Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4842
Seungyeong Choi, Minho Bang, Kiwoong Kim, Yong-Ki Park, H. Cho
Thermal design of dual circulating fluidized bed reactors for carbon dioxide (CO2) capture was carried out. To handle large heat duties for regeneration, a thin rectangular reactor was proposed. For feasible thermal design, the effect of varying reactor thickness on the gas-solid flow and heat transfer of the thin rectangular fluidized bed was investigated. Reactor thickness of 10, 30, and 60 mm was tested. Numerical simulations were conducted to analyze the pressure difference, solid particle hold-up distribution, particle velocity, granular temperature, and heat transfer in detail. According to our results, when the reactor is between 10 mm and 30 mm thick, a large solid hold-up occurs adjacent to the narrow wall. This causes a large pressure difference due to the wall effect. Furthermore, the particle velocities were analyzed to evaluate that there is the two-dimensional (2D) particle mixing behaviors. On the other hand, in the case of reactors with a thickness of 60 mm, tuning flows occur adjacent to the narrow wall. This reduced the pressure difference and the three-dimensional (3D) particle mixing behaviors. This difference in particle behavior affected heat transfer. In the case of reactor thicknesses between 10 mm and 30 mm, the heat transfer increased with the reactor thickness. In particular, the heat transfer at the narrow wall of the reactor with a thickness of 10 mm was extremely low due to the low particle mixing. On the other hand, there was more heat transfer with a thickness at the 60 mm wall, despite the low solid hold-up.
{"title":"Effect of Reactor Thickness on Gas-Solid Flow and Heat Transfer of Thin Rectangular Fluidized Bed Reactors for CO2 Capture","authors":"Seungyeong Choi, Minho Bang, Kiwoong Kim, Yong-Ki Park, H. Cho","doi":"10.1115/ajkfluids2019-4842","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4842","url":null,"abstract":"\u0000 Thermal design of dual circulating fluidized bed reactors for carbon dioxide (CO2) capture was carried out. To handle large heat duties for regeneration, a thin rectangular reactor was proposed. For feasible thermal design, the effect of varying reactor thickness on the gas-solid flow and heat transfer of the thin rectangular fluidized bed was investigated. Reactor thickness of 10, 30, and 60 mm was tested. Numerical simulations were conducted to analyze the pressure difference, solid particle hold-up distribution, particle velocity, granular temperature, and heat transfer in detail. According to our results, when the reactor is between 10 mm and 30 mm thick, a large solid hold-up occurs adjacent to the narrow wall. This causes a large pressure difference due to the wall effect. Furthermore, the particle velocities were analyzed to evaluate that there is the two-dimensional (2D) particle mixing behaviors. On the other hand, in the case of reactors with a thickness of 60 mm, tuning flows occur adjacent to the narrow wall. This reduced the pressure difference and the three-dimensional (3D) particle mixing behaviors. This difference in particle behavior affected heat transfer. In the case of reactor thicknesses between 10 mm and 30 mm, the heat transfer increased with the reactor thickness. In particular, the heat transfer at the narrow wall of the reactor with a thickness of 10 mm was extremely low due to the low particle mixing. On the other hand, there was more heat transfer with a thickness at the 60 mm wall, despite the low solid hold-up.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"21 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":"121580317","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/ajkfluids2019-5592
Muraleekrishnan Menon, K. Szewc, Vishal Maurya
Developments in automotive design such as electrification of engines and a growing need to improve driveline efficiency requires adaption of old techniques. The ability to make fast and accurate Computational Fluid Dynamics (CFD) assessment is of high importance to the development of novel powertrains. Consequently, innovative numerical techniques and continuous improvements to existing CFD codes is relevant to ensure reliability. This work extends the capabilities of a Smoothed Particle Hydrodynamics (SPH) code to include multiphase modeling, studied using a gearbox model. A vast majority of CFD codes use grid-based approaches following the Eulerian spatial discretization, which is quite established in engineering applications. Lagrangian based approaches where the moving fluid particles are discretized over time and space present a promising alternative. One of the most common methods of this kind is the Smoothed Particle Hydrodynamics (SPH) method, a fully Lagrangian, particle-based approach for fluid-flow simulations. The main advantage is the absence of numerical grid for computations, which eliminates complexities of interface handling. Nowadays, the SPH approach is more commonly used for hydro-engineering applications involving free-surface flows. New techniques to perform numerical simulations on Graphics Processing Units (GPU) virtually eliminates some of the disadvantages of the method. In this work, we present our multi-GPU solution designed for both GPU-equipped desktops and multi-GPU supercomputers. Fluid dynamic simulations on a single gearbox model is used to validate the multiphase model, by comparing the results with earlier simulations that use a single-phase model omitting air-lubricant interface in the gearbox. The base case in the study is a single bevel gear placed inside a cuboid case with a lubricant depth equivalent to 25% gear diameter. Simulations are performed at various rotational speeds, and corresponding lubricant distribution and churning losses are obtained. The current study targets a comparison of the single-phase and multiphase models in approximating the lubricant distribution and churning loss values at nominal rotational speeds. This serves to standardize the numerical procedure, which will help in improving the accuracy of churning loss calculations through validations against experimental results in the future.
{"title":"Multi-Phase Gearbox Modelling Using GPU-Accelerated Smoothed Particle Hydrodynamics Method","authors":"Muraleekrishnan Menon, K. Szewc, Vishal Maurya","doi":"10.1115/ajkfluids2019-5592","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5592","url":null,"abstract":"\u0000 Developments in automotive design such as electrification of engines and a growing need to improve driveline efficiency requires adaption of old techniques. The ability to make fast and accurate Computational Fluid Dynamics (CFD) assessment is of high importance to the development of novel powertrains. Consequently, innovative numerical techniques and continuous improvements to existing CFD codes is relevant to ensure reliability. This work extends the capabilities of a Smoothed Particle Hydrodynamics (SPH) code to include multiphase modeling, studied using a gearbox model.\u0000 A vast majority of CFD codes use grid-based approaches following the Eulerian spatial discretization, which is quite established in engineering applications. Lagrangian based approaches where the moving fluid particles are discretized over time and space present a promising alternative. One of the most common methods of this kind is the Smoothed Particle Hydrodynamics (SPH) method, a fully Lagrangian, particle-based approach for fluid-flow simulations. The main advantage is the absence of numerical grid for computations, which eliminates complexities of interface handling. Nowadays, the SPH approach is more commonly used for hydro-engineering applications involving free-surface flows. New techniques to perform numerical simulations on Graphics Processing Units (GPU) virtually eliminates some of the disadvantages of the method. In this work, we present our multi-GPU solution designed for both GPU-equipped desktops and multi-GPU supercomputers.\u0000 Fluid dynamic simulations on a single gearbox model is used to validate the multiphase model, by comparing the results with earlier simulations that use a single-phase model omitting air-lubricant interface in the gearbox. The base case in the study is a single bevel gear placed inside a cuboid case with a lubricant depth equivalent to 25% gear diameter. Simulations are performed at various rotational speeds, and corresponding lubricant distribution and churning losses are obtained. The current study targets a comparison of the single-phase and multiphase models in approximating the lubricant distribution and churning loss values at nominal rotational speeds. This serves to standardize the numerical procedure, which will help in improving the accuracy of churning loss calculations through validations against experimental results in the future.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"201 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":"116625831","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/ajkfluids2019-5017
Y. Jeong, Seongmin Son, Seong Kuk Cho, Seungjoon Baik, Jeong-Ik Lee
Most of the power plants operating nowadays mainly have adopted a steam Rankine cycle or a gas Brayton cycle. To devise a better power conversion cycle, various approaches were taken by researchers and one of the examples is an S-CO2 (supercritical CO2) power cycle. Over the past decades, the S-CO2 power cycle was invented and studied. Eventually the cycle was successful for attracting attentions from a wide range of applications. Basically, an S-CO2 power cycle is a variation of a gas Brayton cycle. In contrast to the fact that an ordinary Brayton cycle operates with a gas phase fluid, the S-CO2 power cycle operates with a supercritical phase fluid, where temperatures and pressures of working fluid are above the critical point. Many advantages of S-CO2 power cycle are rooted from its novel characteristics. Particularly, a compressor in an S-CO2 power cycle operates near the critical point, where the compressibility is greatly reduced. Since the S-CO2 power cycle greatly benefits from the reduced compression work, an S-CO2 compressor prediction under off-design condition has a huge impact on overall cycle performance. When off-design operations of a power cycle are considered, the compressor performance needs to be specified. One of the approaches for a compressor off-design performance evaluation is to use the correction methods based on similitude analysis. However, there are several approaches for deriving the equivalent conditions but none of the approaches has been thoroughly examined for S-CO2 conditions based on data. The purpose of this paper is comparing these correction models to identify the best fitted approach, in order to predict a compressor off-design operation performance more accurately from limited amount of information. Each correction method was applied to two sets of data, SCEIL experiment data and 1D turbomachinery code off-design prediction code generated data, and evaluated in this paper.
{"title":"A Comparison Study for Off-Design Performance Prediction of a Supercritical CO2 Compressor With Similitude Analysis","authors":"Y. Jeong, Seongmin Son, Seong Kuk Cho, Seungjoon Baik, Jeong-Ik Lee","doi":"10.1115/ajkfluids2019-5017","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5017","url":null,"abstract":"\u0000 Most of the power plants operating nowadays mainly have adopted a steam Rankine cycle or a gas Brayton cycle. To devise a better power conversion cycle, various approaches were taken by researchers and one of the examples is an S-CO2 (supercritical CO2) power cycle. Over the past decades, the S-CO2 power cycle was invented and studied. Eventually the cycle was successful for attracting attentions from a wide range of applications. Basically, an S-CO2 power cycle is a variation of a gas Brayton cycle. In contrast to the fact that an ordinary Brayton cycle operates with a gas phase fluid, the S-CO2 power cycle operates with a supercritical phase fluid, where temperatures and pressures of working fluid are above the critical point. Many advantages of S-CO2 power cycle are rooted from its novel characteristics.\u0000 Particularly, a compressor in an S-CO2 power cycle operates near the critical point, where the compressibility is greatly reduced. Since the S-CO2 power cycle greatly benefits from the reduced compression work, an S-CO2 compressor prediction under off-design condition has a huge impact on overall cycle performance. When off-design operations of a power cycle are considered, the compressor performance needs to be specified. One of the approaches for a compressor off-design performance evaluation is to use the correction methods based on similitude analysis. However, there are several approaches for deriving the equivalent conditions but none of the approaches has been thoroughly examined for S-CO2 conditions based on data. The purpose of this paper is comparing these correction models to identify the best fitted approach, in order to predict a compressor off-design operation performance more accurately from limited amount of information. Each correction method was applied to two sets of data, SCEIL experiment data and 1D turbomachinery code off-design prediction code generated data, and evaluated in this paper.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"68 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":"122728353","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/ajkfluids2019-4693
Jeong Park, S. H. Park, M. Cha, S. Chung
The effect of DC electric field on the behaviors of spreading flame over polyethylene (PE)-insulated twin electrical wires was investigated by varying the wire gap (S) and voltage (VDC). The twin flame spreads with the same flame spread rate (FSR) independently when no electric field is applied. With an applied DC electric field, the twin flame interacts such that FSR, flame width, and the leaning direction of interacting twin flames vary appreciably. The spread rate for wire flame with negative voltage (SF–) was larger than that with positive voltage (SF+) during transient period and then the two became the same in a developed region (a quasi-steady spread). Such a flame behavior could be grouped into two: twin flame spread (regime I) and single flame spread (regime II) after the extinction of SF+. Each regime could be categorized into three sub-regimes depending on S and VDC. For small VDC, the flame leaned toward the burnt wire, reducing FSR. With further increasing VDC, FSR increased due to the ionic wind effect and then decreased via the mass loss of molten PE. These non-monotonic behavior of FSR with DC voltage can be attributed the behaviors of molten PE, exhibiting dripping, electrospray, and di-electrophoresis phenomena. For further increased voltage, the flames were extinguished by streamer generation and an electrical short occurred at excessive voltages.
{"title":"Effect of DC Electric Fields on Flame Spread Over Twin Electrical Wires","authors":"Jeong Park, S. H. Park, M. Cha, S. Chung","doi":"10.1115/ajkfluids2019-4693","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4693","url":null,"abstract":"\u0000 The effect of DC electric field on the behaviors of spreading flame over polyethylene (PE)-insulated twin electrical wires was investigated by varying the wire gap (S) and voltage (VDC). The twin flame spreads with the same flame spread rate (FSR) independently when no electric field is applied. With an applied DC electric field, the twin flame interacts such that FSR, flame width, and the leaning direction of interacting twin flames vary appreciably. The spread rate for wire flame with negative voltage (SF–) was larger than that with positive voltage (SF+) during transient period and then the two became the same in a developed region (a quasi-steady spread). Such a flame behavior could be grouped into two: twin flame spread (regime I) and single flame spread (regime II) after the extinction of SF+. Each regime could be categorized into three sub-regimes depending on S and VDC. For small VDC, the flame leaned toward the burnt wire, reducing FSR. With further increasing VDC, FSR increased due to the ionic wind effect and then decreased via the mass loss of molten PE. These non-monotonic behavior of FSR with DC voltage can be attributed the behaviors of molten PE, exhibiting dripping, electrospray, and di-electrophoresis phenomena. For further increased voltage, the flames were extinguished by streamer generation and an electrical short occurred at excessive voltages.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"2 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":"123899084","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/ajkfluids2019-5101
J. Weinmeister, E. Dominguez-Ontiveros, C. Barbier
The Proton Power Upgrade (PPU) project will increase the proton beam power at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL), requiring new cavitation erosion mitigation techniques for the mercury target vessel. More precisely, a gas wall layer will be injected on the wall surface where heavy cavitation erosion is observed. In this paper, a series of experiments were performed to develop a gas layer on a simplified target geometry. First, experiments in water were used to test a prototype injection strategy in a simplified target nose geometry. Then the experiment was repeated at the Target Test Facility (TTF) at ORNL where mercury wass flowed in the same geometry. Observations showed that gas injection into liquid metal was much more sensitive to flow velocity than in water. Ultimately, the experiments showed the gas injection must be located very close to the area of interest in a non-intrusive configuration to reduce shear stresses in the flow for good gas coverage. This technique will be next implemented in a more prototypical target.
{"title":"Gas Wall Layer Experiments for SNS Target","authors":"J. Weinmeister, E. Dominguez-Ontiveros, C. Barbier","doi":"10.1115/ajkfluids2019-5101","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5101","url":null,"abstract":"\u0000 The Proton Power Upgrade (PPU) project will increase the proton beam power at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL), requiring new cavitation erosion mitigation techniques for the mercury target vessel. More precisely, a gas wall layer will be injected on the wall surface where heavy cavitation erosion is observed. In this paper, a series of experiments were performed to develop a gas layer on a simplified target geometry. First, experiments in water were used to test a prototype injection strategy in a simplified target nose geometry. Then the experiment was repeated at the Target Test Facility (TTF) at ORNL where mercury wass flowed in the same geometry. Observations showed that gas injection into liquid metal was much more sensitive to flow velocity than in water. Ultimately, the experiments showed the gas injection must be located very close to the area of interest in a non-intrusive configuration to reduce shear stresses in the flow for good gas coverage. This technique will be next implemented in a more prototypical target.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"25 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":"131723470","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/ajkfluids2019-5138
Junya Ishiyama, K. Fujii, K. Asada, S. Sekimoto, M. Koishi, Toshiyuki Ikeda
Acoustic fields obtained by large-eddy simulations around a rotating tire with the grooves are investigated to clarify the relationships between the shape parameters of the grooves and the directivity of noise sound. To acquire acoustic field around the rotating tire, the large-eddy simulations using the sixth-order compact finite difference scheme and the tridiagonal filter are performed. The sixteen cases including the non-groove case are considered in the present study. To evaluate the acoustic noise from the groove, the sound pressure level (SPL) of each point is computed, and the difference between the cases with and without the groove is investigated. The obtained Results indicate that the width at the opening side of the groove strongly impacts on the acoustic field, and the acoustic noise is reduced as the width at the opening side increases. Additionally, the acoustic noise is reduced as the width at the bottom side increases. However, the depth and the area of the groove do not have a strong relation to the acoustic field. In the viewpoint of the noise directivity, larger the widths at the opening side and the bottom side, and the angle between the bottom and the side wall reduce the acoustic noise on the side of the rotating tire, while that in front of the tire increase. These results provide new insight into our understanding the mechanism of noise generated from the rotating tire with grooves and may help to make intelligent design for noise reduction.
{"title":"Evaluations of Shape Parameter of Groove for Reducing Noise Generated From Rotating Tires","authors":"Junya Ishiyama, K. Fujii, K. Asada, S. Sekimoto, M. Koishi, Toshiyuki Ikeda","doi":"10.1115/ajkfluids2019-5138","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5138","url":null,"abstract":"\u0000 Acoustic fields obtained by large-eddy simulations around a rotating tire with the grooves are investigated to clarify the relationships between the shape parameters of the grooves and the directivity of noise sound. To acquire acoustic field around the rotating tire, the large-eddy simulations using the sixth-order compact finite difference scheme and the tridiagonal filter are performed. The sixteen cases including the non-groove case are considered in the present study. To evaluate the acoustic noise from the groove, the sound pressure level (SPL) of each point is computed, and the difference between the cases with and without the groove is investigated. The obtained Results indicate that the width at the opening side of the groove strongly impacts on the acoustic field, and the acoustic noise is reduced as the width at the opening side increases. Additionally, the acoustic noise is reduced as the width at the bottom side increases. However, the depth and the area of the groove do not have a strong relation to the acoustic field. In the viewpoint of the noise directivity, larger the widths at the opening side and the bottom side, and the angle between the bottom and the side wall reduce the acoustic noise on the side of the rotating tire, while that in front of the tire increase. These results provide new insight into our understanding the mechanism of noise generated from the rotating tire with grooves and may help to make intelligent design for noise reduction.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"1 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":"129098407","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/ajkfluids2019-4902
K. Yousef, A. Hegazy, A. Engeda
Computational Fluid Dynamics (CFD) for air/water-vapor and water-liquid two-phase flow mixing with condensation in a vertical inverted U-tube is presented in this paper. This study is to investigate the flow behaviors and underlying some physical mechanisms encountered in air/water-vapor and water-liquid mixing flow when condensation is considered. Water-liquid flows upward-downward through the inverted U-tube while the air/water-vapor mixture is extracted from a side-tube just after the flow oriented downward. The CFD simulation is carried out for a side air/water-vapor mixture volume fraction (αm) of 0.2–0.7, water-vapor mass fraction (Xv) of 0.1–0.5 in the side air/water-vapor mixture and water-liquid mass flowrate (mw) of 2,4,6, and 8 kg/s. The present results reveal that, at lower air mass flow rate, no significant effect of Xv on the generated static pressure at the inverted U-tube higher part. However, by increasing the air mass flow rates, ma ≥ 0.001 at mw = 2 kg/s, and ma ≥ 0.00125 at mw = 4 kg/s, we can infer that the lowest static pressure can be attained at Xv = 0.1. This may be attributed to the increased vapor and air mass flow rates from the side tube which results in shifting the condensation from the tube highest part due to air accumulation. This leads to increasing the flow pressure and decelerating the water-liquid flow. Raising mw from 2 to 4 kg/s at the same vapor mass ratio results in a lower static pressure due to more condensation of water vapor. The turbulent intensity and kinetic energy starts to drop approximately at ma = 0.002 kg/s, and αm = 0.55–0.76 at mw = 2 kg/s for all Xv values but no noticeable change at mw = 4 kg/s occurs. These findings estimate the operational values of air and water mass flow rates for stable air entrainment from the side-tube. Increasing the air and vapor mass ratio over these values may block the evacuation process and fails the system continuance. Likewise more air entrainment from the side-tube will decelerate the water flow through the inverted U-tube and hence the flow velocity will decrease thereafter. Moreover, this study reveals that the inverted U-tube is able to generate a vacuum pressure down to 55.104 kPa for the present model when vapor condensation is considered. This generated low-pressure helps to vent an engineering system from the non-condensable gases and water vapor that fail its function if these are accumulated with time. Moreover, the water-liquid mass flow rate in the inverted U-tube can be used to sustain the required operating pressure for this system and extract the non-condensable gases with a less energy consuming system. The present CFD model provides a good physical understanding of the flow behavior for air/water-vapor and water-liquid flow for possible future application in the steam power plant.
{"title":"Effect of Moisture Content on Mixing Air With Water-Liquid Flowing Through Inverted U-Tube for Power Plant Condenser Applications","authors":"K. Yousef, A. Hegazy, A. Engeda","doi":"10.1115/ajkfluids2019-4902","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4902","url":null,"abstract":"\u0000 Computational Fluid Dynamics (CFD) for air/water-vapor and water-liquid two-phase flow mixing with condensation in a vertical inverted U-tube is presented in this paper. This study is to investigate the flow behaviors and underlying some physical mechanisms encountered in air/water-vapor and water-liquid mixing flow when condensation is considered. Water-liquid flows upward-downward through the inverted U-tube while the air/water-vapor mixture is extracted from a side-tube just after the flow oriented downward. The CFD simulation is carried out for a side air/water-vapor mixture volume fraction (αm) of 0.2–0.7, water-vapor mass fraction (Xv) of 0.1–0.5 in the side air/water-vapor mixture and water-liquid mass flowrate (mw) of 2,4,6, and 8 kg/s. The present results reveal that, at lower air mass flow rate, no significant effect of Xv on the generated static pressure at the inverted U-tube higher part. However, by increasing the air mass flow rates, ma ≥ 0.001 at mw = 2 kg/s, and ma ≥ 0.00125 at mw = 4 kg/s, we can infer that the lowest static pressure can be attained at Xv = 0.1. This may be attributed to the increased vapor and air mass flow rates from the side tube which results in shifting the condensation from the tube highest part due to air accumulation. This leads to increasing the flow pressure and decelerating the water-liquid flow. Raising mw from 2 to 4 kg/s at the same vapor mass ratio results in a lower static pressure due to more condensation of water vapor. The turbulent intensity and kinetic energy starts to drop approximately at ma = 0.002 kg/s, and αm = 0.55–0.76 at mw = 2 kg/s for all Xv values but no noticeable change at mw = 4 kg/s occurs. These findings estimate the operational values of air and water mass flow rates for stable air entrainment from the side-tube. Increasing the air and vapor mass ratio over these values may block the evacuation process and fails the system continuance. Likewise more air entrainment from the side-tube will decelerate the water flow through the inverted U-tube and hence the flow velocity will decrease thereafter. Moreover, this study reveals that the inverted U-tube is able to generate a vacuum pressure down to 55.104 kPa for the present model when vapor condensation is considered. This generated low-pressure helps to vent an engineering system from the non-condensable gases and water vapor that fail its function if these are accumulated with time. Moreover, the water-liquid mass flow rate in the inverted U-tube can be used to sustain the required operating pressure for this system and extract the non-condensable gases with a less energy consuming system. The present CFD model provides a good physical understanding of the flow behavior for air/water-vapor and water-liquid flow for possible future application in the steam power plant.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"1 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":"129800399","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/ajkfluids2019-5146
Young-Seok Choi, Yong-In Kim, Sung Kim, Seul Lee, Hyeon-Mo Yang, Kyoung-Yong Lee
This paper describes the numerical optimization of an axial fan focused on the blade and guide vane (GV). For numerical analysis, three-dimensional (3D) steady-state Reynolds-averaged Navier-Stokes (RANS) equations with the shear stress transport (SST) turbulence model are discretized by the finite volume method (FVM). The objective function is enhancement of aerodynamic performance with specified total pressure. To select the design variables which have main effect to the objective function, 2k factorial design is employed as a method for design of experiment (DOE). In addition, response surface method (RSM) based on the central composite design applied to carry out the single-objective optimization. Effects on the components such as bell mouth and hub cap are considered with previous analysis. The internal flow characteristics between base and optimized model are analyzed and discussed.
{"title":"A Study on Improvement of Aerodynamic Performance for 100HP Axial Fan Blade and Guide Vane Using Response Surface Method","authors":"Young-Seok Choi, Yong-In Kim, Sung Kim, Seul Lee, Hyeon-Mo Yang, Kyoung-Yong Lee","doi":"10.1115/ajkfluids2019-5146","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5146","url":null,"abstract":"\u0000 This paper describes the numerical optimization of an axial fan focused on the blade and guide vane (GV). For numerical analysis, three-dimensional (3D) steady-state Reynolds-averaged Navier-Stokes (RANS) equations with the shear stress transport (SST) turbulence model are discretized by the finite volume method (FVM). The objective function is enhancement of aerodynamic performance with specified total pressure. To select the design variables which have main effect to the objective function, 2k factorial design is employed as a method for design of experiment (DOE). In addition, response surface method (RSM) based on the central composite design applied to carry out the single-objective optimization. Effects on the components such as bell mouth and hub cap are considered with previous analysis. The internal flow characteristics between base and optimized model are analyzed and discussed.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"71 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":"133730805","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/ajkfluids2019-4993
Chang Qiu, Han Zhang, Chen Yang, Cong-wei Hou, Zhi-jiang Jin, J. Qian
Steam trap valves are mainly used in thermal power systems to pour out condensate water and keep steam inside. While during the condensate water flowing through steam trap valves, the condensate water is easy to reaching cavitation, which may cause serious damage to the piping system. In order to reducing the cavitation occupation in steam trap valves, this paper mainly deals with an optimization study. With Computational Fluid Dynamics codes, numerical model of a typical steam trap valve is established with Mixture model. The inner pressure field, flow field and steam volume fraction are all achieved under both maximum flow rate working condition and regular working condition. Based on the cavitation results, the throttling stages of the steam trap valve are optimized. And the results show that cavitation range inside the steam trap valve is reduced.
{"title":"An Optimization Study on Cavitation Flow in a Steam Trap Valve","authors":"Chang Qiu, Han Zhang, Chen Yang, Cong-wei Hou, Zhi-jiang Jin, J. Qian","doi":"10.1115/ajkfluids2019-4993","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4993","url":null,"abstract":"\u0000 Steam trap valves are mainly used in thermal power systems to pour out condensate water and keep steam inside. While during the condensate water flowing through steam trap valves, the condensate water is easy to reaching cavitation, which may cause serious damage to the piping system. In order to reducing the cavitation occupation in steam trap valves, this paper mainly deals with an optimization study. With Computational Fluid Dynamics codes, numerical model of a typical steam trap valve is established with Mixture model. The inner pressure field, flow field and steam volume fraction are all achieved under both maximum flow rate working condition and regular working condition. Based on the cavitation results, the throttling stages of the steam trap valve are optimized. And the results show that cavitation range inside the steam trap valve is reduced.","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":"121244292","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/ajkfluids2019-4719
Cheng Liu, Meng Guo, Wei Wei, Q. Yan, P. Li
A lot of efforts were put into the design of torque converter blade angles and the analysis of transient flow behaviors; yet little is known about the influence of the blade thickness distribution on the performance or structural response of a torque converter. This study proposed a parameterized blade thickness design model and analyzed the effects of the blade thickness on hydrodynamic performance and structural response using fluid-structure interaction (FSI) models. Both one-way FSI model and two-way FSI model were built and evaluated against test data, and it was found that the transient two-way FSI model outperformed the steady-state FSI model in terms of both flow and structure simulations. It was found that the stall torque ratio and peak efficiency exhibited positive correlations with blade thicknesses, whereas the stall capacity constant was inversely related to blade thicknesses. Both numerical and experimental results suggested that the pump-turbine interaction induced serious flow fluctuations, and FSI simulations were required in the design process to avoid potential resonance.
{"title":"Investigation on the Effects of Torque Converter Blade Thickness Based on FSI Simulation","authors":"Cheng Liu, Meng Guo, Wei Wei, Q. Yan, P. Li","doi":"10.1115/ajkfluids2019-4719","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4719","url":null,"abstract":"\u0000 A lot of efforts were put into the design of torque converter blade angles and the analysis of transient flow behaviors; yet little is known about the influence of the blade thickness distribution on the performance or structural response of a torque converter. This study proposed a parameterized blade thickness design model and analyzed the effects of the blade thickness on hydrodynamic performance and structural response using fluid-structure interaction (FSI) models. Both one-way FSI model and two-way FSI model were built and evaluated against test data, and it was found that the transient two-way FSI model outperformed the steady-state FSI model in terms of both flow and structure simulations. It was found that the stall torque ratio and peak efficiency exhibited positive correlations with blade thicknesses, whereas the stall capacity constant was inversely related to blade thicknesses. Both numerical and experimental results suggested that the pump-turbine interaction induced serious flow fluctuations, and FSI simulations were required in the design process to avoid potential resonance.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"1 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":"131125086","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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