Dépouillements

On model design of a surrogate fuel formulation / Nadezhda A. Slavinskaya in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 11 p. Titre : On model design of a surrogate fuel formulation Type de document : texte imprimé Auteurs : Nadezhda A. Slavinskaya, Auteur ; Anton Zizin, Auteur ; Aigner, Manfred, Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Distillation  Enthalpy  Evaporation  Fuel  Phase  diagrams  Phase  equilibrium  Reaction  kinetics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Calculations of evaporation characteristics (distillation curve, two-phase diagram, and critical points) of surrogates are described in detail. The efficiency of some surrogate blends, represented in literature, in reflecting the evaporation characteristics was analyzed. Based on the analysis, the chemical capabilities of surrogate models are not linked to their abilities to reflect the phase-equilibrium properties of real fuel. It is shown that model design of practical fuels must include the phase-equilibrium and distillation curve calculations. A surrogate mixture was selected, which closely matches the boiling-point curve and two-phase diagram for jet-A. Next, physical properties of reference fuel were taken into consideration: combustion enthalpy, formation enthalpy, molar weight, approximate formula (carbon per hydrogen ratio), sooting tendency index, critical point, two-phase diagram, and distillation curve. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] On model design of a surrogate fuel formulation [texte imprimé] / Nadezhda A. Slavinskaya, Auteur ; Anton Zizin, Auteur ; Aigner, Manfred, Auteur . - 2011 . - 11 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 11 p. Mots-clés : Combustion  Distillation  Enthalpy  Evaporation  Fuel  Phase  diagrams  Phase  equilibrium  Reaction  kinetics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Calculations of evaporation characteristics (distillation curve, two-phase diagram, and critical points) of surrogates are described in detail. The efficiency of some surrogate blends, represented in literature, in reflecting the evaporation characteristics was analyzed. Based on the analysis, the chemical capabilities of surrogate models are not linked to their abilities to reflect the phase-equilibrium properties of real fuel. It is shown that model design of practical fuels must include the phase-equilibrium and distillation curve calculations. A surrogate mixture was selected, which closely matches the boiling-point curve and two-phase diagram for jet-A. Next, physical properties of reference fuel were taken into consideration: combustion enthalpy, formation enthalpy, molar weight, approximate formula (carbon per hydrogen ratio), sooting tendency index, critical point, two-phase diagram, and distillation curve. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Dynamics of premixed H2/CH4 flames under near blowoff conditions / Qingguo Zhang in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 08 p. Titre : Dynamics of premixed H2/CH4 flames under near blowoff conditions Type de document : texte imprimé Auteurs : Qingguo Zhang, Auteur ; Santosh J. Shanbhogue,, Auteur ; Tim Lieuwen, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon  compounds  Flames  Hydrogen  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Swirling flows are widely used in industrial burners and gas turbine combustors for flame stabilization. Several prior studies have shown that these flames exhibit complex dynamics under near blowoff conditions, associated with local flamelet extinction and alteration in the vortex breakdown flow structure. These extinction events are apparently due to the local strain rate irregularly oscillating above and below the extinction strain rate values near the attachment point. In this work, global temporally resolved and detailed spatial measurements were obtained of hydrogen/methane flames. Supporting calculations of extinction strain rates were also performed using detailed kinetics. It is shown that flames become unsteady (or local extinctions happen) at a nearly constant extinction strain rate for different hydrogen/methane mixtures. Based upon analysis of these results, it is suggested that classic Damköhler number correlations of blowoff are, in fact, correlations for the onset of local extinction events, not blowoff itself. Corresponding Mie scattering imaging of near blowoff flames also was used to characterize the spatio-temporal dynamics of holes along the flame that are associated with local extinction. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Dynamics of premixed H2/CH4 flames under near blowoff conditions [texte imprimé] / Qingguo Zhang, Auteur ; Santosh J. Shanbhogue,, Auteur ; Tim Lieuwen, Auteur . - 2011 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 08 p. Mots-clés : Carbon  compounds  Flames  Hydrogen  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Swirling flows are widely used in industrial burners and gas turbine combustors for flame stabilization. Several prior studies have shown that these flames exhibit complex dynamics under near blowoff conditions, associated with local flamelet extinction and alteration in the vortex breakdown flow structure. These extinction events are apparently due to the local strain rate irregularly oscillating above and below the extinction strain rate values near the attachment point. In this work, global temporally resolved and detailed spatial measurements were obtained of hydrogen/methane flames. Supporting calculations of extinction strain rates were also performed using detailed kinetics. It is shown that flames become unsteady (or local extinctions happen) at a nearly constant extinction strain rate for different hydrogen/methane mixtures. Based upon analysis of these results, it is suggested that classic Damköhler number correlations of blowoff are, in fact, correlations for the onset of local extinction events, not blowoff itself. Corresponding Mie scattering imaging of near blowoff flames also was used to characterize the spatio-temporal dynamics of holes along the flame that are associated with local extinction. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Thermoacoustic modeling of a gas turbine using transfer functions measured under full engine pressure / Bruno Schuermans in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 09 p. Titre : Thermoacoustic modeling of a gas turbine using transfer functions measured under full engine pressure Type de document : texte imprimé Auteurs : Bruno Schuermans, Auteur ; Felix Guethe, Auteur ; Douglas Pennell, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Acoustic  signal  processing  Acoustic  wave  propagation  Combustion  Engines  Flames  Gas  turbines  Photomultipliers  Transfer  functions Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Thermoacoustic transfer functions of a full-scale gas turbine burner operating under full engine pressure have been measured. The excitation of the high-pressure test facility was done using a siren that modulated a part of the combustion airflow. Pulsation probes have been used to record the acoustic response of the system to this excitation. In addition, the flame's luminescence response was measured by multiple photomultiplier probes and a light spectrometer. Three techniques to obtain the thermoacoustic transfer function are proposed and employed: two acoustic-optical techniques and a purely acoustic technique. The first acoustical-optical technique uses one single optical signal capturing the chemiluminescence intensity of the flame as a measure for the heat release in the flame. This technique only works if heat release fluctuations in the flame have only one generic source, e.g., equivalence ratio or mass flow fluctuations. The second acoustic-optical technique makes use of the different response of the flame's luminescence at different optical wavelengths bands to acoustic excitation. It also works, if the heat release fluctuations have two contributions, e.g., equivalence ratio and mass flow fluctuation. For the purely acoustic technique, a new method was developed in order to obtain the flame transfer function, burner transfer function, and flame source term from only three pressure transducer signals. The purely acoustic method could be validated by the results obtained from the acoustic-optical techniques. The acoustic and acoustic-optical methods have been compared and a discussion on the benefits and limitations of each is given. The measured transfer functions have been implemented into a nonlinear, three-dimensional, time domain network model of a gas turbine with an annular combustion chamber. The predicted pulsation behavior shows a good agreement with pulsation measurements on a field gas turbine. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Thermoacoustic modeling of a gas turbine using transfer functions measured under full engine pressure [texte imprimé] / Bruno Schuermans, Auteur ; Felix Guethe, Auteur ; Douglas Pennell, Auteur . - 2011 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 09 p. Mots-clés : Acoustic  signal  processing  Acoustic  wave  propagation  Combustion  Engines  Flames  Gas  turbines  Photomultipliers  Transfer  functions Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Thermoacoustic transfer functions of a full-scale gas turbine burner operating under full engine pressure have been measured. The excitation of the high-pressure test facility was done using a siren that modulated a part of the combustion airflow. Pulsation probes have been used to record the acoustic response of the system to this excitation. In addition, the flame's luminescence response was measured by multiple photomultiplier probes and a light spectrometer. Three techniques to obtain the thermoacoustic transfer function are proposed and employed: two acoustic-optical techniques and a purely acoustic technique. The first acoustical-optical technique uses one single optical signal capturing the chemiluminescence intensity of the flame as a measure for the heat release in the flame. This technique only works if heat release fluctuations in the flame have only one generic source, e.g., equivalence ratio or mass flow fluctuations. The second acoustic-optical technique makes use of the different response of the flame's luminescence at different optical wavelengths bands to acoustic excitation. It also works, if the heat release fluctuations have two contributions, e.g., equivalence ratio and mass flow fluctuation. For the purely acoustic technique, a new method was developed in order to obtain the flame transfer function, burner transfer function, and flame source term from only three pressure transducer signals. The purely acoustic method could be validated by the results obtained from the acoustic-optical techniques. The acoustic and acoustic-optical methods have been compared and a discussion on the benefits and limitations of each is given. The measured transfer functions have been implemented into a nonlinear, three-dimensional, time domain network model of a gas turbine with an annular combustion chamber. The predicted pulsation behavior shows a good agreement with pulsation measurements on a field gas turbine. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

3D RANS simulation of turbulent flow and combustion in a 5 MW reverse-flow type gas turbine combustor / Daero Joung in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 09 p. Titre : 3D RANS simulation of turbulent flow and combustion in a 5 MW reverse-flow type gas turbine combustor Type de document : texte imprimé Auteurs : Daero Joung, Auteur ; Kang Y. Huh, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Flames  Gas  turbines  Nozzles  Swirling  flow  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This study is concerned with 3D RANS simulation of turbulent flow and combustion in a 5 MW commercial gas turbine combustor. The combustor under consideration is a reverse flow, dry low NOx type, in which methane and air are partially mixed inside swirl vanes. We evaluated different turbulent combustion models to provide insights into mixing, temperature distribution, and emission in the combustor. Validation is performed for the models in STAR-CCM+ against the measurement data for a simple swirl flame (http://public.ca.sandia.gov/TNF/swirlflames.html). The standard k-epsilon model with enhanced wall treatment is employed to model turbulent swirl flow, whereas eddy break-up (EBU), presumed probability density function laminar flamelet model, and partially premixed coherent flame model (PCFM) are tried for reacting flow in the combustor. Independent simulations are carried out for the main and pilot nozzles to avoid flashback and to provide realistic inflow boundary conditions for the combustor. Geometrical details such as air swirlers, vane passages, and liner holes are all taken into account. Tested combustion models show similar downstream distributions of the mean flow and temperature, while EBU and PCFM show a lifted flame with stronger effects of swirl due to limited increase in axial momentum by expansion. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] 3D RANS simulation of turbulent flow and combustion in a 5 MW reverse-flow type gas turbine combustor [texte imprimé] / Daero Joung, Auteur ; Kang Y. Huh, Auteur . - 2011 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 09 p. Mots-clés : Combustion  Flames  Gas  turbines  Nozzles  Swirling  flow  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This study is concerned with 3D RANS simulation of turbulent flow and combustion in a 5 MW commercial gas turbine combustor. The combustor under consideration is a reverse flow, dry low NOx type, in which methane and air are partially mixed inside swirl vanes. We evaluated different turbulent combustion models to provide insights into mixing, temperature distribution, and emission in the combustor. Validation is performed for the models in STAR-CCM+ against the measurement data for a simple swirl flame (http://public.ca.sandia.gov/TNF/swirlflames.html). The standard k-epsilon model with enhanced wall treatment is employed to model turbulent swirl flow, whereas eddy break-up (EBU), presumed probability density function laminar flamelet model, and partially premixed coherent flame model (PCFM) are tried for reacting flow in the combustor. Independent simulations are carried out for the main and pilot nozzles to avoid flashback and to provide realistic inflow boundary conditions for the combustor. Geometrical details such as air swirlers, vane passages, and liner holes are all taken into account. Tested combustion models show similar downstream distributions of the mean flow and temperature, while EBU and PCFM show a lifted flame with stronger effects of swirl due to limited increase in axial momentum by expansion. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Proportional integral derivative based fault tolerant control for a gas turbine / Marino Sanchez-Parra in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 11 p. Titre : Proportional integral derivative based fault tolerant control for a gas turbine Type de document : texte imprimé Auteurs : Marino Sanchez-Parra, Auteur ; Cristina Verde, Auteur ; Dionisio A. Suarez, Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combined  cycle  power  stations  Gas  turbine  power  stations  Three-term  control  Turbogenerators Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a fault tolerant control switching scheme with embedded fault detection and isolation system for the gas turbine of a combined cycle power plant. Mechanical faults of the turbogenerator are considered as case study. Previous to the control design, the detection and isolation capabilities of the gas turbine are studied by applying structural analysis to a first principles based gas turbine model. As a result, a new sensor was suggested to improve the detectability and isolability with respect to mechanical faults and sensors faults. Furthermore, the active fault tolerant control developed is based on stabilizing families of proportional integral derivative (PID) controllers, which are tuned off-line and the plant switching scheme preserves the stability of the whole closed-loop system, thanks to a careful selection of controller according to fault conditions. Simulation results with nonlinear model show the potential of the procedure. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Proportional integral derivative based fault tolerant control for a gas turbine [texte imprimé] / Marino Sanchez-Parra, Auteur ; Cristina Verde, Auteur ; Dionisio A. Suarez, Auteur . - 2011 . - 11 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 11 p. Mots-clés : Combined  cycle  power  stations  Gas  turbine  power  stations  Three-term  control  Turbogenerators Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a fault tolerant control switching scheme with embedded fault detection and isolation system for the gas turbine of a combined cycle power plant. Mechanical faults of the turbogenerator are considered as case study. Previous to the control design, the detection and isolation capabilities of the gas turbine are studied by applying structural analysis to a first principles based gas turbine model. As a result, a new sensor was suggested to improve the detectability and isolability with respect to mechanical faults and sensors faults. Furthermore, the active fault tolerant control developed is based on stabilizing families of proportional integral derivative (PID) controllers, which are tuned off-line and the plant switching scheme preserves the stability of the whole closed-loop system, thanks to a careful selection of controller according to fault conditions. Simulation results with nonlinear model show the potential of the procedure. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Thermodynamic analysis of part-flow cycle supercritical CO2 gas turbines / Motoaki Utamura in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 07 p. Titre : Thermodynamic analysis of part-flow cycle supercritical CO2 gas turbines Type de document : texte imprimé Auteurs : Motoaki Utamura, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Brayton  cycle  Carbon  compounds  Gas  turbines  Heat  exchangers  Heat  transfer Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Cycle characteristics of closed gas turbines using supercritical carbon dioxide as a working fluid are investigated. It is found that an anomalous behavior of the physical properties of CO2 at the pseudocritical point may limit the heat exchange rate of a regenerative heat exchanger due to the presence of a pinch point inside the regenerative heat exchanger. Taking such a pinch problem into consideration, the cycle efficiency of the Brayton cycle is assessed. Its value is found to be limited to 39% degraded by 8% compared with the case without the pinch present inside. As an alternative, a part-flow cycle is investigated and its operable range has been identified. It is revealed that the part-flow cycle is effective to recover heat transfer capability and may achieve the cycle thermal efficiency of 45% under maximum operating conditions of 20 MPa and 800 K. Optimal combination of turbine expansion ratio and a part-flow ratio is 2.5 and 0.68, respectively. Parametric study is carried out. In neither compressor nor turbine, deteriorated adiabatic efficiency may affect cycle efficiency significantly. However, pressure drop characteristics of heat exchangers govern the cycle efficiency. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Thermodynamic analysis of part-flow cycle supercritical CO2 gas turbines [texte imprimé] / Motoaki Utamura, Auteur . - 2011 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 07 p. Mots-clés : Brayton  cycle  Carbon  compounds  Gas  turbines  Heat  exchangers  Heat  transfer Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Cycle characteristics of closed gas turbines using supercritical carbon dioxide as a working fluid are investigated. It is found that an anomalous behavior of the physical properties of CO2 at the pseudocritical point may limit the heat exchange rate of a regenerative heat exchanger due to the presence of a pinch point inside the regenerative heat exchanger. Taking such a pinch problem into consideration, the cycle efficiency of the Brayton cycle is assessed. Its value is found to be limited to 39% degraded by 8% compared with the case without the pinch present inside. As an alternative, a part-flow cycle is investigated and its operable range has been identified. It is revealed that the part-flow cycle is effective to recover heat transfer capability and may achieve the cycle thermal efficiency of 45% under maximum operating conditions of 20 MPa and 800 K. Optimal combination of turbine expansion ratio and a part-flow ratio is 2.5 and 0.68, respectively. Parametric study is carried out. In neither compressor nor turbine, deteriorated adiabatic efficiency may affect cycle efficiency significantly. However, pressure drop characteristics of heat exchangers govern the cycle efficiency. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Life prediction method of CC and DS Ni base superalloys under high temperature biaxial fatigue loading / Takashi Ogata in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 06 p. Titre : Life prediction method of CC and DS Ni base superalloys under high temperature biaxial fatigue loading Type de document : texte imprimé Auteurs : Takashi Ogata, Auteur Année de publication : 2011 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Blades  Casting  Failure  (mechanical)  Fatigue  cracks  Fatigue  testing  Gas  turbines  Nickel  alloys  Polymer  blends  Stress  analysis  Stress-strain  relations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Polycrystalline conventional casting (CC) and directionally solidified (DS) Ni base superalloys are widely used as gas turbine blade materials. It was reported that the surface of a gas turbine blade is subjected to a biaxial tensile-compressive fatigue loading during a start-stop operation, based on finite element stress analysis results. It is necessary to establish the life prediction method of these superalloys under biaxial fatigue loading for reliable operations. In this study, the in-plane biaxial fatigue tests with different phases of x and y directional strain cycles were conducted on both CC and DS Ni base superalloys (IN738LC and GTD111DS) at high temperatures. The strain ratio phi was defined as the ratio between the x and y directional strains at 1/4 cycle and was varied from 1 to −1. In phi=1 and −1. The main cracks propagated in both the x and y directions in the CC superalloy. On the other hand, the main cracks of the DS superalloy propagated only in the x direction, indicating that the failure resistance in the solidified direction is weaker than that in the direction normal to the solidified direction. Although the biaxial fatigue life of the CC superalloy was correlated with the conventional Mises equivalent strain range, that of the DS superalloy depended on phi. The new biaxial fatigue life criterion, equivalent normal strain range for the DS superalloy was derived from the iso-fatigue life curve on a principal strain plane defined in this study. Fatigue life of the DS superalloy was correlated with the equivalent normal strain range. Fatigue life of the DS superalloy under equibiaxial fatigue loading was significantly reduced by introducing compressive strain hold dwell. Life prediction under equibiaxial fatigue loading with the compressive strain hold was successfully made by the nonlinear damage accumulation model. This suggests that the proposed method can be applied to life prediction of the gas turbine DS blades, which are subjected to biaxial fatigue loading during operation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Life prediction method of CC and DS Ni base superalloys under high temperature biaxial fatigue loading [texte imprimé] / Takashi Ogata, Auteur . - 2011 . - 06 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 06 p. Mots-clés : Blades  Casting  Failure  (mechanical)  Fatigue  cracks  Fatigue  testing  Gas  turbines  Nickel  alloys  Polymer  blends  Stress  analysis  Stress-strain  relations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Polycrystalline conventional casting (CC) and directionally solidified (DS) Ni base superalloys are widely used as gas turbine blade materials. It was reported that the surface of a gas turbine blade is subjected to a biaxial tensile-compressive fatigue loading during a start-stop operation, based on finite element stress analysis results. It is necessary to establish the life prediction method of these superalloys under biaxial fatigue loading for reliable operations. In this study, the in-plane biaxial fatigue tests with different phases of x and y directional strain cycles were conducted on both CC and DS Ni base superalloys (IN738LC and GTD111DS) at high temperatures. The strain ratio phi was defined as the ratio between the x and y directional strains at 1/4 cycle and was varied from 1 to −1. In phi=1 and −1. The main cracks propagated in both the x and y directions in the CC superalloy. On the other hand, the main cracks of the DS superalloy propagated only in the x direction, indicating that the failure resistance in the solidified direction is weaker than that in the direction normal to the solidified direction. Although the biaxial fatigue life of the CC superalloy was correlated with the conventional Mises equivalent strain range, that of the DS superalloy depended on phi. The new biaxial fatigue life criterion, equivalent normal strain range for the DS superalloy was derived from the iso-fatigue life curve on a principal strain plane defined in this study. Fatigue life of the DS superalloy was correlated with the equivalent normal strain range. Fatigue life of the DS superalloy under equibiaxial fatigue loading was significantly reduced by introducing compressive strain hold dwell. Life prediction under equibiaxial fatigue loading with the compressive strain hold was successfully made by the nonlinear damage accumulation model. This suggests that the proposed method can be applied to life prediction of the gas turbine DS blades, which are subjected to biaxial fatigue loading during operation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Design of electromagnetic dampers for aero-engine applications / Andrea Tonoli in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 11 p. Titre : Design of electromagnetic dampers for aero-engine applications Type de document : texte imprimé Auteurs : Andrea Tonoli, Auteur ; Nicola Amati, Auteur ; Angelo Bonfitto, Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  engines  Gas  turbines  Magnetic  bearings  Rolling  bearings  Rotors  Steam  turbines  Vibration  control Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The vibration control of rotors for gas or steam turbines is usually performed using passive dampers when hydrodynamic bearings are not used. In layouts where the rotating parts are supported by rolling bearings, the damping is usually provided by squeeze film dampers. Their passive nature and the variability of their performances with temperature and frequency represent the main disadvantages. Dampers with magnetorheological and electrorheological fluid allow solving only a part of the abovementioned drawbacks. Active magnetic bearings (AMBs) are promising since they are very effective in controlling the vibration of the rotor and offering the possibility of monitoring the rotor's behavior using their displacement sensors. However they show serious drawbacks related to their stiffness. Electromagnetic dampers seem to be a valid alternative to visco-elastic, hydraulic dampers due to, among the others, the absence of all fatigue and tribology issues resulting from the absence of contact, the small sensitivity to the working environment, the wide possibility of tuning even during operation, the predictability of the behavior, the smaller mass compared with AMBs, and the failsafe capability. The aim of the present paper is to describe a design methodology adopted to develop electromagnetic dampers to be installed in aero-engines. The procedure has been validated using a reduced scale laboratory test rig. The same approach has then been adopted to design the electromagnetic dampers for real civil aircraft engines. The results in terms of achievable vibration reductions, mass, and overall dimensions are hence presented. A trade-off between the various proposed solutions has been carried out evaluating quantitative performance parameters together with qualitative aspects that this “more electric” technology implies. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Design of electromagnetic dampers for aero-engine applications [texte imprimé] / Andrea Tonoli, Auteur ; Nicola Amati, Auteur ; Angelo Bonfitto, Auteur . - 2011 . - 11 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 11 p. Mots-clés : Aerospace  engines  Gas  turbines  Magnetic  bearings  Rolling  bearings  Rotors  Steam  turbines  Vibration  control Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The vibration control of rotors for gas or steam turbines is usually performed using passive dampers when hydrodynamic bearings are not used. In layouts where the rotating parts are supported by rolling bearings, the damping is usually provided by squeeze film dampers. Their passive nature and the variability of their performances with temperature and frequency represent the main disadvantages. Dampers with magnetorheological and electrorheological fluid allow solving only a part of the abovementioned drawbacks. Active magnetic bearings (AMBs) are promising since they are very effective in controlling the vibration of the rotor and offering the possibility of monitoring the rotor's behavior using their displacement sensors. However they show serious drawbacks related to their stiffness. Electromagnetic dampers seem to be a valid alternative to visco-elastic, hydraulic dampers due to, among the others, the absence of all fatigue and tribology issues resulting from the absence of contact, the small sensitivity to the working environment, the wide possibility of tuning even during operation, the predictability of the behavior, the smaller mass compared with AMBs, and the failsafe capability. The aim of the present paper is to describe a design methodology adopted to develop electromagnetic dampers to be installed in aero-engines. The procedure has been validated using a reduced scale laboratory test rig. The same approach has then been adopted to design the electromagnetic dampers for real civil aircraft engines. The results in terms of achievable vibration reductions, mass, and overall dimensions are hence presented. A trade-off between the various proposed solutions has been carried out evaluating quantitative performance parameters together with qualitative aspects that this “more electric” technology implies. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

A reduced-order model of detuned cyclic dynamical systems with geometric modifications using a basis of cyclic modes / Moustapha Mbaye in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 09 p. Titre : A reduced-order model of detuned cyclic dynamical systems with geometric modifications using a basis of cyclic modes Type de document : texte imprimé Auteurs : Moustapha Mbaye, Auteur ; Christian Soize, Auteur ; Jean-Philippe Ousty, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Blades  Discs  (structures)  Finite  element  analysis  Modal  analysis  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A new reduction method for vibration analysis of intentionally mistuned bladed disks is presented. The method is built for solving the dynamic problem of cyclic structures with geometric modifications. It is based on the use of the cyclic modes of the different sectors, which can be obtained from a usual cyclic symmetry modal analysis. Hence the projection basis is constituted; as well as, on the whole bladed disk, each sector matrix is reduced by its own modes. The method is validated numerically on a real bladed disk model, by comparing free and forced responses of a full model finite element analysis to those of a reduced-order model using the new reduction method. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] A reduced-order model of detuned cyclic dynamical systems with geometric modifications using a basis of cyclic modes [texte imprimé] / Moustapha Mbaye, Auteur ; Christian Soize, Auteur ; Jean-Philippe Ousty, Auteur . - 2011 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 09 p. Mots-clés : Blades  Discs  (structures)  Finite  element  analysis  Modal  analysis  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A new reduction method for vibration analysis of intentionally mistuned bladed disks is presented. The method is built for solving the dynamic problem of cyclic structures with geometric modifications. It is based on the use of the cyclic modes of the different sectors, which can be obtained from a usual cyclic symmetry modal analysis. Hence the projection basis is constituted; as well as, on the whole bladed disk, each sector matrix is reduced by its own modes. The method is validated numerically on a real bladed disk model, by comparing free and forced responses of a full model finite element analysis to those of a reduced-order model using the new reduction method. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Measurements of drag torque, lift-off journal speed, and temperature in a metal mesh foil bearing / Luis San Andrés in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 07 p. Titre : Measurements of drag torque, lift-off journal speed, and temperature in a metal mesh foil bearing Type de document : texte imprimé Auteurs : Luis San Andrés, Auteur ; Thomas Abraham Chirathadam, Auteur ; Ryu, Keun, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Automotive  engineering  Helicopters  Lubricating  oils  Machine  bearings  Rotary  engines  Torque  measurement  Turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Metal mesh foil bearings (MMFBs) are a promising low cost gas bearing technology for high performance oil-free microturbomachinery. Elimination of complex oil lubrication and sealing system by deploying MMFBs in rotorcraft gas turbine engines offers distinctive advantages such as reduced system weight, enhanced reliability at high rotational speeds and extreme temperatures, and extended maintenance intervals compared with mineral oil lubricated bearings. MMFBs for oil-free rotorcraft engines must demonstrate adequate load capacity, reliable rotordynamic performance, and low frictional losses in a high temperature environment. The paper presents the measurements of MMFB break-away torque, rotor lift-off and touchdown speeds, and temperature at increasing static load conditions. The tests, which were conducted in a test rig driven by an automotive turbocharger turbine, demonstrate the airborne operation (hydrodynamic gas film) of the floating test MMFB with little frictional loses at increasing loads. The measured drag torque peaks when the rotor starts and stops, and drops significantly once the bearing lifts off. The estimated rotor speed for lift-off increases linearly with the applied static load. During continuous operation, the MMFB temperature measured at the back surface of the top foil increases both with rotor speed and static load. Nonetheless, the temperature rise is mild, demonstrating reliable performance. Application of a sacrificial layer of solid lubricant on the top foil surface reduces the rotor break-away torque. The measurements give confidence on this simple bearing technology for ready application into oil-free turbomachinery. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Measurements of drag torque, lift-off journal speed, and temperature in a metal mesh foil bearing [texte imprimé] / Luis San Andrés, Auteur ; Thomas Abraham Chirathadam, Auteur ; Ryu, Keun, Auteur . - 2011 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 07 p. Mots-clés : Automotive  engineering  Helicopters  Lubricating  oils  Machine  bearings  Rotary  engines  Torque  measurement  Turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Metal mesh foil bearings (MMFBs) are a promising low cost gas bearing technology for high performance oil-free microturbomachinery. Elimination of complex oil lubrication and sealing system by deploying MMFBs in rotorcraft gas turbine engines offers distinctive advantages such as reduced system weight, enhanced reliability at high rotational speeds and extreme temperatures, and extended maintenance intervals compared with mineral oil lubricated bearings. MMFBs for oil-free rotorcraft engines must demonstrate adequate load capacity, reliable rotordynamic performance, and low frictional losses in a high temperature environment. The paper presents the measurements of MMFB break-away torque, rotor lift-off and touchdown speeds, and temperature at increasing static load conditions. The tests, which were conducted in a test rig driven by an automotive turbocharger turbine, demonstrate the airborne operation (hydrodynamic gas film) of the floating test MMFB with little frictional loses at increasing loads. The measured drag torque peaks when the rotor starts and stops, and drops significantly once the bearing lifts off. The estimated rotor speed for lift-off increases linearly with the applied static load. During continuous operation, the MMFB temperature measured at the back surface of the top foil increases both with rotor speed and static load. Nonetheless, the temperature rise is mild, demonstrating reliable performance. Application of a sacrificial layer of solid lubricant on the top foil surface reduces the rotor break-away torque. The measurements give confidence on this simple bearing technology for ready application into oil-free turbomachinery. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Predicted rotordynamic behavior of a labyrinth seal as rotor surface speed approaches mach 1 / Manish R. Thorat in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 08 p. Titre : Predicted rotordynamic behavior of a labyrinth seal as rotor surface speed approaches mach 1 Type de document : texte imprimé Auteurs : Manish R. Thorat, Auteur ; Childs, Dara W., Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerodynamics  Damping  Elastic  constants  Flow  instability  Mach  number  Rotors  Sealing  materials  Transfer  functions Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Prior one-control-volume (1CV) models for rotor-fluid interaction in labyrinth seals produce synchronously reduced (at running speed), frequency-independent stiffness and damping coefficients. The 1CV model, consisting of a leakage equation, a continuity equation, and a circumferential-momentum equation (for each cavity), was stated to be invalid for rotor surface speeds approaching the speed of sound. However, the present results show that while the 1CV fluid-mechanic model continues to be valid, the calculated rotordynamic coefficients become strongly dependent on the rotor's precession frequency. A solution is developed for the reaction-force components for a range of precession frequencies, producing frequency-dependent stiffness and damping coefficients. They can be used to define a Laplace-domain transfer-function model for the reaction-force/rotor-motion components. Calculated results are presented for a simple Jeffcott rotor model acted on by a labyrinth seal. The model's undamped natural frequency is 7.6 krpm. The fluid properties, seal radius Rs, and running speed omega cause the rotor surface velocity Rsomega to equal the speed of sound c0 at omega=58 krpm. Calculated synchronous-response results due to imbalance coincide for the synchronously reduced and the frequency-dependent models. For an inlet preswirl ratio of 0.5, both models predict the same log-dec out to omega[approximate]14.5 krpm. The synchronously reduced model predicts an onset speed of instability (OSI) at 10 krpm, but a return to stability at 48 krpm, with subsequent increases in log-dec out to 70 krpm. The frequency-dependent model predicts an OSI of 10 krpm and no return to stability out to 70 krpm. The frequency-dependent models predict small changes in the rotor's damped natural frequencies. The synchronously reduced model predicts large changes. The stability-analysis results show that a frequency-dependent labyrinth seal model should be used if the rotor surface speed approaches a significant fraction of the speed of sound. For the present example, observable discrepancies arose when Rsomega=0.26c0. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Predicted rotordynamic behavior of a labyrinth seal as rotor surface speed approaches mach 1 [texte imprimé] / Manish R. Thorat, Auteur ; Childs, Dara W., Auteur . - 2011 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 08 p. Mots-clés : Aerodynamics  Damping  Elastic  constants  Flow  instability  Mach  number  Rotors  Sealing  materials  Transfer  functions Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Prior one-control-volume (1CV) models for rotor-fluid interaction in labyrinth seals produce synchronously reduced (at running speed), frequency-independent stiffness and damping coefficients. The 1CV model, consisting of a leakage equation, a continuity equation, and a circumferential-momentum equation (for each cavity), was stated to be invalid for rotor surface speeds approaching the speed of sound. However, the present results show that while the 1CV fluid-mechanic model continues to be valid, the calculated rotordynamic coefficients become strongly dependent on the rotor's precession frequency. A solution is developed for the reaction-force components for a range of precession frequencies, producing frequency-dependent stiffness and damping coefficients. They can be used to define a Laplace-domain transfer-function model for the reaction-force/rotor-motion components. Calculated results are presented for a simple Jeffcott rotor model acted on by a labyrinth seal. The model's undamped natural frequency is 7.6 krpm. The fluid properties, seal radius Rs, and running speed omega cause the rotor surface velocity Rsomega to equal the speed of sound c0 at omega=58 krpm. Calculated synchronous-response results due to imbalance coincide for the synchronously reduced and the frequency-dependent models. For an inlet preswirl ratio of 0.5, both models predict the same log-dec out to omega[approximate]14.5 krpm. The synchronously reduced model predicts an onset speed of instability (OSI) at 10 krpm, but a return to stability at 48 krpm, with subsequent increases in log-dec out to 70 krpm. The frequency-dependent model predicts an OSI of 10 krpm and no return to stability out to 70 krpm. The frequency-dependent models predict small changes in the rotor's damped natural frequencies. The synchronously reduced model predicts large changes. The stability-analysis results show that a frequency-dependent labyrinth seal model should be used if the rotor surface speed approaches a significant fraction of the speed of sound. For the present example, observable discrepancies arose when Rsomega=0.26c0. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

A comprehensive procedure to estimate the probability of extreme vibration levels due to mistuning / Y.-J. Chan in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 08 p. Titre : A comprehensive procedure to estimate the probability of extreme vibration levels due to mistuning Type de document : texte imprimé Auteurs : Y.-J. Chan, Auteur ; D. J. Ewins, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Blades  Conjugate  gradient  methods  Curve  fitting  Gas  turbines  Monte  Carlo  methods  Vibration  measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A new procedure is developed to find the probabilities of extremely high amplification factors in mistuned bladed disk vibration levels, typical of events which occur rarely. While a rough estimate can be made by curve-fitting the distribution function generated in a Monte Carlo simulation, the procedure presented here can determine a much more accurate upper bound and the probabilities of amplification factors near to that bound. The procedure comprises an optimization analysis based on the conjugate gradient method and a stochastic simulation using the importance sampling method. Two examples are provided to illustrate the efficiency of the procedure, which can be 2 or 3 orders of magnitude more efficient than Monte Carlo simulations. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] A comprehensive procedure to estimate the probability of extreme vibration levels due to mistuning [texte imprimé] / Y.-J. Chan, Auteur ; D. J. Ewins, Auteur . - 2011 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 08 p. Mots-clés : Blades  Conjugate  gradient  methods  Curve  fitting  Gas  turbines  Monte  Carlo  methods  Vibration  measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A new procedure is developed to find the probabilities of extremely high amplification factors in mistuned bladed disk vibration levels, typical of events which occur rarely. While a rough estimate can be made by curve-fitting the distribution function generated in a Monte Carlo simulation, the procedure presented here can determine a much more accurate upper bound and the probabilities of amplification factors near to that bound. The procedure comprises an optimization analysis based on the conjugate gradient method and a stochastic simulation using the importance sampling method. Two examples are provided to illustrate the efficiency of the procedure, which can be 2 or 3 orders of magnitude more efficient than Monte Carlo simulations. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Effect of exhaust gas temperature limits on the peak power performance of a turbocharged gasoline engine / Amey Y. Karnik in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 07 p. Titre : Effect of exhaust gas temperature limits on the peak power performance of a turbocharged gasoline engine Type de document : texte imprimé Auteurs : Amey Y. Karnik, Auteur ; Michael H. Shelby, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerodynamics  Combustion  Compressors  Electric  breakdown  Gas  turbines  Internal  combustion  engines  Petroleum Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Peak power of an engine is typically constrained by the maximum obtainable airflow. This constraint could arise directly from the airflow limitation imposed by the throttle restriction (typical for a naturally aspirated engine), or indirectly from other factors, such as various temperature limits for component protection. In this work, we evaluate the airflow limit for a turbocharged gasoline engine as dictated by the constraints on the turbine inlet temperature. Increasing the limit on the turbine inlet temperature requires the exhaust manifolds and turbine to be made out of more expensive materials that withstand higher temperatures. This expense is justifiable if operating with higher turbine inlet temperature allows noticeably higher power output, and not merely increases the allowable airflow. Experimental data show that under some conditions the increase in airflow does not increase the peak power. The effects of increasing airflow on the peak power and turbine inlet temperatures are systematically analyzed through individual accounting for the different losses affecting the engine torque. The breakdown analysis presented in this work indicates combustion phasing as a major contributing factor to whether increasing the flange temperature limit would increase the peak power. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Effect of exhaust gas temperature limits on the peak power performance of a turbocharged gasoline engine [texte imprimé] / Amey Y. Karnik, Auteur ; Michael H. Shelby, Auteur . - 2011 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 07 p. Mots-clés : Aerodynamics  Combustion  Compressors  Electric  breakdown  Gas  turbines  Internal  combustion  engines  Petroleum Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Peak power of an engine is typically constrained by the maximum obtainable airflow. This constraint could arise directly from the airflow limitation imposed by the throttle restriction (typical for a naturally aspirated engine), or indirectly from other factors, such as various temperature limits for component protection. In this work, we evaluate the airflow limit for a turbocharged gasoline engine as dictated by the constraints on the turbine inlet temperature. Increasing the limit on the turbine inlet temperature requires the exhaust manifolds and turbine to be made out of more expensive materials that withstand higher temperatures. This expense is justifiable if operating with higher turbine inlet temperature allows noticeably higher power output, and not merely increases the allowable airflow. Experimental data show that under some conditions the increase in airflow does not increase the peak power. The effects of increasing airflow on the peak power and turbine inlet temperatures are systematically analyzed through individual accounting for the different losses affecting the engine torque. The breakdown analysis presented in this work indicates combustion phasing as a major contributing factor to whether increasing the flange temperature limit would increase the peak power. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Effects of B20 on emissions and the performance of a diesel particulate filter in a light-duty diesel engine / Amy M. Peterson in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 08 p. Titre : Effects of B20 on emissions and the performance of a diesel particulate filter in a light-duty diesel engine Type de document : texte imprimé Auteurs : Amy M. Peterson, Auteur ; Po-I Lee, Auteur ; Ming-Chia Lai, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Biofuel  Catalysts  Diesel  engines  Fourier  transform  spectroscopy  Infrared  spectroscopy  Nitrogen  compounds  Organic  compounds  Viscosity  measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper compares 20% biodiesel (B20-choice white grease) fuel with baseline ultra low sulfur diesel (ULSD) fuel on the emissions and performance of a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) coupled to a light duty four-cylinder 2.8-l common-rail DI diesel engine. The present paper focuses on the comparison of the fuel effects on loading and active regeneration of the DPF between B20 and ULSD. B20, in general, produces less soot and has lower regeneration temperature, compared with soot loaded with ULSD. NO2 concentrations before the DPF were found to be 6% higher with B20, indicating more availability of NO2 to oxidize the soot. Exhaust speciation of the NO2 availability indicates that the slight increase in NOx from B20 is not the dominant cause for the lower temperature regeneration and faster regeneration rate, but the reactivity of the soot that is in the DPF. Formaldehyde concentrations are found to be higher with B20 during regeneration, due to increased oxygen concentrations in the exhaust stream. Finally, the oil dilution effect due to post injection to actively regenerate the DPF is also investigated using a prototype oil sensor and Fourier transform infrared (FTIR) instrumentation. Utilizing an active regeneration strategy accentuates the possibility of fuel oil dilution of the engine oil. The onboard viscosity oil sensor used was in good agreement with the viscosity bench test and FTIR analysis, and provided oil viscosity measurement over the course of the project. The operation with B20 shows significant fuel dilution and needs to be monitored to prevent engine deterioration. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Effects of B20 on emissions and the performance of a diesel particulate filter in a light-duty diesel engine [texte imprimé] / Amy M. Peterson, Auteur ; Po-I Lee, Auteur ; Ming-Chia Lai, Auteur . - 2011 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 08 p. Mots-clés : Biofuel  Catalysts  Diesel  engines  Fourier  transform  spectroscopy  Infrared  spectroscopy  Nitrogen  compounds  Organic  compounds  Viscosity  measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper compares 20% biodiesel (B20-choice white grease) fuel with baseline ultra low sulfur diesel (ULSD) fuel on the emissions and performance of a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) coupled to a light duty four-cylinder 2.8-l common-rail DI diesel engine. The present paper focuses on the comparison of the fuel effects on loading and active regeneration of the DPF between B20 and ULSD. B20, in general, produces less soot and has lower regeneration temperature, compared with soot loaded with ULSD. NO2 concentrations before the DPF were found to be 6% higher with B20, indicating more availability of NO2 to oxidize the soot. Exhaust speciation of the NO2 availability indicates that the slight increase in NOx from B20 is not the dominant cause for the lower temperature regeneration and faster regeneration rate, but the reactivity of the soot that is in the DPF. Formaldehyde concentrations are found to be higher with B20 during regeneration, due to increased oxygen concentrations in the exhaust stream. Finally, the oil dilution effect due to post injection to actively regenerate the DPF is also investigated using a prototype oil sensor and Fourier transform infrared (FTIR) instrumentation. Utilizing an active regeneration strategy accentuates the possibility of fuel oil dilution of the engine oil. The onboard viscosity oil sensor used was in good agreement with the viscosity bench test and FTIR analysis, and provided oil viscosity measurement over the course of the project. The operation with B20 shows significant fuel dilution and needs to be monitored to prevent engine deterioration. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Investigation of hydrogen emissions in partially premixed diesel combustion / William F. Northrop in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 06 p. Titre : Investigation of hydrogen emissions in partially premixed diesel combustion Type de document : texte imprimé Auteurs : William F. Northrop, Auteur ; Lucas M. Vanderpool, Auteur ; Praveen V. Madathil, Auteur Année de publication : 2011 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Biofuel  Diesel  engines  Petroleum Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Partially premixed combustion strategies offer many advantages for compression ignition engines. One such advantage for those operating on diesel fuels is the simultaneous reduction in soot and NOx achievable over a wide range of equivalence ratios. Though often not measured in engine experiments, gaseous H2 is a byproduct of incomplete combustion and can be useful for the regeneration of aftertreatment devices. Correlations for the exhaust concentration of H2, mostly derived from experiments with homogeneous spark ignition engines, indicate that it is emitted either in proportion to CO directly or as a function of a pseudowater gas shift equilibrium constant. In this work, H2 is measured over a range of equivalence ratios in a multicylinder diesel engine operating in a partially premixed low temperature combustion (LTC) mode using both low sulfur diesel fuel and soy-based biodiesel. Biodiesel was found to have the same bulk gas emissions of major species including H2 over the range of equivalence ratio in LTC for a constant load and combustion phasing. It also was found that the experimental H2 concentration was near the value predicted by the equilibrium constant for equivalence ratios greater that 0.85 but was increasingly lower for leaner points. DEWEY : 620.1 ISSN : 0742-4795 En ligne : scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000011 [...] [article] Investigation of hydrogen emissions in partially premixed diesel combustion [texte imprimé] / William F. Northrop, Auteur ; Lucas M. Vanderpool, Auteur ; Praveen V. Madathil, Auteur . - 2011 . - 06 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 06 p. Mots-clés : Biofuel  Diesel  engines  Petroleum Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Partially premixed combustion strategies offer many advantages for compression ignition engines. One such advantage for those operating on diesel fuels is the simultaneous reduction in soot and NOx achievable over a wide range of equivalence ratios. Though often not measured in engine experiments, gaseous H2 is a byproduct of incomplete combustion and can be useful for the regeneration of aftertreatment devices. Correlations for the exhaust concentration of H2, mostly derived from experiments with homogeneous spark ignition engines, indicate that it is emitted either in proportion to CO directly or as a function of a pseudowater gas shift equilibrium constant. In this work, H2 is measured over a range of equivalence ratios in a multicylinder diesel engine operating in a partially premixed low temperature combustion (LTC) mode using both low sulfur diesel fuel and soy-based biodiesel. Biodiesel was found to have the same bulk gas emissions of major species including H2 over the range of equivalence ratio in LTC for a constant load and combustion phasing. It also was found that the experimental H2 concentration was near the value predicted by the equilibrium constant for equivalence ratios greater that 0.85 but was increasingly lower for leaner points. DEWEY : 620.1 ISSN : 0742-4795 En ligne : scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000011 [...]

Exhaust-stream and in-cylinder measurements and analysis of the soot emissions from a common rail diesel engine using two fuels / Patrick Kirchen in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 08 p. Titre : Exhaust-stream and in-cylinder measurements and analysis of the soot emissions from a common rail diesel engine using two fuels Type de document : texte imprimé Auteurs : Patrick Kirchen, Auteur ; Peter Obrecht, Auteur ; Konstantinos Boulouchos, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air  pollution  measurement  Combustion  Diesel  engines  Evaporation  Exhaust  systems  Petroleum  Soot Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The operation and emissions of a four cylinder, passenger car common-rail diesel engine operating with two different fuels was investigated on the basis of exhaust-stream and in-cylinder soot measurements, as well as a thermodynamic analysis of the combustion process. The two fuels considered were a standard diesel fuel and a synthetic diesel (fuel two) with a lower aromatic content, evaporation temperature, and cetane number than the standard diesel. The exhaust-stream soot emissions, measured using a filter smoke number system, as well as a photo-acoustic soot sensor (AVL Micro Soot Sensor), were lower with the second fuel throughout the entire engine operating map. To elucidate the cause of the reduced exhaust-stream soot emissions, the in-cylinder soot temperature and the KL factor (proportional to concentration) were measured using miniature, three-color pyrometers mounted in the glow plug bores. Using the maximum KL factor value to quantify the soot formation process, it was seen that for all operating points, less soot was formed in the combustion chamber using the second fuel. The oxidation of the soot, however, was not strongly influenced by the fuel, as the relative oxidized soot fraction was not significantly different for the two fuels. The reduced soot formation of fuel two was attributed to the lower aromatic content of the fuel. The soot cloud temperatures for operation with the two fuels were not seen differ significantly. Similar correlations between the cylinder-out soot emissions, characterized using the pyrometers, and the exhaust-stream soot emissions were seen for both fuels. The combustion process itself was only seen to differ between the two fuels to a much lesser degree than the soot formation process. The predominant differences were seen as higher maximum fuel conversion rates during premixed combustion at several operating points, when fuel two was used. This was attributed to the lower evaporation temperatures and longer ignition delays (characterized by the lower cetane number) leading to larger premixed combustion fractions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Exhaust-stream and in-cylinder measurements and analysis of the soot emissions from a common rail diesel engine using two fuels [texte imprimé] / Patrick Kirchen, Auteur ; Peter Obrecht, Auteur ; Konstantinos Boulouchos, Auteur . - 2011 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 08 p. Mots-clés : Air  pollution  measurement  Combustion  Diesel  engines  Evaporation  Exhaust  systems  Petroleum  Soot Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The operation and emissions of a four cylinder, passenger car common-rail diesel engine operating with two different fuels was investigated on the basis of exhaust-stream and in-cylinder soot measurements, as well as a thermodynamic analysis of the combustion process. The two fuels considered were a standard diesel fuel and a synthetic diesel (fuel two) with a lower aromatic content, evaporation temperature, and cetane number than the standard diesel. The exhaust-stream soot emissions, measured using a filter smoke number system, as well as a photo-acoustic soot sensor (AVL Micro Soot Sensor), were lower with the second fuel throughout the entire engine operating map. To elucidate the cause of the reduced exhaust-stream soot emissions, the in-cylinder soot temperature and the KL factor (proportional to concentration) were measured using miniature, three-color pyrometers mounted in the glow plug bores. Using the maximum KL factor value to quantify the soot formation process, it was seen that for all operating points, less soot was formed in the combustion chamber using the second fuel. The oxidation of the soot, however, was not strongly influenced by the fuel, as the relative oxidized soot fraction was not significantly different for the two fuels. The reduced soot formation of fuel two was attributed to the lower aromatic content of the fuel. The soot cloud temperatures for operation with the two fuels were not seen differ significantly. Similar correlations between the cylinder-out soot emissions, characterized using the pyrometers, and the exhaust-stream soot emissions were seen for both fuels. The combustion process itself was only seen to differ between the two fuels to a much lesser degree than the soot formation process. The predominant differences were seen as higher maximum fuel conversion rates during premixed combustion at several operating points, when fuel two was used. This was attributed to the lower evaporation temperatures and longer ignition delays (characterized by the lower cetane number) leading to larger premixed combustion fractions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Numerical prediction of void distribution in two-phase turbulent flow in a subchannel / Tsutomu Ikeno in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 07 p. Titre : Numerical prediction of void distribution in two-phase turbulent flow in a subchannel Type de document : texte imprimé Auteurs : Tsutomu Ikeno, Auteur ; Tatsuya Sasakawa, Auteur ; Isao Kataoka, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Atmospheric  turbulence  Boltzmann  equation  Finite  volume  methods  Fission  reactors  Numerical  analysis  Poisson  equation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Numerical simulation code for predicting void distribution in two-phase turbulent flow in a subchannel was developed. The purpose is to obtain a profile of void distribution in the subchannel. The result will be used for predicting a heat flux at departure from nucleate boiling in a rod-bundle for the pressurized water reactor (PWR). The fundamental equations were represented by a generalized transport equation and the transport equation was transformed onto the generalized coordinate system fitted to the rod surface and the symmetric lines in the subchannel. Using the finite-volume method the transport equation was discretized for the SIMPLE algorithm. The flow field and void fraction at the steady-state were calculated for different average void fractions. The computational result for atmospheric pressure condition was successfully compared with experimental data. Sensitivity analysis for the PWR condition was performed, and the result showed that the secondary flow slightly contributed to homogenizing the void distribution. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Numerical prediction of void distribution in two-phase turbulent flow in a subchannel [texte imprimé] / Tsutomu Ikeno, Auteur ; Tatsuya Sasakawa, Auteur ; Isao Kataoka, Auteur . - 2011 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 07 p. Mots-clés : Atmospheric  turbulence  Boltzmann  equation  Finite  volume  methods  Fission  reactors  Numerical  analysis  Poisson  equation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Numerical simulation code for predicting void distribution in two-phase turbulent flow in a subchannel was developed. The purpose is to obtain a profile of void distribution in the subchannel. The result will be used for predicting a heat flux at departure from nucleate boiling in a rod-bundle for the pressurized water reactor (PWR). The fundamental equations were represented by a generalized transport equation and the transport equation was transformed onto the generalized coordinate system fitted to the rod surface and the symmetric lines in the subchannel. Using the finite-volume method the transport equation was discretized for the SIMPLE algorithm. The flow field and void fraction at the steady-state were calculated for different average void fractions. The computational result for atmospheric pressure condition was successfully compared with experimental data. Sensitivity analysis for the PWR condition was performed, and the result showed that the secondary flow slightly contributed to homogenizing the void distribution. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

ASTEC, COCOSYS, and LIRIC interpretation of the iodine behavior in the large-scale THAI test iod-9 / G. Weber in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 12 p. Titre : ASTEC, COCOSYS, and LIRIC interpretation of the iodine behavior in the large-scale THAI test iod-9 Type de document : texte imprimé Auteurs : G. Weber, Auteur ; L. Bosland, Auteur ; F. Funke, Auteur Année de publication : 2011 Article en page(s) : 12 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Adsorption  Desorption  Fission  reactor  accidents  Fission  reactor  kinetics  Iodine  Transport  processes Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The large-scale iodine test Iod-9 of the German Thermal hydraulics, Hydrogen, Aerosols, Iodine (THAI) program was jointly interpreted by means of post-test analyses within the THAI Circle of the Severe Accident Research NETwork (SARNET)/Work Package 16. In this test, molecular iodine (I2) was injected into the vessel dome of the 60 m3 THAI vessel to observe the evolution of its distribution between water, gas, and surfaces. The main processes addressed in Iod-9 are (a) the mass transfer of I2 between the gas and the two sumps, (b) the iodine transport in the main sump when it is stratified and then mixed, and (c) the I2 adsorption onto, and desorption from, the vessel walls in the presence and absence of wall condensation. The codes applied by the THAI Circle partners were the Accident Source Term Evaluation Code (ASTEC)-IODE (IRSN, Saint Paul Lez Durance, France), Containment Code System (COCOSYS)-Advanced Iodine Model (AIM) (GRS, Garching, Germany), and Library of Iodine Reactions in Containment (LIRIC; AECL, Chalk River, ON, Canada). ASTEC-IODE and the Advanced Iodine Model (AIM) are semi-empirical iodine models integrated in the lumped-parameter codes ASTEC and COCOSYS, respectively. With both codes multicompartment iodine calculations can be performed. LIRIC is a mechanistic iodine model for single stand-alone calculations. The simulation results are compared with each other and with the experimental measurements. Special issues that were encountered during this work were studied in more details: I2 diffusion in the sump water, I2 reaction with the steel of the vessel wall in gaseous and aqueous phases, and I2 mass transfer from the gas to the sump. Iodine transport and behavior in THAI test Iod-9 are fairly well simulated by ASTEC-IODE, COCOSYS-AIM, and LIRIC in post-test calculations. The measured iodine behavior is well understood and all measured data are found to be consistent. The very slow iodine transport within the stratified main sump was simulated with COCOSYS only, in a qualitative way. Consequently, this work highlighted the need to improve modeling of (a) the wet iodine adsorption and the washdown from the walls, (b) the I2 mass transfer between gas and sump, and (c) the I2/steel reaction in the gaseous and aqueous phases. In any case, the analysis of the large-scale iodine test Iod-9 has been an important validation step for the codes applied. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] ASTEC, COCOSYS, and LIRIC interpretation of the iodine behavior in the large-scale THAI test iod-9 [texte imprimé] / G. Weber, Auteur ; L. Bosland, Auteur ; F. Funke, Auteur . - 2011 . - 12 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 12 p. Mots-clés : Adsorption  Desorption  Fission  reactor  accidents  Fission  reactor  kinetics  Iodine  Transport  processes Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The large-scale iodine test Iod-9 of the German Thermal hydraulics, Hydrogen, Aerosols, Iodine (THAI) program was jointly interpreted by means of post-test analyses within the THAI Circle of the Severe Accident Research NETwork (SARNET)/Work Package 16. In this test, molecular iodine (I2) was injected into the vessel dome of the 60 m3 THAI vessel to observe the evolution of its distribution between water, gas, and surfaces. The main processes addressed in Iod-9 are (a) the mass transfer of I2 between the gas and the two sumps, (b) the iodine transport in the main sump when it is stratified and then mixed, and (c) the I2 adsorption onto, and desorption from, the vessel walls in the presence and absence of wall condensation. The codes applied by the THAI Circle partners were the Accident Source Term Evaluation Code (ASTEC)-IODE (IRSN, Saint Paul Lez Durance, France), Containment Code System (COCOSYS)-Advanced Iodine Model (AIM) (GRS, Garching, Germany), and Library of Iodine Reactions in Containment (LIRIC; AECL, Chalk River, ON, Canada). ASTEC-IODE and the Advanced Iodine Model (AIM) are semi-empirical iodine models integrated in the lumped-parameter codes ASTEC and COCOSYS, respectively. With both codes multicompartment iodine calculations can be performed. LIRIC is a mechanistic iodine model for single stand-alone calculations. The simulation results are compared with each other and with the experimental measurements. Special issues that were encountered during this work were studied in more details: I2 diffusion in the sump water, I2 reaction with the steel of the vessel wall in gaseous and aqueous phases, and I2 mass transfer from the gas to the sump. Iodine transport and behavior in THAI test Iod-9 are fairly well simulated by ASTEC-IODE, COCOSYS-AIM, and LIRIC in post-test calculations. The measured iodine behavior is well understood and all measured data are found to be consistent. The very slow iodine transport within the stratified main sump was simulated with COCOSYS only, in a qualitative way. Consequently, this work highlighted the need to improve modeling of (a) the wet iodine adsorption and the washdown from the walls, (b) the I2 mass transfer between gas and sump, and (c) the I2/steel reaction in the gaseous and aqueous phases. In any case, the analysis of the large-scale iodine test Iod-9 has been an important validation step for the codes applied. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Assessment of the spent life fraction of gas turbine blades by coating life modeling and photostimulated luminescence piezospectroscopy / C. Rinaldi in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 04 p. Titre : Assessment of the spent life fraction of gas turbine blades by coating life modeling and photostimulated luminescence piezospectroscopy Type de document : texte imprimé Auteurs : C. Rinaldi, Auteur ; L. De Maria, Auteur ; M. Mandelli, Auteur Année de publication : 2011 Article en page(s) : 04 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Blades  Gas  turbines  Inverse  problems  Nondestructive  testing  Remaining  life  assessment  Thermal  barrier  coatings Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper describes the application of a double-sided approach to assess the spent life fraction of thermal barrier coatings (TBCs) at local positions of ex-service blades with NiCoCrAlY-Re bond coat and EB-PVD TBC. A life prediction code implemented with inverse problem solution routines was applied to determine the mean local temperature. On the single blade, large differences (>150°C) of mean local temperature were estimated between regions just after the cooling holes and far from them. A self-developed portable photostimulated luminescence piezospectroscopy (PLPS) instrument was also applied and the coating spent life fraction was evaluated with a recently proposed PLPS diagnostic parameter. The spent life fractions evaluated from mean local temperature values were in good agreement with those estimated from PLPS measurements. Lower spent life fractions were found in well cooled regions of all blades, while higher spent life fractions were calculated at the hottest positions of the blades, particularly on components coming from a plant with a double number of starts. The results confirm the reliability of the PLPS technique and its diagnostic capability also for NiCoCrAlY-Re bond coats; both local differences on the single component and blade-to-blade variations in coating spent life can be evidenced in a nondestructive way. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Assessment of the spent life fraction of gas turbine blades by coating life modeling and photostimulated luminescence piezospectroscopy [texte imprimé] / C. Rinaldi, Auteur ; L. De Maria, Auteur ; M. Mandelli, Auteur . - 2011 . - 04 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 04 p. Mots-clés : Blades  Gas  turbines  Inverse  problems  Nondestructive  testing  Remaining  life  assessment  Thermal  barrier  coatings Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper describes the application of a double-sided approach to assess the spent life fraction of thermal barrier coatings (TBCs) at local positions of ex-service blades with NiCoCrAlY-Re bond coat and EB-PVD TBC. A life prediction code implemented with inverse problem solution routines was applied to determine the mean local temperature. On the single blade, large differences (>150°C) of mean local temperature were estimated between regions just after the cooling holes and far from them. A self-developed portable photostimulated luminescence piezospectroscopy (PLPS) instrument was also applied and the coating spent life fraction was evaluated with a recently proposed PLPS diagnostic parameter. The spent life fractions evaluated from mean local temperature values were in good agreement with those estimated from PLPS measurements. Lower spent life fractions were found in well cooled regions of all blades, while higher spent life fractions were calculated at the hottest positions of the blades, particularly on components coming from a plant with a double number of starts. The results confirm the reliability of the PLPS technique and its diagnostic capability also for NiCoCrAlY-Re bond coats; both local differences on the single component and blade-to-blade variations in coating spent life can be evidenced in a nondestructive way. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Numerical simulation of the performance of a sudden expansion with fence viewed as a diffuser in low reynolds number regime / S. Chakrabarti in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 04 p. Titre : Numerical simulation of the performance of a sudden expansion with fence viewed as a diffuser in low reynolds number regime Type de document : texte imprimé Auteurs : S. Chakrabarti, Auteur ; S. Rao, Auteur ; D. K. Mandal, Auteur Année de publication : 2011 Article en page(s) : 04 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Differential  equations  Diffusion  Laminar  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this paper, the results of numerical simulation on the performance of a sudden expansion with fence viewed as a diffuser are presented. The two-dimensional steady differential equations for conservation of mass and momentum have been solved using the semi-implicit method for pressure-linked equations (SIMPLE) algorithm. The Reynolds number is in the range of 20–100 and fence subtended angle (FSA) between 10 deg and 30 deg. An aspect ratio of 2 is fixed for all the computations. The effect of each variable on average static pressure and diffuser effectiveness has been studied. Computations have revealed that for higher Reynolds number, the use of a fence always increases the effectiveness of the diffusion process when compared with a simple sudden expansion configuration. In low Reynolds number regime, depending on the positioning of the fence and the fence subtended angle, the fence may increase or decrease the diffuser effectiveness in comparison with sudden expansion without fence. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Numerical simulation of the performance of a sudden expansion with fence viewed as a diffuser in low reynolds number regime [texte imprimé] / S. Chakrabarti, Auteur ; S. Rao, Auteur ; D. K. Mandal, Auteur . - 2011 . - 04 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 04 p. Mots-clés : Differential  equations  Diffusion  Laminar  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this paper, the results of numerical simulation on the performance of a sudden expansion with fence viewed as a diffuser are presented. The two-dimensional steady differential equations for conservation of mass and momentum have been solved using the semi-implicit method for pressure-linked equations (SIMPLE) algorithm. The Reynolds number is in the range of 20–100 and fence subtended angle (FSA) between 10 deg and 30 deg. An aspect ratio of 2 is fixed for all the computations. The effect of each variable on average static pressure and diffuser effectiveness has been studied. Computations have revealed that for higher Reynolds number, the use of a fence always increases the effectiveness of the diffusion process when compared with a simple sudden expansion configuration. In low Reynolds number regime, depending on the positioning of the fence and the fence subtended angle, the fence may increase or decrease the diffuser effectiveness in comparison with sudden expansion without fence. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Design and analysis of an intercooled turbofan engine / Lei Xu in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 04 p. Titre : Design and analysis of an intercooled turbofan engine Type de document : texte imprimé Auteurs : Lei Xu, Auteur ; Tomas Grönstedt, Auteur Année de publication : 2011 Article en page(s) : 04 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Compressors  Design  engineering  Heat  transfer  Jet  engines  Optimisation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The performance of an intercooled turbofan engine is analyzed by multidisciplinary optimization. A model for making preliminary simplified analysis of the mechanical design of the engine is coupled to an aircraft model and an engine performance model. A conventional turbofan engine with technology representative for a year 2013 entry of service is compared with a corresponding intercooled engine. A mission fuel burn reduction of 3.4% is observed. The results are analyzed in terms of the relevant constraints such as compressor exit temperature, turbine entry temperature, turbine rotor blade temperature, and compressor exit blade height. It is shown that the gas path of an intercooled engine for medium range commercial transport applications, having an overall pressure ratio greater than 70 in top of climb, may still be optimized to fulfill a compressor exit blade height constraint. This indicates that a state of the art high pressure compressor efficiency can be achieved. Empirical data and a parametric computational fluid dynamics (CFD) study are used to verify the intercooler heat transfer and pressure loss characteristics. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Design and analysis of an intercooled turbofan engine [texte imprimé] / Lei Xu, Auteur ; Tomas Grönstedt, Auteur . - 2011 . - 04 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 04 p. Mots-clés : Compressors  Design  engineering  Heat  transfer  Jet  engines  Optimisation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The performance of an intercooled turbofan engine is analyzed by multidisciplinary optimization. A model for making preliminary simplified analysis of the mechanical design of the engine is coupled to an aircraft model and an engine performance model. A conventional turbofan engine with technology representative for a year 2013 entry of service is compared with a corresponding intercooled engine. A mission fuel burn reduction of 3.4% is observed. The results are analyzed in terms of the relevant constraints such as compressor exit temperature, turbine entry temperature, turbine rotor blade temperature, and compressor exit blade height. It is shown that the gas path of an intercooled engine for medium range commercial transport applications, having an overall pressure ratio greater than 70 in top of climb, may still be optimized to fulfill a compressor exit blade height constraint. This indicates that a state of the art high pressure compressor efficiency can be achieved. Empirical data and a parametric computational fluid dynamics (CFD) study are used to verify the intercooler heat transfer and pressure loss characteristics. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Hydrogen peroxide-based gas generator design and performance testing as an aircraft emergency power unit / Gyaebyung Yang in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 06 p. Titre : Hydrogen peroxide-based gas generator design and performance testing as an aircraft emergency power unit Type de document : texte imprimé Auteurs : Gyaebyung Yang, Auteur ; Daejong Park, Auteur ; Chun Taek Kim, Auteur Année de publication : 2011 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  propulsion  Aircraft  power  systems  Catalysts  Emergency  power  supply  Hydrogen  compounds Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Hydrazine monopropellant is often used with a spontaneous catalyst a high-performance aircraft emergency power unit (EPU) and in aerospace propulsion; however, it is toxic and requires special handling. A hydrogen peroxide (H2O2)-based gas generator, which is suitable for a new family of environmentally friendly monopropellants and is a substitute for toxic hydrazine in EPUs, is introduced in this study. A MnO2/Al2O3 catalyst for H2O2 decomposition, superior to silver catalysts at normal starting and reactivity capabilities, was selected and developed. The performance tests of coupling the gas generator with a turbocharger showed acceptable results for an aircraft EPU with decomposition above 90%, 37 kW maximum turbine output power, and a maximum starting delay of 1.2 s during normal starting operation. The gas generator also demonstrated satisfactory performance during repeated pulse operation at a pulse duration of 3 s and 60 s under various output conditions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Hydrogen peroxide-based gas generator design and performance testing as an aircraft emergency power unit [texte imprimé] / Gyaebyung Yang, Auteur ; Daejong Park, Auteur ; Chun Taek Kim, Auteur . - 2011 . - 06 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 06 p. Mots-clés : Aerospace  propulsion  Aircraft  power  systems  Catalysts  Emergency  power  supply  Hydrogen  compounds Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Hydrazine monopropellant is often used with a spontaneous catalyst a high-performance aircraft emergency power unit (EPU) and in aerospace propulsion; however, it is toxic and requires special handling. A hydrogen peroxide (H2O2)-based gas generator, which is suitable for a new family of environmentally friendly monopropellants and is a substitute for toxic hydrazine in EPUs, is introduced in this study. A MnO2/Al2O3 catalyst for H2O2 decomposition, superior to silver catalysts at normal starting and reactivity capabilities, was selected and developed. The performance tests of coupling the gas generator with a turbocharger showed acceptable results for an aircraft EPU with decomposition above 90%, 37 kW maximum turbine output power, and a maximum starting delay of 1.2 s during normal starting operation. The gas generator also demonstrated satisfactory performance during repeated pulse operation at a pulse duration of 3 s and 60 s under various output conditions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Gas turbine combustion / Arthur H. Lefebvre in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 11 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 01 p. Titre : Gas turbine combustion : alternative fuels and emissions Type de document : texte imprimé Auteurs : Arthur H. Lefebvre, Auteur ; Ballal, Dilip R., Auteur ; Donald W. Bahr, Auteur Année de publication : 2011 Article en page(s) : 01 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Biofuel  Combustion  Gas  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Gas turbine combustion : alternative fuels and emissions [texte imprimé] / Arthur H. Lefebvre, Auteur ; Ballal, Dilip R., Auteur ; Donald W. Bahr, Auteur . - 2011 . - 01 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 11 (Novembre 2010) . - 01 p. Mots-clés : Biofuel  Combustion  Gas  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

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