Dépouillements

Fluid-power harvesting by under-foot bellows during human gait / Robin Chin in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 07 p. Titre : Fluid-power harvesting by under-foot bellows during human gait Type de document : texte imprimé Auteurs : Robin Chin, Auteur ; Elizabeth T. Hsiao-Wecksler, Auteur ; Eric Loth, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : energy-harvesting;  assistive  device;  ankle-foof-orthosis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Pneumatic and hydraulic bellows were investigated for under-foot power harvesting during human walking. Placement under the heel allows the bellow to be compressed during the heel strike of the gait cycle, whereas placement under the metatarsal allows compression during the mid-stance and toe-off phases. In either case, body weight is used as the power source for a self-contained fluid power circuit. Once unweighted, air is drawn into the bellow through a one-way valve allowing the bellow to recharge as it expands during the swing phase of the gait cycle. A collapsible spring was placed inside the bellow to ensure full opened conditions for this phase. To evaluate this concept, experimental studies were conducted on two circular bellows with outside diameters of 4.13 cm and 6.35 cm placed under the heel or the metatarsal of the foot, on a person walking on a treadmill. These pressure profiles were then reproduced on a compression testing machine to investigate the power generated per cycle. During normal walking, the pneumatic bellows generated peak power levels of 20–25 W and maximum pressures of 450 kPa. The average power available over a single cycle was 1.5 and 4.5 W for the small and large bellows, respectively. This novel use of bellows demonstrates the ability to use these devices for regenerative fluid power harvesting capabilities during walking. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Fluid-power harvesting by under-foot bellows during human gait [texte imprimé] / Robin Chin, Auteur ; Elizabeth T. Hsiao-Wecksler, Auteur ; Eric Loth, Auteur . - 2012 . - 07 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 07 p. Mots-clés : energy-harvesting;  assistive  device;  ankle-foof-orthosis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Pneumatic and hydraulic bellows were investigated for under-foot power harvesting during human walking. Placement under the heel allows the bellow to be compressed during the heel strike of the gait cycle, whereas placement under the metatarsal allows compression during the mid-stance and toe-off phases. In either case, body weight is used as the power source for a self-contained fluid power circuit. Once unweighted, air is drawn into the bellow through a one-way valve allowing the bellow to recharge as it expands during the swing phase of the gait cycle. A collapsible spring was placed inside the bellow to ensure full opened conditions for this phase. To evaluate this concept, experimental studies were conducted on two circular bellows with outside diameters of 4.13 cm and 6.35 cm placed under the heel or the metatarsal of the foot, on a person walking on a treadmill. These pressure profiles were then reproduced on a compression testing machine to investigate the power generated per cycle. During normal walking, the pneumatic bellows generated peak power levels of 20–25 W and maximum pressures of 450 kPa. The average power available over a single cycle was 1.5 and 4.5 W for the small and large bellows, respectively. This novel use of bellows demonstrates the ability to use these devices for regenerative fluid power harvesting capabilities during walking. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

An investigation on turbocharger turbine performance parameters under inlet pulsating flow / Tabatabaei Hamidreza in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 08 p. Titre : An investigation on turbocharger turbine performance parameters under inlet pulsating flow Type de document : texte imprimé Auteurs : Tabatabaei Hamidreza, Auteur ; Boroomand Masoud, Auteur ; Mohammad Taeibi Rahni, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : computational  fluid  dynamics;  unsteady  flow;  compressible  flow;  SI-engine;  simulation Résumé : Three-dimensional steady and unsteady (pulsating) compressible flows in a vane-less turbocharger turbine of a 1.7 liter SI engine are simulated numerically, and the results are validated experimentally using a turbocharged on-engine test cell. Simulations are carried out for a 720° engine cycle at three engine speeds, and the complete forms of volute and rotor vanes are modeled. Two ways for modeling the rotating wheel, multiple reference frames (MRF), and sliding mesh (SM) techniques are also examined. Finally, the effects of pulsating flow on the turbocharger turbine performance parameters (TTPP) such as the inlet static pressure, reduced mass flow rate, and efficiency are obtained and compared with their values under steady flow. The results show that the accuracy of steady characteristic map to estimate the TTPPs has some source of ambiguity, which should be considered for detailed analysis. TTPP values under steady flow conditions are found to be significantly deviated from the unsteady results. These deviations are decreased as the engine speed increases. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] An investigation on turbocharger turbine performance parameters under inlet pulsating flow [texte imprimé] / Tabatabaei Hamidreza, Auteur ; Boroomand Masoud, Auteur ; Mohammad Taeibi Rahni, Auteur . - 2012 . - 08 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 08 p. Mots-clés : computational  fluid  dynamics;  unsteady  flow;  compressible  flow;  SI-engine;  simulation Résumé : Three-dimensional steady and unsteady (pulsating) compressible flows in a vane-less turbocharger turbine of a 1.7 liter SI engine are simulated numerically, and the results are validated experimentally using a turbocharged on-engine test cell. Simulations are carried out for a 720° engine cycle at three engine speeds, and the complete forms of volute and rotor vanes are modeled. Two ways for modeling the rotating wheel, multiple reference frames (MRF), and sliding mesh (SM) techniques are also examined. Finally, the effects of pulsating flow on the turbocharger turbine performance parameters (TTPP) such as the inlet static pressure, reduced mass flow rate, and efficiency are obtained and compared with their values under steady flow. The results show that the accuracy of steady characteristic map to estimate the TTPPs has some source of ambiguity, which should be considered for detailed analysis. TTPP values under steady flow conditions are found to be significantly deviated from the unsteady results. These deviations are decreased as the engine speed increases. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Analytic approximations for cooling turbine disks / A. El-Nahhas in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 07 p. Titre : Analytic approximations for cooling turbine disks Type de document : texte imprimé Auteurs : A. El-Nahhas, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : partial  differencial  equations;  channel  flows;  non-newtonian  fluids;  heat  transfer,  homotopy  analysis  method Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this paper, we use the homotopy analysis method as a tool to obtain analytic approximations to the nonlinear problem of the cooling of turbine disks with a non-Newtonian viscoelastic fluid. The application of this method is executed via a polynomial exponential basis. The effects on velocity and temperature profiles with variations of the cross viscosity parameter, the Reynolds number, and the Prandtl number are discussed. A comparison with corresponding results of the perturbation method is illustrated and also, as a result of application of the homotopy analysis method, an analytic evaluation for the Nusselt number compared to the perturbation method is achieved. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Analytic approximations for cooling turbine disks [texte imprimé] / A. El-Nahhas, Auteur . - 2012 . - 07 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 07 p. Mots-clés : partial  differencial  equations;  channel  flows;  non-newtonian  fluids;  heat  transfer,  homotopy  analysis  method Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this paper, we use the homotopy analysis method as a tool to obtain analytic approximations to the nonlinear problem of the cooling of turbine disks with a non-Newtonian viscoelastic fluid. The application of this method is executed via a polynomial exponential basis. The effects on velocity and temperature profiles with variations of the cross viscosity parameter, the Reynolds number, and the Prandtl number are discussed. A comparison with corresponding results of the perturbation method is illustrated and also, as a result of application of the homotopy analysis method, an analytic evaluation for the Nusselt number compared to the perturbation method is achieved. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Unsteady pressure analysis of a swirling flow with vortex rope and axial water injection in a discharge cone / Alin Ilie Bosioc in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 11 p. Titre : Unsteady pressure analysis of a swirling flow with vortex rope and axial water injection in a discharge cone Type de document : texte imprimé Auteurs : Alin Ilie Bosioc, Auteur ; Romeo Susan-Resiga, Auteur ; Sebastian Muntean, Auteur Année de publication : 2012 Article en page(s) : 11 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : decelerated  swirling  flow;  vortex  rope;  water  injection  method;  unsteady  pressure;  experimental  investigation Résumé : The variable demand of the energy market requires that hydraulic turbines operate at variable conditions, which includes regimes far from the best efficiency point. The vortex rope developed at partial discharges in the conical diffuser is responsible for large pressure pulsations, runner blades breakdowns and may lead to power swing phenomena. A novel method introduced by Resiga et al. (2006, “Jet Control of the Draft Tube in Francis Turbines at Partial Discharge,” Proceedings of the 23rd IAHR Symposium on Hydraulic Machinery and Systems, Yokohama, Japan, Paper No. F192) injects an axial water jet from the runner crown downstream in the draft tube cone to mitigate the vortex rope and its consequences. A special test rig was developed at “Politehnica” University of Timisoara in order to investigate different flow control techniques. Consequently, a vortex rope similar to the one developed in a Francis turbine cone at 70% partial discharge is generated in the rig's test section. In order to investigate the new jet control method an auxiliary hydraulic circuit was designed in order to supply the jet. The experimental investigations presented in this paper are concerned with pressure measurements at the wall of the conical diffuser. The pressure fluctuations' Fourier spectra are analyzed in order to assess how the amplitude and dominating frequency are modified by the water injection. It is shown that the water jet injection significantly reduces both the amplitude and the frequency of pressure fluctuations, while improving the pressure recovery in the conical diffuser. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Unsteady pressure analysis of a swirling flow with vortex rope and axial water injection in a discharge cone [texte imprimé] / Alin Ilie Bosioc, Auteur ; Romeo Susan-Resiga, Auteur ; Sebastian Muntean, Auteur . - 2012 . - 11 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 11 p. Mots-clés : decelerated  swirling  flow;  vortex  rope;  water  injection  method;  unsteady  pressure;  experimental  investigation Résumé : The variable demand of the energy market requires that hydraulic turbines operate at variable conditions, which includes regimes far from the best efficiency point. The vortex rope developed at partial discharges in the conical diffuser is responsible for large pressure pulsations, runner blades breakdowns and may lead to power swing phenomena. A novel method introduced by Resiga et al. (2006, “Jet Control of the Draft Tube in Francis Turbines at Partial Discharge,” Proceedings of the 23rd IAHR Symposium on Hydraulic Machinery and Systems, Yokohama, Japan, Paper No. F192) injects an axial water jet from the runner crown downstream in the draft tube cone to mitigate the vortex rope and its consequences. A special test rig was developed at “Politehnica” University of Timisoara in order to investigate different flow control techniques. Consequently, a vortex rope similar to the one developed in a Francis turbine cone at 70% partial discharge is generated in the rig's test section. In order to investigate the new jet control method an auxiliary hydraulic circuit was designed in order to supply the jet. The experimental investigations presented in this paper are concerned with pressure measurements at the wall of the conical diffuser. The pressure fluctuations' Fourier spectra are analyzed in order to assess how the amplitude and dominating frequency are modified by the water injection. It is shown that the water jet injection significantly reduces both the amplitude and the frequency of pressure fluctuations, while improving the pressure recovery in the conical diffuser. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Numerical analysis of external gear pumps including cavitation / D. del Campo in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 12 p. Titre : Numerical analysis of external gear pumps including cavitation Type de document : texte imprimé Auteurs : D. del Campo, Auteur ; R. Castilla, Auteur ; G. A. Raush, Auteur Année de publication : 2012 Article en page(s) : 12 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : cavitation;  CFD;  gear  pumps;  volumetric  efficiency Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Hydraulic machines are faced with increasingly severe performance requirements. The need to design smaller and more powerful machines rotating at higher speeds in order to provide increasing efficiencies has to face a major limitation: cavitation. The problem is inherently three-dimensional, due to the axial clearances, the relief and circumferential grooves, and to the circular pipes through which the fluid enters and exits the pump. A simplified two-dimensional numerical approach by means of computational fluid dynamics (CFD) has been developed for studying the effect of cavitation in the volumetric efficiency of external gear pumps. The assumptions employed prevent from predicting realistic values of the volumetric efficiency, but show to be valid to understand the complex flow patterns that take place inside the pump and to study the influence of cavitation on volumetric efficiency. A method for simulating the contact between solid boundaries by imposing changes in viscosity has been developed. Experiments of unsteady cavitation in water and oil performed by other authors have been numerically reproduced using different cavitation models in order to select the most appropriate one and to adjust its parameters. The influence of the rotational speed of the pump has been analyzed. Cavitation in the suction chamber very effectively damps the water hammer associated to the sudden change of the contact point position at the end of the gearing cycle. At high rotational speeds, the volume of air becomes more stable, reducing the flow irregularity. When cavitation takes place at the meshing region downstream from the contact point, the volume of air that appears acts as a virtual second contact point, increasing the volumetric efficiency of the pump. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Numerical analysis of external gear pumps including cavitation [texte imprimé] / D. del Campo, Auteur ; R. Castilla, Auteur ; G. A. Raush, Auteur . - 2012 . - 12 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 12 p. Mots-clés : cavitation;  CFD;  gear  pumps;  volumetric  efficiency Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Hydraulic machines are faced with increasingly severe performance requirements. The need to design smaller and more powerful machines rotating at higher speeds in order to provide increasing efficiencies has to face a major limitation: cavitation. The problem is inherently three-dimensional, due to the axial clearances, the relief and circumferential grooves, and to the circular pipes through which the fluid enters and exits the pump. A simplified two-dimensional numerical approach by means of computational fluid dynamics (CFD) has been developed for studying the effect of cavitation in the volumetric efficiency of external gear pumps. The assumptions employed prevent from predicting realistic values of the volumetric efficiency, but show to be valid to understand the complex flow patterns that take place inside the pump and to study the influence of cavitation on volumetric efficiency. A method for simulating the contact between solid boundaries by imposing changes in viscosity has been developed. Experiments of unsteady cavitation in water and oil performed by other authors have been numerically reproduced using different cavitation models in order to select the most appropriate one and to adjust its parameters. The influence of the rotational speed of the pump has been analyzed. Cavitation in the suction chamber very effectively damps the water hammer associated to the sudden change of the contact point position at the end of the gearing cycle. At high rotational speeds, the volume of air becomes more stable, reducing the flow irregularity. When cavitation takes place at the meshing region downstream from the contact point, the volume of air that appears acts as a virtual second contact point, increasing the volumetric efficiency of the pump. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Measurement and observation of jet thrust for water flow through micro-orifice / Akiomi Ushida in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 07 p. Titre : Measurement and observation of jet thrust for water flow through micro-orifice Type de document : texte imprimé Auteurs : Akiomi Ushida, Auteur ; Tomiichi Hasegawa, Auteur ; Takehiro Hoshina, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : micro-orifice;  water;  jet  thrust;  jet  swell;  elastic  stress Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Owing to the many potential industrial and biological applications of microfluid mechanics, it has recently become an attractive research topic. However, researchers have mainly concentrated on microchannel flows and studies investigating micro-orifice flows are rare cases. In the present study, the results from experiments conducted on flows through micro-orifices with diameters of 100 µm, 50 µm, and 25 µm are presented. In these experiments, the thrust and diameter of observed outflow jets are measured. The resultant thrust and diameter of the jets for the 100 µm orifice flow agree with the numerical predictions obtained via the Navier–Stokes equations. Conversely, for an orifice with a diameter of 50 µm or less, it is found that the thrust is lower than that predicted and the existence of jet swell becomes apparent. With the estimated elastic stress proportional to squared mean velocity, a change in the elasticity of the water as it flows through a micro-orifice is strongly suggested. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Measurement and observation of jet thrust for water flow through micro-orifice [texte imprimé] / Akiomi Ushida, Auteur ; Tomiichi Hasegawa, Auteur ; Takehiro Hoshina, Auteur . - 2012 . - 07 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 07 p. Mots-clés : micro-orifice;  water;  jet  thrust;  jet  swell;  elastic  stress Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Owing to the many potential industrial and biological applications of microfluid mechanics, it has recently become an attractive research topic. However, researchers have mainly concentrated on microchannel flows and studies investigating micro-orifice flows are rare cases. In the present study, the results from experiments conducted on flows through micro-orifices with diameters of 100 µm, 50 µm, and 25 µm are presented. In these experiments, the thrust and diameter of observed outflow jets are measured. The resultant thrust and diameter of the jets for the 100 µm orifice flow agree with the numerical predictions obtained via the Navier–Stokes equations. Conversely, for an orifice with a diameter of 50 µm or less, it is found that the thrust is lower than that predicted and the existence of jet swell becomes apparent. With the estimated elastic stress proportional to squared mean velocity, a change in the elasticity of the water as it flows through a micro-orifice is strongly suggested. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Stagnation point flow through ap orous medium towards a radially stretching sheet in the presence of uniform suction or injection and heat generation / Attia, Hazem Ali in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 05 p. Titre : Stagnation point flow through ap orous medium towards a radially stretching sheet in the presence of uniform suction or injection and heat generation Type de document : texte imprimé Auteurs : Attia, Hazem Ali, Auteur ; Karem Mahmoud Ewis, Auteur ; Mostafa A. M. Abdeen, Auteur Année de publication : 2012 Article en page(s) : 05 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : numerical  solution;  stagnation  point;  stretching  sheet;  suction;  heat  generation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An analysis is made of the steady laminar axisymmetric stagnation point flow of an incompressible viscous fluid in a porous medium impinging on a permeable radially stretching sheet with heat generation or absorption. A uniform suction or blowing is applied normal to the plate which is maintained at a constant temperature. Similarity transformation is used to transform the governing partial differential equations to ordinary differential equations. The finite difference method and generalized Thomas algorithm are used to solve the governing nonlinear momentum and energy equations. The effects of the uniform suction/blowing velocity, the stretching parameter and the heat generation/absorption coefficient on both the flow field and heat transfer are presented and discussed. The results indicate that increasing the stretching parameter or the suction/blowing velocity decreases both the velocity and thermal boundary layer thicknesses. The effect of the stretching parameter on the velocity components is more apparent for suction than blowing while its effect on the temperature and rate of heat transfer at the wall is clearer in the case of blowing than suction. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Stagnation point flow through ap orous medium towards a radially stretching sheet in the presence of uniform suction or injection and heat generation [texte imprimé] / Attia, Hazem Ali, Auteur ; Karem Mahmoud Ewis, Auteur ; Mostafa A. M. Abdeen, Auteur . - 2012 . - 05 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 05 p. Mots-clés : numerical  solution;  stagnation  point;  stretching  sheet;  suction;  heat  generation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An analysis is made of the steady laminar axisymmetric stagnation point flow of an incompressible viscous fluid in a porous medium impinging on a permeable radially stretching sheet with heat generation or absorption. A uniform suction or blowing is applied normal to the plate which is maintained at a constant temperature. Similarity transformation is used to transform the governing partial differential equations to ordinary differential equations. The finite difference method and generalized Thomas algorithm are used to solve the governing nonlinear momentum and energy equations. The effects of the uniform suction/blowing velocity, the stretching parameter and the heat generation/absorption coefficient on both the flow field and heat transfer are presented and discussed. The results indicate that increasing the stretching parameter or the suction/blowing velocity decreases both the velocity and thermal boundary layer thicknesses. The effect of the stretching parameter on the velocity components is more apparent for suction than blowing while its effect on the temperature and rate of heat transfer at the wall is clearer in the case of blowing than suction. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Boundary-layer flow and heat transfer of nanofluid over a vertical plate with convective surface boundary condition / Wubshet Ibrahim in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 08 p. Titre : Boundary-layer flow and heat transfer of nanofluid over a vertical plate with convective surface boundary condition Type de document : texte imprimé Auteurs : Wubshet Ibrahim, Auteur ; Bandari Shanker, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : boundary  layer  flow;  heat  transfer;  Runge-Kutta  fourth  order  method;  Nusselt  number;  Sherwood  number Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The problem of boundary layer flow and heat transfer induced due to nanofluid over a vertical plate is investigated. The transport equations employed in the analysis include the effect of Brownian motion and thermophoresis. We used a convective heating boundary condition instead of a widely employed thermal conduction of constant temperature or constant heat flux. The solution for the temperature and nanoparticle concentration depends on six parameters, viz., convective heating parameter A, Prandtl number Pr, Lewis number Le, Brownian motion Nb, buoyancy ratio parameter Nr, and the thermophoresis parameter Nt. Similarity transformation is used to convert the governing nonlinear boundary-layer equations into coupled higher order ordinary differential equations. These equations were solved numerically using Runge-Kutta fourth order method with shooting technique. The effects of the governing parameters on flow field and heat transfer characteristics were obtained and discussed. Numerical results are obtained for velocity, temperature, and concentration distribution as well as the local Nusselt number and Sherwood number. It is found that the local Nusselt number and Sherwood number increase with an increase in convective parameter A and Lewis number Le. Likewise, the local Sherwood number increases with an increase in both A and Le. A comparison with the previous study available in literature has been done and we found an excellent agreement with them. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Boundary-layer flow and heat transfer of nanofluid over a vertical plate with convective surface boundary condition [texte imprimé] / Wubshet Ibrahim, Auteur ; Bandari Shanker, Auteur . - 2012 . - 08 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 08 p. Mots-clés : boundary  layer  flow;  heat  transfer;  Runge-Kutta  fourth  order  method;  Nusselt  number;  Sherwood  number Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The problem of boundary layer flow and heat transfer induced due to nanofluid over a vertical plate is investigated. The transport equations employed in the analysis include the effect of Brownian motion and thermophoresis. We used a convective heating boundary condition instead of a widely employed thermal conduction of constant temperature or constant heat flux. The solution for the temperature and nanoparticle concentration depends on six parameters, viz., convective heating parameter A, Prandtl number Pr, Lewis number Le, Brownian motion Nb, buoyancy ratio parameter Nr, and the thermophoresis parameter Nt. Similarity transformation is used to convert the governing nonlinear boundary-layer equations into coupled higher order ordinary differential equations. These equations were solved numerically using Runge-Kutta fourth order method with shooting technique. The effects of the governing parameters on flow field and heat transfer characteristics were obtained and discussed. Numerical results are obtained for velocity, temperature, and concentration distribution as well as the local Nusselt number and Sherwood number. It is found that the local Nusselt number and Sherwood number increase with an increase in convective parameter A and Lewis number Le. Likewise, the local Sherwood number increases with an increase in both A and Le. A comparison with the previous study available in literature has been done and we found an excellent agreement with them. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Investigation of dam-break flow over abruptly contracting channel with trapezoidal-shaped lateral obstacles / Hatice Ozmen-Cagatay in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 07 p. Titre : Investigation of dam-break flow over abruptly contracting channel with trapezoidal-shaped lateral obstacles Type de document : texte imprimé Auteurs : Hatice Ozmen-Cagatay, Auteur ; Selahattin Kocaman, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : dam-break;  unsteady  flow;  negative  bore;  abrupt  contraction;  virtual  wave  probe Résumé : The present paper aims to investigate the dam-break flow over dry channel with an abrupt contracting part in certain downstream section. A new experiment was carried out in a smooth-prismatic channel with rectangular cross section and horizontal bed. A digital imaging technique was adopted for flow measurement and thus flood wave propagation was sensitively obtained. Synchronous filmed images of the dam-break flow were nonintrusively acquired with three cameras, through glass sidewalls of the channel. Free surface profiles and time evolution of water levels were derived directly from the recorded video images using virtual wave probe without disturbing the flow. Furthermore, the present study highlights the formation and propagation of the negative bore due to abruptly contracting channel. The measured results were compared with the numerical solution of Reynolds averaged Navier–Stokes (RANS) equations with k-epsilon turbulence model and good agreement was achieved. New experimental data can be useful for scientific community to validate numerical models. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Investigation of dam-break flow over abruptly contracting channel with trapezoidal-shaped lateral obstacles [texte imprimé] / Hatice Ozmen-Cagatay, Auteur ; Selahattin Kocaman, Auteur . - 2012 . - 07 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 07 p. Mots-clés : dam-break;  unsteady  flow;  negative  bore;  abrupt  contraction;  virtual  wave  probe Résumé : The present paper aims to investigate the dam-break flow over dry channel with an abrupt contracting part in certain downstream section. A new experiment was carried out in a smooth-prismatic channel with rectangular cross section and horizontal bed. A digital imaging technique was adopted for flow measurement and thus flood wave propagation was sensitively obtained. Synchronous filmed images of the dam-break flow were nonintrusively acquired with three cameras, through glass sidewalls of the channel. Free surface profiles and time evolution of water levels were derived directly from the recorded video images using virtual wave probe without disturbing the flow. Furthermore, the present study highlights the formation and propagation of the negative bore due to abruptly contracting channel. The measured results were compared with the numerical solution of Reynolds averaged Navier–Stokes (RANS) equations with k-epsilon turbulence model and good agreement was achieved. New experimental data can be useful for scientific community to validate numerical models. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Analytical Simulation of Annular Two-Phase Flow Considering the Four Involved Mass Transfers / Zahra Baniamerian in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 09 p. Titre : Analytical Simulation of Annular Two-Phase Flow Considering the Four Involved Mass Transfers Type de document : texte imprimé Auteurs : Zahra Baniamerian, Auteur ; Ramin Mehdipour, Auteur ; Cyrus Aghanajafi, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : two-phase  flow;  annular  flow;  liquid  film  thickness;  vapor  core;  mass  transfer Résumé : Efficiently employing two-phase flows for cooling objectives requires comprehensive knowledge of their behavior in different conditions. Models, capable of predicting heat transfer and fluid flow trends in this area, are of great value. Numerical/analytical models in the literature are one-dimensional models involving with many simplifying assumptions. These assumptions in most cases include neglecting some mechanisms of mass transfer in two-phase flows. This study is devoted to developing an analytical two-dimensional model for simulation of fluid flow and mass transfer in two-phase flows considering the all mass transfer mechanisms (entrainment, evaporation, deposition and condensation). The correlation employed for modeling entrainment in this study, is a semiempirical correlation derived based on physical concept of entrainment phenomenon. Emphasis is put on the annular flow pattern of liquid vapor two-phase flow since this regime is the last encountered two-phase regime and has a higher heat transfer coefficient among other two-phase flow patterns. Attempts are made to employ the least possible simplification assumptions and empirical correlations in the modeling procedure. The model is then verified with experimental models of Shanawany et al., Stevanovic et al. and analytical model of Qu and Mudawar. It will be shown, considering pressure variations in both radial and axial directions along with applying our semiempirical entrainment correlation has improved the present analytical model accuracy in comparison with the accuracy of available analytical models. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Analytical Simulation of Annular Two-Phase Flow Considering the Four Involved Mass Transfers [texte imprimé] / Zahra Baniamerian, Auteur ; Ramin Mehdipour, Auteur ; Cyrus Aghanajafi, Auteur . - 2012 . - 09 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 09 p. Mots-clés : two-phase  flow;  annular  flow;  liquid  film  thickness;  vapor  core;  mass  transfer Résumé : Efficiently employing two-phase flows for cooling objectives requires comprehensive knowledge of their behavior in different conditions. Models, capable of predicting heat transfer and fluid flow trends in this area, are of great value. Numerical/analytical models in the literature are one-dimensional models involving with many simplifying assumptions. These assumptions in most cases include neglecting some mechanisms of mass transfer in two-phase flows. This study is devoted to developing an analytical two-dimensional model for simulation of fluid flow and mass transfer in two-phase flows considering the all mass transfer mechanisms (entrainment, evaporation, deposition and condensation). The correlation employed for modeling entrainment in this study, is a semiempirical correlation derived based on physical concept of entrainment phenomenon. Emphasis is put on the annular flow pattern of liquid vapor two-phase flow since this regime is the last encountered two-phase regime and has a higher heat transfer coefficient among other two-phase flow patterns. Attempts are made to employ the least possible simplification assumptions and empirical correlations in the modeling procedure. The model is then verified with experimental models of Shanawany et al., Stevanovic et al. and analytical model of Qu and Mudawar. It will be shown, considering pressure variations in both radial and axial directions along with applying our semiempirical entrainment correlation has improved the present analytical model accuracy in comparison with the accuracy of available analytical models. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Experiments on cake development in crossflow filtration for high level waste / Mark R. Duignan in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 09 p. Titre : Experiments on cake development in crossflow filtration for high level waste Type de document : texte imprimé Auteurs : Mark R. Duignan, Auteur ; Charles A. Nash, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : radioactive  sludge;  non-newtonian;  filter  cake;  filtration Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Crossflow filtration is a key process step in many operating and planned waste treatment facilities to separate undissolved solids from supernatant slurries. This separation technology generally has the advantage of self-cleaning through the action of wall shear stress created by the flow of waste slurry through the filter tubes. However, the ability of filter wall self-cleaning depends on the slurry being filtered. Many of the alkaline radioactive wastes are extremely challenging to filtration, e.g., those containing compounds of aluminum and iron having particles whose particle size and morphology reduce cake permeability. Low filter flux can be a bottleneck in waste processing facilities such as the Salt Waste Processing Facility at the Savannah River Site and the Waste Treatment Plant at the Hanford Site. To date, increased rates are generally realized by either increasing the crossflow filter axial flow rate, limited by pump capacity, or by increasing filter surface area limited by space and increasing the required pump load. The Savannah River National Laboratory (SRNL) set up both dead-end and crossflow filter tests to better understand filter performance based on filter media structure, flow conditions, and filter cleaning. Using nonradioactive simulated wastes, both chemically and physically similar to the actual radioactive wastes, the authors performed several tests to demonstrate increases in filter performance. With the proper use of filter flow conditions, filter flow rates can be increased over rates currently realized today. This paper describes the selection of a challenging simulated waste and crossflow filter tests to demonstrate how performance can be improved by varied filter operation methods. Those methods were a slow startup to better develop the filter cake and scouring the filter wall. The results showed that for salt waste and metal oxide hydroxide sludges, the process of backpulsing is not necessary to maintain a good filter flux, and the process of periodically scouring the filter improves filter performance. The results also imply that initial filter operation is important to develop a filter cake that minimized pressure drop, the presence of a filter cake can lead to improved solids separation, and a well-developed cake with periodic scouring may allow a good filter flux to be maintained for long periods of time. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Experiments on cake development in crossflow filtration for high level waste [texte imprimé] / Mark R. Duignan, Auteur ; Charles A. Nash, Auteur . - 2012 . - 09 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 09 p. Mots-clés : radioactive  sludge;  non-newtonian;  filter  cake;  filtration Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Crossflow filtration is a key process step in many operating and planned waste treatment facilities to separate undissolved solids from supernatant slurries. This separation technology generally has the advantage of self-cleaning through the action of wall shear stress created by the flow of waste slurry through the filter tubes. However, the ability of filter wall self-cleaning depends on the slurry being filtered. Many of the alkaline radioactive wastes are extremely challenging to filtration, e.g., those containing compounds of aluminum and iron having particles whose particle size and morphology reduce cake permeability. Low filter flux can be a bottleneck in waste processing facilities such as the Salt Waste Processing Facility at the Savannah River Site and the Waste Treatment Plant at the Hanford Site. To date, increased rates are generally realized by either increasing the crossflow filter axial flow rate, limited by pump capacity, or by increasing filter surface area limited by space and increasing the required pump load. The Savannah River National Laboratory (SRNL) set up both dead-end and crossflow filter tests to better understand filter performance based on filter media structure, flow conditions, and filter cleaning. Using nonradioactive simulated wastes, both chemically and physically similar to the actual radioactive wastes, the authors performed several tests to demonstrate increases in filter performance. With the proper use of filter flow conditions, filter flow rates can be increased over rates currently realized today. This paper describes the selection of a challenging simulated waste and crossflow filter tests to demonstrate how performance can be improved by varied filter operation methods. Those methods were a slow startup to better develop the filter cake and scouring the filter wall. The results showed that for salt waste and metal oxide hydroxide sludges, the process of backpulsing is not necessary to maintain a good filter flux, and the process of periodically scouring the filter improves filter performance. The results also imply that initial filter operation is important to develop a filter cake that minimized pressure drop, the presence of a filter cake can lead to improved solids separation, and a well-developed cake with periodic scouring may allow a good filter flux to be maintained for long periods of time. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Modeling the onset of gas entrainment in a reduced T-junction with co-current stratified gas-liquid flow / Bowden, Robert C. in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 12 p. Titre : Modeling the onset of gas entrainment in a reduced T-junction with co-current stratified gas-liquid flow Type de document : texte imprimé Auteurs : Bowden, Robert C., Auteur ; Hassan, Ibrahim G., Auteur Année de publication : 2012 Article en page(s) : 12 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : co-current  stratified  gas-liquid;  onset  of  gas  entrainment;  critical  height;  digital  imaging;  T-junction Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A model was developed to predict the onset of gas entrainment in a single downward oriented branch. The branch was installed on a horizontal square cross-sectional channel having a smooth stratified co-currently flowing gas-liquid regime in the inlet region. The branch flow was simulated as a three-dimensional point-sink while the run flow was treated as a uniform velocity at the critical dip. Experiments were performed to determine the critical liquid flow distribution between the run and the branch. A correlation was developed relating the branch Froude number to the ratio of the superficial liquid mass fluxes in the run and the branch. The correlation was used as a boundary condition in the model. A methodology was developed using digital imaging to record the coordinates of the critical dip at the onset of as entrainment. The dip angle was found to range between 40 to 60 degrees and constant dip angles of 40, 50 and 60 degrees were selected as boundary conditions. The critical height was predicted to within 50% of experiments with the error attributed to differences in the modeled and experimental geometries. A semi-empirical analysis using the experimental geometry yielded a critical height prediction to within 20% of experimental results. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Modeling the onset of gas entrainment in a reduced T-junction with co-current stratified gas-liquid flow [texte imprimé] / Bowden, Robert C., Auteur ; Hassan, Ibrahim G., Auteur . - 2012 . - 12 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 12 p. Mots-clés : co-current  stratified  gas-liquid;  onset  of  gas  entrainment;  critical  height;  digital  imaging;  T-junction Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A model was developed to predict the onset of gas entrainment in a single downward oriented branch. The branch was installed on a horizontal square cross-sectional channel having a smooth stratified co-currently flowing gas-liquid regime in the inlet region. The branch flow was simulated as a three-dimensional point-sink while the run flow was treated as a uniform velocity at the critical dip. Experiments were performed to determine the critical liquid flow distribution between the run and the branch. A correlation was developed relating the branch Froude number to the ratio of the superficial liquid mass fluxes in the run and the branch. The correlation was used as a boundary condition in the model. A methodology was developed using digital imaging to record the coordinates of the critical dip at the onset of as entrainment. The dip angle was found to range between 40 to 60 degrees and constant dip angles of 40, 50 and 60 degrees were selected as boundary conditions. The critical height was predicted to within 50% of experiments with the error attributed to differences in the modeled and experimental geometries. A semi-empirical analysis using the experimental geometry yielded a critical height prediction to within 20% of experimental results. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Influence of the blade number on inducer cavitating behavior / O. Coutier-Delgosha in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 11 p. Titre : Influence of the blade number on inducer cavitating behavior Type de document : texte imprimé Auteurs : O. Coutier-Delgosha, Auteur ; G. Caignaert, Auteur ; G. Bois, Auteur Année de publication : 2012 Article en page(s) : 11 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : blade  number;  rocket  engine  turbopump  inducer;  cavitation  number Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Effects of the blade number on the performance of a rocket engine turbopump inducer are investigated in the present paper. For that purpose, two inducers characterized by three blades and five blades, respectively, were manufactured and tested experimentally. The two inducers were designed on the basis of identical design flow rate and identical pressure elevation at nominal flow rate. The first part of the study focuses on the steady behavior of the inducers in cavitating conditions: evolutions of performance, torque, mass flow rate, and amplitude of radial forces on the shaft according to the inlet pressure are considered. Several flow rates and rotation speeds are investigated. Significant differences between the inducers are obtained concerning the critical cavitation number, the amplitude of the radial forces, and the organization of cavitation in the machinery. Cavitation instabilities are investigated in the second part of the study. Various flow patterns are detected according to the mass flow rate and the cavitation number. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Influence of the blade number on inducer cavitating behavior [texte imprimé] / O. Coutier-Delgosha, Auteur ; G. Caignaert, Auteur ; G. Bois, Auteur . - 2012 . - 11 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 11 p. Mots-clés : blade  number;  rocket  engine  turbopump  inducer;  cavitation  number Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Effects of the blade number on the performance of a rocket engine turbopump inducer are investigated in the present paper. For that purpose, two inducers characterized by three blades and five blades, respectively, were manufactured and tested experimentally. The two inducers were designed on the basis of identical design flow rate and identical pressure elevation at nominal flow rate. The first part of the study focuses on the steady behavior of the inducers in cavitating conditions: evolutions of performance, torque, mass flow rate, and amplitude of radial forces on the shaft according to the inlet pressure are considered. Several flow rates and rotation speeds are investigated. Significant differences between the inducers are obtained concerning the critical cavitation number, the amplitude of the radial forces, and the organization of cavitation in the machinery. Cavitation instabilities are investigated in the second part of the study. Various flow patterns are detected according to the mass flow rate and the cavitation number. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Comparisons of annular hydrodynamic structures in 3D fluidized beds using x-ray computed tomography imaging / Joshua B. Drake in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 08 p. Titre : Comparisons of annular hydrodynamic structures in 3D fluidized beds using x-ray computed tomography imaging Type de document : texte imprimé Auteurs : Joshua B. Drake, Auteur ; Heindel, Theodore J., Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : annular  flow;  fluidized  bed;  gas  holdup;  hydrodynamic  structure;  x-ray  computed  tomography Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Fluidized beds are common equipment in many process industries. Knowledge of the hydrodynamics within a fluidized bed on the local scale is important for the improvement of scale-up and process efficiencies. This knowledge is lacking due to limited observational technologies at the local scale. This paper uses X-ray computed tomography (CT) imaging to describe the local time-average gas holdup differences of annular hydrodynamic structures that arise through axisymmetric annular flow in a 10.2 cm and 15.2 cm diameter cold flow fluidized bed. The aeration scheme used is similar to that provided by a porous plate and hydrodynamic results can be directly compared. Geldart type B glass bead, ground walnut shell, and crushed corncob particles were studied at various superficial gas velocities. Assuming axisymmetry, the local 3D time-average gas holdup data acquired through X-ray CT imaging was averaged over concentric annuli, resulting in a 2D annular and time-average gas holdup map. These gas holdup maps show that four different types of annular hydrodynamic structures occur in the fluidized beds of this study: zones of (1) aeration jetting, (2) bubble coalescence, (3) bubble rise, and (4) particle shear. Changes in the superficial gas velocities, bed diameters, and bed material densities display changes in these zones. The 2D gas holdup maps provide a benchmark that can be used by computational fluid dynamic (CFD) users for the direct comparisons of 2D models, assuming axisymmetric annular flow. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Comparisons of annular hydrodynamic structures in 3D fluidized beds using x-ray computed tomography imaging [texte imprimé] / Joshua B. Drake, Auteur ; Heindel, Theodore J., Auteur . - 2012 . - 08 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 08 p. Mots-clés : annular  flow;  fluidized  bed;  gas  holdup;  hydrodynamic  structure;  x-ray  computed  tomography Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Fluidized beds are common equipment in many process industries. Knowledge of the hydrodynamics within a fluidized bed on the local scale is important for the improvement of scale-up and process efficiencies. This knowledge is lacking due to limited observational technologies at the local scale. This paper uses X-ray computed tomography (CT) imaging to describe the local time-average gas holdup differences of annular hydrodynamic structures that arise through axisymmetric annular flow in a 10.2 cm and 15.2 cm diameter cold flow fluidized bed. The aeration scheme used is similar to that provided by a porous plate and hydrodynamic results can be directly compared. Geldart type B glass bead, ground walnut shell, and crushed corncob particles were studied at various superficial gas velocities. Assuming axisymmetry, the local 3D time-average gas holdup data acquired through X-ray CT imaging was averaged over concentric annuli, resulting in a 2D annular and time-average gas holdup map. These gas holdup maps show that four different types of annular hydrodynamic structures occur in the fluidized beds of this study: zones of (1) aeration jetting, (2) bubble coalescence, (3) bubble rise, and (4) particle shear. Changes in the superficial gas velocities, bed diameters, and bed material densities display changes in these zones. The 2D gas holdup maps provide a benchmark that can be used by computational fluid dynamic (CFD) users for the direct comparisons of 2D models, assuming axisymmetric annular flow. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

The drag coefficient and the shape for a single bubble rising in non-newtonian fluids / Shaobai Li in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 04 p. Titre : The drag coefficient and the shape for a single bubble rising in non-newtonian fluids Type de document : texte imprimé Auteurs : Shaobai Li, Auteur ; Youguang Ma, Auteur ; Shaokun Jiang, Auteur Année de publication : 2012 Article en page(s) : 04 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : bubble;  dragcoefficient;  non-newtonian  fluids;  bubble  shape Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The dynamical characteristic of a single bubble rising in non-Newtonian fluid was investigated experimentally. The bubble aspect ratio and rising velocity were measured by high speed camera. The shape regimes for bubbles in non-Newtonian fluids was plotted by means of Reynolds number Re, Eötvös number Eo and Morton number Mo. The effects of bubble shape and liquid rheological property on the total bubble drag coefficient were studied. A new empirical drag coefficient correlation covering spherical bubble and deformed bubble was proposed, the predicted results shows good conformity to experimental values over a wide range of 0.05 < Re < 300. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] The drag coefficient and the shape for a single bubble rising in non-newtonian fluids [texte imprimé] / Shaobai Li, Auteur ; Youguang Ma, Auteur ; Shaokun Jiang, Auteur . - 2012 . - 04 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 04 p. Mots-clés : bubble;  dragcoefficient;  non-newtonian  fluids;  bubble  shape Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The dynamical characteristic of a single bubble rising in non-Newtonian fluid was investigated experimentally. The bubble aspect ratio and rising velocity were measured by high speed camera. The shape regimes for bubbles in non-Newtonian fluids was plotted by means of Reynolds number Re, Eötvös number Eo and Morton number Mo. The effects of bubble shape and liquid rheological property on the total bubble drag coefficient were studied. A new empirical drag coefficient correlation covering spherical bubble and deformed bubble was proposed, the predicted results shows good conformity to experimental values over a wide range of 0.05 < Re < 300. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Effect of corrugated roughness on developed laminar flow in microtubes / F. Talay Akyildiz in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 02 p. Titre : Effect of corrugated roughness on developed laminar flow in microtubes Type de document : texte imprimé Auteurs : F. Talay Akyildiz, Auteur ; Dennis A. Siginer, Auteur Année de publication : 2012 Article en page(s) : 02 p. Note générale : fluids engineering Langues : Anglais (eng) Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Fully developed continuum flow through corrugated tubes with slip at the boundary is solved by perturbations and the results are compared with the work of Duan and Muzychka (Duan and Muzychka, 2008, “Effects of Corrugated Roughness on Developed Laminar Flow in Microtubes,” ASME Trans. J. Fluids Eng., 130, p. 031102). This note brings out and corrects the errata and extends the results obtained. Note de contenu : Discussion: “Effect of Corrugated Roughness on Developed Laminar Flow in Microtubes,” (Duan, Z. and Muzychka, Y. M., 2008, ASME Trans. J. Fluids Eng., 130, p. 031102) DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Effect of corrugated roughness on developed laminar flow in microtubes [texte imprimé] / F. Talay Akyildiz, Auteur ; Dennis A. Siginer, Auteur . - 2012 . - 02 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 02 p. Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Fully developed continuum flow through corrugated tubes with slip at the boundary is solved by perturbations and the results are compared with the work of Duan and Muzychka (Duan and Muzychka, 2008, “Effects of Corrugated Roughness on Developed Laminar Flow in Microtubes,” ASME Trans. J. Fluids Eng., 130, p. 031102). This note brings out and corrects the errata and extends the results obtained. Note de contenu : Discussion: “Effect of Corrugated Roughness on Developed Laminar Flow in Microtubes,” (Duan, Z. and Muzychka, Y. M., 2008, ASME Trans. J. Fluids Eng., 130, p. 031102) DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

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