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Ajouter le résultat dans votre panierExperimental study on characteristics of methane–coal-dust mixture explosion and its mitigation by ultra-fine water mist / Hongli Xu in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 6 (Juin 2012)
Titre : Experimental study on characteristics of methane–coal-dust mixture explosion and its mitigation by ultra-fine water mist Type de document : texte imprimé Auteurs : Hongli Xu, Auteur ; Xishi Wang, Auteur ; Rui Gu, Auteur Année de publication : 2012 Article en page(s) : 06 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Methane–coal-dust mixture Ultra-fine water mist Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents the results of an experimental investigation on the characteristics of methane–coal-dust mixture explosion and its mitigation by ultra-fine water mist. Four E12-1-K-type fast response thermocouples, two printed circuit board (PCB) piezotronic pressure transducers were used to obtain the temperature and pressure history, while a GigaView high-speed camera was used to visualize the processes. Different methane concentrations, coal-dust concentrations, diameters of coal particles, and volumes of ultra-fine water mist were considered to investigate their effects on methane–coal-dust mixture explosion. The temperature of explosion flame, the maximum explosion overpressure, the maximum rate of overpressure rise, and the critical volume flux of ultra-fine water mist were experimentally determined. The results show that the characteristics of the methane–coal-dust mixture explosion and the mitigating effectiveness by ultra-fine water mist are influenced by the methane concentration, the coal-dust concentration, the coal-dust diameter and the applied volume flux of ultra-fine water mist. For example, both the maximum explosion overpressure and rate of overpressure rise increased with increasing of coal-dust concentrations and methane concentrations. All of the test cases indicate that ultra-fine water mist can mitigate the mixture explosion and suppress the flame propagation efficiently from the images recorded by the high-speed video camera. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 06 p.[article] Experimental study on characteristics of methane–coal-dust mixture explosion and its mitigation by ultra-fine water mist [texte imprimé] / Hongli Xu, Auteur ; Xishi Wang, Auteur ; Rui Gu, Auteur . - 2012 . - 06 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 06 p.
Mots-clés : Methane–coal-dust mixture Ultra-fine water mist Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents the results of an experimental investigation on the characteristics of methane–coal-dust mixture explosion and its mitigation by ultra-fine water mist. Four E12-1-K-type fast response thermocouples, two printed circuit board (PCB) piezotronic pressure transducers were used to obtain the temperature and pressure history, while a GigaView high-speed camera was used to visualize the processes. Different methane concentrations, coal-dust concentrations, diameters of coal particles, and volumes of ultra-fine water mist were considered to investigate their effects on methane–coal-dust mixture explosion. The temperature of explosion flame, the maximum explosion overpressure, the maximum rate of overpressure rise, and the critical volume flux of ultra-fine water mist were experimentally determined. The results show that the characteristics of the methane–coal-dust mixture explosion and the mitigating effectiveness by ultra-fine water mist are influenced by the methane concentration, the coal-dust concentration, the coal-dust diameter and the applied volume flux of ultra-fine water mist. For example, both the maximum explosion overpressure and rate of overpressure rise increased with increasing of coal-dust concentrations and methane concentrations. All of the test cases indicate that ultra-fine water mist can mitigate the mixture explosion and suppress the flame propagation efficiently from the images recorded by the high-speed video camera. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Gas turbine emission characteristics in perfectly premixed combustion Type de document : texte imprimé Auteurs : A. M. Elkady, Auteur ; J. Herbon, Auteur ; D. M. Kalitan, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Gas turbine Combustion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In the present study, a simple perfectly premixed research burner was utilized at temperatures, pressures and residence times representative of an industrial gas turbine cycle to identify the lower limit of NOx and CO emissions, and to establish an emissions benchmark for practical gas turbine combustors. In addition to experimental data, a chemical reactor model has been utilized for the prediction of the NOx and CO, based on detailed chemical reaction mechanisms. Several current kinetics mechanisms were evaluated and subsequently compared to the experimental data. In addition, sensitivity analysis was performed to identify important reactions at the conditions tested, and will be discussed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 07 p.[article] Gas turbine emission characteristics in perfectly premixed combustion [texte imprimé] / A. M. Elkady, Auteur ; J. Herbon, Auteur ; D. M. Kalitan, Auteur . - 2012 . - 07 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 07 p.
Mots-clés : Gas turbine Combustion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In the present study, a simple perfectly premixed research burner was utilized at temperatures, pressures and residence times representative of an industrial gas turbine cycle to identify the lower limit of NOx and CO emissions, and to establish an emissions benchmark for practical gas turbine combustors. In addition to experimental data, a chemical reactor model has been utilized for the prediction of the NOx and CO, based on detailed chemical reaction mechanisms. Several current kinetics mechanisms were evaluated and subsequently compared to the experimental data. In addition, sensitivity analysis was performed to identify important reactions at the conditions tested, and will be discussed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Open-loop control of combustion instabilities and the role of the flame response to two-frequency forcing Type de document : texte imprimé Auteurs : Bernhard Cosic, Auteur ; Bernhard C. Bobusch, Auteur ; Jonas P. Moeck, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Combustion instabilities Open-loop control Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Controlling combustion instabilities by means of open-loop forcing at non-resonant frequencies is attractive because neither a dynamic sensor signal nor a signal processor is required. On the other hand, since the mechanism by which this type of control suppresses an unstable thermoacoustic mode is inherently nonlinear, a comprehensive explanation for success (or failure) of open-loop control has not been found. The present work contributes to the understanding of this process in that it interprets open-loop forcing at non-resonant frequencies in terms of the flame's nonlinear response to a superposition of two approximately sinusoidal input signals. For a saturation-type nonlinearity, the fundamental gain at one frequency may be decreased by increasing the amplitude of a secondary frequency component in the input signal. This effect is first illustrated on the basis of an elementary model problem. In addition, an experimental investigation is conducted at an atmospheric combustor test-rig to corroborate the proposed explanation. Open-loop acoustic and fuel-flow forcing at various frequencies and amplitudes is applied at unstable operating conditions that exhibit high-amplitude limit-cycle oscillations. The effectiveness of specific forcing parameters in suppressing self-excited oscillations is correlated with flame response measurements that include a secondary forcing frequency. The results demonstrate that a reduction in the fundamental harmonic gain at the instability frequency through the additional forcing at a non-resonant frequency is one possible indicator of successful open-loop control. Since this mechanism is independent of the system acoustics, an assessment of favorable forcing parameters, which stabilize thermoacoustic oscillations, may be based solely on an investigation of burner and flame. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 08 p.[article] Open-loop control of combustion instabilities and the role of the flame response to two-frequency forcing [texte imprimé] / Bernhard Cosic, Auteur ; Bernhard C. Bobusch, Auteur ; Jonas P. Moeck, Auteur . - 2012 . - 08 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 08 p.
Mots-clés : Combustion instabilities Open-loop control Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Controlling combustion instabilities by means of open-loop forcing at non-resonant frequencies is attractive because neither a dynamic sensor signal nor a signal processor is required. On the other hand, since the mechanism by which this type of control suppresses an unstable thermoacoustic mode is inherently nonlinear, a comprehensive explanation for success (or failure) of open-loop control has not been found. The present work contributes to the understanding of this process in that it interprets open-loop forcing at non-resonant frequencies in terms of the flame's nonlinear response to a superposition of two approximately sinusoidal input signals. For a saturation-type nonlinearity, the fundamental gain at one frequency may be decreased by increasing the amplitude of a secondary frequency component in the input signal. This effect is first illustrated on the basis of an elementary model problem. In addition, an experimental investigation is conducted at an atmospheric combustor test-rig to corroborate the proposed explanation. Open-loop acoustic and fuel-flow forcing at various frequencies and amplitudes is applied at unstable operating conditions that exhibit high-amplitude limit-cycle oscillations. The effectiveness of specific forcing parameters in suppressing self-excited oscillations is correlated with flame response measurements that include a secondary forcing frequency. The results demonstrate that a reduction in the fundamental harmonic gain at the instability frequency through the additional forcing at a non-resonant frequency is one possible indicator of successful open-loop control. Since this mechanism is independent of the system acoustics, an assessment of favorable forcing parameters, which stabilize thermoacoustic oscillations, may be based solely on an investigation of burner and flame. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Measurement of volatile particulate matter emissions from aircraft engines using a simulated plume aging system Type de document : texte imprimé Auteurs : Peck, Jay, Auteur ; Michael T. Timko, Auteur ; Zhenhong Yu, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Volatile particulate matter emissions Aircraft engines Plume aging system Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Aircraft exhaust contains nonvolatile (soot) particulate matter (PM), trace gas pollutants, and volatile PM precursor material. Nonvolatile soot particles are predominantly present at the engine exit plane, but volatile PM precursors form new particles or add mass to the existing ones as the exhaust is diluted and cooled. Accurately characterizing the volatile PM mass, number, and size distribution is challenging due to this evolving nature and the impact of local ambient conditions on the gas-to-particle conversion processes. To accurately and consistently measure the aircraft PM emissions, a dilution and aging sampling system that can condense volatile precursors to particle phase to simulate the atmospheric evolution of aircraft engine exhaust has been developed. In this paper, a field demonstration of its operation is described. The dilution/aging probe system was tested using both a combustor rig and on-wing CFM56-7 engines. During the combustor rig testing at NASA Glenn Research Center, the dilution/aging probe supported formation of both nucleation/growth mode particles and soot coatings. The results showed that by increasing residence time, the nucleation particles become larger in size, increase in total mass, and decrease in number. During the on-wing CFM56-7 engine testing at Chicago Midway Airport, the dilution/aging probe was able to form soot coatings along with nucleation mode particles, unlike conventional 1-m probe engine measurements. The number concentration of nucleation particles depended on the sample fraction and relative humidity of the dilution air. The performance of the instrument is analyzed and explained using computational microphysics simulations. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 08 p.[article] Measurement of volatile particulate matter emissions from aircraft engines using a simulated plume aging system [texte imprimé] / Peck, Jay, Auteur ; Michael T. Timko, Auteur ; Zhenhong Yu, Auteur . - 2012 . - 08 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 08 p.
Mots-clés : Volatile particulate matter emissions Aircraft engines Plume aging system Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Aircraft exhaust contains nonvolatile (soot) particulate matter (PM), trace gas pollutants, and volatile PM precursor material. Nonvolatile soot particles are predominantly present at the engine exit plane, but volatile PM precursors form new particles or add mass to the existing ones as the exhaust is diluted and cooled. Accurately characterizing the volatile PM mass, number, and size distribution is challenging due to this evolving nature and the impact of local ambient conditions on the gas-to-particle conversion processes. To accurately and consistently measure the aircraft PM emissions, a dilution and aging sampling system that can condense volatile precursors to particle phase to simulate the atmospheric evolution of aircraft engine exhaust has been developed. In this paper, a field demonstration of its operation is described. The dilution/aging probe system was tested using both a combustor rig and on-wing CFM56-7 engines. During the combustor rig testing at NASA Glenn Research Center, the dilution/aging probe supported formation of both nucleation/growth mode particles and soot coatings. The results showed that by increasing residence time, the nucleation particles become larger in size, increase in total mass, and decrease in number. During the on-wing CFM56-7 engine testing at Chicago Midway Airport, the dilution/aging probe was able to form soot coatings along with nucleation mode particles, unlike conventional 1-m probe engine measurements. The number concentration of nucleation particles depended on the sample fraction and relative humidity of the dilution air. The performance of the instrument is analyzed and explained using computational microphysics simulations. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : A high temperature high bandwidth fast response total pressure probe for measurements in a multistage axial compressor Type de document : texte imprimé Auteurs : Mersinligil, Mehmet, Auteur ; Brouckaert, Jean-François, Auteur ; Nicolas Courtiade, Auteur Année de publication : 2012 Article en page(s) : 11 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Response aerodynamic Axial compressor Measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Over the last decades, fast response aerodynamic probes have been recognized as a robust measurement technique to provide time-resolved flow field data in turbomachinery environments. Still, most of the existing probe designs are restricted to low temperature applications ( DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 11 p.[article] A high temperature high bandwidth fast response total pressure probe for measurements in a multistage axial compressor [texte imprimé] / Mersinligil, Mehmet, Auteur ; Brouckaert, Jean-François, Auteur ; Nicolas Courtiade, Auteur . - 2012 . - 11 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 11 p.
Mots-clés : Response aerodynamic Axial compressor Measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Over the last decades, fast response aerodynamic probes have been recognized as a robust measurement technique to provide time-resolved flow field data in turbomachinery environments. Still, most of the existing probe designs are restricted to low temperature applications ( DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : In-flight isolation of degraded engine components by shape comparison of transient outputs Type de document : texte imprimé Auteurs : Jeffrey C. Simmons, Auteur ; Danai, Kourosh, Auteur Année de publication : 2012 Article en page(s) : 11 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Degraded engine components In-flight isolation Transient output Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A direct method of aircraft engine health monitoring is introduced that can isolate a degraded engine component in-flight. The method utilizes continuous wavelet transformations of transient engine sensory data to represent their shape attributes in the time scale domain. This enables contrasting the shapes of the current engine outputs with those previously collected from the engine. Continuous wavelet transforms also provide enhanced delineation of the engine transients in the time scale domain. This enables identification of minute differences between the outputs affected by component degradations and between the sensitivities of modeled outputs with respect to the health parameters or components. The presence of these differences is used in this method as evidence of degradation effects on the outputs and/or parameters or components effects on the outputs. The effectiveness of the proposed method is evaluated in engine simulations. The results indicate that with the suite of outputs currently available on-board 70% to 96% of the degraded components simulated can be isolated for new and older engines. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 11 p.[article] In-flight isolation of degraded engine components by shape comparison of transient outputs [texte imprimé] / Jeffrey C. Simmons, Auteur ; Danai, Kourosh, Auteur . - 2012 . - 11 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 11 p.
Mots-clés : Degraded engine components In-flight isolation Transient output Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A direct method of aircraft engine health monitoring is introduced that can isolate a degraded engine component in-flight. The method utilizes continuous wavelet transformations of transient engine sensory data to represent their shape attributes in the time scale domain. This enables contrasting the shapes of the current engine outputs with those previously collected from the engine. Continuous wavelet transforms also provide enhanced delineation of the engine transients in the time scale domain. This enables identification of minute differences between the outputs affected by component degradations and between the sensitivities of modeled outputs with respect to the health parameters or components. The presence of these differences is used in this method as evidence of degradation effects on the outputs and/or parameters or components effects on the outputs. The effectiveness of the proposed method is evaluated in engine simulations. The results indicate that with the suite of outputs currently available on-board 70% to 96% of the degraded components simulated can be isolated for new and older engines. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Prediction of rotordynamic coefficients for short labyrinth gas seals using computational fluid dynamics Type de document : texte imprimé Auteurs : Alexander O. Pugachev, Auteur ; Ulrich Kleinhans, Auteur ; Manuel Gaszner, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Computational fluid dynamics Labyrinth gas seals Rotordynamic stability Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The analysis is presented for the computational fluid dynamics (CFD)-based modeling of short labyrinth gas seals. Seal leakage performance can be reliably predicted with CFD for a wide operating range and various sealing configurations. Prediction of seal influence on the rotordynamic stability, however, is a challenging task requiring relatively high computer processing power. A full 3D eccentric CFD model of a short staggered three-tooth-on-stator labyrinth seal is built in ANSYS CFX. An extensive grid independence study is carried out showing influence of the grid refinement on the stiffness coefficients. Three methods for the prediction of stiffness and damping coefficients as well as the effect of turbulence modeling, boundary conditions, and solver parameters are presented. The rest of the paper shows the results of a parameter variation (inlet pressure, preswirl, and shaft rotational speed) for two labyrinth seals with a tooth radial clearance of 0.5 mm and 0.27 mm, respectively. The latter was compared with experimental data in Pugachev and Deckner, 2010, “Analysis of the Experimental and CFD-Based Theoretical Methods for Studying Rotordynamic Characteristics of Labyrinth Gas Seals,” Proceedings of ASME Turbo Expo 2010, Paper No. GT2010-22058. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 10 p.[article] Prediction of rotordynamic coefficients for short labyrinth gas seals using computational fluid dynamics [texte imprimé] / Alexander O. Pugachev, Auteur ; Ulrich Kleinhans, Auteur ; Manuel Gaszner, Auteur . - 2012 . - 10 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 10 p.
Mots-clés : Computational fluid dynamics Labyrinth gas seals Rotordynamic stability Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The analysis is presented for the computational fluid dynamics (CFD)-based modeling of short labyrinth gas seals. Seal leakage performance can be reliably predicted with CFD for a wide operating range and various sealing configurations. Prediction of seal influence on the rotordynamic stability, however, is a challenging task requiring relatively high computer processing power. A full 3D eccentric CFD model of a short staggered three-tooth-on-stator labyrinth seal is built in ANSYS CFX. An extensive grid independence study is carried out showing influence of the grid refinement on the stiffness coefficients. Three methods for the prediction of stiffness and damping coefficients as well as the effect of turbulence modeling, boundary conditions, and solver parameters are presented. The rest of the paper shows the results of a parameter variation (inlet pressure, preswirl, and shaft rotational speed) for two labyrinth seals with a tooth radial clearance of 0.5 mm and 0.27 mm, respectively. The latter was compared with experimental data in Pugachev and Deckner, 2010, “Analysis of the Experimental and CFD-Based Theoretical Methods for Studying Rotordynamic Characteristics of Labyrinth Gas Seals,” Proceedings of ASME Turbo Expo 2010, Paper No. GT2010-22058. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Probabilistic high-cycle fretting fatigue assessment of gas turbine engine components Type de document : texte imprimé Auteurs : Kwai S. Chan, Auteur ; Enright, Michael P., Auteur ; Patrick J. Golden, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Gas turbine High-cycle fatigue Fret methods Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : High-cycle fatigue (HCF) is arguably one of the costliest sources of in-service damage in military aircraft engines. HCF of turbine blades and disks can pose a significant engine risk because fatigue failure can result from resonant vibratory stresses sustained over a relatively short time. A common approach to mitigate HCF risk is to avoid dangerous resonant vibration modes (first bending and torsion modes, etc.) and instabilities (flutter and rotating stall) in the operating range. However, it might be impossible to avoid all the resonance for all flight conditions. In this paper, a methodology is presented to assess the influences of HCF loading on the fracture risk of gas turbine engine components subjected to fretting fatigue. The methodology is based on an integration of a global finite element analysis of the disk-blade assembly, numerical solution of the singular integral equations using the CAPRI (Contact Analysis for Profiles of Random Indenters) and Worst Case Fret methods, and risk assessment using the DARWIN (Design Assessment of Reliability with Inspection) probabilistic fracture mechanics code. The methodology is illustrated for an actual military engine disk under real life loading conditions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 08 p.[article] Probabilistic high-cycle fretting fatigue assessment of gas turbine engine components [texte imprimé] / Kwai S. Chan, Auteur ; Enright, Michael P., Auteur ; Patrick J. Golden, Auteur . - 2012 . - 08 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 08 p.
Mots-clés : Gas turbine High-cycle fatigue Fret methods Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : High-cycle fatigue (HCF) is arguably one of the costliest sources of in-service damage in military aircraft engines. HCF of turbine blades and disks can pose a significant engine risk because fatigue failure can result from resonant vibratory stresses sustained over a relatively short time. A common approach to mitigate HCF risk is to avoid dangerous resonant vibration modes (first bending and torsion modes, etc.) and instabilities (flutter and rotating stall) in the operating range. However, it might be impossible to avoid all the resonance for all flight conditions. In this paper, a methodology is presented to assess the influences of HCF loading on the fracture risk of gas turbine engine components subjected to fretting fatigue. The methodology is based on an integration of a global finite element analysis of the disk-blade assembly, numerical solution of the singular integral equations using the CAPRI (Contact Analysis for Profiles of Random Indenters) and Worst Case Fret methods, and risk assessment using the DARWIN (Design Assessment of Reliability with Inspection) probabilistic fracture mechanics code. The methodology is illustrated for an actual military engine disk under real life loading conditions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Analytical investigation of the effects of induction motor transients on compressor drive shafts Type de document : texte imprimé Auteurs : Anand Srinivasan, Auteur Année de publication : 2012 Article en page(s) : 06 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Induction motor Centrifugal compressors Turbomachinery industry Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Centrifugal compressors driven by induction motors are most common in the turbomachinery industry. When sudden transients occur in the driver due to upsets in electrical supply to the motor, the air-gap torque generated by the motor undergoes a transient spike. This in turn gets transmitted through the coupling to the drive-shaft of the driven equipment, causing momentary high spikes in vibration that are torsional in nature, and can sometimes result in shaft torques that can create catastrophic damage to driven equipment components. In order to analytically predict these peak torques that can occur during transients, a complete drive-train torsional model needs to be created for the mechanical system, and the driving torque values need to be derived from the motor electrical system of equations. Various line faults are possible with induction motor driven equipment. A generalized analytical procedure based on motor electrical parameters to predict the peak shaft torques of compressor drive shafts is investigated in this paper. The effects of shaft transients due to 3-phase short circuits and reclosures are analyzed. The simulation has been performed for an industrial compressor train, and has been presented from a mechanical system point of view, rather than electrical. Comparisons and inferences are also made based on the simulation results. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 06 p.[article] Analytical investigation of the effects of induction motor transients on compressor drive shafts [texte imprimé] / Anand Srinivasan, Auteur . - 2012 . - 06 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 06 p.
Mots-clés : Induction motor Centrifugal compressors Turbomachinery industry Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Centrifugal compressors driven by induction motors are most common in the turbomachinery industry. When sudden transients occur in the driver due to upsets in electrical supply to the motor, the air-gap torque generated by the motor undergoes a transient spike. This in turn gets transmitted through the coupling to the drive-shaft of the driven equipment, causing momentary high spikes in vibration that are torsional in nature, and can sometimes result in shaft torques that can create catastrophic damage to driven equipment components. In order to analytically predict these peak torques that can occur during transients, a complete drive-train torsional model needs to be created for the mechanical system, and the driving torque values need to be derived from the motor electrical system of equations. Various line faults are possible with induction motor driven equipment. A generalized analytical procedure based on motor electrical parameters to predict the peak shaft torques of compressor drive shafts is investigated in this paper. The effects of shaft transients due to 3-phase short circuits and reclosures are analyzed. The simulation has been performed for an industrial compressor train, and has been presented from a mechanical system point of view, rather than electrical. Comparisons and inferences are also made based on the simulation results. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Diesel injector coking : optical-chemical analysis of deposits and influence on injected flow-rate, fuel spray and engine performance Type de document : texte imprimé Auteurs : S. d'Ambrosio, Auteur ; A. Ferrari, Auteur Année de publication : 2012 Article en page(s) : 14 p. Note générale : Génie mécanique Langues : Anglais (eng) Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The physical origin of injector coking in diesel engines has been clarified and the most critical design parameters and operating variables pertaining to the occurrence of the phenomenon have been identified. Fouling has been shown to be affected by many factors, such as injector temperature, nozzle configuration, hole diameter and conicity as well as fuel composition. Optical and scanning electron microscope (SEM) analyses have been conducted both inside and outside injectors of different type and four locations have been identified as the main deposition sites. Furthermore, different coking typologies, i.e., dry and wet coking, have been assessed and discussed. Energy Dispersive X-ray (EDX) spectroscopy images of the deposits on the spray hole walls have revealed that minute quantities of Zn catalyze the coking reactions to a great extent. Significant quantities of Zn have also been found in the injector deposits. An extensive experimental test campaign has been carried out at the engine test bench with different nozzle setups in order to evaluate performance deterioration after different ageing procedures. The effects of both the Zn concentration in the fuel and running time have been assessed separately on the fouling rate. Injection rate time histories have been acquired at the hydraulic test rig, under different working conditions, for both new and aged injectors. The experimental changes in the EVI profiles subsequent to fouling have been analyzed and related to the corresponding variations in engine power measured at the engine test bench. A previously developed combustion multi-zone diagnostic model has also been applied to gain a further insight into the cause and effect relationships between the experimental in-cylinder pressure time histories and engine-out emissions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 14 p.[article] Diesel injector coking : optical-chemical analysis of deposits and influence on injected flow-rate, fuel spray and engine performance [texte imprimé] / S. d'Ambrosio, Auteur ; A. Ferrari, Auteur . - 2012 . - 14 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 14 p.
Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The physical origin of injector coking in diesel engines has been clarified and the most critical design parameters and operating variables pertaining to the occurrence of the phenomenon have been identified. Fouling has been shown to be affected by many factors, such as injector temperature, nozzle configuration, hole diameter and conicity as well as fuel composition. Optical and scanning electron microscope (SEM) analyses have been conducted both inside and outside injectors of different type and four locations have been identified as the main deposition sites. Furthermore, different coking typologies, i.e., dry and wet coking, have been assessed and discussed. Energy Dispersive X-ray (EDX) spectroscopy images of the deposits on the spray hole walls have revealed that minute quantities of Zn catalyze the coking reactions to a great extent. Significant quantities of Zn have also been found in the injector deposits. An extensive experimental test campaign has been carried out at the engine test bench with different nozzle setups in order to evaluate performance deterioration after different ageing procedures. The effects of both the Zn concentration in the fuel and running time have been assessed separately on the fouling rate. Injection rate time histories have been acquired at the hydraulic test rig, under different working conditions, for both new and aged injectors. The experimental changes in the EVI profiles subsequent to fouling have been analyzed and related to the corresponding variations in engine power measured at the engine test bench. A previously developed combustion multi-zone diagnostic model has also been applied to gain a further insight into the cause and effect relationships between the experimental in-cylinder pressure time histories and engine-out emissions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Characterizing diesel fuel spray cone angle from back-scattered imaging by fitting Gaussian profiles to radial spray intensity distributions Type de document : texte imprimé Auteurs : Jaclyn E. Johnson, Auteur ; Jeffrey D. Naber, Auteur ; Seong-Young Lee, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Diesel fuel spray Backscattered imaging Gaussian fitting Spray intensity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Quantifying fuel spray properties including penetration, cone angle, and vaporization processes sheds light on fuel-air mixing phenomenon, which governs subsequent combustion and emissions formation in diesel engines. Accurate experimental determination of these spray properties is a challenge but imperative to validate computational fluid dynamic (CFD) models for combustion prediction. This study proposes a new threshold independent method for determination of spray cone angle when using Mie back-scattering optical diagnostics to visualize diesel sprays in an optically accessible constant volume vessel. Test conditions include the influence of charge density (17.6 and 34.9 kg/m3) at 1990 bar injection pressure, and the influence of injection pressure (990, 1370, and 1980 bar) at a charge density of 34.8 kg/m3 on diesel fuel spray formation from a multi-hole injector into nitrogen at a temperature of 100 °C. Conventional thresholding to convert an image to black and white for processing and determination of cone angle is threshold subjective. As an alternative, an image processing method was developed, which fits a Gaussian curve to the intensity distribution of the spray at radial spray cross-sections and uses the resulting parameters to define the spray edge and hence cone angle. This Gaussian curve fitting methodology is shown to provide a robust method for cone angle determination, accounting for reductions in intensity at the radial spray edge. Results are presented for non-vaporizing sprays using this Gaussian curve fitting method and compared to the conventional thresholding based method. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 08 p.[article] Characterizing diesel fuel spray cone angle from back-scattered imaging by fitting Gaussian profiles to radial spray intensity distributions [texte imprimé] / Jaclyn E. Johnson, Auteur ; Jeffrey D. Naber, Auteur ; Seong-Young Lee, Auteur . - 2012 . - 08 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 08 p.
Mots-clés : Diesel fuel spray Backscattered imaging Gaussian fitting Spray intensity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Quantifying fuel spray properties including penetration, cone angle, and vaporization processes sheds light on fuel-air mixing phenomenon, which governs subsequent combustion and emissions formation in diesel engines. Accurate experimental determination of these spray properties is a challenge but imperative to validate computational fluid dynamic (CFD) models for combustion prediction. This study proposes a new threshold independent method for determination of spray cone angle when using Mie back-scattering optical diagnostics to visualize diesel sprays in an optically accessible constant volume vessel. Test conditions include the influence of charge density (17.6 and 34.9 kg/m3) at 1990 bar injection pressure, and the influence of injection pressure (990, 1370, and 1980 bar) at a charge density of 34.8 kg/m3 on diesel fuel spray formation from a multi-hole injector into nitrogen at a temperature of 100 °C. Conventional thresholding to convert an image to black and white for processing and determination of cone angle is threshold subjective. As an alternative, an image processing method was developed, which fits a Gaussian curve to the intensity distribution of the spray at radial spray cross-sections and uses the resulting parameters to define the spray edge and hence cone angle. This Gaussian curve fitting methodology is shown to provide a robust method for cone angle determination, accounting for reductions in intensity at the radial spray edge. Results are presented for non-vaporizing sprays using this Gaussian curve fitting method and compared to the conventional thresholding based method. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Quick response fuel injector for direct-injection gasoline engines Type de document : texte imprimé Auteurs : Motoyuki Abe, Auteur ; Noriyuki Maekawa, Auteur ; Yoshihito Yasukawa, Auteur Année de publication : 2012 Article en page(s) : 05 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Fuel injector Gasoline engines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : We developed a new injector for direct injection gasoline engines that reduce the exhaust emissions and help to reduce fuel consumption. The newly developed actuator in this injector has two features. One is a bounceless valve closing mechanism, and the second is quick response moving parts. The first feature, the bounceless valve closing mechanism, can prevent ejecting a coarse droplet, which causes unburned gas emission. The new actuation mechanism realizes the bounceless valve closing. We analyzed the valve motion and injection behavior. The second feature, the quick-response actuator, achieves a smaller minimum injection quantity. This feature assists in reducing the fuel consumption under low load engine conditions. The closing delay time of the needle valve is the dominant factor of the minimum injection quantity because the injection quantity is controlled by the duration time of the valve opening. The new actuator movements can be operated with a shorter closing delay time. The closing delay time is caused by a magnetic delay and kinematic delay. A compact magnetic circuit of the actuator reduces the closing delay time by 26%. In addition, the kinematic delay was improved when the hydraulic resistance was reduced by 9%. As a result, the new injector realizes reduction of the minimum injection quantity by 25% compared to a conventional injector. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 05 p.[article] Quick response fuel injector for direct-injection gasoline engines [texte imprimé] / Motoyuki Abe, Auteur ; Noriyuki Maekawa, Auteur ; Yoshihito Yasukawa, Auteur . - 2012 . - 05 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 05 p.
Mots-clés : Fuel injector Gasoline engines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : We developed a new injector for direct injection gasoline engines that reduce the exhaust emissions and help to reduce fuel consumption. The newly developed actuator in this injector has two features. One is a bounceless valve closing mechanism, and the second is quick response moving parts. The first feature, the bounceless valve closing mechanism, can prevent ejecting a coarse droplet, which causes unburned gas emission. The new actuation mechanism realizes the bounceless valve closing. We analyzed the valve motion and injection behavior. The second feature, the quick-response actuator, achieves a smaller minimum injection quantity. This feature assists in reducing the fuel consumption under low load engine conditions. The closing delay time of the needle valve is the dominant factor of the minimum injection quantity because the injection quantity is controlled by the duration time of the valve opening. The new actuator movements can be operated with a shorter closing delay time. The closing delay time is caused by a magnetic delay and kinematic delay. A compact magnetic circuit of the actuator reduces the closing delay time by 26%. In addition, the kinematic delay was improved when the hydraulic resistance was reduced by 9%. As a result, the new injector realizes reduction of the minimum injection quantity by 25% compared to a conventional injector. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : A study of the effects of biofuel use on piston lubrication during fuel post injection in a direct injection diesel engine Type de document : texte imprimé Auteurs : Koji Kikuhara, Auteur ; Akihiro Shibata, Auteur ; Akemi Ito, Auteur Année de publication : 2012 Article en page(s) : 06 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Diesel engines Fuel post injection Direct Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The reduction of both exhaust gases and carbon dioxide emissions is necessary to meet future emissions regulations for diesel engines. Exhaust after-treatment devices are gradually being applied to diesel engines to reduce exhaust gases. Diesel particulate filters (DPF), an after-treatment device for diesel engines, in some cases require fuel post injection for regeneration. Post injection is usually conducted at the midpoint of the expansion stroke, and therefore causes fuel adhesion to the cylinder wall. However, using biofuels in a diesel engine is an effective way of reducing carbon dioxide emissions. It is well known that biofuels are chemically unstable, but the effects of biofuels on piston lubrication condition have not been thoroughly studied. In this study, piston lubrication condition during post injection in a single cylinder DI diesel engine using biofuel was investigated. Piston and ring friction forces were measured under engine operating conditions by means of a floating liner device to investigate the lubrication condition of the piston and rings. Both light fuel oil and biofuel were used in the measurements, with rapeseed methyl ester (RME) being used as the biofuel. Lubricating oil on the cylinder wall was also sampled under engine operating conditions, and the effect of post injection on fuel adhesion to the cylinder wall was analyzed. It was found that the effect of post injection on fuel adhesion to the cylinder wall was remarkable around the top dead center (TDC), and the fuel dilution rate reached approximately 90%. The results of the measurement of the piston friction forces showed that post injection caused an increase in the friction forces at the compression TDC (CTDC) in the cases of both RME and light fuel oil, and the friction forces at CTDC increased according to the delay of the post injection timing. The increase in the piston friction forces was moderate in the case of RME. It seems that the higher viscosity and the oiliness of RME suppressed the increase in piston friction forces at TDC. The following effects were found in this study. Fuel post injection caused fuel adhesion to the cylinder wall. Such phenomena affected the lubrication condition of the piston. In the case of RME, the increase in the piston friction forces caused by post injection was smaller than that of light fuel oil, but the effects on piston lubrication condition in the case of using other biofuels needs to be investigated. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 06 p.[article] A study of the effects of biofuel use on piston lubrication during fuel post injection in a direct injection diesel engine [texte imprimé] / Koji Kikuhara, Auteur ; Akihiro Shibata, Auteur ; Akemi Ito, Auteur . - 2012 . - 06 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 06 p.
Mots-clés : Diesel engines Fuel post injection Direct Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The reduction of both exhaust gases and carbon dioxide emissions is necessary to meet future emissions regulations for diesel engines. Exhaust after-treatment devices are gradually being applied to diesel engines to reduce exhaust gases. Diesel particulate filters (DPF), an after-treatment device for diesel engines, in some cases require fuel post injection for regeneration. Post injection is usually conducted at the midpoint of the expansion stroke, and therefore causes fuel adhesion to the cylinder wall. However, using biofuels in a diesel engine is an effective way of reducing carbon dioxide emissions. It is well known that biofuels are chemically unstable, but the effects of biofuels on piston lubrication condition have not been thoroughly studied. In this study, piston lubrication condition during post injection in a single cylinder DI diesel engine using biofuel was investigated. Piston and ring friction forces were measured under engine operating conditions by means of a floating liner device to investigate the lubrication condition of the piston and rings. Both light fuel oil and biofuel were used in the measurements, with rapeseed methyl ester (RME) being used as the biofuel. Lubricating oil on the cylinder wall was also sampled under engine operating conditions, and the effect of post injection on fuel adhesion to the cylinder wall was analyzed. It was found that the effect of post injection on fuel adhesion to the cylinder wall was remarkable around the top dead center (TDC), and the fuel dilution rate reached approximately 90%. The results of the measurement of the piston friction forces showed that post injection caused an increase in the friction forces at the compression TDC (CTDC) in the cases of both RME and light fuel oil, and the friction forces at CTDC increased according to the delay of the post injection timing. The increase in the piston friction forces was moderate in the case of RME. It seems that the higher viscosity and the oiliness of RME suppressed the increase in piston friction forces at TDC. The following effects were found in this study. Fuel post injection caused fuel adhesion to the cylinder wall. Such phenomena affected the lubrication condition of the piston. In the case of RME, the increase in the piston friction forces caused by post injection was smaller than that of light fuel oil, but the effects on piston lubrication condition in the case of using other biofuels needs to be investigated. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : The effect of the location of nucleation sites on the thermal-hydraulic stability of a short-tube natural circulation loop Type de document : texte imprimé Auteurs : Marek Kapitz, Auteur ; Stefan aus der Wiesche, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Nucleation sites Thermal-hydraulic stability Artificial nucleation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The use of small two-phase natural circulation loops is an attractive option for efficient cooling applications and innovative steam generators. An experimental study was conducted to examine how the thermal-hydraulic stability and operating conditions of these devices are affected by nucleation sites. A very smooth glass tube with artificial nucleation sites was used as a boiling channel. The mass flow rate was obtained as a function of heat flux and nucleation site location. Nucleation sites have a strong impact on stability behavior, particularly for low heat flux levels. The observed flow instabilities were analyzed with regard to nonlinear effects and chaotic behavior. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 08 p.[article] The effect of the location of nucleation sites on the thermal-hydraulic stability of a short-tube natural circulation loop [texte imprimé] / Marek Kapitz, Auteur ; Stefan aus der Wiesche, Auteur . - 2012 . - 08 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 08 p.
Mots-clés : Nucleation sites Thermal-hydraulic stability Artificial nucleation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The use of small two-phase natural circulation loops is an attractive option for efficient cooling applications and innovative steam generators. An experimental study was conducted to examine how the thermal-hydraulic stability and operating conditions of these devices are affected by nucleation sites. A very smooth glass tube with artificial nucleation sites was used as a boiling channel. The mass flow rate was obtained as a function of heat flux and nucleation site location. Nucleation sites have a strong impact on stability behavior, particularly for low heat flux levels. The observed flow instabilities were analyzed with regard to nonlinear effects and chaotic behavior. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Development of al-alloy coating for advanced nuclear systems using lead alloys Type de document : texte imprimé Auteurs : Yuji Kurata, Auteur ; Hitoshi Yokota, Auteur ; Tetsuya Suzuki, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Al-alloy Nuclear systems Lead alloys Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Small and medium reactors using lead alloys as coolants are one of the promising reactor concepts with improved safety because of their thermal-physical and chemical properties. This paper focuses on the development of Al-alloy coating for nuclear systems using liquid lead-bismuth eutectic (LBE). Since corrosion attack becomes severe against structural steels at high temperatures in liquid LBE, it is necessary to improve the corrosion resistance of steels. An Al-alloy coating method using Al, Ti, and Fe powders, and laser beam heating has been developed. The main defects formed in the Al-powder-alloy coating process are surface defects and cracks. The conditions required to avoid these defects are the employment of the laser beam scanning rate of 20 mm/min and the adjustment of the Al concentration in the coating layer. According to the results of the corrosion tests at 550°C in liquid LBE, the Al-alloy coating layers on 316SS prevent severe corrosion attack such as grain boundary corrosion and LBE penetration observed in the 316SS without coating. The good corrosion resistance of the Al-alloy coating is based on the thin Al-oxide film, which can be regenerated in liquid LBE. From the viewpoint of the soundness of the produced Al-powder-alloy coating layers and the preservation of their corrosion resistance, it is estimated that the range of adequate Al concentration in the coating layer is from 4 to 12 wt. %. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 07 p.[article] Development of al-alloy coating for advanced nuclear systems using lead alloys [texte imprimé] / Yuji Kurata, Auteur ; Hitoshi Yokota, Auteur ; Tetsuya Suzuki, Auteur . - 2012 . - 07 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 07 p.
Mots-clés : Al-alloy Nuclear systems Lead alloys Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Small and medium reactors using lead alloys as coolants are one of the promising reactor concepts with improved safety because of their thermal-physical and chemical properties. This paper focuses on the development of Al-alloy coating for nuclear systems using liquid lead-bismuth eutectic (LBE). Since corrosion attack becomes severe against structural steels at high temperatures in liquid LBE, it is necessary to improve the corrosion resistance of steels. An Al-alloy coating method using Al, Ti, and Fe powders, and laser beam heating has been developed. The main defects formed in the Al-powder-alloy coating process are surface defects and cracks. The conditions required to avoid these defects are the employment of the laser beam scanning rate of 20 mm/min and the adjustment of the Al concentration in the coating layer. According to the results of the corrosion tests at 550°C in liquid LBE, the Al-alloy coating layers on 316SS prevent severe corrosion attack such as grain boundary corrosion and LBE penetration observed in the 316SS without coating. The good corrosion resistance of the Al-alloy coating is based on the thin Al-oxide film, which can be regenerated in liquid LBE. From the viewpoint of the soundness of the produced Al-powder-alloy coating layers and the preservation of their corrosion resistance, it is estimated that the range of adequate Al concentration in the coating layer is from 4 to 12 wt. %. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Advanced combined cycle systems based on methanol indirect combustion Type de document : texte imprimé Auteurs : Shimin Deng, Auteur ; Rory Hynes, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Combined cycle systems Conventional combined Methanol indirect combustion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this paper, two new combined cycle systems with/without CO2 capture based on methanol indirect combustion are developed, which have significantly higher efficiency than methanol fueled conventional combined cycle. The performance of the new systems is compared with conventional combined cycle to identify the potential of methanol indirect combustion. The systems are modeled by using Aspen PlusTM and GTProTM. Exergy analysis and the principle of cascade utilization of chemical exergy reasonably explain the improved efficiency of the new systems. Other merits of the combined cycle systems based on methanol indirect combustion are discussed and their promising commercial application aspects are pointed out. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 09 p.[article] Advanced combined cycle systems based on methanol indirect combustion [texte imprimé] / Shimin Deng, Auteur ; Rory Hynes, Auteur . - 2012 . - 09 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 09 p.
Mots-clés : Combined cycle systems Conventional combined Methanol indirect combustion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this paper, two new combined cycle systems with/without CO2 capture based on methanol indirect combustion are developed, which have significantly higher efficiency than methanol fueled conventional combined cycle. The performance of the new systems is compared with conventional combined cycle to identify the potential of methanol indirect combustion. The systems are modeled by using Aspen PlusTM and GTProTM. Exergy analysis and the principle of cascade utilization of chemical exergy reasonably explain the improved efficiency of the new systems. Other merits of the combined cycle systems based on methanol indirect combustion are discussed and their promising commercial application aspects are pointed out. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Oxidative activity of hydrogen on nickel and inconel Type de document : texte imprimé Auteurs : Kimberly N. Urness, Auteur ; G. Barney Ellison, Auteur ; John W. Daily, Auteur Année de publication : 2012 Article en page(s) : 05 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Nickel Inconel Hydrogen oxidation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Experiments were carried out to determine whether nickel or Inconel are catalytically active for hydrogen oxidation. The work was motivated by the problem of flame flashback and/or inlet preignition in hydrogen-rich syngas fueled premixed/prevaporized gas turbine combustors. The experiments were performed using small resistively heated tubular reactors with matrix isolation/infrared diagnostics. Reactors were manufactured from stainless steel, nickel and Inconel. For the flow conditions studied, the conversion efficiency was about 3% for the nickel reactor and 0.9% for the Inconel reactor. No activity was seen for stainless steel. Comparison with a published surface kinetic reaction mechanism for nickel suggests that the surface oxidation rate of H2 in our reactors is about two orders of magnitude less than for specially prepared surfaces. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 05 p.[article] Oxidative activity of hydrogen on nickel and inconel [texte imprimé] / Kimberly N. Urness, Auteur ; G. Barney Ellison, Auteur ; John W. Daily, Auteur . - 2012 . - 05 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 05 p.
Mots-clés : Nickel Inconel Hydrogen oxidation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Experiments were carried out to determine whether nickel or Inconel are catalytically active for hydrogen oxidation. The work was motivated by the problem of flame flashback and/or inlet preignition in hydrogen-rich syngas fueled premixed/prevaporized gas turbine combustors. The experiments were performed using small resistively heated tubular reactors with matrix isolation/infrared diagnostics. Reactors were manufactured from stainless steel, nickel and Inconel. For the flow conditions studied, the conversion efficiency was about 3% for the nickel reactor and 0.9% for the Inconel reactor. No activity was seen for stainless steel. Comparison with a published surface kinetic reaction mechanism for nickel suggests that the surface oxidation rate of H2 in our reactors is about two orders of magnitude less than for specially prepared surfaces. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : The port width and position determination for pressure-exchange ejector Type de document : texte imprimé Auteurs : Wenjing Zhao, Auteur ; Dapeng Hu, Auteur ; Peiqi Liu, Auteur Année de publication : 2012 Article en page(s) : 04 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Pressure-exchange ejector Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A pressure-exchange ejector transferring energy by compression and expansion waves has the potential for higher efficiency. The width and position of each port are essential in pressure-exchange ejector design. A dimensionless time tau expressing both port widths and the positions of port ends was introduced. A prototype was designed and the experimental system was set up. Many sets of experiment with different geometrical arrangements were conducted. The results suggest that the efficiency greatly changes with the geometrical arrangements. The efficiency is about 60% at proper port widths and positions, while at improper geometrical arrangements, the efficiency is much lower and the maximum deviation may reach about 20%. The proper dimensionless port widths and positions at different operating conditions are obtained. For a fixed overall pressure ratio, the widths of the high pressure flow inlet and middle pressure flow outlet increase as the outlet pressure increases and the low pressure flow inlet width is reduced with a larger outlet pressure. The middle pressure flow outlet (MO) opening end remains constant at different outlet pressures. The positions of the high pressure flow inlet (HI) closed end and the low pressure flow inlet (LI) open end increase with the elevation of outlet pressure, however, the distance between the HI closing end and the LI opening end is constant. The port widths and positions have a significant influence on the performance of the pressure-exchange ejector. The dimensionless data obtained are very valuable for pressure-exchange ejector design and performance optimization. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 04 p.[article] The port width and position determination for pressure-exchange ejector [texte imprimé] / Wenjing Zhao, Auteur ; Dapeng Hu, Auteur ; Peiqi Liu, Auteur . - 2012 . - 04 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 04 p.
Mots-clés : Pressure-exchange ejector Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A pressure-exchange ejector transferring energy by compression and expansion waves has the potential for higher efficiency. The width and position of each port are essential in pressure-exchange ejector design. A dimensionless time tau expressing both port widths and the positions of port ends was introduced. A prototype was designed and the experimental system was set up. Many sets of experiment with different geometrical arrangements were conducted. The results suggest that the efficiency greatly changes with the geometrical arrangements. The efficiency is about 60% at proper port widths and positions, while at improper geometrical arrangements, the efficiency is much lower and the maximum deviation may reach about 20%. The proper dimensionless port widths and positions at different operating conditions are obtained. For a fixed overall pressure ratio, the widths of the high pressure flow inlet and middle pressure flow outlet increase as the outlet pressure increases and the low pressure flow inlet width is reduced with a larger outlet pressure. The middle pressure flow outlet (MO) opening end remains constant at different outlet pressures. The positions of the high pressure flow inlet (HI) closed end and the low pressure flow inlet (LI) open end increase with the elevation of outlet pressure, however, the distance between the HI closing end and the LI opening end is constant. The port widths and positions have a significant influence on the performance of the pressure-exchange ejector. The dimensionless data obtained are very valuable for pressure-exchange ejector design and performance optimization. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Reduction of combustion gases' temperature and heating capacity by CO2 and H2O dissociation and NO formation Type de document : texte imprimé Auteurs : Leonardo Flores, Auteur ; Jaime Cervantes de Gortari, Auteur Année de publication : 2012 Article en page(s) : 05 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Combustion gases CO2 H2O NO formation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : he combustion gases theoretical adiabatic temperatures are reduced to equilibrium temperatures mainly because of the endothermic reactions of CO2 and H2O dissociation and NO formation. Therefore, the heating capacity of the gases is reduced to the equilibrium gases enthalpy. In the paper, these reactions and the way to consider them to calculate the gases' final equilibrium are exemplified, covering an ample range of temperatures. It is shown the method sensitivity and the results are verified against some registered values. The procedure allows calculation of the NO formation, evidencing its increment with the temperature. The reductions in combustion gases' adiabatic temperature and heating capacity are proportional to the theoretical adiabatic combustion temperature, apparent when the respective percentage decrements go from 2.2 and 2.7 at 2224 K to 46.8 and 50.9 at 7427 K for the studied combustion systems. This trend points out some maximum temperature reachable by oxidation, possibly 6000 K-the approximate energy emission sun temperature. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 05 p.[article] Reduction of combustion gases' temperature and heating capacity by CO2 and H2O dissociation and NO formation [texte imprimé] / Leonardo Flores, Auteur ; Jaime Cervantes de Gortari, Auteur . - 2012 . - 05 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 05 p.
Mots-clés : Combustion gases CO2 H2O NO formation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : he combustion gases theoretical adiabatic temperatures are reduced to equilibrium temperatures mainly because of the endothermic reactions of CO2 and H2O dissociation and NO formation. Therefore, the heating capacity of the gases is reduced to the equilibrium gases enthalpy. In the paper, these reactions and the way to consider them to calculate the gases' final equilibrium are exemplified, covering an ample range of temperatures. It is shown the method sensitivity and the results are verified against some registered values. The procedure allows calculation of the NO formation, evidencing its increment with the temperature. The reductions in combustion gases' adiabatic temperature and heating capacity are proportional to the theoretical adiabatic combustion temperature, apparent when the respective percentage decrements go from 2.2 and 2.7 at 2224 K to 46.8 and 50.9 at 7427 K for the studied combustion systems. This trend points out some maximum temperature reachable by oxidation, possibly 6000 K-the approximate energy emission sun temperature. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Assessment of low cycle fatigue life of steam turbine rotor based on a thermodynamic approach Type de document : texte imprimé Auteurs : Yong-Jian Sun, Auteur ; Li-Sheng Hu, Auteur Année de publication : 2012 Article en page(s) : 04 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Low cycle fatigue life Steam turbine rotor Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A new nonlinear model is proposed to assess the low cycle fatigue life of a 300 MW steam turbine rotor. Manson-Coffin equation and cyclic stress-strain relationship are employed to eliminate the unmeasured parameters, so all the parameters in model are measurable. Through comparison with that from the linear accumulation theory and continuum damage mechanics theory the results show this new nonlinear model describes the damage accumulation well and precisely in accordance with the practical test data. This approach supplies a new way to assess the damage of steam turbine rotor with satisfactory precision in engineering. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 04 p.[article] Assessment of low cycle fatigue life of steam turbine rotor based on a thermodynamic approach [texte imprimé] / Yong-Jian Sun, Auteur ; Li-Sheng Hu, Auteur . - 2012 . - 04 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 04 p.
Mots-clés : Low cycle fatigue life Steam turbine rotor Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A new nonlinear model is proposed to assess the low cycle fatigue life of a 300 MW steam turbine rotor. Manson-Coffin equation and cyclic stress-strain relationship are employed to eliminate the unmeasured parameters, so all the parameters in model are measurable. Through comparison with that from the linear accumulation theory and continuum damage mechanics theory the results show this new nonlinear model describes the damage accumulation well and precisely in accordance with the practical test data. This approach supplies a new way to assess the damage of steam turbine rotor with satisfactory precision in engineering. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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Titre : Air/water counter-current flow experiments in a model of the hot leg of a pressurized water reactor Type de document : texte imprimé Auteurs : Christophe Vallée, Auteur ; Deendarlianto, Auteur ; Matthias Beyer, Auteur Année de publication : 2012 Article en page(s) : 02 p. Note générale : Génie mécanique Langues : Anglais (eng) Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Note de contenu : Erratum: “Air/Water Counter-Current Flow Experiments in a Model of the Hot Leg of a Pressurized Water Reactor” [Journal of Engineering for Gas Turbines and Power, 2009, 131(2), p. 022905] DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 02 p.[article] Air/water counter-current flow experiments in a model of the hot leg of a pressurized water reactor [texte imprimé] / Christophe Vallée, Auteur ; Deendarlianto, Auteur ; Matthias Beyer, Auteur . - 2012 . - 02 p.
Génie mécanique
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 6 (Juin 2012) . - 02 p.
Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Note de contenu : Erratum: “Air/Water Counter-Current Flow Experiments in a Model of the Hot Leg of a Pressurized Water Reactor” [Journal of Engineering for Gas Turbines and Power, 2009, 131(2), p. 022905] DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000006 [...] Exemplaires
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