Dépouillements

Study on performance and flow condition of a cross-flow wind turbine with a symmetrical casing / Fukutomi, Junichiro in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 09 p. Titre : Study on performance and flow condition of a cross-flow wind turbine with a symmetrical casing Type de document : texte imprimé Auteurs : Fukutomi, Junichiro, Auteur ; Shigemitsu, Toru, Auteur ; Daito, Hiroki, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Rotational  flow  Rotors  Torquemeters  Wind  tunnels  Wind  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A cross-flow wind turbine has a high torque coefficient at a low tip speed ratio. Therefore, it is a good candidate for use as a self-starting turbine. Furthermore, it has low noise and excellent stability; therefore, it has attracted attention from the viewpoint of applications as a small wind turbine for an urban district. However, its maximum power coefficient is extremely low (10%) as compared to that of other small wind turbines. Prevailing winds in two directions often blow in urban and coastal regions. Therefore, in order to improve the performance and the flow condition of the cross-flow rotor, a casing suitable for this sort of prevailing wind conditions is designed in this research and the effect of the casing is investigated by experimental and numerical analysis. In the experiment, a wind tunnel with a square discharge is used and main flow velocity is set as 20 m/s. A torque meter, a rotational speed pickup, and a motor are assembled with the same axis as the test wind turbine and the tip speed ratio is changeable by a rotational speed controller. The casing is set around the cross-flow rotor and flow distribution at the rotor inlet and the outlet is measured by a one-hole pitot tube. The maximum power coefficient is obtained as Cpmax = 0.19 with the casing, however Cpmax = 0.098 without the casing. It is clear that the inlet and the outlet flow condition is improved by the casing. In the present paper, in order to improve the performance of a cross-flow wind turbine, a symmetrical casing suitable for prevailing winds in two directions is proposed. Then, the performance and the internal flow condition of the cross-flow wind turbine with the casing are clarified. Furthermore, the influence of the symmetrical casing on performance is discussed and the relation between the flow condition and performance is considered. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Study on performance and flow condition of a cross-flow wind turbine with a symmetrical casing [texte imprimé] / Fukutomi, Junichiro, Auteur ; Shigemitsu, Toru, Auteur ; Daito, Hiroki, Auteur . - 2011 . - 09 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 09 p. Mots-clés : Rotational  flow  Rotors  Torquemeters  Wind  tunnels  Wind  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A cross-flow wind turbine has a high torque coefficient at a low tip speed ratio. Therefore, it is a good candidate for use as a self-starting turbine. Furthermore, it has low noise and excellent stability; therefore, it has attracted attention from the viewpoint of applications as a small wind turbine for an urban district. However, its maximum power coefficient is extremely low (10%) as compared to that of other small wind turbines. Prevailing winds in two directions often blow in urban and coastal regions. Therefore, in order to improve the performance and the flow condition of the cross-flow rotor, a casing suitable for this sort of prevailing wind conditions is designed in this research and the effect of the casing is investigated by experimental and numerical analysis. In the experiment, a wind tunnel with a square discharge is used and main flow velocity is set as 20 m/s. A torque meter, a rotational speed pickup, and a motor are assembled with the same axis as the test wind turbine and the tip speed ratio is changeable by a rotational speed controller. The casing is set around the cross-flow rotor and flow distribution at the rotor inlet and the outlet is measured by a one-hole pitot tube. The maximum power coefficient is obtained as Cpmax = 0.19 with the casing, however Cpmax = 0.098 without the casing. It is clear that the inlet and the outlet flow condition is improved by the casing. In the present paper, in order to improve the performance of a cross-flow wind turbine, a symmetrical casing suitable for prevailing winds in two directions is proposed. Then, the performance and the internal flow condition of the cross-flow wind turbine with the casing are clarified. Furthermore, the influence of the symmetrical casing on performance is discussed and the relation between the flow condition and performance is considered. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

On the modeling and simulation of ion drag electrohydrodynamic micropumps / Hasnain, S. Mohammed in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 07 p. Titre : On the modeling and simulation of ion drag electrohydrodynamic micropumps Type de document : texte imprimé Auteurs : Hasnain, S. Mohammed, Auteur ; Bakshi, Akhilesh, Auteur ; Selvaganapathy, P. Ravi, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Boundary  layers  Drag  Electrodes  Electrohydrodynamics  Flow  simulation  Microchannel  flow  Micropumps  Numerical  analysis  Poisson  equation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A numerical model for ion-drag electrohydrodynamic (EHD) micropumps has been developed. The Poisson and charge conservation equations are solved to determine the electric body force within the flow domain. The charge distribution at the electrodes is assumed to depend on the magnitude and the gradient of the electric field at the surface of the electrode. The flow field is then determined by solving the momentum equation with the inclusion of the electric body force. Simulations were performed for micropump configurations that consisted of a series of planar electrode pairs embedded along the bottom wall of a microchannel. A two-dimensional segment of the channel with a single electrode pair is simulated using periodic boundary conditions at the inlet and outlet for the charge and electric fields. An empirical model was developed to estimate the charge boundary condition for the simulations. The simulation results were in good agreement with existing experimental data. The model was then used to perform a parametric study of the effect of channel height on the pump performance. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] On the modeling and simulation of ion drag electrohydrodynamic micropumps [texte imprimé] / Hasnain, S. Mohammed, Auteur ; Bakshi, Akhilesh, Auteur ; Selvaganapathy, P. Ravi, Auteur . - 2011 . - 07 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 07 p. Mots-clés : Boundary  layers  Drag  Electrodes  Electrohydrodynamics  Flow  simulation  Microchannel  flow  Micropumps  Numerical  analysis  Poisson  equation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A numerical model for ion-drag electrohydrodynamic (EHD) micropumps has been developed. The Poisson and charge conservation equations are solved to determine the electric body force within the flow domain. The charge distribution at the electrodes is assumed to depend on the magnitude and the gradient of the electric field at the surface of the electrode. The flow field is then determined by solving the momentum equation with the inclusion of the electric body force. Simulations were performed for micropump configurations that consisted of a series of planar electrode pairs embedded along the bottom wall of a microchannel. A two-dimensional segment of the channel with a single electrode pair is simulated using periodic boundary conditions at the inlet and outlet for the charge and electric fields. An empirical model was developed to estimate the charge boundary condition for the simulations. The simulation results were in good agreement with existing experimental data. The model was then used to perform a parametric study of the effect of channel height on the pump performance. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Manifold Design for Micro-Channel Cooling With uniform flow distribution / Solovitz, Stephen A. in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 11 p. Titre : Manifold Design for Micro-Channel Cooling With uniform flow distribution Type de document : texte imprimé Auteurs : Solovitz, Stephen A., Auteur ; Mainka, Jeffrey, Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Cooling  Laminar  flow  Microchannel  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : High-power electronic systems often require temperature uniformity for optimal performance. While many advanced cooling systems, such as micro-channels, result in significant heat removal, they are also susceptible to flow mal-distribution that can impact the local temperature variation on a device. By examining the pressure drops through each flow path in a multi-channel cooling system, an analytical model is predicted for the optimal manifold shape to produce uniform velocities. This is a simple power law, whose exponent depends on the flow regime in the manifold passages. The model is validated for laminar fully developed conditions using a series of computational simulations. With the power law design, the speeds in a parallel channel design are uniformly distributed at low Reynolds numbers, with a standard deviation of less than 3% of the overall mean channel speed. At higher Reynolds numbers, some mal-distribution is observed due to developing flow conditions, but it is not as significant as with typical untapered designs. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Manifold Design for Micro-Channel Cooling With uniform flow distribution [texte imprimé] / Solovitz, Stephen A., Auteur ; Mainka, Jeffrey, Auteur . - 2011 . - 11 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 11 p. Mots-clés : Cooling  Laminar  flow  Microchannel  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : High-power electronic systems often require temperature uniformity for optimal performance. While many advanced cooling systems, such as micro-channels, result in significant heat removal, they are also susceptible to flow mal-distribution that can impact the local temperature variation on a device. By examining the pressure drops through each flow path in a multi-channel cooling system, an analytical model is predicted for the optimal manifold shape to produce uniform velocities. This is a simple power law, whose exponent depends on the flow regime in the manifold passages. The model is validated for laminar fully developed conditions using a series of computational simulations. With the power law design, the speeds in a parallel channel design are uniformly distributed at low Reynolds numbers, with a standard deviation of less than 3% of the overall mean channel speed. At higher Reynolds numbers, some mal-distribution is observed due to developing flow conditions, but it is not as significant as with typical untapered designs. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Experimental evidence of rotating stall in a pump-turbine at off-design conditions in generating mode / Hasmatuchi, Vlad in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 08 p. Titre : Experimental evidence of rotating stall in a pump-turbine at off-design conditions in generating mode Type de document : texte imprimé Auteurs : Hasmatuchi, Vlad, Auteur ; Farhat, Mohamed, Auteur ; Roth, Steven, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Blades  Bubbles  Channel  flow  Flow  separation  Flow  visualisation  Image  reconstruction  Pattern  formation  Pumps  Spectral  analysis  Stators  Turbines  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An experimental investigation of the rotating stall in reduced scale model of a low specific speed radial pump-turbine at runaway and turbine brake conditions in generating mode is achieved. Measurements of wall pressure in the stator are performed along with high-speed flow visualizations in the vaneless gap with the help of air bubbles injection. When starting from the best efficiency point (BEP) and increasing the impeller speed, a significant increase of the pressure fluctuations is observed mainly in the wicket gates channels. The spectral analysis shows a rise of a low frequency component (about 70% of the impeller rotational frequency) at runaway, which further increases as the zero discharge condition is approached. Analysis of the instantaneous pressure peripheral distribution in the vaneless gap reveals one stall cell rotating with the impeller at sub-synchronous speed. High-speed movies reveal a quite uniform flow pattern in the guide vanes channels at the normal operating range, whereas at runaway the flow is highly disturbed by the rotating stall passage. The situation is even more critical at very low positive discharge, where backflow and vortices in the guide vanes channels develop during the stall cell passage. A specific image processing technique is applied to reconstruct the rotating stall evolution in the entire guide vanes circumference for a low positive discharge operating point. The findings of this study suggest that one stall cell rotates with the impeller at sub-synchronous velocity in the vaneless gap between the impeller and the guide vanes. It is the result of rotating flow separations developed in several consecutive impeller channels which lead to their blockage. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Experimental evidence of rotating stall in a pump-turbine at off-design conditions in generating mode [texte imprimé] / Hasmatuchi, Vlad, Auteur ; Farhat, Mohamed, Auteur ; Roth, Steven, Auteur . - 2011 . - 08 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 08 p. Mots-clés : Blades  Bubbles  Channel  flow  Flow  separation  Flow  visualisation  Image  reconstruction  Pattern  formation  Pumps  Spectral  analysis  Stators  Turbines  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An experimental investigation of the rotating stall in reduced scale model of a low specific speed radial pump-turbine at runaway and turbine brake conditions in generating mode is achieved. Measurements of wall pressure in the stator are performed along with high-speed flow visualizations in the vaneless gap with the help of air bubbles injection. When starting from the best efficiency point (BEP) and increasing the impeller speed, a significant increase of the pressure fluctuations is observed mainly in the wicket gates channels. The spectral analysis shows a rise of a low frequency component (about 70% of the impeller rotational frequency) at runaway, which further increases as the zero discharge condition is approached. Analysis of the instantaneous pressure peripheral distribution in the vaneless gap reveals one stall cell rotating with the impeller at sub-synchronous speed. High-speed movies reveal a quite uniform flow pattern in the guide vanes channels at the normal operating range, whereas at runaway the flow is highly disturbed by the rotating stall passage. The situation is even more critical at very low positive discharge, where backflow and vortices in the guide vanes channels develop during the stall cell passage. A specific image processing technique is applied to reconstruct the rotating stall evolution in the entire guide vanes circumference for a low positive discharge operating point. The findings of this study suggest that one stall cell rotates with the impeller at sub-synchronous velocity in the vaneless gap between the impeller and the guide vanes. It is the result of rotating flow separations developed in several consecutive impeller channels which lead to their blockage. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Internal flow losses / Schmandt, Bastian in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 10 p. Titre : Internal flow losses : a fresh look at old concepts Type de document : texte imprimé Auteurs : Schmandt, Bastian, Auteur ; Herwig, Heinz, Auteur Année de publication : 2011 Article en page(s) : 10 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Channel  flow  Entropy Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Losses in a flow field due to single conduit components often are characterized by experimentally determined head loss coefficients K. These coefficients are defined and determined with the pressure as the critical quantity. A thermodynamic definition, given here as an alternative, is closer to the physics of flow losses, however. This definition is based upon the dissipation of mechanical energy as main quantity. With the second law of thermodynamics this dissipation can be linked to the local entropy generation in the flow field. For various conduit components K values are determined and physically interpreted by determining the entropy generation in the component as well as upstream and downstream of it. It turns out that most of the losses occur downstream of the components what carefully has to be taken into account when several components are combined in a flow network. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Internal flow losses : a fresh look at old concepts [texte imprimé] / Schmandt, Bastian, Auteur ; Herwig, Heinz, Auteur . - 2011 . - 10 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 10 p. Mots-clés : Channel  flow  Entropy Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Losses in a flow field due to single conduit components often are characterized by experimentally determined head loss coefficients K. These coefficients are defined and determined with the pressure as the critical quantity. A thermodynamic definition, given here as an alternative, is closer to the physics of flow losses, however. This definition is based upon the dissipation of mechanical energy as main quantity. With the second law of thermodynamics this dissipation can be linked to the local entropy generation in the flow field. For various conduit components K values are determined and physically interpreted by determining the entropy generation in the component as well as upstream and downstream of it. It turns out that most of the losses occur downstream of the components what carefully has to be taken into account when several components are combined in a flow network. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Manipulating flow to reduce drag of a square cylinder by using a self-sustained vibrating rod / Rong Fung Huang in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 14 p. Titre : Manipulating flow to reduce drag of a square cylinder by using a self-sustained vibrating rod Type de document : texte imprimé Auteurs : Rong Fung Huang, Auteur ; Cheng, Jeng Cha, Auteur ; Chen, Jia-Kun, Auteur Année de publication : 2011 Article en page(s) : 14 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Anemometry  Boundary  layer  turbulence  Drag  reduction  External  flows  Flow  control  Flow  instability  Flow  separation  Flow  visualisation  Pressure  measurement  Rods  (structures)  Vibrations  Vortices  Wakes Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The flow, vortex shedding, and surface pressure of a square cylinder at incidence were manipulated by means of a self-sustained vibrating rod placed around the leading edge of the upwind-facing lateral face of the square cylinder. The flow patterns on the cylinder surface were studied by using the surface-oil flow method for a Reynolds number between 4.5 × 104 and 1.1 × 105 as the incidence angle varied from 0° to 45°. Vortex-shedding characteristics were measured by means of a single-component hot-wire anemometer, and surface-pressure distributions were detected by using a linear-pressure scanner. The results show that owing to the influence of the rod vibration, the flow pattern on the agitated face changed from its natural state of a dual-ring bubble to the mode of boundary-layer separation. The critical incidence angle separating the dual-ring bubble and single-ring bubble modes was advanced to 11° from its natural state of 15°. The locations of the characteristic points on the cylinder surface were altered by the rod vibration, implying that the whole flow field surrounding the square cylinder was modified by the vibrating rod installed around the leading edge of the upwind-facing lateral face. The Strouhal numbers of wake instability of the controlled and uncontrolled cylinders did not present significant difference. The variations of the pressure coefficients induced by the rod vibration were closely related with the modification of the flow field on the cylinder surface. The decreases in the pressure coefficients on the upwind-facing faces and on the leeward-facing faces lead to drag reduction of the controlled cylinder by ~25% when compared with the uncontrolled cylinder. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Manipulating flow to reduce drag of a square cylinder by using a self-sustained vibrating rod [texte imprimé] / Rong Fung Huang, Auteur ; Cheng, Jeng Cha, Auteur ; Chen, Jia-Kun, Auteur . - 2011 . - 14 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 14 p. Mots-clés : Anemometry  Boundary  layer  turbulence  Drag  reduction  External  flows  Flow  control  Flow  instability  Flow  separation  Flow  visualisation  Pressure  measurement  Rods  (structures)  Vibrations  Vortices  Wakes Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The flow, vortex shedding, and surface pressure of a square cylinder at incidence were manipulated by means of a self-sustained vibrating rod placed around the leading edge of the upwind-facing lateral face of the square cylinder. The flow patterns on the cylinder surface were studied by using the surface-oil flow method for a Reynolds number between 4.5 × 104 and 1.1 × 105 as the incidence angle varied from 0° to 45°. Vortex-shedding characteristics were measured by means of a single-component hot-wire anemometer, and surface-pressure distributions were detected by using a linear-pressure scanner. The results show that owing to the influence of the rod vibration, the flow pattern on the agitated face changed from its natural state of a dual-ring bubble to the mode of boundary-layer separation. The critical incidence angle separating the dual-ring bubble and single-ring bubble modes was advanced to 11° from its natural state of 15°. The locations of the characteristic points on the cylinder surface were altered by the rod vibration, implying that the whole flow field surrounding the square cylinder was modified by the vibrating rod installed around the leading edge of the upwind-facing lateral face. The Strouhal numbers of wake instability of the controlled and uncontrolled cylinders did not present significant difference. The variations of the pressure coefficients induced by the rod vibration were closely related with the modification of the flow field on the cylinder surface. The decreases in the pressure coefficients on the upwind-facing faces and on the leeward-facing faces lead to drag reduction of the controlled cylinder by ~25% when compared with the uncontrolled cylinder. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Characteristics of turbulent three-dimensional offset jets / Agelin-Chaab, M. in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 09 p. Titre : Characteristics of turbulent three-dimensional offset jets Type de document : texte imprimé Auteurs : Agelin-Chaab, M., Auteur ; Tachie, M. F., Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Boundary  layer  turbulence  Flow  separation  Flow  visualisation  Fractals  Jets  Shear  turbulence  Wetting Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three-dimensional turbulent offset jets were investigated using a particle image velocimetry technique. Three jet exit Reynolds numbers, Rej = 5000, 10,000, and 20,000, and four offset heights, h/d = 0.5, 1.0, 2.0, and 4.0, were studied. The mean flow and turbulence statistics were studied over larger downstream distances than in previous studies. The decay and spread rates were found to be nearly independent of Reynolds number and offset height at certain exit diameters (x = 73d) downstream and h/d <= 2. The decay rates of 1.18 ± 0.03 and spread rates of 0.055 ± 0.001 and 0.250 ± 0.005 in the wall-normal and lateral directions were obtained, respectively. The reattachment lengths are also independent of Rej but increase with offset height. The locations of the maximum mean velocities increased linearly with streamwise distance in the self-similar region. It was observed that profiles of the mean velocities, turbulence intensities, and Reynolds shears stresses are nearly independent of Rej and h/d far downstream. The triple products in the symmetry plane indicated turbulence transport from the outer region of the jet towards the wall region. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Characteristics of turbulent three-dimensional offset jets [texte imprimé] / Agelin-Chaab, M., Auteur ; Tachie, M. F., Auteur . - 2011 . - 09 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 09 p. Mots-clés : Boundary  layer  turbulence  Flow  separation  Flow  visualisation  Fractals  Jets  Shear  turbulence  Wetting Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three-dimensional turbulent offset jets were investigated using a particle image velocimetry technique. Three jet exit Reynolds numbers, Rej = 5000, 10,000, and 20,000, and four offset heights, h/d = 0.5, 1.0, 2.0, and 4.0, were studied. The mean flow and turbulence statistics were studied over larger downstream distances than in previous studies. The decay and spread rates were found to be nearly independent of Reynolds number and offset height at certain exit diameters (x = 73d) downstream and h/d <= 2. The decay rates of 1.18 ± 0.03 and spread rates of 0.055 ± 0.001 and 0.250 ± 0.005 in the wall-normal and lateral directions were obtained, respectively. The reattachment lengths are also independent of Rej but increase with offset height. The locations of the maximum mean velocities increased linearly with streamwise distance in the self-similar region. It was observed that profiles of the mean velocities, turbulence intensities, and Reynolds shears stresses are nearly independent of Rej and h/d far downstream. The triple products in the symmetry plane indicated turbulence transport from the outer region of the jet towards the wall region. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Influence of geometry on starting vortex and ejector performance / Zheng, Fei in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 08 p. Titre : Influence of geometry on starting vortex and ejector performance Type de document : texte imprimé Auteurs : Zheng, Fei, Auteur ; Andrey V. Kuznetsov, Auteur ; Roberts, William L., Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Acoustic  waves  Detonation  waves  Engines  Jets  Navier-Stokes  equations  Propulsion  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : For many propulsion devices, the thrust may be augmented considerably by adding a passive ejector, and these devices are especially attractive for unsteady propulsion systems such as pulse detonation engines and pulsejets. Starting vortices from these unsteady devices dominate the flowfield and control to a great extent the level of the thrust augmentation. Therefore, it is of fundamental interest to understand the geometric influences on the starting vortex and how these manifest themselves in augmenter/ejector performance. An unsteady Reynolds averaged Navier–Stokes calculation was used to study the physics of a starting vortex generated at the exit of a pulsed jet and its interaction with an ejector. A 50 cm long pulsejet (typical hobby scale, allowing comparison with experimental data) with a circular exit was modeled as the resonant driving source and used to suggest an optimal ejector geometry and relative position. Computed limit-cycle thrust augmentation values compared favorably to experimentally obtained values for the same ejector geometries. Results suggest that the optimal diameter of the ejector is related to its relative position, dictated by the trajectory of the vortex toroid. The effect of the length of the ejector (which determines the natural frequency of the ejector, related to the acoustic processes occurring in the ejector) on overall performance was also investigated and shown to be less important than the ejector diameter. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Influence of geometry on starting vortex and ejector performance [texte imprimé] / Zheng, Fei, Auteur ; Andrey V. Kuznetsov, Auteur ; Roberts, William L., Auteur . - 2011 . - 08 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 08 p. Mots-clés : Acoustic  waves  Detonation  waves  Engines  Jets  Navier-Stokes  equations  Propulsion  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : For many propulsion devices, the thrust may be augmented considerably by adding a passive ejector, and these devices are especially attractive for unsteady propulsion systems such as pulse detonation engines and pulsejets. Starting vortices from these unsteady devices dominate the flowfield and control to a great extent the level of the thrust augmentation. Therefore, it is of fundamental interest to understand the geometric influences on the starting vortex and how these manifest themselves in augmenter/ejector performance. An unsteady Reynolds averaged Navier–Stokes calculation was used to study the physics of a starting vortex generated at the exit of a pulsed jet and its interaction with an ejector. A 50 cm long pulsejet (typical hobby scale, allowing comparison with experimental data) with a circular exit was modeled as the resonant driving source and used to suggest an optimal ejector geometry and relative position. Computed limit-cycle thrust augmentation values compared favorably to experimentally obtained values for the same ejector geometries. Results suggest that the optimal diameter of the ejector is related to its relative position, dictated by the trajectory of the vortex toroid. The effect of the length of the ejector (which determines the natural frequency of the ejector, related to the acoustic processes occurring in the ejector) on overall performance was also investigated and shown to be less important than the ejector diameter. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Co-current gas-liquid smooth-stratified flow in a horizontal reduced T-junction including wavy and slug regime transition boundaries / Bowden, Robert C. in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 11 p. Titre : Co-current gas-liquid smooth-stratified flow in a horizontal reduced T-junction including wavy and slug regime transition boundaries Type de document : texte imprimé Auteurs : Bowden, Robert C., Auteur ; Hassan, Ibrahim G., Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Air  Boundary  layers  Flow  visualisation  Pipe  flow  Stratified  flow  Two-phase  flow  Water Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Experiments were performed in a horizontal reduced T-junction using a branch diameter of 6.35 mm and an inlet pipe diameter of 50.8 mm. The inlet length was 1.8 m and three branch orientations were tested at 0, 45, and 90 degrees down from the horizontal. Water and air, operating at 206 kPa, were used to provide an adiabatic two-phase environment. Both fluids flowed co-currently within the inlet towards the branch in the smooth-stratified regime. Results demonstrate the relationship between the interface height and the inlet and branch two-phase quantities, including the inlet superficial liquid and gas velocities, and branch two-phase mass flow rate and quality. In certain instances transitions to wavy-stratified or slug regimes were observed and these limits are quantified for each branch orientation. Flow visualization was used to identify the initiation of two-phase flow in the branch, including the onsets of gas and liquid entrainment. The critical height at the onset of gas entrainment was quantified as a function of the single phase liquid branch Froude number for the 45 and 90 degree branches, respectively. The branch quality results were scaled using the critical height and showed good agreement with selected models. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Co-current gas-liquid smooth-stratified flow in a horizontal reduced T-junction including wavy and slug regime transition boundaries [texte imprimé] / Bowden, Robert C., Auteur ; Hassan, Ibrahim G., Auteur . - 2011 . - 11 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 11 p. Mots-clés : Air  Boundary  layers  Flow  visualisation  Pipe  flow  Stratified  flow  Two-phase  flow  Water Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Experiments were performed in a horizontal reduced T-junction using a branch diameter of 6.35 mm and an inlet pipe diameter of 50.8 mm. The inlet length was 1.8 m and three branch orientations were tested at 0, 45, and 90 degrees down from the horizontal. Water and air, operating at 206 kPa, were used to provide an adiabatic two-phase environment. Both fluids flowed co-currently within the inlet towards the branch in the smooth-stratified regime. Results demonstrate the relationship between the interface height and the inlet and branch two-phase quantities, including the inlet superficial liquid and gas velocities, and branch two-phase mass flow rate and quality. In certain instances transitions to wavy-stratified or slug regimes were observed and these limits are quantified for each branch orientation. Flow visualization was used to identify the initiation of two-phase flow in the branch, including the onsets of gas and liquid entrainment. The critical height at the onset of gas entrainment was quantified as a function of the single phase liquid branch Froude number for the 45 and 90 degree branches, respectively. The branch quality results were scaled using the critical height and showed good agreement with selected models. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Dissipation and cavitation characteristics of single-hole orifices / Malavasi, Stefano in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 08 p. Titre : Dissipation and cavitation characteristics of single-hole orifices Type de document : texte imprimé Auteurs : Malavasi, Stefano, Auteur ; Vittorio Messa, Gianandrea, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Boundary  layer  turbulence  Cavitation  Computational  fluid  dynamics  Flow  simulation  Fractals  Pipe  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The purpose of this work is to study the dependence of the pressure losses through sharp-edged orifices with respect to the most significant parameters and to find an efficient way to check whether cavitation is likely to occur. Computational fluid dynamics was used to simulate the flow through orifices with different geometrical characteristics for various incoming flow velocities. In particular, the diameter ratio was varied between 0.39 and 0.70, the relative thickness between 0.30 and 1.40, and the pipe Reynolds number between 3.85 × 104 and 1.54 × 105. The computed pressure drop coefficient in the region of self-similarity with respect to the pipe Reynolds number was first compared to that obtained from some literature models. Afterwards, the comparison with experimental data revealed that an extended pressure criterion is suitable to predict the presence of cavitating conditions. A dimensionless minimum pressure coefficient was then defined, and its dependence upon the above mentioned geometrical and flow parameters was investigated. Finally, a practical formula for the prediction of cavitation was provided. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Dissipation and cavitation characteristics of single-hole orifices [texte imprimé] / Malavasi, Stefano, Auteur ; Vittorio Messa, Gianandrea, Auteur . - 2011 . - 08 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 08 p. Mots-clés : Boundary  layer  turbulence  Cavitation  Computational  fluid  dynamics  Flow  simulation  Fractals  Pipe  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The purpose of this work is to study the dependence of the pressure losses through sharp-edged orifices with respect to the most significant parameters and to find an efficient way to check whether cavitation is likely to occur. Computational fluid dynamics was used to simulate the flow through orifices with different geometrical characteristics for various incoming flow velocities. In particular, the diameter ratio was varied between 0.39 and 0.70, the relative thickness between 0.30 and 1.40, and the pipe Reynolds number between 3.85 × 104 and 1.54 × 105. The computed pressure drop coefficient in the region of self-similarity with respect to the pipe Reynolds number was first compared to that obtained from some literature models. Afterwards, the comparison with experimental data revealed that an extended pressure criterion is suitable to predict the presence of cavitating conditions. A dimensionless minimum pressure coefficient was then defined, and its dependence upon the above mentioned geometrical and flow parameters was investigated. Finally, a practical formula for the prediction of cavitation was provided. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Using CFD to study combustion and steam flow distribution effects on reheater tubes operation / Poursaeidi, Esmaeil in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 11 p. Titre : Using CFD to study combustion and steam flow distribution effects on reheater tubes operation Type de document : texte imprimé Auteurs : Poursaeidi, Esmaeil, Auteur ; Arablu, Masoud, Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Boilers  Chemically  reactive  flow  Combustion  Computational  fluid  dynamics  Flow  simulation  Hardness  Heat  transfer  Metallography  Pipe  flow  Temperature  distribution  Wear Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The thickness measurements showed that boilers of the Shahid Rajaee power plant have a non-uniform thickness in some regions of the final reheater tubes after 80,000 h of operation. Experimental tests on areas such as thickness, hardness, metallography, and recorded temperature showed that high temperature erosion is the most obvious reason for thinning in these tubes. Therefore, two possible reasons for the non-uniform tube thinning (problems due to combustion and steam mal-distribution in the tubes) were explored. This paper presents simulations of combustion, flow distribution in reheater tubes, and heat exchange process in Pass 1 of the boiler using FLUENT software. Combustion simulation results showed temperature distribution and mass flux of combustion products are not uniform at the chamber outlet. But these non-uniformities are not proportional to the tubes' thickness non-uniformity; whereas, simulations showed steam is mal-distributed in the tubes so that steam maldistribution is proportional to the tubes' thickness non-uniformities. Because steam maldistribution was due to mal-feeding and offloading of headers (U-type headers), all possible ways of feeding and offloading of headers were studied, and the results showed that the H-type configuration has the most uniform flow distribution. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Using CFD to study combustion and steam flow distribution effects on reheater tubes operation [texte imprimé] / Poursaeidi, Esmaeil, Auteur ; Arablu, Masoud, Auteur . - 2011 . - 11 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 11 p. Mots-clés : Boilers  Chemically  reactive  flow  Combustion  Computational  fluid  dynamics  Flow  simulation  Hardness  Heat  transfer  Metallography  Pipe  flow  Temperature  distribution  Wear Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The thickness measurements showed that boilers of the Shahid Rajaee power plant have a non-uniform thickness in some regions of the final reheater tubes after 80,000 h of operation. Experimental tests on areas such as thickness, hardness, metallography, and recorded temperature showed that high temperature erosion is the most obvious reason for thinning in these tubes. Therefore, two possible reasons for the non-uniform tube thinning (problems due to combustion and steam mal-distribution in the tubes) were explored. This paper presents simulations of combustion, flow distribution in reheater tubes, and heat exchange process in Pass 1 of the boiler using FLUENT software. Combustion simulation results showed temperature distribution and mass flux of combustion products are not uniform at the chamber outlet. But these non-uniformities are not proportional to the tubes' thickness non-uniformity; whereas, simulations showed steam is mal-distributed in the tubes so that steam maldistribution is proportional to the tubes' thickness non-uniformities. Because steam maldistribution was due to mal-feeding and offloading of headers (U-type headers), all possible ways of feeding and offloading of headers were studied, and the results showed that the H-type configuration has the most uniform flow distribution. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Experimental study of near-field entrainment of moderately overpressured jets / Solovitz, Stephen A. in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 12 p. Titre : Experimental study of near-field entrainment of moderately overpressured jets Type de document : texte imprimé Auteurs : Solovitz, Stephen A., Auteur ; Mastin, Larry G., Auteur ; Saffaraval, Farhad, Auteur Année de publication : 2011 Article en page(s) : 12 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Jets  Shock  waves  Stratified  flow  Velocimeters Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Particle image velocimetry (PIV) experiments have been conducted to study the velocity flow fields in the developing flow region of high-speed jets. These velocity distributions were examined to determine the entrained mass flow over a range of geometric and flow conditions, including overpressured cases up to an overpressure ratio of 2.83. In the region near the jet exit, all measured flows exhibited the same entrainment up until the location of the first shock when overpressured. Beyond this location, the entrainment was reduced with increasing overpressure ratio, falling to approximately 60% of the magnitudes seen when subsonic. Since entrainment ratios based on lower speed, subsonic results are typically used in one-dimensional volcanological models of plume development, the current analytical methods will underestimate the likelihood of column collapse. In addition, the concept of the entrainment ratio normalization is examined in detail, as several key assumptions in this methodology do not apply when overpressured. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Experimental study of near-field entrainment of moderately overpressured jets [texte imprimé] / Solovitz, Stephen A., Auteur ; Mastin, Larry G., Auteur ; Saffaraval, Farhad, Auteur . - 2011 . - 12 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 12 p. Mots-clés : Jets  Shock  waves  Stratified  flow  Velocimeters Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Particle image velocimetry (PIV) experiments have been conducted to study the velocity flow fields in the developing flow region of high-speed jets. These velocity distributions were examined to determine the entrained mass flow over a range of geometric and flow conditions, including overpressured cases up to an overpressure ratio of 2.83. In the region near the jet exit, all measured flows exhibited the same entrainment up until the location of the first shock when overpressured. Beyond this location, the entrainment was reduced with increasing overpressure ratio, falling to approximately 60% of the magnitudes seen when subsonic. Since entrainment ratios based on lower speed, subsonic results are typically used in one-dimensional volcanological models of plume development, the current analytical methods will underestimate the likelihood of column collapse. In addition, the concept of the entrainment ratio normalization is examined in detail, as several key assumptions in this methodology do not apply when overpressured. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Flow bistability downstream of three-dimensional double backward facing steps at zero-degree sideslip / Herry, Benjamin B. in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 04 p. Titre : Flow bistability downstream of three-dimensional double backward facing steps at zero-degree sideslip Type de document : texte imprimé Auteurs : Herry, Benjamin B., Auteur ; Keirsbulck, Laurent, Auteur ; Labraga, Larbi, Auteur Année de publication : 2011 Article en page(s) : 04 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Flow  control  Flow  instability  Flow  visualisation  Turbulence  Two-phase  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The flow downstream of a three-dimensional double backward facing step (3D DBWFS) is investigated for Reynolds number Reh ranging from 5×103 to 8×104 (based on the first step height h). The flow is studied both qualitatively by means of laser tomoscopy and oil-flow visualizations and quantitatively by means of particle image velocimetry (PIV) measurements. In particular, the results show a mean flow asymmetry. A sensitivity study around zero degree sideslip has shown that the flow is bistable for this geometry. This bistability has been observed in two different wind tunnels for very different upstream conditions. As a main consequence, the zero degree drift angle could be a relevant validation case of unstable flow computation. More tests are carried out to understand and control this particular flow feature. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Flow bistability downstream of three-dimensional double backward facing steps at zero-degree sideslip [texte imprimé] / Herry, Benjamin B., Auteur ; Keirsbulck, Laurent, Auteur ; Labraga, Larbi, Auteur . - 2011 . - 04 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 04 p. Mots-clés : Flow  control  Flow  instability  Flow  visualisation  Turbulence  Two-phase  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The flow downstream of a three-dimensional double backward facing step (3D DBWFS) is investigated for Reynolds number Reh ranging from 5×103 to 8×104 (based on the first step height h). The flow is studied both qualitatively by means of laser tomoscopy and oil-flow visualizations and quantitatively by means of particle image velocimetry (PIV) measurements. In particular, the results show a mean flow asymmetry. A sensitivity study around zero degree sideslip has shown that the flow is bistable for this geometry. This bistability has been observed in two different wind tunnels for very different upstream conditions. As a main consequence, the zero degree drift angle could be a relevant validation case of unstable flow computation. More tests are carried out to understand and control this particular flow feature. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Modeling and simulation of capillary microfluidic networks based on electrical analogies / Kang, Seok-Won in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 06 p. Titre : Modeling and simulation of capillary microfluidic networks based on electrical analogies Type de document : texte imprimé Auteurs : Kang, Seok-Won, Auteur ; Debjyoti Banerjee, Auteur Année de publication : 2011 Article en page(s) : 06 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Bifurcation  Capillarity  Computational  fluid  dynamics  Flow  simulation  Microfluidics  Numerical  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this study we implemented the network simulation techniques using macromodels (lumped models) for capillary driven flows in microfluidic networks. The flow characteristics in a flow junction, such as meniscus stretching and bifurcation, were studied and their effects on filling time as well as pressure drop were explored for various network configurations. The results from the network simulator are validated numerically using computational fluid dynamics (CFD) simulations by employing the volume-of-fluids (VOF) method. The predictions by the network simulator for free-surface flows in different microfluidic networks were found to be in good agreement with the results obtained from the VOF simulations for filling time and meniscus position. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Modeling and simulation of capillary microfluidic networks based on electrical analogies [texte imprimé] / Kang, Seok-Won, Auteur ; Debjyoti Banerjee, Auteur . - 2011 . - 06 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 06 p. Mots-clés : Bifurcation  Capillarity  Computational  fluid  dynamics  Flow  simulation  Microfluidics  Numerical  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this study we implemented the network simulation techniques using macromodels (lumped models) for capillary driven flows in microfluidic networks. The flow characteristics in a flow junction, such as meniscus stretching and bifurcation, were studied and their effects on filling time as well as pressure drop were explored for various network configurations. The results from the network simulator are validated numerically using computational fluid dynamics (CFD) simulations by employing the volume-of-fluids (VOF) method. The predictions by the network simulator for free-surface flows in different microfluidic networks were found to be in good agreement with the results obtained from the VOF simulations for filling time and meniscus position. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

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