Dépouillements

High-resolution numerical simulation of low Reynolds number incompressible flow about two cylinders in tandem / Sintu Singha in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 10 p. Titre : High-resolution numerical simulation of low Reynolds number incompressible flow about two cylinders in tandem Type de document : texte imprimé Auteurs : Sintu Singha, Auteur ; K.P. Sinhamahapatra, Auteur Année de publication : 2010 Article en page(s) : 10 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : Reynolds  number;  cylinder Résumé : Low Reynolds number steady and unsteady incompressible flows over two circular cylinders in tandem are numerically simulated for a range of Reynolds numbers with varying gap size. The governing equations are solved on an unstructured collocated mesh using a second-order implicit finite volume method. The effects of the gap and Reynolds number on the vortex structure of the wake and on the fluid dynamic forces acting on the cylinders are reported and discussed. Both the parameters have significant influence on the flow field. An attempt is made to unify their influence on some global parameters. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] High-resolution numerical simulation of low Reynolds number incompressible flow about two cylinders in tandem [texte imprimé] / Sintu Singha, Auteur ; K.P. Sinhamahapatra, Auteur . - 2010 . - 10 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 10 p. Mots-clés : Reynolds  number;  cylinder Résumé : Low Reynolds number steady and unsteady incompressible flows over two circular cylinders in tandem are numerically simulated for a range of Reynolds numbers with varying gap size. The governing equations are solved on an unstructured collocated mesh using a second-order implicit finite volume method. The effects of the gap and Reynolds number on the vortex structure of the wake and on the fluid dynamic forces acting on the cylinders are reported and discussed. Both the parameters have significant influence on the flow field. An attempt is made to unify their influence on some global parameters. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Vorticity dynamics in axial compressor flow diagnosis and design—Part II: methodology and application of boundary vorticity flux / Qiushi Li in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 12 p. Titre : Vorticity dynamics in axial compressor flow diagnosis and design—Part II: methodology and application of boundary vorticity flux Type de document : texte imprimé Auteurs : Qiushi Li, Auteur ; Hong Wu, Auteur ; Ming Guo, Auteur Année de publication : 2010 Article en page(s) : 12 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : boundary  vorticity  flux;  axial  compressor  flow Résumé : In a companion paper (2008, “Vorticity Dynamics in Axial Compressor Flow Diagnosis and Design,” ASME J. Fluids Eng., 130, p. 041102), a study has been made on the critical role of circumferential vorticity (CV) in the performance of axial compressor in through-flow design (TFD). It has been shown there that to enhance the pressure ratio, the positive and negative CV peaks should be pushed to the casing and hub, respectively. This criterion has led to an optimal TFD that indeed improves the pressure ratio and efficiency. The CV also has great impact on the stall margin as it reflects the end wall blockage, especially at the tip region of the compressor. While that work was based on inviscid and axisymmetric theory, in this paper, we move on to the diagnosis and optimal design of fully three-dimensional (3D) viscous flow in axial compressors, focusing on the boundary vorticity flux (BVF), which captures the highly localized peaks of pressure gradient on the surface of the compressor blade, and thereby signifies the boundary layer separation and dominates the work rate done to the fluid by the compressor. For the 2D cascade flow we show that the BVF is directly related to the blade geometry. BVF-based 2D and 3D optimal blade design methodologies are developed to control the velocity diffusion, of which the results are confirmed by Reynolds-averaged Navier–Stokes simulations to more significantly improve the compressor performance than that of CV-based TFD. The methodology enriches the current aerodynamic design system of compressors. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Vorticity dynamics in axial compressor flow diagnosis and design—Part II: methodology and application of boundary vorticity flux [texte imprimé] / Qiushi Li, Auteur ; Hong Wu, Auteur ; Ming Guo, Auteur . - 2010 . - 12 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 12 p. Mots-clés : boundary  vorticity  flux;  axial  compressor  flow Résumé : In a companion paper (2008, “Vorticity Dynamics in Axial Compressor Flow Diagnosis and Design,” ASME J. Fluids Eng., 130, p. 041102), a study has been made on the critical role of circumferential vorticity (CV) in the performance of axial compressor in through-flow design (TFD). It has been shown there that to enhance the pressure ratio, the positive and negative CV peaks should be pushed to the casing and hub, respectively. This criterion has led to an optimal TFD that indeed improves the pressure ratio and efficiency. The CV also has great impact on the stall margin as it reflects the end wall blockage, especially at the tip region of the compressor. While that work was based on inviscid and axisymmetric theory, in this paper, we move on to the diagnosis and optimal design of fully three-dimensional (3D) viscous flow in axial compressors, focusing on the boundary vorticity flux (BVF), which captures the highly localized peaks of pressure gradient on the surface of the compressor blade, and thereby signifies the boundary layer separation and dominates the work rate done to the fluid by the compressor. For the 2D cascade flow we show that the BVF is directly related to the blade geometry. BVF-based 2D and 3D optimal blade design methodologies are developed to control the velocity diffusion, of which the results are confirmed by Reynolds-averaged Navier–Stokes simulations to more significantly improve the compressor performance than that of CV-based TFD. The methodology enriches the current aerodynamic design system of compressors. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Slip flow in the hydrodynamic entrance region of circular and noncircular microchannels / Zhipeng Duan in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 13 p. Titre : Slip flow in the hydrodynamic entrance region of circular and noncircular microchannels Type de document : texte imprimé Auteurs : Zhipeng Duan, Auteur ; Y. S. Muzychka, Auteur Année de publication : 2010 Article en page(s) : 13 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : microchannels;  slip  flow Résumé : Microscale fluid dynamics has received intensive interest due to the emergence of micro-electro-mechanical systems (MEMS) technology. When the mean free path of the gas is comparable to the channel’s characteristic dimension, the continuum assumption is no longer valid and a velocity slip may occur at the duct walls. Noncircular cross sections are common channel shapes that can be produced by microfabrication. The noncircular microchannels have extensive practical applications in MEMS. The paper deals with issues of hydrodynamic flow development. Slip flow in the entrance of circular and parallel plate microchannels is first considered by solving a linearized momentum equation. It is found that slip flow is less sensitive to analytical linearized approximations than continuum flow and the linearization method is an accurate approximation for slip flow. Also, it is found that the entrance friction factor Reynolds product is of finite value and dependent on the Kn and tangential momentum accommodation coefficient but independent of the cross-sectional geometry. Slip flow and continuum flow in the hydrodynamic entrance of noncircular microchannels has been examined and a model is proposed to predict the friction factor and Reynolds product f Re for developing slip flow and continuum flow in most noncircular microchannels. It is shown that the complete problem may be easily analyzed by combining the asymptotic results for short and long ducts. Through the selection of a characteristic length scale, the square root of cross-sectional area, the effect of duct shape has been minimized. The proposed model has an approximate accuracy of 10% for most common duct shapes. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Slip flow in the hydrodynamic entrance region of circular and noncircular microchannels [texte imprimé] / Zhipeng Duan, Auteur ; Y. S. Muzychka, Auteur . - 2010 . - 13 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 13 p. Mots-clés : microchannels;  slip  flow Résumé : Microscale fluid dynamics has received intensive interest due to the emergence of micro-electro-mechanical systems (MEMS) technology. When the mean free path of the gas is comparable to the channel’s characteristic dimension, the continuum assumption is no longer valid and a velocity slip may occur at the duct walls. Noncircular cross sections are common channel shapes that can be produced by microfabrication. The noncircular microchannels have extensive practical applications in MEMS. The paper deals with issues of hydrodynamic flow development. Slip flow in the entrance of circular and parallel plate microchannels is first considered by solving a linearized momentum equation. It is found that slip flow is less sensitive to analytical linearized approximations than continuum flow and the linearization method is an accurate approximation for slip flow. Also, it is found that the entrance friction factor Reynolds product is of finite value and dependent on the Kn and tangential momentum accommodation coefficient but independent of the cross-sectional geometry. Slip flow and continuum flow in the hydrodynamic entrance of noncircular microchannels has been examined and a model is proposed to predict the friction factor and Reynolds product f Re for developing slip flow and continuum flow in most noncircular microchannels. It is shown that the complete problem may be easily analyzed by combining the asymptotic results for short and long ducts. Through the selection of a characteristic length scale, the square root of cross-sectional area, the effect of duct shape has been minimized. The proposed model has an approximate accuracy of 10% for most common duct shapes. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Stability of plane channel flow with viscous heating / K. C. Sahu in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 07 p. Titre : Stability of plane channel flow with viscous heating Type de document : texte imprimé Auteurs : K. C. Sahu, Auteur ; O. K. Matar, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : channel;  linear  stability Résumé : The linear stability analysis of pressure-driven flow undergoing viscous heating through a channel is considered. The walls of the channel are maintained at different constant temperatures and Nahme’s law is applied to model the temperature dependence of the fluid viscosity. A modified Orr–Sommerfeld equation coupled with a linearized energy equation is derived and solved using an efficient spectral collocation method. Our results indicate that increasing the influence of viscous heating is destabilizing. It is also shown that the critical Reynolds number decreases by one order of magnitude with increase in the Nahme number. An energy analysis is conducted to understand the underlying physical mechanism of the instability. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Stability of plane channel flow with viscous heating [texte imprimé] / K. C. Sahu, Auteur ; O. K. Matar, Auteur . - 2010 . - 07 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 07 p. Mots-clés : channel;  linear  stability Résumé : The linear stability analysis of pressure-driven flow undergoing viscous heating through a channel is considered. The walls of the channel are maintained at different constant temperatures and Nahme’s law is applied to model the temperature dependence of the fluid viscosity. A modified Orr–Sommerfeld equation coupled with a linearized energy equation is derived and solved using an efficient spectral collocation method. Our results indicate that increasing the influence of viscous heating is destabilizing. It is also shown that the critical Reynolds number decreases by one order of magnitude with increase in the Nahme number. An energy analysis is conducted to understand the underlying physical mechanism of the instability. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Effect of grooves on cavitation around the body of revolution / Yongjian Li in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 07 p. Titre : Effect of grooves on cavitation around the body of revolution Type de document : texte imprimé Auteurs : Yongjian Li, Auteur ; Haosheng, Chen, Auteur ; Jiadao Wang, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : grooves;  cavitation Résumé : Cavitation occurs widely in hydraulic machines, water and underwater vehicles, and lots of other equipments operating with liquids. Much research has been carried out to find out the factors affecting the degree of cavitation for better control of this phenomenon. In this study, the effects of grooves distributed around the body of revolution on cavitation are investigated using experimental and numerical methods. The experimental results show that the position and shape of the cavity clouds are affected by the dimensions of the grooves. A numerical simulation using the finite volume method indicates that the grooves influence the pressure distribution in the whole flow field and induce significant pressure fluctuation. The minimum pressure in each groove occurs on the top of the groove’s “windward” edge and decreases as the groove width is increased. Comparing the experimental and numerical results, it is found that cavitation is closely related to the local pressure of the fluid. Multiple grooves around the body of revolution induce pressure fluctuation. The groove width affects the amplitude and interval of the fluctuation and consequently influences the distribution of cavitation. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Effect of grooves on cavitation around the body of revolution [texte imprimé] / Yongjian Li, Auteur ; Haosheng, Chen, Auteur ; Jiadao Wang, Auteur . - 2010 . - 07 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 07 p. Mots-clés : grooves;  cavitation Résumé : Cavitation occurs widely in hydraulic machines, water and underwater vehicles, and lots of other equipments operating with liquids. Much research has been carried out to find out the factors affecting the degree of cavitation for better control of this phenomenon. In this study, the effects of grooves distributed around the body of revolution on cavitation are investigated using experimental and numerical methods. The experimental results show that the position and shape of the cavity clouds are affected by the dimensions of the grooves. A numerical simulation using the finite volume method indicates that the grooves influence the pressure distribution in the whole flow field and induce significant pressure fluctuation. The minimum pressure in each groove occurs on the top of the groove’s “windward” edge and decreases as the groove width is increased. Comparing the experimental and numerical results, it is found that cavitation is closely related to the local pressure of the fluid. Multiple grooves around the body of revolution induce pressure fluctuation. The groove width affects the amplitude and interval of the fluctuation and consequently influences the distribution of cavitation. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Modeling blockage of particles in conduit constrictions / A. J. Parry in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 10 p. Titre : Modeling blockage of particles in conduit constrictions : dense granular-suspension flow Type de document : texte imprimé Auteurs : A. J. Parry, Auteur ; O. Millet, Auteur Année de publication : 2010 Article en page(s) : 10 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : dense  granular-suspension  flow;  numerical  simulation Résumé : This paper presents a numerical simulation study of dense granular-suspension flow in a conduit with constriction. An empirical function of solid concentrations and Reynolds number prescribes the force between a particle and the fluid. This simplification reduces the computing load of the fine flow-field details around each particle. In the fluid-momentum equation, a source term distributes the force over the particle volume. The study addresses particle-laden flow at constant liquid-flow rate. Two different algorithms of the interparticle contact show that the bridging phenomenon causing the blockage of the particles persists in the presence of the fluid flow. While the particles are in movement, there are frequent interparticle and particle-wall impacts and vigorous fluctuations of the net reaction force on the wall from the particle phase. There is close correlation between the component of this reaction oriented in the flow direction and the rate of change in the pressure drop across the constricted conduit. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Modeling blockage of particles in conduit constrictions : dense granular-suspension flow [texte imprimé] / A. J. Parry, Auteur ; O. Millet, Auteur . - 2010 . - 10 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 10 p. Mots-clés : dense  granular-suspension  flow;  numerical  simulation Résumé : This paper presents a numerical simulation study of dense granular-suspension flow in a conduit with constriction. An empirical function of solid concentrations and Reynolds number prescribes the force between a particle and the fluid. This simplification reduces the computing load of the fine flow-field details around each particle. In the fluid-momentum equation, a source term distributes the force over the particle volume. The study addresses particle-laden flow at constant liquid-flow rate. Two different algorithms of the interparticle contact show that the bridging phenomenon causing the blockage of the particles persists in the presence of the fluid flow. While the particles are in movement, there are frequent interparticle and particle-wall impacts and vigorous fluctuations of the net reaction force on the wall from the particle phase. There is close correlation between the component of this reaction oriented in the flow direction and the rate of change in the pressure drop across the constricted conduit. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Liquid sheet breakup in gas-centered swirl coaxial atomizers / V. Kulkarni in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 07 p. Titre : Liquid sheet breakup in gas-centered swirl coaxial atomizers Type de document : texte imprimé Auteurs : V. Kulkarni, Auteur ; D. Sivakumar, Auteur ; C. Oommen, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : inertia  (mechanics);  flow  (dynamics);  measurement;  Reynolds  number;  air  jets;  sprays;  swirling  flow;  water Résumé : The study deals with the breakup behavior of swirling liquid sheets discharging from gas-centered swirl coaxial atomizers with attention focused toward the understanding of the role of central gas jet on the liquid sheet breakup. Cold flow experiments on the liquid sheet breakup were carried out by employing custom fabricated gas-centered swirl coaxial atomizers using water and air as experimental fluids. Photographic techniques were employed to capture the flow behavior of liquid sheets at different flow conditions. Quantitative variation on the breakup length of the liquid sheet and spray width were obtained from the measurements deduced from the images of liquid sheets. The sheet breakup process is significantly influenced by the central air jet. It is observed that low inertia liquid sheets are more vulnerable to the presence of the central air jet and develop shorter breakup lengths at smaller values of the air jet Reynolds number Reg. High inertia liquid sheets ignore the presence of the central air jet at smaller values of Reg and eventually develop shorter breakup lengths at higher values of Reg. The experimental evidences suggest that the central air jet causes corrugations on the liquid sheet surface, which may be promoting the production of thick liquid ligaments from the sheet surface. The level of surface corrugations on the liquid sheet increases with increasing Reg. Qualitative analysis of experimental observations reveals that the entrainment process of air established between the inner surface of the liquid sheet and the central air jet is the primary trigger for the sheet breakup. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Liquid sheet breakup in gas-centered swirl coaxial atomizers [texte imprimé] / V. Kulkarni, Auteur ; D. Sivakumar, Auteur ; C. Oommen, Auteur . - 2010 . - 07 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 07 p. Mots-clés : inertia  (mechanics);  flow  (dynamics);  measurement;  Reynolds  number;  air  jets;  sprays;  swirling  flow;  water Résumé : The study deals with the breakup behavior of swirling liquid sheets discharging from gas-centered swirl coaxial atomizers with attention focused toward the understanding of the role of central gas jet on the liquid sheet breakup. Cold flow experiments on the liquid sheet breakup were carried out by employing custom fabricated gas-centered swirl coaxial atomizers using water and air as experimental fluids. Photographic techniques were employed to capture the flow behavior of liquid sheets at different flow conditions. Quantitative variation on the breakup length of the liquid sheet and spray width were obtained from the measurements deduced from the images of liquid sheets. The sheet breakup process is significantly influenced by the central air jet. It is observed that low inertia liquid sheets are more vulnerable to the presence of the central air jet and develop shorter breakup lengths at smaller values of the air jet Reynolds number Reg. High inertia liquid sheets ignore the presence of the central air jet at smaller values of Reg and eventually develop shorter breakup lengths at higher values of Reg. The experimental evidences suggest that the central air jet causes corrugations on the liquid sheet surface, which may be promoting the production of thick liquid ligaments from the sheet surface. The level of surface corrugations on the liquid sheet increases with increasing Reg. Qualitative analysis of experimental observations reveals that the entrainment process of air established between the inner surface of the liquid sheet and the central air jet is the primary trigger for the sheet breakup. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Effect of capsule density and concentration on pressure drops of spherical capsule train conveyed by water / Deniz Ulusarslan in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 06 p. Titre : Effect of capsule density and concentration on pressure drops of spherical capsule train conveyed by water Type de document : texte imprimé Auteurs : Deniz Ulusarslan, Auteur Année de publication : 2010 Article en page(s) : 06 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : density;  flow  (dynamics);  pipes;  mixtures;  pressure  drop;  pressure  gradient;  trains;  water Résumé : This experimental investigation concerns the hydraulic transport of a spherical capsule train, whose density is equal to that of water (relative density; s=1), in horizontal pipes. In a system where the carrier fluid is water, pressure drops of two phase flow and capsule velocities were measured at 0.2–1.0 m/s bulk velocities and 5–20% capsule transport concentrations. The results found were compared with the pressure gradient (pressure drops per unit length) ratios ((ΔP/L)m/(ΔP/L)w) measured for less dense capsules. The capsule velocity and the velocity ratio (Vc/Vb) increased with increasing the bulk velocity. As concentration increases, the pressure gradient of the capsule-water mixture increases. For all concentrations, the pressure gradient ratio decreases (getting closer to 1) with increasing bulk velocity. This result is similar to that of capsules with less relative density. However, the pressure gradient ratio of the capsule flow with less density is higher than that of capsules with equal density at constant transport concentrations. The reason for this difference is that the capsules with a density equal to that of water move along the axis of the pipe for a longer time. When capsules with equal density are used, the mass flow rate will remain the same, but energy consumption will decrease. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Effect of capsule density and concentration on pressure drops of spherical capsule train conveyed by water [texte imprimé] / Deniz Ulusarslan, Auteur . - 2010 . - 06 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 06 p. Mots-clés : density;  flow  (dynamics);  pipes;  mixtures;  pressure  drop;  pressure  gradient;  trains;  water Résumé : This experimental investigation concerns the hydraulic transport of a spherical capsule train, whose density is equal to that of water (relative density; s=1), in horizontal pipes. In a system where the carrier fluid is water, pressure drops of two phase flow and capsule velocities were measured at 0.2–1.0 m/s bulk velocities and 5–20% capsule transport concentrations. The results found were compared with the pressure gradient (pressure drops per unit length) ratios ((ΔP/L)m/(ΔP/L)w) measured for less dense capsules. The capsule velocity and the velocity ratio (Vc/Vb) increased with increasing the bulk velocity. As concentration increases, the pressure gradient of the capsule-water mixture increases. For all concentrations, the pressure gradient ratio decreases (getting closer to 1) with increasing bulk velocity. This result is similar to that of capsules with less relative density. However, the pressure gradient ratio of the capsule flow with less density is higher than that of capsules with equal density at constant transport concentrations. The reason for this difference is that the capsules with a density equal to that of water move along the axis of the pipe for a longer time. When capsules with equal density are used, the mass flow rate will remain the same, but energy consumption will decrease. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Assessment of the performance of acoustic and mass balance methods for leak detection in pipelines for transporting liquids / Jaqueline Costa Martins in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 08 p. Titre : Assessment of the performance of acoustic and mass balance methods for leak detection in pipelines for transporting liquids Type de document : texte imprimé Auteurs : Jaqueline Costa Martins, Auteur ; Paulo Seleghim, Jr., Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : fluids engineering Langues : Anglais (eng) Résumé : On-line leak detection is a main concern for the safe operation of pipelines. Acoustic and mass balance are the most important and extensively applied technologies in field problems. The objective of this work is to compare these leak detection methods with respect to a given reference situation, i.e., the same pipeline and monitoring signals acquired at the inlet and outlet ends. Experimental tests were conducted in a 749 m long laboratory pipeline transporting water as the working fluid. The instrumentation included pressure transducers and electromagnetic flowmeters. Leaks were simulated by opening solenoid valves placed at known positions and previously calibrated to produce known average leak flow rates. Results have clearly shown the limitations and advantages of each method. It is also quite clear that acoustics and mass balance technologies are, in fact, complementary. In general, an acoustic leak detection system sends out an alarm more rapidly and locates the leak more precisely, provided that the rupture of the pipeline occurs abruptly enough. On the other hand, a mass balance leak detection method is capable of quantifying the leak flow rate very accurately and of detecting progressive leaks. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Assessment of the performance of acoustic and mass balance methods for leak detection in pipelines for transporting liquids [texte imprimé] / Jaqueline Costa Martins, Auteur ; Paulo Seleghim, Jr., Auteur . - 2010 . - 08 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 08 p. Résumé : On-line leak detection is a main concern for the safe operation of pipelines. Acoustic and mass balance are the most important and extensively applied technologies in field problems. The objective of this work is to compare these leak detection methods with respect to a given reference situation, i.e., the same pipeline and monitoring signals acquired at the inlet and outlet ends. Experimental tests were conducted in a 749 m long laboratory pipeline transporting water as the working fluid. The instrumentation included pressure transducers and electromagnetic flowmeters. Leaks were simulated by opening solenoid valves placed at known positions and previously calibrated to produce known average leak flow rates. Results have clearly shown the limitations and advantages of each method. It is also quite clear that acoustics and mass balance technologies are, in fact, complementary. In general, an acoustic leak detection system sends out an alarm more rapidly and locates the leak more precisely, provided that the rupture of the pipeline occurs abruptly enough. On the other hand, a mass balance leak detection method is capable of quantifying the leak flow rate very accurately and of detecting progressive leaks. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

General geometrical model of scroll compression chamber for scroll fluid machine / Qiang Jianguo in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 04 p. Titre : General geometrical model of scroll compression chamber for scroll fluid machine Type de document : texte imprimé Auteurs : Qiang Jianguo, Auteur Année de publication : 2010 Article en page(s) : 04 p. Note générale : fluids engineering Langues : Anglais (eng) Résumé : For a scroll fluid machine with an arbitrary number of scroll wraps on its individual scroll, the phase difference between adjacent scroll profiles on one scroll is defined as the characteristic angle of the scroll. Based on general profile theory, a scroll pitch line is defined as of A-type with which the outer profile of orbiting scroll and the inner profile of fixed scroll can be formed. Another scroll pitch line is defined as B-type with which the inner profile of orbiting scroll and the outer profile of fixed scroll can be formed. The scroll compression chambers corresponding to the pitch lines of A-type and that of B-type are defined as compression chambers of A-series and B-series, respectively. Then the general geometrical model of scroll compression chamber is set up. It can demonstrate the deforming, opening, and vanishing process of all scroll chambers. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] General geometrical model of scroll compression chamber for scroll fluid machine [texte imprimé] / Qiang Jianguo, Auteur . - 2010 . - 04 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 04 p. Résumé : For a scroll fluid machine with an arbitrary number of scroll wraps on its individual scroll, the phase difference between adjacent scroll profiles on one scroll is defined as the characteristic angle of the scroll. Based on general profile theory, a scroll pitch line is defined as of A-type with which the outer profile of orbiting scroll and the inner profile of fixed scroll can be formed. Another scroll pitch line is defined as B-type with which the inner profile of orbiting scroll and the outer profile of fixed scroll can be formed. The scroll compression chambers corresponding to the pitch lines of A-type and that of B-type are defined as compression chambers of A-series and B-series, respectively. Then the general geometrical model of scroll compression chamber is set up. It can demonstrate the deforming, opening, and vanishing process of all scroll chambers. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Single phase compressible steady flow in pipes / David Hullender in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 04 p. Titre : Single phase compressible steady flow in pipes Type de document : texte imprimé Auteurs : David Hullender, Auteur ; Robert Woods, Auteur ; Yi-Wei Huang, Auteur Année de publication : 2010 Article en page(s) : 04 p. Note générale : fluids engineering Langues : Anglais (eng) Résumé : In general, the computation of single phase subsonic mass velocity of gas flowing through a pipe requires a computerized iterative analysis. The equations for the friction factor for laminar and turbulent flow are used to obtain explicit equations for the subsonic mass velocity as a function of the pressures at the ends of a pipe. Explicit equations for mass velocity are presented. Included within the equations is a heat transfer ratio, which can vary between 0 for adiabatic flow conditions to 1 for isothermal flow conditions. The use of this heat transfer ratio also enables the formulation of an explicit equation for the gas temperature along the pipe for nonisothermal flow conditions. The explicit equations eliminate the need for an iterative solution. Laboratory data are used to support the accuracy of the model. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Single phase compressible steady flow in pipes [texte imprimé] / David Hullender, Auteur ; Robert Woods, Auteur ; Yi-Wei Huang, Auteur . - 2010 . - 04 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 1 (Janvier 2010) . - 04 p. Résumé : In general, the computation of single phase subsonic mass velocity of gas flowing through a pipe requires a computerized iterative analysis. The equations for the friction factor for laminar and turbulent flow are used to obtain explicit equations for the subsonic mass velocity as a function of the pressures at the ends of a pipe. Explicit equations for mass velocity are presented. Included within the equations is a heat transfer ratio, which can vary between 0 for adiabatic flow conditions to 1 for isothermal flow conditions. The use of this heat transfer ratio also enables the formulation of an explicit equation for the gas temperature along the pipe for nonisothermal flow conditions. The explicit equations eliminate the need for an iterative solution. Laboratory data are used to support the accuracy of the model. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

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