and αa = 0.43 and thereafter stabilized. After this point for water mass flow rate of 4 kg/s, increasing air mass flow rate may block the water flow and the whole inverted U-tube system possible stop flowing. Therefore, this study is able to estimate the required operational conditions and mass ratios for stable air entrainment process. Beyond these operational conditions, air entrainment may be blocked and the whole system discontinues its normal induced gravitational flow. In addition, this study proves that the inverted U-tube is able to generate a vacuum pressure up to 53.382 kPa based on the present geometrical configuration. This generated low-pressure by the inverted U-tube can be used for engineering applications which are working under vacuum and need continuous evacuating form the dry air and non-condensable gases. Furthermore, these findings motivate the utilizing of inverted U-tube for the air evacuation purposes for less power consuming in power plants.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114552224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4802
Nakyeong Seo, N. Kharoua, L. Khezzar, M. Alshehhi, M. Méribout
The present study addresses itself to the performance assessment of a novel in-line gas-liquid separator. The separator is developed by FRAMES company under the name of SwirlSep based on the interaction of a swirling flow, generated by an innovative devise called swirl cage, and a hollow conical bluff body designed to deviate the gaseous phase internally.. The separator is intended to be implemented within a multiphase flow metering system in oil field gathering stations in the Gulf region. The study represents a preliminary step among a design process including elaborate lab-scale and filed tests. The flow in the gas-liquid separator is studied using Computational Fluid Dynamics CFD. The Shear Stress Transport (SST) k-ω turbulence and Eulerian-Eulerian multiphase models, under different flow conditions, were used to simulate real flow scenarios. The scenarios were chosen to replicate flow conditions that could exist during the operation of oil wells over their lifetime with the aim to provide guidance for proper control of the separator valves. The fraction of the total flow is prescribed at each outlet, using an outflow boundary condition, to mimic the action of the control valves. At the inlet, the phase velocity and volume fraction were prescribed. The outlet streams and their phase’s content were, then, analyzed together with the distribution of the velocity and concentration fields inside the separator. Velocity and pressure drop were found to increase with the increase of the outflow in one outlet when changing the flow split. Flow control, at the outlets, caused an increase of the oil-in-gas entrainment when trying to minimize gas-in-oil entrainment which is a non-trivial task. The effects of the flow split specified appeared downstream of the conical bluff body only when the inflow conditions were kept constant whereas the flow field remained identical upstream of the cone. A recirculation zone was generated in the annular space downstream of the cone and affected the separator performance considerably. The recirculation zone was due to the effect of the higher flow rate towards the gas outlet and disappeared when the flow rate towards the oil outlet tended to be equal or higher. The phase distribution was identical upstream of the cone and depended on the flow split downstream of the cone. The cases considered served as an assessment of the separator performance under different multiphase flow conditions replicating realistic scenarios.
{"title":"Multiphase Flow Simulation of In-Line Gas-Liquid Separator for Multiphase Metering","authors":"Nakyeong Seo, N. Kharoua, L. Khezzar, M. Alshehhi, M. Méribout","doi":"10.1115/ajkfluids2019-4802","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4802","url":null,"abstract":"\u0000 The present study addresses itself to the performance assessment of a novel in-line gas-liquid separator. The separator is developed by FRAMES company under the name of SwirlSep based on the interaction of a swirling flow, generated by an innovative devise called swirl cage, and a hollow conical bluff body designed to deviate the gaseous phase internally.. The separator is intended to be implemented within a multiphase flow metering system in oil field gathering stations in the Gulf region. The study represents a preliminary step among a design process including elaborate lab-scale and filed tests.\u0000 The flow in the gas-liquid separator is studied using Computational Fluid Dynamics CFD. The Shear Stress Transport (SST) k-ω turbulence and Eulerian-Eulerian multiphase models, under different flow conditions, were used to simulate real flow scenarios. The scenarios were chosen to replicate flow conditions that could exist during the operation of oil wells over their lifetime with the aim to provide guidance for proper control of the separator valves. The fraction of the total flow is prescribed at each outlet, using an outflow boundary condition, to mimic the action of the control valves. At the inlet, the phase velocity and volume fraction were prescribed.\u0000 The outlet streams and their phase’s content were, then, analyzed together with the distribution of the velocity and concentration fields inside the separator. Velocity and pressure drop were found to increase with the increase of the outflow in one outlet when changing the flow split. Flow control, at the outlets, caused an increase of the oil-in-gas entrainment when trying to minimize gas-in-oil entrainment which is a non-trivial task. The effects of the flow split specified appeared downstream of the conical bluff body only when the inflow conditions were kept constant whereas the flow field remained identical upstream of the cone. A recirculation zone was generated in the annular space downstream of the cone and affected the separator performance considerably. The recirculation zone was due to the effect of the higher flow rate towards the gas outlet and disappeared when the flow rate towards the oil outlet tended to be equal or higher. The phase distribution was identical upstream of the cone and depended on the flow split downstream of the cone.\u0000 The cases considered served as an assessment of the separator performance under different multiphase flow conditions replicating realistic scenarios.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117224989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4611
U. Shrestha, Jungwan Park, Young-Do Choi
Optimization is uprising technology in the engineering field, which enhance the performance of mechanical components. Likewise, upcoming turbomachinery designs need to be more efficient, cost-effective and easy manufacturing. Many optimization techniques have implemented for the development of efficient turbomachines. In this study, the optimization has mostly confined to the stay vane of reaction turbine like Francis, Pump Turbine etc. Stay vanes are mainly used to direct the flow towards guide vane and runner in the reaction type turbine (Francis, Pump Turbine). The three-dimensional flow field from the spiral casing is highly distorted, which causes secondary flow. However, the uniform flow field has maintained by stay vane. Due to steady flow field from stay vane, the performance of the runner has improved. Therefore, the better design of stay vane has been required for the improvement of the flow field around the runner passage. The design parameters of the stay vane are vane angle distribution and thickness distribution from leading edge to trailing edge. The vane angle distribution controls the stability of flow field direction and momentum towards the runner. Similarly, the thickness distribution will maintain the profile of the stay vane. The optimization of stay vane has improved turbine efficiency, flow uniformity, and pressure loss. The multi-objective genetic algorithm (MOGA) was selected for the optimization of stay vane because it satisfies all the objective functions without being dominated by any specific solution. MOGA is a more realistic approach to optimization. The validation test of performance is conducted to compare the result of experimental and numerical methods. The optimized stay vane has improved the flow uniformity around the stay vane.
{"title":"Optimal Design of Reaction Hydro Turbine Model Stay Vane by Vane Angle and Thickness Distribution","authors":"U. Shrestha, Jungwan Park, Young-Do Choi","doi":"10.1115/ajkfluids2019-4611","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4611","url":null,"abstract":"\u0000 Optimization is uprising technology in the engineering field, which enhance the performance of mechanical components. Likewise, upcoming turbomachinery designs need to be more efficient, cost-effective and easy manufacturing. Many optimization techniques have implemented for the development of efficient turbomachines. In this study, the optimization has mostly confined to the stay vane of reaction turbine like Francis, Pump Turbine etc. Stay vanes are mainly used to direct the flow towards guide vane and runner in the reaction type turbine (Francis, Pump Turbine). The three-dimensional flow field from the spiral casing is highly distorted, which causes secondary flow. However, the uniform flow field has maintained by stay vane. Due to steady flow field from stay vane, the performance of the runner has improved. Therefore, the better design of stay vane has been required for the improvement of the flow field around the runner passage. The design parameters of the stay vane are vane angle distribution and thickness distribution from leading edge to trailing edge. The vane angle distribution controls the stability of flow field direction and momentum towards the runner. Similarly, the thickness distribution will maintain the profile of the stay vane. The optimization of stay vane has improved turbine efficiency, flow uniformity, and pressure loss. The multi-objective genetic algorithm (MOGA) was selected for the optimization of stay vane because it satisfies all the objective functions without being dominated by any specific solution. MOGA is a more realistic approach to optimization. The validation test of performance is conducted to compare the result of experimental and numerical methods. The optimized stay vane has improved the flow uniformity around the stay vane.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"1247 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131734503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4733
Cong-wei Hou, Mu Juan, Wen-qing Li, Zhi-jiang Jin, J. Qian
Piston type valve cores are widely adopted in check valves, globe valves, pressure reducing valves and so forth. With the irregular inlet flow channel, the bottom of piston type valve core exits unbalanced torques usually. The unbalanced torque causes the valve core to squeeze sealing elements and increases the energy consumption. To analyze the unbalanced torque on the bottom of the piston type valve core, a transient numerical model of the piston type valve core is established and the simulation results are compared with the theoretical formula for the purpose of validation. The dynamic flow characteristics are studied to investigate pressure characteristics on the bottom of the piston type valve core with the dynamic motion of the valve core. Meanwhile, pressure characteristics under different valve core displacements are obtained, and the sensitive range of the unbalanced torque is found. This work can be helpful for the further structural optimization on the valves with piston type valve cores.
{"title":"Transient Simulation on Unbalanced Torque of Piston Type Valve Cores During Dynamic Motion","authors":"Cong-wei Hou, Mu Juan, Wen-qing Li, Zhi-jiang Jin, J. Qian","doi":"10.1115/ajkfluids2019-4733","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4733","url":null,"abstract":"Piston type valve cores are widely adopted in check valves, globe valves, pressure reducing valves and so forth. With the irregular inlet flow channel, the bottom of piston type valve core exits unbalanced torques usually. The unbalanced torque causes the valve core to squeeze sealing elements and increases the energy consumption. To analyze the unbalanced torque on the bottom of the piston type valve core, a transient numerical model of the piston type valve core is established and the simulation results are compared with the theoretical formula for the purpose of validation. The dynamic flow characteristics are studied to investigate pressure characteristics on the bottom of the piston type valve core with the dynamic motion of the valve core. Meanwhile, pressure characteristics under different valve core displacements are obtained, and the sensitive range of the unbalanced torque is found. This work can be helpful for the further structural optimization on the valves with piston type valve cores.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121361616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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