In recent years, the increasing demand for more and more compact and efficient solutions has highlighted the need to have appropriate tools in order to optimize the internal design, to avoid thermal problems, ensuring proper lubrication and to increase the reliability of the systems. Typical high power density gearbox designs are based on planetary, harmonic and cycloidal architectures. Although many analytical and numerical models are already available for the prediction of the power losses related to gear meshing (sliding), bearings and seals, literature is lacking in terms of hydraulic power loss models (deep lubrication, churning, windage and squeezing). Some numerical multiphase CFD and experimental studies on parallel axis and planetary gear sets have been already performed by the authors in previous research. The aim of this paper is to extend the applicability of the previously developed numerical techniques to cycloidal architectures, taking into account the typical lubricants used for these type of drives. With respect to the load independent power losses (related to the interaction of the mechanical component and the surrounding lubricant), the cycloidal gear set has been numerically simulated with an especially developed CFD code implemented in the OpenFOAM® environment. A specific mesh handling technique allows us to manage the topological changes of the domain ensuring the numerical stability of the simulation and the correct calculation of the complex multiphase flows that take place in gearboxes. The results have been compared with those already available for other gear architectures with similar performances (dimensions, reduction ratios and loads).
{"title":"LUBRICATION OF GEARBOXES: CFD ANALYSIS OF A CYCLOIDAL GEAR SET","authors":"F. Concli, L. Maccioni, C. Gorla","doi":"10.2495/MPF190101","DOIUrl":"https://doi.org/10.2495/MPF190101","url":null,"abstract":"In recent years, the increasing demand for more and more compact and efficient solutions has highlighted the need to have appropriate tools in order to optimize the internal design, to avoid thermal problems, ensuring proper lubrication and to increase the reliability of the systems. Typical high power density gearbox designs are based on planetary, harmonic and cycloidal architectures. Although many analytical and numerical models are already available for the prediction of the power losses related to gear meshing (sliding), bearings and seals, literature is lacking in terms of hydraulic power loss models (deep lubrication, churning, windage and squeezing). Some numerical multiphase CFD and experimental studies on parallel axis and planetary gear sets have been already performed by the authors in previous research. The aim of this paper is to extend the applicability of the previously developed numerical techniques to cycloidal architectures, taking into account the typical lubricants used for these type of drives. With respect to the load independent power losses (related to the interaction of the mechanical component and the surrounding lubricant), the cycloidal gear set has been numerically simulated with an especially developed CFD code implemented in the OpenFOAM® environment. A specific mesh handling technique allows us to manage the topological changes of the domain ensuring the numerical stability of the simulation and the correct calculation of the complex multiphase flows that take place in gearboxes. The results have been compared with those already available for other gear architectures with similar performances (dimensions, reduction ratios and loads).","PeriodicalId":399001,"journal":{"name":"Computational and Experimental Methods in Multiphase and Complex Flow X","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132189606","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}
K. Hughes, K. Prestridge, N. Kim, R. Haftka, S. Balachandar
A series of experiments performed at Los Alamos National Laboratory aimed to provide validation data for numerical simulations performed at the Centre of Compressible Multiphase Turbulence at the University of Florida. Five explosive tests were performed. Approximately 2.8 g of PBX-9501 was initiated by a RP-80 detonator. A 13 x 6 mm cylindrical packet of 100 μm steel particles was dispersed by the explosive. Three ambient carrier fluids were investigated: air, xenon, and SF6. To penetrate the optically opaque explosive products at the early time and track the dispersed particle cloud, radiography was required. Proton radiography performed at the Los Alamos Neutron Science Centre allowed extraction of 21 radiograph images at 2 μs temporal resolution. Upstream and downstream particle fronts were extracted from the transmission radiographs. Centreline particle fronts for the three carrier phases demonstrated close agreement, suggesting the shock traversing the bed of particles provided little additional impulse to the dispersed particles in this regime. An additional shot was performed in vacuum and showed close agreement with the carrier phase shots, furthering this conclusion.
在洛斯阿拉莫斯国家实验室进行的一系列实验旨在为佛罗里达大学可压缩多相湍流中心进行的数值模拟提供验证数据。进行了五次爆炸试验。大约2.8 g PBX-9501由RP-80雷管引爆。由100 μm钢颗粒组成的13 × 6 mm圆柱形包被炸药分散。研究了三种环境载液:空气、氙气和SF6。为了及早穿透光学不透明的爆炸产物并追踪分散的颗粒云，需要采用射线照相技术。在洛斯阿拉莫斯中子科学中心进行的质子射线照相允许以2 μs的时间分辨率提取21张射线图像。从透射射线图中提取了上游和下游粒子锋面。三个载流子相的中心线粒子锋面表现出密切的一致性，这表明在该状态下，穿过粒子床的激波对分散的粒子几乎没有额外的冲击。在真空中进行了额外的射击，并显示与载体相射击密切一致，进一步证实了这一结论。
{"title":"PROTON RADIOGRAPHY OF EXPLOSIVELY DISPERSED METAL PARTICLES WITH VARYING CARRIER FLUID","authors":"K. Hughes, K. Prestridge, N. Kim, R. Haftka, S. Balachandar","doi":"10.2495/MPF190211","DOIUrl":"https://doi.org/10.2495/MPF190211","url":null,"abstract":"A series of experiments performed at Los Alamos National Laboratory aimed to provide validation data for numerical simulations performed at the Centre of Compressible Multiphase Turbulence at the University of Florida. Five explosive tests were performed. Approximately 2.8 g of PBX-9501 was initiated by a RP-80 detonator. A 13 x 6 mm cylindrical packet of 100 μm steel particles was dispersed by the explosive. Three ambient carrier fluids were investigated: air, xenon, and SF6. To penetrate the optically opaque explosive products at the early time and track the dispersed particle cloud, radiography was required. Proton radiography performed at the Los Alamos Neutron Science Centre allowed extraction of 21 radiograph images at 2 μs temporal resolution. Upstream and downstream particle fronts were extracted from the transmission radiographs. Centreline particle fronts for the three carrier phases demonstrated close agreement, suggesting the shock traversing the bed of particles provided little additional impulse to the dispersed particles in this regime. An additional shot was performed in vacuum and showed close agreement with the carrier phase shots, furthering this conclusion.","PeriodicalId":399001,"journal":{"name":"Computational and Experimental Methods in Multiphase and Complex Flow X","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123231324","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}
In this work, a novel homotopy analysis method for the solution of two-fluid models is presented. A fully developed bubbly through a pipe is considered. Different physical and mathematical properties of the two-fluid model were identified. The problem was solved in the central region of the pipe where the wall forces were neglected, which implies that void fractions and velocity profiles are not affected by the wall. The system of equations was reduced to a single equation without parameters with an intrinsic length scale L. Away from the wall of the pipe, the flat void fraction depends on the applied pressure gradient, the density of different phases and gravity. It was also found that the effective specific weight of the fluid column was cancelled by the pressure gradient.
{"title":"FULLY DEVELOPED BUBBLY TWO-PHASE FLOW THROUGH A PIPE: AN ANALYTICAL SOLUTION","authors":"W. Ali, M. Nazeer, A. Zeeshan","doi":"10.2495/MPF190141","DOIUrl":"https://doi.org/10.2495/MPF190141","url":null,"abstract":"In this work, a novel homotopy analysis method for the solution of two-fluid models is presented. A fully developed bubbly through a pipe is considered. Different physical and mathematical properties of the two-fluid model were identified. The problem was solved in the central region of the pipe where the wall forces were neglected, which implies that void fractions and velocity profiles are not affected by the wall. The system of equations was reduced to a single equation without parameters with an intrinsic length scale L. Away from the wall of the pipe, the flat void fraction depends on the applied pressure gradient, the density of different phases and gravity. It was also found that the effective specific weight of the fluid column was cancelled by the pressure gradient.","PeriodicalId":399001,"journal":{"name":"Computational and Experimental Methods in Multiphase and Complex Flow X","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125975321","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}
B. Houchens, Sarah N. Scott, Victor E. Brunini, E. Jones, M. Montoya, Wendy Flores-Brito, K. Hoffmeister
It is experimentally observed that multilayer fibre–resin composites can soften and swell significantly when heated above their designed operating temperatures. This swelling is expected to further accelerate the pyrolysis, releasing volatile components which can ignite in an oxygenated environment if exposed to a spark, flame or sufficiently elevated temperature. Here the intumescent behaviour of resin-infused carbon-fibre is investigated. Preliminary experiments and simulations are compared for a carbon-fibre sample radiatively heated on the top side and insulated on the bottom. Simulations consider coupled thermal and porous media flow.
{"title":"SWELLING DURING PYROLYSIS OF FIBRERESIN COMPOSITES WHEN HEATED ABOVE NORMAL OPERATING TEMPERATURES","authors":"B. Houchens, Sarah N. Scott, Victor E. Brunini, E. Jones, M. Montoya, Wendy Flores-Brito, K. Hoffmeister","doi":"10.2495/MPF190171","DOIUrl":"https://doi.org/10.2495/MPF190171","url":null,"abstract":"It is experimentally observed that multilayer fibre–resin composites can soften and swell significantly when heated above their designed operating temperatures. This swelling is expected to further accelerate the pyrolysis, releasing volatile components which can ignite in an oxygenated environment if exposed to a spark, flame or sufficiently elevated temperature. Here the intumescent behaviour of resin-infused carbon-fibre is investigated. Preliminary experiments and simulations are compared for a carbon-fibre sample radiatively heated on the top side and insulated on the bottom. Simulations consider coupled thermal and porous media flow.","PeriodicalId":399001,"journal":{"name":"Computational and Experimental Methods in Multiphase and Complex Flow X","volume":"594 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134063033","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}
J. Muñoz-Cobo, S. M. Iglesias, D. S. Dominguez, A. Escrivá, C. Berna
Gravity-driven falling film flows in vertical pipes are relevant in many industrial processes like evaporators, chemical reactors, and condensers. The wave formation and propagation processes, which continuously take place in the film, have a strong influence on the flow hydrodynamics and the heat and mass transfer phenomena. Several researchers have been studying the wave behaviour in these multiphase regimes through experimental works and computational fluid dynamics simulation techniques. In some simplified cases, like high viscosity fluids and infinity inclined plates, analytical solutions have been obtained. In this work, we propose an analytical model for falling film flow regimes in vertical pipes. Starting from the incompressible axisymmetric Navier–Stokes equations in cylindrical coordinates, we consider the force balance in the fluid, an asymptotic long-wave approximation and the first-order perturbation approximation for axial velocity. From this balance, we obtain a partial differential equation that describes the interface behaviour through the film thickness. The resulting equation can be solved using a numerical approach. The main resulting equation represents a stiff problem, thus, we perform a stability analysis using the fluid viscosity as a parameter. Finally, we set the model validity conditions and suggest some actions to improve the numerical strategy in order to better describe low viscosity fluids.
{"title":"ANALYTICAL MODEL AND NUMERICAL STABILITY ANALYSIS FOR FALLING LIQUID FILM REGIMES IN VERTICAL PIPES","authors":"J. Muñoz-Cobo, S. M. Iglesias, D. S. Dominguez, A. Escrivá, C. Berna","doi":"10.2495/MPF190091","DOIUrl":"https://doi.org/10.2495/MPF190091","url":null,"abstract":"Gravity-driven falling film flows in vertical pipes are relevant in many industrial processes like evaporators, chemical reactors, and condensers. The wave formation and propagation processes, which continuously take place in the film, have a strong influence on the flow hydrodynamics and the heat and mass transfer phenomena. Several researchers have been studying the wave behaviour in these multiphase regimes through experimental works and computational fluid dynamics simulation techniques. In some simplified cases, like high viscosity fluids and infinity inclined plates, analytical solutions have been obtained. In this work, we propose an analytical model for falling film flow regimes in vertical pipes. Starting from the incompressible axisymmetric Navier–Stokes equations in cylindrical coordinates, we consider the force balance in the fluid, an asymptotic long-wave approximation and the first-order perturbation approximation for axial velocity. From this balance, we obtain a partial differential equation that describes the interface behaviour through the film thickness. The resulting equation can be solved using a numerical approach. The main resulting equation represents a stiff problem, thus, we perform a stability analysis using the fluid viscosity as a parameter. Finally, we set the model validity conditions and suggest some actions to improve the numerical strategy in order to better describe low viscosity fluids.","PeriodicalId":399001,"journal":{"name":"Computational and Experimental Methods in Multiphase and Complex Flow X","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130285426","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}
L. Prada, A. Chaves, Julio Pedraza, Jose Gómez, S. Muñoz
Polymeric liquids have been used in the oil industry, especially at enhanced oil recovery (EOR). From the rheological point of view, polymers have the particularity of being viscoelastic liquids. One of the most common and useful models to describe that behavior is the upper convected Maxwell model (UCM). The main characteristic of the polymer used in the EOR process is the increase in viscosity which pushes the oil outside of the reservoir. The elasticity could contribute to the drag of the oil that stays in the reservoir. Studying the elastic effect on the oil drop at the pore scale, brings an explanation if the addition of elastic force could mobilize the oil. This research explores if the contraction and expansion of the polymer in the pore-scale may increase the elastic behavior of this kind of fluid. For that reason, this work simplified the pore geometry and built two simple geometries with micrometer lengths. Using source terms with the user defined function this work introduces the UCM model in the ANSYS Fluent simulator with the purpose of evaluating the elastic effect of the polymer in a contraction and expansion geometry. Also, using the Eulerian multiphase model this research considers the possibility that extra elastic force will show a deformation effect on the oil, for that reason, this work considers an oil drop on the upper wall of the geometry. Finally, all the simulations exhibit that at pore scale conditions extra vortices exist in the UCM model but it is not possible to deform the oil completely and push it outside of the restrictions.
{"title":"STUDY OF POLYMER ELASTIC BEHAVIOR IN THE DISPLACEMENT OF OIL DROPS AT PORE SCALE","authors":"L. Prada, A. Chaves, Julio Pedraza, Jose Gómez, S. Muñoz","doi":"10.2495/MPF190161","DOIUrl":"https://doi.org/10.2495/MPF190161","url":null,"abstract":"Polymeric liquids have been used in the oil industry, especially at enhanced oil recovery (EOR). From the rheological point of view, polymers have the particularity of being viscoelastic liquids. One of the most common and useful models to describe that behavior is the upper convected Maxwell model (UCM). The main characteristic of the polymer used in the EOR process is the increase in viscosity which pushes the oil outside of the reservoir. The elasticity could contribute to the drag of the oil that stays in the reservoir. Studying the elastic effect on the oil drop at the pore scale, brings an explanation if the addition of elastic force could mobilize the oil. This research explores if the contraction and expansion of the polymer in the pore-scale may increase the elastic behavior of this kind of fluid. For that reason, this work simplified the pore geometry and built two simple geometries with micrometer lengths. Using source terms with the user defined function this work introduces the UCM model in the ANSYS Fluent simulator with the purpose of evaluating the elastic effect of the polymer in a contraction and expansion geometry. Also, using the Eulerian multiphase model this research considers the possibility that extra elastic force will show a deformation effect on the oil, for that reason, this work considers an oil drop on the upper wall of the geometry. Finally, all the simulations exhibit that at pore scale conditions extra vortices exist in the UCM model but it is not possible to deform the oil completely and push it outside of the restrictions.","PeriodicalId":399001,"journal":{"name":"Computational and Experimental Methods in Multiphase and Complex Flow X","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124594265","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}
Mass exchange through gas–liquid interfaces, whose liquid side has a turbulent nature, are still difficult to quantify due to the unclosed set of turbulence equations, which are also nonlinear. This paper describes an efficient method to overcome this difficulty, by substituting the statistical variables of the original equations by statistical relationships furnished by the Random Square Waves (RSW) tool. Oscillatory records are simplified using random square waves (ideal and binary), which allow a theoretical statistical treatment of the signals. This tool was applied to the concentration boundary layer at the gas–liquid interface. Normalized mass fluxes and mean concentration profiles were obtained using Taylor-series-based solutions, which allow for consideration of transient situations through the successive calculation of the higher order coefficients (derivatives). Comparisons with experimental data available in open literature are presented as a first evaluation of the Taylor series, showing promising results. This method is a viable tool, and this study shows novel conclusions that reproduce general tendencies observed in one-dimensional mass transfer phenomena in boundary layers.
{"title":"MASS TRANSFER THROUGH FREE SURFACE BOUNDARY LAYERS USING A STATISTICAL APPROACH","authors":"Francisco Antonio Loyola Lavin, H. Schulz","doi":"10.2495/MPF190081","DOIUrl":"https://doi.org/10.2495/MPF190081","url":null,"abstract":"Mass exchange through gas–liquid interfaces, whose liquid side has a turbulent nature, are still difficult to quantify due to the unclosed set of turbulence equations, which are also nonlinear. This paper describes an efficient method to overcome this difficulty, by substituting the statistical variables of the original equations by statistical relationships furnished by the Random Square Waves (RSW) tool. Oscillatory records are simplified using random square waves (ideal and binary), which allow a theoretical statistical treatment of the signals. This tool was applied to the concentration boundary layer at the gas–liquid interface. Normalized mass fluxes and mean concentration profiles were obtained using Taylor-series-based solutions, which allow for consideration of transient situations through the successive calculation of the higher order coefficients (derivatives). Comparisons with experimental data available in open literature are presented as a first evaluation of the Taylor series, showing promising results. This method is a viable tool, and this study shows novel conclusions that reproduce general tendencies observed in one-dimensional mass transfer phenomena in boundary layers.","PeriodicalId":399001,"journal":{"name":"Computational and Experimental Methods in Multiphase and Complex Flow X","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133650079","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}
ABSTRACT An antibubble is the opposite of a bubble: a thin spherical gas shell containing liquid inside and surrounded by liquid outside. Although antibubbles are rarely used in industry, they do have some potential applications, such as cleaning, lubrication, filtration and material transport. The dynamic behaviour of antibubbles and spark-induced cavitation bubbles is experimentally studied by using highspeed photography. It is found that when spark discharges occur between the electrodes and the cavitation bubble begin to expand, the antibubble splits into upper and lower parts. The upper parts with more gas produces annular liquid jet under the action of shock wave, and split into two bubbles in the next few cycles under the action of inertial force. The lower parts are composed of semi-spherical shell-like gas film. When the compression wave arrives, the gas film becomes thinner and contacts between the two sides of the gas film appear at some points. When the expansion wave arrives, the gas film becomes thicker and the contact point becomes larger to form holes. As the holes become larger and the gas film shrinks, many scattered microbubbles are formed. The secondary shock wave caused by the collapse of the cavitation bubble which occur a few milliseconds after the first shock wave (spark discharge) was observed by schlieren photography. The physical mechanism of interaction between cavitation bubble and antibubble is analysed.
{"title":"INTERACTION OF A CAVITATION BUBBLE WITH AN ANTIBUBBLE","authors":"Bai Lixin, Xu. Weilin, Yan Jiuchun, Zeng Zhijie","doi":"10.2495/MPF190131","DOIUrl":"https://doi.org/10.2495/MPF190131","url":null,"abstract":"ABSTRACT An antibubble is the opposite of a bubble: a thin spherical gas shell containing liquid inside and surrounded by liquid outside. Although antibubbles are rarely used in industry, they do have some potential applications, such as cleaning, lubrication, filtration and material transport. The dynamic behaviour of antibubbles and spark-induced cavitation bubbles is experimentally studied by using highspeed photography. It is found that when spark discharges occur between the electrodes and the cavitation bubble begin to expand, the antibubble splits into upper and lower parts. The upper parts with more gas produces annular liquid jet under the action of shock wave, and split into two bubbles in the next few cycles under the action of inertial force. The lower parts are composed of semi-spherical shell-like gas film. When the compression wave arrives, the gas film becomes thinner and contacts between the two sides of the gas film appear at some points. When the expansion wave arrives, the gas film becomes thicker and the contact point becomes larger to form holes. As the holes become larger and the gas film shrinks, many scattered microbubbles are formed. The secondary shock wave caused by the collapse of the cavitation bubble which occur a few milliseconds after the first shock wave (spark discharge) was observed by schlieren photography. The physical mechanism of interaction between cavitation bubble and antibubble is analysed.","PeriodicalId":399001,"journal":{"name":"Computational and Experimental Methods in Multiphase and Complex Flow X","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130971838","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}
Polymer devolatilization is a vital process in polymer manufacturing and is significantly impactful on the successful creation of high quality polymers, meeting both rigorous product specifications and regulatory requirements. Polymers resulting from such processes have wide applications ranging from agricultural and biomedical solutions to aerospace components and even to modern day clothing and accessories. Although there are several popular methods used to accomplish the devolatilization process, this research focuses specifically on steam stripping, where superheated steam is used to remove any unwanted substances, such as volatiles and solvents, from the polymer mixture. This polymer mixture, referred to as ”cement” and comprised of polymer and a cyclohexane solvent, undergoes mixing with superheated steam in a contactor to evaporate and remove the cyclohexane. Between the heat and the aerodynamic forces caused by the mixing, the liquid polymer experiences sheet breakup. The objective of the current study is to create a computational fluid dynamics (CFD) model that solves for the initial breakup of the liquid mixture, and then use the resulting diameter distribution to simulate the trajectory and multiphase mass transfer of the cement as it forms into smaller and smaller droplets. A parametric
{"title":"COMPUTATIONAL INVESTIGATIONS OF POLYMER SHEET BREAKUP FOR OPTIMIZATION OF DEVOLATILIZATION PROCESSES IN STEAM CONTACTORS","authors":"Bradley Shindle, A. Chandy","doi":"10.2495/MPF190111","DOIUrl":"https://doi.org/10.2495/MPF190111","url":null,"abstract":"Polymer devolatilization is a vital process in polymer manufacturing and is significantly impactful on the successful creation of high quality polymers, meeting both rigorous product specifications and regulatory requirements. Polymers resulting from such processes have wide applications ranging from agricultural and biomedical solutions to aerospace components and even to modern day clothing and accessories. Although there are several popular methods used to accomplish the devolatilization process, this research focuses specifically on steam stripping, where superheated steam is used to remove any unwanted substances, such as volatiles and solvents, from the polymer mixture. This polymer mixture, referred to as ”cement” and comprised of polymer and a cyclohexane solvent, undergoes mixing with superheated steam in a contactor to evaporate and remove the cyclohexane. Between the heat and the aerodynamic forces caused by the mixing, the liquid polymer experiences sheet breakup. The objective of the current study is to create a computational fluid dynamics (CFD) model that solves for the initial breakup of the liquid mixture, and then use the resulting diameter distribution to simulate the trajectory and multiphase mass transfer of the cement as it forms into smaller and smaller droplets. A parametric","PeriodicalId":399001,"journal":{"name":"Computational and Experimental Methods in Multiphase and Complex Flow X","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126074464","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}
Experimental studies were conducted on the behaviour of water films in a horizontal pipe with a sudden contraction to achieve a fundamental understanding of the film mechanisms of annular flow using high-speed video imaging analysis. The sudden contraction area ratios A C = (d 2 /d 1 ) 2 = 0.36 and 0.64, where d 1 is the inlet pipe diameter (50 mm) and d 2 is the contracted pipe diameter were examined. The experiments were carried out for various values of superficial gas and liquid velocities. The superficial gas velocity after mixing (j G1 ) ranged from 18.02 to 24.41 m/s (the calculated velocity from the cross-sectional at the sudden contraction was j G2 = 27.98–67.39 m/s) and the superficial liquid velocity (j L1 ) ranged from 8.62×10 -2 to 1.23×10 -1 m/s (j L2 = 1.35×10 -1 –3.42×10 -1 m/s). Four flow regimes were observed after the sudden contraction, namely, huge-wave (HW), two-dimensional disturbance wave (DW 1 ) which is formed perpendicularly to a pipe axis having a distinct coherence, three-dimensional disturbance wave (DW 2 ) which is formed obliquely to the pipe axis, and bow wave (DW 3 ) which is transitional wave to “Misty wave” from DW 2 . The disturbance wave occurrence frequencies were studied under various conditions of flow rate combination of air and water. DW 2 occurs over wide range of the superficial gas and liquid velocities. As the superficial gas velocity and the superficial liquid velocity increase, two-dimensional disturbance waves change into three-dimensional ones. The wave occurrence frequencies in the pipe with the sudden contraction ratio A C = 0.36 were mostly higher than those in the pipe with A C = 0.64.
{"title":"TWO-PHASE FLOW PHENOMENA IN A HORIZONTAL PIPE WITH A SUDDEN CONTRACTION: EFFECTS OF CONTRACTION RATIO ON FILM BEHAVIOUR","authors":"T. Fujimatsu, M. Kito, K. Kondo","doi":"10.2495/MPF190061","DOIUrl":"https://doi.org/10.2495/MPF190061","url":null,"abstract":"Experimental studies were conducted on the behaviour of water films in a horizontal pipe with a sudden contraction to achieve a fundamental understanding of the film mechanisms of annular flow using high-speed video imaging analysis. The sudden contraction area ratios A C = (d 2 /d 1 ) 2 = 0.36 and 0.64, where d 1 is the inlet pipe diameter (50 mm) and d 2 is the contracted pipe diameter were examined. The experiments were carried out for various values of superficial gas and liquid velocities. The superficial gas velocity after mixing (j G1 ) ranged from 18.02 to 24.41 m/s (the calculated velocity from the cross-sectional at the sudden contraction was j G2 = 27.98–67.39 m/s) and the superficial liquid velocity (j L1 ) ranged from 8.62×10 -2 to 1.23×10 -1 m/s (j L2 = 1.35×10 -1 –3.42×10 -1 m/s). Four flow regimes were observed after the sudden contraction, namely, huge-wave (HW), two-dimensional disturbance wave (DW 1 ) which is formed perpendicularly to a pipe axis having a distinct coherence, three-dimensional disturbance wave (DW 2 ) which is formed obliquely to the pipe axis, and bow wave (DW 3 ) which is transitional wave to “Misty wave” from DW 2 . The disturbance wave occurrence frequencies were studied under various conditions of flow rate combination of air and water. DW 2 occurs over wide range of the superficial gas and liquid velocities. As the superficial gas velocity and the superficial liquid velocity increase, two-dimensional disturbance waves change into three-dimensional ones. The wave occurrence frequencies in the pipe with the sudden contraction ratio A C = 0.36 were mostly higher than those in the pipe with A C = 0.64.","PeriodicalId":399001,"journal":{"name":"Computational and Experimental Methods in Multiphase and Complex Flow X","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115056063","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：