Results from a study of p-nucleus interactions in emulsion at an incident energy of 300 GeV are p... more Results from a study of p-nucleus interactions in emulsion at an incident energy of 300 GeV are presented. The observed events were separated into those belonging to the light (C,N,O) and the heavy (Ag, Br) groups of target nuclei. Some characteristics of the fast-charged- ...
Abstract The mean-free-path for inelastic interactions of 200 GeV protons in nuclear emulsion has... more Abstract The mean-free-path for inelastic interactions of 200 GeV protons in nuclear emulsion has been measured using the techniques of along-the-track scanning and area scanning. The results obtained are, respectively, lambdainel= 35.3+/-1.0 cm and ...
Proton-nucleus interactions have been studied in nuclear emulsion exposed to the NAL 200 GeV prot... more Proton-nucleus interactions have been studied in nuclear emulsion exposed to the NAL 200 GeV proton beam. The inelastic mean free path is found to be 35.5 ± 0.8 cm and the average shower particle multiplicity is 12.9 ± 0.2. The angular distribution reveals some ...
2248 SOME TRENDS IN HIGH-ENERGY PROTON-NUCLEUS INTERACTIONS IN NUCLEAR EMULSION J. Hébert, CJD Hé... more 2248 SOME TRENDS IN HIGH-ENERGY PROTON-NUCLEUS INTERACTIONS IN NUCLEAR EMULSION J. Hébert, CJD Hébert, H. Areti, University of Ottawa, Ottawa, Canada 0. Adaniovic and M. Juric ... Busza, JE Elias, DF Jacobs, PA Swartz, CC Young and MR Sogard, Phys. ...
The velocity field in a vortex heat cell was investigated experimentally using laser Doppler velo... more The velocity field in a vortex heat cell was investigated experimentally using laser Doppler velocimetry for a wide range of flow conditions. Experimental results point out the three dimensionality of the exchanger's flow, which is composed into a main vortex flow developing along the side walls. The strength of the flow increases up to a limiting value reached for a Reynolds number ranging between 15,000 and 30,000; a secondary flow, caused by interaction between centrifugal and inertial forces, extends perpendicularly to the main flow and remains Reynolds number dependent. It is composed of multiple counter-rotating structures occurring at the exchanger periphery with low inlet Reynolds numbers, thus reducing the rate of centripetal momentum transfer. With increasing inlet Reynolds number, the secondary flow extends across the whole exchanger radius, thus increasing the rate of mixing of the treated fluid. The appearance of so-called Taylor-Görtler vortices tends to reduce the z- and r-axis vorticity transfer.
International Journal of Heat and Mass Transfer, 1999
ABSTRACT This work presents experimental and numerical results concerning heat transfer for Hersc... more ABSTRACT This work presents experimental and numerical results concerning heat transfer for Herschel–Bulkley fluids, the consistency of which depends on temperature. We have considered the flow through a horizontal cylindrical duct submitted to a wall cooling by an external counter current flow. According to the experimental conditions, the wall temperature may fall below the freezing temperature of the non-Newtonian fluid, for some locations. The numerical model shows that the Nusselt number, which characterizes the internal heat transfer, may be written as constant (Pe′/Z*)1/3. Z* corresponds to a dimensionless abscissa, Pe′ being a particular Péclet number. This last parameter depends on the wall shear rate, determined for the inlet section, which indirectly takes into account the rheological properties. A very simple model predicting the wall temperature distribution has been developed. The evolution of this quantity allows us to distinguish roughly two zones along the duct. For the first zone, the temperature drop is abrupt and is mainly affected by the internal heat transfer coefficient. For the second zone, the evolution is smoother, the external condition being prevalent.
International Journal of Heat and Fluid Flow, 1995
ABSTRACT We present results concerning heat transfer for pseudoplastic fluids flowing inside cyli... more ABSTRACT We present results concerning heat transfer for pseudoplastic fluids flowing inside cylindrical tubes. The fluids are cooled by an external turbulent counterflow of water. A method is developed to evaluate the values of the local heat exchange coefficients. The variations of the associated Nusselt numbers can be approached using the dimensionless axial abscissa X(sub +) = (2z/D)/Pe. Experimentation shows that the Nusselt numbers remain slightly dependent on the difference between the inlet temperature of the pseudoplastic fluid T(sub e) and the wall temperatures T(sub w)(z). This last phenomenum, attributed to the variations of consistency K and rheological index n with temperature, can be linked to the evolutions of the axial velocity profiles, experimentally determined by laser Doppler anemometry. A very simple correlation Nu(z) = 1.15 ((3n + 1)/4n)(sup 1/3) (1 - 0.008 (T(sub e) - T(sub w)(z))) X(sub +)(sup -0.36) seem to be acceptable in our experimental range. Comparisons with numerical predictions are also proposed.
ABSTRACT In this paper, we study the flow of a fluid possessing a yield stress, in a cylindrical ... more ABSTRACT In this paper, we study the flow of a fluid possessing a yield stress, in a cylindrical pipe being the wall heated with a constant flux; experimental and numerical results being presented here. We are interested in the influence of the different parameters on the Nusselt number, and in the pressure variation. We propose a model which enables us to estimate the Nusselt number and pressure variation, which takes into account the variation of the physical properties due to temperature variations. The proposed correlations agree well with experimental measurement.In dieser Arbeit wird das Strmungsverhalten eines Fluids mit temperatur- und scherspannungsabhngigem Flievermgen in einem mit konstanter Wrmestromdichte beaufschlagten Kreisrohr untersucht. Hierbei fallen experimentell und numerisch gefundene Ergebnisse an. Besonders interessiert der Einflu verschiedener Parameter auf die Nusselt-Zahl und den Druckverlust. Es wird ein Modell zur Bercksichtigung der Auswirkung temperaturabhngiger Stoffwerte auf beide Intensittsparameter vorgeschlagen. Die hieraus resultierenden Korrelationen stimmen gut mit den experimentellen Befunden berein.
Results from a study of p-nucleus interactions in emulsion at an incident energy of 300 GeV are p... more Results from a study of p-nucleus interactions in emulsion at an incident energy of 300 GeV are presented. The observed events were separated into those belonging to the light (C,N,O) and the heavy (Ag, Br) groups of target nuclei. Some characteristics of the fast-charged- ...
Abstract The mean-free-path for inelastic interactions of 200 GeV protons in nuclear emulsion has... more Abstract The mean-free-path for inelastic interactions of 200 GeV protons in nuclear emulsion has been measured using the techniques of along-the-track scanning and area scanning. The results obtained are, respectively, lambdainel= 35.3+/-1.0 cm and ...
Proton-nucleus interactions have been studied in nuclear emulsion exposed to the NAL 200 GeV prot... more Proton-nucleus interactions have been studied in nuclear emulsion exposed to the NAL 200 GeV proton beam. The inelastic mean free path is found to be 35.5 ± 0.8 cm and the average shower particle multiplicity is 12.9 ± 0.2. The angular distribution reveals some ...
2248 SOME TRENDS IN HIGH-ENERGY PROTON-NUCLEUS INTERACTIONS IN NUCLEAR EMULSION J. Hébert, CJD Hé... more 2248 SOME TRENDS IN HIGH-ENERGY PROTON-NUCLEUS INTERACTIONS IN NUCLEAR EMULSION J. Hébert, CJD Hébert, H. Areti, University of Ottawa, Ottawa, Canada 0. Adaniovic and M. Juric ... Busza, JE Elias, DF Jacobs, PA Swartz, CC Young and MR Sogard, Phys. ...
The velocity field in a vortex heat cell was investigated experimentally using laser Doppler velo... more The velocity field in a vortex heat cell was investigated experimentally using laser Doppler velocimetry for a wide range of flow conditions. Experimental results point out the three dimensionality of the exchanger's flow, which is composed into a main vortex flow developing along the side walls. The strength of the flow increases up to a limiting value reached for a Reynolds number ranging between 15,000 and 30,000; a secondary flow, caused by interaction between centrifugal and inertial forces, extends perpendicularly to the main flow and remains Reynolds number dependent. It is composed of multiple counter-rotating structures occurring at the exchanger periphery with low inlet Reynolds numbers, thus reducing the rate of centripetal momentum transfer. With increasing inlet Reynolds number, the secondary flow extends across the whole exchanger radius, thus increasing the rate of mixing of the treated fluid. The appearance of so-called Taylor-Görtler vortices tends to reduce the z- and r-axis vorticity transfer.
International Journal of Heat and Mass Transfer, 1999
ABSTRACT This work presents experimental and numerical results concerning heat transfer for Hersc... more ABSTRACT This work presents experimental and numerical results concerning heat transfer for Herschel–Bulkley fluids, the consistency of which depends on temperature. We have considered the flow through a horizontal cylindrical duct submitted to a wall cooling by an external counter current flow. According to the experimental conditions, the wall temperature may fall below the freezing temperature of the non-Newtonian fluid, for some locations. The numerical model shows that the Nusselt number, which characterizes the internal heat transfer, may be written as constant (Pe′/Z*)1/3. Z* corresponds to a dimensionless abscissa, Pe′ being a particular Péclet number. This last parameter depends on the wall shear rate, determined for the inlet section, which indirectly takes into account the rheological properties. A very simple model predicting the wall temperature distribution has been developed. The evolution of this quantity allows us to distinguish roughly two zones along the duct. For the first zone, the temperature drop is abrupt and is mainly affected by the internal heat transfer coefficient. For the second zone, the evolution is smoother, the external condition being prevalent.
International Journal of Heat and Fluid Flow, 1995
ABSTRACT We present results concerning heat transfer for pseudoplastic fluids flowing inside cyli... more ABSTRACT We present results concerning heat transfer for pseudoplastic fluids flowing inside cylindrical tubes. The fluids are cooled by an external turbulent counterflow of water. A method is developed to evaluate the values of the local heat exchange coefficients. The variations of the associated Nusselt numbers can be approached using the dimensionless axial abscissa X(sub +) = (2z/D)/Pe. Experimentation shows that the Nusselt numbers remain slightly dependent on the difference between the inlet temperature of the pseudoplastic fluid T(sub e) and the wall temperatures T(sub w)(z). This last phenomenum, attributed to the variations of consistency K and rheological index n with temperature, can be linked to the evolutions of the axial velocity profiles, experimentally determined by laser Doppler anemometry. A very simple correlation Nu(z) = 1.15 ((3n + 1)/4n)(sup 1/3) (1 - 0.008 (T(sub e) - T(sub w)(z))) X(sub +)(sup -0.36) seem to be acceptable in our experimental range. Comparisons with numerical predictions are also proposed.
ABSTRACT In this paper, we study the flow of a fluid possessing a yield stress, in a cylindrical ... more ABSTRACT In this paper, we study the flow of a fluid possessing a yield stress, in a cylindrical pipe being the wall heated with a constant flux; experimental and numerical results being presented here. We are interested in the influence of the different parameters on the Nusselt number, and in the pressure variation. We propose a model which enables us to estimate the Nusselt number and pressure variation, which takes into account the variation of the physical properties due to temperature variations. The proposed correlations agree well with experimental measurement.In dieser Arbeit wird das Strmungsverhalten eines Fluids mit temperatur- und scherspannungsabhngigem Flievermgen in einem mit konstanter Wrmestromdichte beaufschlagten Kreisrohr untersucht. Hierbei fallen experimentell und numerisch gefundene Ergebnisse an. Besonders interessiert der Einflu verschiedener Parameter auf die Nusselt-Zahl und den Druckverlust. Es wird ein Modell zur Bercksichtigung der Auswirkung temperaturabhngiger Stoffwerte auf beide Intensittsparameter vorgeschlagen. Die hieraus resultierenden Korrelationen stimmen gut mit den experimentellen Befunden berein.
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Papers by R. Devienne