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Journal of fluids engineering (Transactions of the ASME) |
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Ajouter le résultat dans votre panierMixing enhancement by microrotor in step channel / Dinh, Thien X. in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 2 (Fevrier 2011)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 06 p.
Titre : Mixing enhancement by microrotor in step channel Type de document : texte imprimé Auteurs : Dinh, Thien X., Auteur ; Ogami, Yoshifumi, Auteur Année de publication : 2011 Article en page(s) : 06 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Micromixers Mixing efficiency Microrotor Numerical simulation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this paper, the mixing enhancement of a micromixer consisting of a step channel and a shuttlecock rotor suspended in the step is numerically analyzed. Asymptotic mixing performance is investigated as a function of Strouhal and Peclet numbers by particle tracking simulation and the Eulerian approach. The simulation results show that the rotor creates downward and inward flows in behind the rotor paddles, whereas the upward and outward flows are produced in front of the rotor paddles. At a small Strouhal number, convective mixing is very poor. However, the mixing direction is rotated by 90 deg, which can reduce the mixing time by the square of the aspect ratio of the cross section of the channel. In contrast, at a relatively large Strouhal number, good convective mixing occurs. Quantitative analysis of mixing performance of the mixer demonstrates that the mixing structures are similar for the same Strouhal number and mixing is improved with increasing Strouhal number. The mixing efficiency of the mixer decreases linearly with increasing log of the Peclet number at a relatively large Strouhal number. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Mixing enhancement by microrotor in step channel [texte imprimé] / Dinh, Thien X., Auteur ; Ogami, Yoshifumi, Auteur . - 2011 . - 06 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 06 p.
Mots-clés : Micromixers Mixing efficiency Microrotor Numerical simulation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this paper, the mixing enhancement of a micromixer consisting of a step channel and a shuttlecock rotor suspended in the step is numerically analyzed. Asymptotic mixing performance is investigated as a function of Strouhal and Peclet numbers by particle tracking simulation and the Eulerian approach. The simulation results show that the rotor creates downward and inward flows in behind the rotor paddles, whereas the upward and outward flows are produced in front of the rotor paddles. At a small Strouhal number, convective mixing is very poor. However, the mixing direction is rotated by 90 deg, which can reduce the mixing time by the square of the aspect ratio of the cross section of the channel. In contrast, at a relatively large Strouhal number, good convective mixing occurs. Quantitative analysis of mixing performance of the mixer demonstrates that the mixing structures are similar for the same Strouhal number and mixing is improved with increasing Strouhal number. The mixing efficiency of the mixer decreases linearly with increasing log of the Peclet number at a relatively large Strouhal number. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 08 p.
Titre : Application of large gurney flaps on low reynolds number fan blades Type de document : texte imprimé Auteurs : Greenblatt, David, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Aerodynamics Aerospace components Automotive components Blades Drag reduction Fans Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : On the basis of a semi-empirical model, large Gurney flaps of 10%, 20%, and 30% of the fan blade chord length were tested in a specially designed ventilation fan facility. At the highest volumetric flowrates tested, the flapped blades all produced higher pressures than the baseline nonflapped case. When proper accounting was made of fan rotational speed, all flapped blades produced consistently higher dimensionless pressures, with the 30% flap producing the highest pressures at large volumetric flowrates. Based on the assumption that sound power varies with the sixth power of fan rotation speed, it was shown that the sound pressure level could be reduced by nearly 4 dB. All flapped configurations produced higher mechanical efficiency than the baseline case but the mass of the flap relative to that of the blade emerged as an important parameter. A 10% flap, whose mass was negligible relative to the blade, produced the largest increase of 18% in static efficiency. Further research will focus on testing the flaps over the entire operational range, as well as on redesigning stiffer and lighter Gurney flaps. The introduction of three-dimensionality such as spanwise spaced holes, slits, or serrations that have previously been used to reduce airfoil drag will also be considered. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Application of large gurney flaps on low reynolds number fan blades [texte imprimé] / Greenblatt, David, Auteur . - 2011 . - 08 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 08 p.
Mots-clés : Aerodynamics Aerospace components Automotive components Blades Drag reduction Fans Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : On the basis of a semi-empirical model, large Gurney flaps of 10%, 20%, and 30% of the fan blade chord length were tested in a specially designed ventilation fan facility. At the highest volumetric flowrates tested, the flapped blades all produced higher pressures than the baseline nonflapped case. When proper accounting was made of fan rotational speed, all flapped blades produced consistently higher dimensionless pressures, with the 30% flap producing the highest pressures at large volumetric flowrates. Based on the assumption that sound power varies with the sixth power of fan rotation speed, it was shown that the sound pressure level could be reduced by nearly 4 dB. All flapped configurations produced higher mechanical efficiency than the baseline case but the mass of the flap relative to that of the blade emerged as an important parameter. A 10% flap, whose mass was negligible relative to the blade, produced the largest increase of 18% in static efficiency. Further research will focus on testing the flaps over the entire operational range, as well as on redesigning stiffer and lighter Gurney flaps. The introduction of three-dimensionality such as spanwise spaced holes, slits, or serrations that have previously been used to reduce airfoil drag will also be considered. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 08 p.
Titre : Modeling the blow-blow forming process in glass container manufacturing : a comparison between computations and experiments Type de document : texte imprimé Auteurs : Giannopapa, C. G., Auteur ; Groot, J. A. W. M., Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Forming processes Glass manufacture Vitrification Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The blow-blow forming process is a widely used technique in glass container manufacturing (e.g., production of glass bottles and jars). This process typically takes few seconds and is characterized by large deformations and temperature gradients. In the work of Giannopapa (2008, “Development of a Computer Simulation Model for Blowing Glass Containers,” ASME J. Manuf. Sci. Eng., 130, p. 041003), the development of a computer simulation model for glass blowing was presented and demonstrated on dummy problems with an initially uniform glass temperature. The objective of this paper is to extend and further develop the simulation model to be used for industrial purposes. To achieve this, both steps of the blow-blow forming process of glass containers are simulated and tested against real industrial problems. In this paper, a nonuniform temperature distribution is considered for the blowing of the preform, which is reconstructed from temperature data provided by the industry. The model is validated by means of several examples regarding conservation properties, behavior of the flow, and comparison of the glass thickness with experimental measurements. Furthermore, by means of these examples, the sensitivity of the glass thickness to inaccuracies in the measurement and reconstruction of the initial temperature distribution is verified. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Modeling the blow-blow forming process in glass container manufacturing : a comparison between computations and experiments [texte imprimé] / Giannopapa, C. G., Auteur ; Groot, J. A. W. M., Auteur . - 2011 . - 08 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 08 p.
Mots-clés : Forming processes Glass manufacture Vitrification Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The blow-blow forming process is a widely used technique in glass container manufacturing (e.g., production of glass bottles and jars). This process typically takes few seconds and is characterized by large deformations and temperature gradients. In the work of Giannopapa (2008, “Development of a Computer Simulation Model for Blowing Glass Containers,” ASME J. Manuf. Sci. Eng., 130, p. 041003), the development of a computer simulation model for glass blowing was presented and demonstrated on dummy problems with an initially uniform glass temperature. The objective of this paper is to extend and further develop the simulation model to be used for industrial purposes. To achieve this, both steps of the blow-blow forming process of glass containers are simulated and tested against real industrial problems. In this paper, a nonuniform temperature distribution is considered for the blowing of the preform, which is reconstructed from temperature data provided by the industry. The model is validated by means of several examples regarding conservation properties, behavior of the flow, and comparison of the glass thickness with experimental measurements. Furthermore, by means of these examples, the sensitivity of the glass thickness to inaccuracies in the measurement and reconstruction of the initial temperature distribution is verified. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 12 p.
Titre : Characteristics of turbulent three-dimensional wall jets Type de document : texte imprimé Auteurs : Agelin-Chaab, M., Auteur ; Tachie, M. F., Auteur Année de publication : 2011 Article en page(s) : 12 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Boundary layer turbulence Correlation methods Flow visualisation Jets Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three-dimensional turbulent wall jet was investigated using a particle image velocimetry technique. Three Reynolds numbers based on the jet exit velocity and diameter of 5000, 10,000, and 20,000 were studied. Profiles of the mean velocities, turbulence intensities, and Reynolds shear stresses as well as two-point velocity correlations and proper orthogonal decomposition analyses were used to document the salient features of the wall jets. The decay and spread rates are independent of Reynolds numbers in the self-similar region. The estimated values of 1.15, 0.054, and 0.255 for the decay rate, wall-normal spread rate, and lateral spread rate, respectively, are within the range of values reported in the literature. The two-point correlation analysis showed that the inclination of the streamwise velocity correlation contours in the inner layer is 11±3 deg in the wall region, which is similar to those of canonical turbulent boundary layers. The results from the proper orthogonal decomposition indicate that low-order modes contribute more to the turbulence statistics in the self-similar region than in the developing region. The Reynolds shear stresses are the biggest benefactors of the low-order mode contribution while the wall-normal turbulence intensities are the least. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Characteristics of turbulent three-dimensional wall jets [texte imprimé] / Agelin-Chaab, M., Auteur ; Tachie, M. F., Auteur . - 2011 . - 12 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 12 p.
Mots-clés : Boundary layer turbulence Correlation methods Flow visualisation Jets Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three-dimensional turbulent wall jet was investigated using a particle image velocimetry technique. Three Reynolds numbers based on the jet exit velocity and diameter of 5000, 10,000, and 20,000 were studied. Profiles of the mean velocities, turbulence intensities, and Reynolds shear stresses as well as two-point velocity correlations and proper orthogonal decomposition analyses were used to document the salient features of the wall jets. The decay and spread rates are independent of Reynolds numbers in the self-similar region. The estimated values of 1.15, 0.054, and 0.255 for the decay rate, wall-normal spread rate, and lateral spread rate, respectively, are within the range of values reported in the literature. The two-point correlation analysis showed that the inclination of the streamwise velocity correlation contours in the inner layer is 11±3 deg in the wall region, which is similar to those of canonical turbulent boundary layers. The results from the proper orthogonal decomposition indicate that low-order modes contribute more to the turbulence statistics in the self-similar region than in the developing region. The Reynolds shear stresses are the biggest benefactors of the low-order mode contribution while the wall-normal turbulence intensities are the least. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 09 p.
Titre : Soret and dufour effects on the stagnation-point flow of a micropolar fluid toward a stretching sheet Type de document : texte imprimé Auteurs : Hayat, T., Auteur ; Mustafa, M., Auteur ; Obaidat, S., Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Micropolar fluid Nonlinear problems Homotopy solution Stretching sheet Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This communication reports the heat and mass transfer analysis in the stagnation-point flow toward a stretching sheet. An incompressible micropolar fluid takes into account the diffusion-thermo- (Dufour) and thermal-diffusion (Soret) effects. The arising nonlinear differential system is solved by homotopy analysis method. Convergence of the obtained homotopy solutions is clearly justified. Special emphasis has been given to various physical parameters through graphs and tables. It is noticed that fields are influenced appreciably with the variation of embedding parameters. A comparison of the present results with the existing numerical solution is discussed in a limiting sense. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Soret and dufour effects on the stagnation-point flow of a micropolar fluid toward a stretching sheet [texte imprimé] / Hayat, T., Auteur ; Mustafa, M., Auteur ; Obaidat, S., Auteur . - 2011 . - 09 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 09 p.
Mots-clés : Micropolar fluid Nonlinear problems Homotopy solution Stretching sheet Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This communication reports the heat and mass transfer analysis in the stagnation-point flow toward a stretching sheet. An incompressible micropolar fluid takes into account the diffusion-thermo- (Dufour) and thermal-diffusion (Soret) effects. The arising nonlinear differential system is solved by homotopy analysis method. Convergence of the obtained homotopy solutions is clearly justified. Special emphasis has been given to various physical parameters through graphs and tables. It is noticed that fields are influenced appreciably with the variation of embedding parameters. A comparison of the present results with the existing numerical solution is discussed in a limiting sense. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 10 p.
Titre : Evaluation of turbulence models using direct numerical and large-eddy simulation data Type de document : texte imprimé Auteurs : Raiesi, Hassan, Auteur ; Piomelli, Ugo, Auteur ; Pollard, Andrew, Auteur Année de publication : 2011 Article en page(s) : 10 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Boundary layers Flow separation Flow simulation Pipe flow Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The performance of some commonly used eddy-viscosity turbulence models has been evaluated using direct numerical simulation (DNS) and large-eddy simulation (LES) data. Two configurations have been tested, a two-dimensional boundary layer undergoing pressure-driven separation, and a square duct. The DNS and LES were used to assess the k−epsilon, zeta−f, k−omega, and Spalart–Allmaras models. For the two-dimensional separated boundary layer, anisotropic effects are not significant and the eddy-viscosity assumption works well. However, the near-wall treatment used in k−epsilon models was found to have a critical effect on the predictive accuracy of the model (and, in particular, of separation and reattachment points). None of the wall treatments tested resulted in accurate prediction of the flow field. Better results were obtained with models that do not require special treatment in the inner layer (zeta−f, k−omega, and Spalart–Allmaras models). For the square duct calculation, only a nonlinear constitutive relation was found to be able to capture the secondary flow, giving results in agreement with the data. Linear models had significant error. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Evaluation of turbulence models using direct numerical and large-eddy simulation data [texte imprimé] / Raiesi, Hassan, Auteur ; Piomelli, Ugo, Auteur ; Pollard, Andrew, Auteur . - 2011 . - 10 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 10 p.
Mots-clés : Boundary layers Flow separation Flow simulation Pipe flow Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The performance of some commonly used eddy-viscosity turbulence models has been evaluated using direct numerical simulation (DNS) and large-eddy simulation (LES) data. Two configurations have been tested, a two-dimensional boundary layer undergoing pressure-driven separation, and a square duct. The DNS and LES were used to assess the k−epsilon, zeta−f, k−omega, and Spalart–Allmaras models. For the two-dimensional separated boundary layer, anisotropic effects are not significant and the eddy-viscosity assumption works well. However, the near-wall treatment used in k−epsilon models was found to have a critical effect on the predictive accuracy of the model (and, in particular, of separation and reattachment points). None of the wall treatments tested resulted in accurate prediction of the flow field. Better results were obtained with models that do not require special treatment in the inner layer (zeta−f, k−omega, and Spalart–Allmaras models). For the square duct calculation, only a nonlinear constitutive relation was found to be able to capture the secondary flow, giving results in agreement with the data. Linear models had significant error. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 08 p.
Titre : A Combined numerical and experimental study of hydrodynamics for an air-water external loop airlift reactor Type de document : texte imprimé Auteurs : Law, Deify, Auteur ; Jones, Samuel T., Auteur ; Heindel, Theodore J., Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Airlift reactor Bubbly flows Computational fluid dynamics Gas holdup Hydrodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The external loop airlift reactor (ELALR) is a modified bubble column reactor that is composed of two vertical columns that are interconnected with two horizontal tubes and is often preferred over traditional bubble column reactors because they can operate over a wider range of conditions. In the present work, the gas-liquid flow dynamics in an ELALR was simulated using an Eulerian–Eulerian ensemble-averaging method in two-dimensional (2D) and three-dimensional (3D) coordinate systems. The computational fluid dynamics (CFD) simulations were compared to experimental measurements from a 10.2 cm diameter ELALR for superficial gas velocities ranging from 1 cm/s to 20 cm/s. The effect of specifying a mean bubble diameter to represent the gas phase in the CFD modeling was investigated, and 2D and 3D simulations were found to be in good agreement with the experimental data. The ELALR flow regimes were compared for the reactor operating in bubble column, closed vent, and open vent modes, and the 2D simulations qualitatively predicted the behavior of bubble growth in the downcomer. However, it was found that 3D simulations were necessary to capture the physics of the ELALR for gas holdup, bulk density differences, and riser superficial liquid velocity. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] A Combined numerical and experimental study of hydrodynamics for an air-water external loop airlift reactor [texte imprimé] / Law, Deify, Auteur ; Jones, Samuel T., Auteur ; Heindel, Theodore J., Auteur . - 2011 . - 08 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 08 p.
Mots-clés : Airlift reactor Bubbly flows Computational fluid dynamics Gas holdup Hydrodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The external loop airlift reactor (ELALR) is a modified bubble column reactor that is composed of two vertical columns that are interconnected with two horizontal tubes and is often preferred over traditional bubble column reactors because they can operate over a wider range of conditions. In the present work, the gas-liquid flow dynamics in an ELALR was simulated using an Eulerian–Eulerian ensemble-averaging method in two-dimensional (2D) and three-dimensional (3D) coordinate systems. The computational fluid dynamics (CFD) simulations were compared to experimental measurements from a 10.2 cm diameter ELALR for superficial gas velocities ranging from 1 cm/s to 20 cm/s. The effect of specifying a mean bubble diameter to represent the gas phase in the CFD modeling was investigated, and 2D and 3D simulations were found to be in good agreement with the experimental data. The ELALR flow regimes were compared for the reactor operating in bubble column, closed vent, and open vent modes, and the 2D simulations qualitatively predicted the behavior of bubble growth in the downcomer. However, it was found that 3D simulations were necessary to capture the physics of the ELALR for gas holdup, bulk density differences, and riser superficial liquid velocity. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 07 p.
Titre : Synergy of resistance reduction effects for a ship with bottom air cavity Type de document : texte imprimé Auteurs : Amromin, E. L., Auteur ; Metcalf, B., Auteur ; Karafiath, G., Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Cavitation Drag reduction Fluid oscillations Friction Ships Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Friction on a surface covered by an air cavity is much less than friction in water but there is a resistance penalty caused by the cavity tail oscillations. Nevertheless, there is a method for designing the ship bottom form for suppressing these oscillations. This study describes the design method and calm water towing tank tests for a ship with a bottom ventilated air cavity operating at Froude range 0.45 DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Synergy of resistance reduction effects for a ship with bottom air cavity [texte imprimé] / Amromin, E. L., Auteur ; Metcalf, B., Auteur ; Karafiath, G., Auteur . - 2011 . - 07 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 07 p.
Mots-clés : Cavitation Drag reduction Fluid oscillations Friction Ships Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Friction on a surface covered by an air cavity is much less than friction in water but there is a resistance penalty caused by the cavity tail oscillations. Nevertheless, there is a method for designing the ship bottom form for suppressing these oscillations. This study describes the design method and calm water towing tank tests for a ship with a bottom ventilated air cavity operating at Froude range 0.45 DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 09 p.
Titre : An experiment for the study of free-flying supercavitating projectiles Type de document : texte imprimé Auteurs : Cameron, Peter J. K., Auteur ; Rogers, Peter H., Auteur ; Doane, John W., Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Supercavitation Multiphase flow Hydrodynamics Expermental techniques Underwater projectile Dynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Applications and research utilizing supercavitation for high-speed underwater flight has motivated study of the phenomenon. In this work, a small scale laboratory experiment for studying supercavitating projectiles has been designed, built, and tested. Similar existing experimental work has been documented in literature but using large, elaborate facilities, or has been presented with ambiguous conclusions from test results. The projectiles were 63.5 mm in length and traveled at speeds on the order of 145 m/s. Measurement techniques are discussed and used to record projectile speed, supercavity dimensions, and target impact location. Experimental observations are compared with a six degrees-of-freedom dynamics simulation based on theoretical models presented in literature for predicting supercavity shape and hydrodynamic forces on the supercavitating projectile during flight. Experimental observations are discussed qualitatively, along with quantitative statistics of the measurements made. Successful operation of the experiment has been demonstrated and verified by agreement with theoretical models. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] An experiment for the study of free-flying supercavitating projectiles [texte imprimé] / Cameron, Peter J. K., Auteur ; Rogers, Peter H., Auteur ; Doane, John W., Auteur . - 2011 . - 09 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 09 p.
Mots-clés : Supercavitation Multiphase flow Hydrodynamics Expermental techniques Underwater projectile Dynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Applications and research utilizing supercavitation for high-speed underwater flight has motivated study of the phenomenon. In this work, a small scale laboratory experiment for studying supercavitating projectiles has been designed, built, and tested. Similar existing experimental work has been documented in literature but using large, elaborate facilities, or has been presented with ambiguous conclusions from test results. The projectiles were 63.5 mm in length and traveled at speeds on the order of 145 m/s. Measurement techniques are discussed and used to record projectile speed, supercavity dimensions, and target impact location. Experimental observations are compared with a six degrees-of-freedom dynamics simulation based on theoretical models presented in literature for predicting supercavity shape and hydrodynamic forces on the supercavitating projectile during flight. Experimental observations are discussed qualitatively, along with quantitative statistics of the measurements made. Successful operation of the experiment has been demonstrated and verified by agreement with theoretical models. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 14 p.
Titre : Spectral method for analyzing motions of ellis fluid over corrugated boundaries Type de document : texte imprimé Auteurs : Bakhsheshi, M. Fazel, Auteur ; Floryan, J. M., Auteur ; Kaloni, P. N., Auteur Année de publication : 2011 Article en page(s) : 14 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Spectral method Non-newtonian fluid Ellis fluid Corrugated boundaries Immersed boundary condition method Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A spectral method for solving the steady flow of a shear-thinning Ellis fluid is discussed for the case of a planar channel with corrugated boundaries. Polynomial approximations are employed for the velocity and viscosity distributions in the regions around singularities. The proposed algorithm employs a fixed computational domain with the physical domain of interest submerged inside the computational domain. The flow boundary conditions are imposed using the concept of immersed boundary conditions. The method, thus, eliminates the need for grid generation. The algorithm relies on Fourier expansions in the flow direction and Chebyshev expansions in the transverse direction. Various tests confirm spectral accuracy of the algorithm. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Spectral method for analyzing motions of ellis fluid over corrugated boundaries [texte imprimé] / Bakhsheshi, M. Fazel, Auteur ; Floryan, J. M., Auteur ; Kaloni, P. N., Auteur . - 2011 . - 14 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 14 p.
Mots-clés : Spectral method Non-newtonian fluid Ellis fluid Corrugated boundaries Immersed boundary condition method Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A spectral method for solving the steady flow of a shear-thinning Ellis fluid is discussed for the case of a planar channel with corrugated boundaries. Polynomial approximations are employed for the velocity and viscosity distributions in the regions around singularities. The proposed algorithm employs a fixed computational domain with the physical domain of interest submerged inside the computational domain. The flow boundary conditions are imposed using the concept of immersed boundary conditions. The method, thus, eliminates the need for grid generation. The algorithm relies on Fourier expansions in the flow direction and Chebyshev expansions in the transverse direction. Various tests confirm spectral accuracy of the algorithm. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 08 p.
Titre : Head curve of noncavitating inducer Type de document : texte imprimé Auteurs : Wen-Guang, Li, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Inducer Noncavitating head Head curve Singularity method Hydraulic loss Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In the inducer hydraulic design, one significantly important task is to estimate its noncavtating head; however, there is not a matured and reliable method for this presently. In this paper, a method was made for predicting the inducer head curve. The method was based on a singularity method and a hydraulic loss model with a variable correction factor. The blade thickness blockage effect on the flow was taken into account. The method was validated with the experimental data of the existing 17 inducers found in references. Moreover, the curves showing the relation of the correction factor with the mean blade angle at tip for two- and three-bladed inducers were established. The method can achieve a very good agreement with experimental observations. Furthermore, the flow field calculated by the method may be instructive to the engineers of inducer hydraulic design. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Head curve of noncavitating inducer [texte imprimé] / Wen-Guang, Li, Auteur . - 2011 . - 08 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 08 p.
Mots-clés : Inducer Noncavitating head Head curve Singularity method Hydraulic loss Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In the inducer hydraulic design, one significantly important task is to estimate its noncavtating head; however, there is not a matured and reliable method for this presently. In this paper, a method was made for predicting the inducer head curve. The method was based on a singularity method and a hydraulic loss model with a variable correction factor. The blade thickness blockage effect on the flow was taken into account. The method was validated with the experimental data of the existing 17 inducers found in references. Moreover, the curves showing the relation of the correction factor with the mean blade angle at tip for two- and three-bladed inducers were established. The method can achieve a very good agreement with experimental observations. Furthermore, the flow field calculated by the method may be instructive to the engineers of inducer hydraulic design. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
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