Dépouillements

A new kind of multifunctional energy system based on moderate conversion of chemical energy of fossil fuels / Wei Han in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 08 p. Titre : A new kind of multifunctional energy system based on moderate conversion of chemical energy of fossil fuels Type de document : texte imprimé Auteurs : Wei Han, Auteur ; HongGuang Jin, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Chemical  energy  conversion  Fossil  fuels  Natural  gas  technology Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper proposes a new kind of multifunctional energy system (MES) using natural gas and coal to more efficiently and more economically produce methanol and power. Traditional chemical processes pursue high conversion ratios of chemical energy of fuels. The new MES focuses on the moderate conversion of the chemical energy of fuels. To do this, about 50% of the coal is partially gasified with pure oxygen and steam as oxidant, and then the unconverted residuals (char) and natural gas are utilized synthetically by char-fired reforming to generate syngas. The combustion of char drives the methane/steam-reforming reaction. Here, the reforming reaction is also moderately converted, and the reforming temperature is decreased 100–150°C compared with that of the conventional method. The carbon-rich syngas from the partial gasifier of coal and hydrogen-rich syngas from char-fired reformer are mixed together and converted into methanol at a proper conversion ratio (lower than that of the conventional chemical process). Finally, the unconverted syngas is used in a combined cycle as fuel for power generation. As a result, the total exergy efficiency of the new system is 55–60%. Comparing to individual systems, including the integrated gasification combined cycle and the natural gas-based methanol synthesis plants, this new system can generate 10–20% more electricity with the same quantity of fossil fuel input and methanol output. In addition, the possibility of reducing the size of gasifier, reformer, and methanol synthesis reactor may reduce investment costs accordingly. These results may provide a new way to use coal and natural gas more efficiently and economically. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] A new kind of multifunctional energy system based on moderate conversion of chemical energy of fossil fuels [texte imprimé] / Wei Han, Auteur ; HongGuang Jin, 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° 5 (Mai 2010) . - 08 p. Mots-clés : Chemical  energy  conversion  Fossil  fuels  Natural  gas  technology Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper proposes a new kind of multifunctional energy system (MES) using natural gas and coal to more efficiently and more economically produce methanol and power. Traditional chemical processes pursue high conversion ratios of chemical energy of fuels. The new MES focuses on the moderate conversion of the chemical energy of fuels. To do this, about 50% of the coal is partially gasified with pure oxygen and steam as oxidant, and then the unconverted residuals (char) and natural gas are utilized synthetically by char-fired reforming to generate syngas. The combustion of char drives the methane/steam-reforming reaction. Here, the reforming reaction is also moderately converted, and the reforming temperature is decreased 100–150°C compared with that of the conventional method. The carbon-rich syngas from the partial gasifier of coal and hydrogen-rich syngas from char-fired reformer are mixed together and converted into methanol at a proper conversion ratio (lower than that of the conventional chemical process). Finally, the unconverted syngas is used in a combined cycle as fuel for power generation. As a result, the total exergy efficiency of the new system is 55–60%. Comparing to individual systems, including the integrated gasification combined cycle and the natural gas-based methanol synthesis plants, this new system can generate 10–20% more electricity with the same quantity of fossil fuel input and methanol output. In addition, the possibility of reducing the size of gasifier, reformer, and methanol synthesis reactor may reduce investment costs accordingly. These results may provide a new way to use coal and natural gas more efficiently and economically. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Effects of a reacting cross-stream on turbine film cooling / Wesly S. Anderson in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 07 p. Titre : Effects of a reacting cross-stream on turbine film cooling Type de document : texte imprimé Auteurs : Wesly S. Anderson, Auteur ; Marc D. Polanka, Auteur ; Joseph Zelina, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Blades  Coolants  Cooling  Engines  Gas  turbines  Heat  transfer  Plates  (structures)  Thermal  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Film cooling plays a critical role in providing effective thermal protection to components in modern gas turbine engines. A significant effort has been undertaken over the last 40 years to improve the distribution of coolant and to ensure that the airfoil is protected by this coolant from the hot gases in the freestream. This film, under conditions with high fuel-air ratios, may actually be detrimental to the underlying metal. The presence of unburned fuel from an upstream combustor may interact with this oxygen rich film coolant jet resulting in secondary combustion. The completion of the reactions can increase the gas temperature locally resulting in higher heat transfer to the airfoil directly along the path line of the film coolant jet. This secondary combustion could damage the turbine blade, resulting in costly repair, reduction in turbine life, or even engine failure. However, knowledge of film cooling in a reactive flow is very limited. The current study explores the interaction of cooling flow from typical cooling holes with the exhaust of a fuel-rich well-stirred reactor operating at high temperatures over a flat plate. Surface temperatures, heat flux, and heat transfer coefficients are calculated for a variety of reactor fuel-to-air ratios, cooling hole geometries, and blowing ratios. Emphasis is placed on the difference between a normal cylindrical hole, an inclined cylindrical hole, and a fan-shaped cooling hole. When both air and nitrogen are injected through the cooling holes, the changes in surface temperature can be directly correlated with the presence of the reaction. Photographs of the localized burning are presented to verify the extent and locations of the reaction. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Effects of a reacting cross-stream on turbine film cooling [texte imprimé] / Wesly S. Anderson, Auteur ; Marc D. Polanka, Auteur ; Joseph Zelina, 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° 5 (Mai 2010) . - 07 p. Mots-clés : Blades  Coolants  Cooling  Engines  Gas  turbines  Heat  transfer  Plates  (structures)  Thermal  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Film cooling plays a critical role in providing effective thermal protection to components in modern gas turbine engines. A significant effort has been undertaken over the last 40 years to improve the distribution of coolant and to ensure that the airfoil is protected by this coolant from the hot gases in the freestream. This film, under conditions with high fuel-air ratios, may actually be detrimental to the underlying metal. The presence of unburned fuel from an upstream combustor may interact with this oxygen rich film coolant jet resulting in secondary combustion. The completion of the reactions can increase the gas temperature locally resulting in higher heat transfer to the airfoil directly along the path line of the film coolant jet. This secondary combustion could damage the turbine blade, resulting in costly repair, reduction in turbine life, or even engine failure. However, knowledge of film cooling in a reactive flow is very limited. The current study explores the interaction of cooling flow from typical cooling holes with the exhaust of a fuel-rich well-stirred reactor operating at high temperatures over a flat plate. Surface temperatures, heat flux, and heat transfer coefficients are calculated for a variety of reactor fuel-to-air ratios, cooling hole geometries, and blowing ratios. Emphasis is placed on the difference between a normal cylindrical hole, an inclined cylindrical hole, and a fan-shaped cooling hole. When both air and nitrogen are injected through the cooling holes, the changes in surface temperature can be directly correlated with the presence of the reaction. Photographs of the localized burning are presented to verify the extent and locations of the reaction. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Ignition and oxidation of 50/50 butane isomer blends / Nicole Donato in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 09 p. Titre : Ignition and oxidation of 50/50 butane isomer blends Type de document : texte imprimé Auteurs : Nicole Donato, Auteur ; Christopher Aul, Auteur ; Eric Petersen, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Gas  turbines  Ignition Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : One of the alkanes found within gaseous fuel blends of interest to gas turbine applications is butane. There are two structural isomers of butane, normal butane and isobutane, and the combustion characteristics of either isomer are not well known. Of particular interest to this work are mixtures of n-butane and isobutane. A shock-tube experiment was performed to produce important ignition-delay-time data for these binary butane isomer mixtures, which are not currently well studied, with emphasis on 50-50 blends of the two isomers. These data represent the most extensive shock-tube results to date for mixtures of n-butane and isobutane. Ignition within the shock tube was determined from the sharp pressure rise measured at the end wall, which is characteristic of such exothermic reactions. Both experimental and kinetics modeling results are presented for a wide range of stoichiometries (phi=0.3−2.0), temperatures (1056–1598 K), and pressures (1–21 atm). The results of this work serve as a validation for the current chemical kinetics model. Correlations in the form of Arrhenius-type expressions are presented, which agree well with both the experimental results and the kinetics modeling. The results of an ignition-delay-time sensitivity analysis are provided, and key reactions are identified. The data from this study are compared with the modeling results of 100% normal butane and 100% isobutane. The 50/50 mixture of n-butane and isobutane was shown to be more readily ignitable than 100% isobutane but reacts slower than 100% n-butane only for the richer mixtures. There was little difference in ignition time between the lean mixtures. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Ignition and oxidation of 50/50 butane isomer blends [texte imprimé] / Nicole Donato, Auteur ; Christopher Aul, Auteur ; Eric Petersen, 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° 5 (Mai 2010) . - 09 p. Mots-clés : Combustion  Gas  turbines  Ignition Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : One of the alkanes found within gaseous fuel blends of interest to gas turbine applications is butane. There are two structural isomers of butane, normal butane and isobutane, and the combustion characteristics of either isomer are not well known. Of particular interest to this work are mixtures of n-butane and isobutane. A shock-tube experiment was performed to produce important ignition-delay-time data for these binary butane isomer mixtures, which are not currently well studied, with emphasis on 50-50 blends of the two isomers. These data represent the most extensive shock-tube results to date for mixtures of n-butane and isobutane. Ignition within the shock tube was determined from the sharp pressure rise measured at the end wall, which is characteristic of such exothermic reactions. Both experimental and kinetics modeling results are presented for a wide range of stoichiometries (phi=0.3−2.0), temperatures (1056–1598 K), and pressures (1–21 atm). The results of this work serve as a validation for the current chemical kinetics model. Correlations in the form of Arrhenius-type expressions are presented, which agree well with both the experimental results and the kinetics modeling. The results of an ignition-delay-time sensitivity analysis are provided, and key reactions are identified. The data from this study are compared with the modeling results of 100% normal butane and 100% isobutane. The 50/50 mixture of n-butane and isobutane was shown to be more readily ignitable than 100% isobutane but reacts slower than 100% n-butane only for the richer mixtures. There was little difference in ignition time between the lean mixtures. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Experimental analysis of the combustion behavior of a gas turbine burner by laser measurement techniques / Holger Ax in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 09 p. Titre : Experimental analysis of the combustion behavior of a gas turbine burner by laser measurement techniques Type de document : texte imprimé Auteurs : Holger Ax, Auteur ; Ulrich Stopper, Auteur ; Wolfgang Meier, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Flames  Gas  turbines  Measurement  by  laser  beam  Raman  spectra Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Experimental results from optical and laser spectroscopic measurements on a scaled industrial gas turbine burner at elevated pressure are presented. Planar laser induced fluorescence on the OH radical and OH* chemiluminescence imaging were applied to natural gas/air flames for a qualitative analysis of the position and shape of the flame brush, the flame front and the stabilization mechanism. The results exhibit two different ways of flame stabilization, a conical more stable flame and a pulsating opened flame. For quantitative results, one-dimensional laser Raman scattering was applied to these flames and evaluated on an average and single-shot basis in order to simultaneously determine the major species concentrations, the mixture fraction, and the temperature. The mixing of fuel and air, as well as the reaction progress, could thus be spatially and temporally resolved, showing differently strong variations depending on the flame stabilization mode and the location in the flame. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Experimental analysis of the combustion behavior of a gas turbine burner by laser measurement techniques [texte imprimé] / Holger Ax, Auteur ; Ulrich Stopper, Auteur ; Wolfgang Meier, 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° 5 (Mai 2010) . - 09 p. Mots-clés : Combustion  Flames  Gas  turbines  Measurement  by  laser  beam  Raman  spectra Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Experimental results from optical and laser spectroscopic measurements on a scaled industrial gas turbine burner at elevated pressure are presented. Planar laser induced fluorescence on the OH radical and OH* chemiluminescence imaging were applied to natural gas/air flames for a qualitative analysis of the position and shape of the flame brush, the flame front and the stabilization mechanism. The results exhibit two different ways of flame stabilization, a conical more stable flame and a pulsating opened flame. For quantitative results, one-dimensional laser Raman scattering was applied to these flames and evaluated on an average and single-shot basis in order to simultaneously determine the major species concentrations, the mixture fraction, and the temperature. The mixing of fuel and air, as well as the reaction progress, could thus be spatially and temporally resolved, showing differently strong variations depending on the flame stabilization mode and the location in the flame. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Hybrid wireless-wired optical sensor for extreme temperature measurement in next generation energy efficient gas turbines / Nabeel A. Riza in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 11 p. Titre : Hybrid wireless-wired optical sensor for extreme temperature measurement in next generation energy efficient gas turbines Type de document : texte imprimé Auteurs : Nabeel A. Riza, Auteur ; Mumtaz Sheikh, Auteur ; Frank Perez, Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Gas  turbine  power  stations  Optical  sensors  Silicon  compounds  Sintering  Temperature  sensors  Thermal  expansion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Accuracy, reliability, and long lifetimes are critical parameters for sensors measuring temperature in gas turbines of clean coal-fired power plants. Greener high efficiency next generation power plants need gas turbines operating at extremely high temperatures of 1500°C, where present thermocouple temperature probe technology fails to operate with reliable and accurate readings over long lifetimes. To solve this pressing problem, we have proposed the concept of a new hybrid class of all-silicon carbide (SiC) optical sensor, where a single crystal SiC optical chip is embedded in a sintered SiC tube assembly, forming a coefficient of thermal expansion (CTE) matched all-SiC front-end probe. Because chip and host material are CTE matched, optimal handling of extreme thermal ramps and temperatures is possible. In this article, we demonstrate the first successful industrial combustor rig test of this hybrid all-SiC temperature sensor front-end probe indicating demonstrated probe structural robustness to 1600°C and rig test data to ~1200°C. The design of the rig test sensor system is presented and data are analyzed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Hybrid wireless-wired optical sensor for extreme temperature measurement in next generation energy efficient gas turbines [texte imprimé] / Nabeel A. Riza, Auteur ; Mumtaz Sheikh, Auteur ; Frank Perez, 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° 5 (Mai 2010) . - 11 p. Mots-clés : Combustion  Gas  turbine  power  stations  Optical  sensors  Silicon  compounds  Sintering  Temperature  sensors  Thermal  expansion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Accuracy, reliability, and long lifetimes are critical parameters for sensors measuring temperature in gas turbines of clean coal-fired power plants. Greener high efficiency next generation power plants need gas turbines operating at extremely high temperatures of 1500°C, where present thermocouple temperature probe technology fails to operate with reliable and accurate readings over long lifetimes. To solve this pressing problem, we have proposed the concept of a new hybrid class of all-silicon carbide (SiC) optical sensor, where a single crystal SiC optical chip is embedded in a sintered SiC tube assembly, forming a coefficient of thermal expansion (CTE) matched all-SiC front-end probe. Because chip and host material are CTE matched, optimal handling of extreme thermal ramps and temperatures is possible. In this article, we demonstrate the first successful industrial combustor rig test of this hybrid all-SiC temperature sensor front-end probe indicating demonstrated probe structural robustness to 1600°C and rig test data to ~1200°C. The design of the rig test sensor system is presented and data are analyzed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Active compressor stability management via a stall margin control mode / Yuan Liu in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 10 p. Titre : Active compressor stability management via a stall margin control mode Type de document : texte imprimé Auteurs : Yuan Liu, Auteur ; Manuj Dhingra, Auteur ; J. V. R. Prasad, Auteur Année de publication : 2011 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  engines  Aircraft  control  Compressors  Gas  turbines  Stability Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An active engine control scheme for protection against compressor instabilities such as rotating stall and surge is presented. Compressor stability detection is accomplished via a parameter known as the correlation measure, which quantifies the repeatability of the pressure fluctuations in the tip region of a compressor rotor. This work investigates the integration of the correlation measure with an aircraft engine control system through the use of a stall margin control mode. The development and implementation of the stall margin mode are described. The effectiveness of the overall active control framework—an active compressor stability management system—is assessed using a computer simulation of a high-bypass, dual-spool, commercial-type turbofan engine. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Active compressor stability management via a stall margin control mode [texte imprimé] / Yuan Liu, Auteur ; Manuj Dhingra, Auteur ; J. V. R. Prasad, Auteur . - 2011 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 10 p. Mots-clés : Aerospace  engines  Aircraft  control  Compressors  Gas  turbines  Stability Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An active engine control scheme for protection against compressor instabilities such as rotating stall and surge is presented. Compressor stability detection is accomplished via a parameter known as the correlation measure, which quantifies the repeatability of the pressure fluctuations in the tip region of a compressor rotor. This work investigates the integration of the correlation measure with an aircraft engine control system through the use of a stall margin control mode. The development and implementation of the stall margin mode are described. The effectiveness of the overall active control framework—an active compressor stability management system—is assessed using a computer simulation of a high-bypass, dual-spool, commercial-type turbofan engine. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

New steel alloys for the design of heat recovery steam generator components of combined cycle gas plants / Jorge Pinto Fernandes in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 07 p. Titre : New steel alloys for the design of heat recovery steam generator components of combined cycle gas plants Type de document : texte imprimé Auteurs : Jorge Pinto Fernandes, Auteur ; Eduardo Manuel Dias Lopes, Auteur ; Vicente Maneta, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Alloy  steel  Boilers  Combined  cycle  power  stations  Finite  element  analysis  Heat  recovery  Martensitic  steel Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Demand for power is growing everyday, mainly due to emerging economies in countries such as China, Russia, India, and Brazil. During the last 50 years steam pressure and temperature in power plants have been continuously raised to improve thermal efficiency. Recent efforts to improve efficiency leads to the development of a new generation of heat recovery steam generator, where the Benson once-through technology is applied to improve the thermal efficiency. The main purpose of this paper is to analyze the mechanical behavior of a high pressure superheater manifold by applying finite element modeling and a finite element analysis with the objective of analyzing stress propagation, leading to the study of damage mechanism, e.g., uniaxial fatigue, uniaxial creep for life prediction. The objective of this paper is also to analyze the mechanical properties of the new high temperature resistant materials in the market such as 2Cr Bainitic steels (T/P23 and T/P24) and also the 9–12Cr Martensitic steels (T/P91, T/P92, E911, and P/T122). For this study the design rules for construction of power boilers to define the geometry of the HPSH manifold were applied. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] New steel alloys for the design of heat recovery steam generator components of combined cycle gas plants [texte imprimé] / Jorge Pinto Fernandes, Auteur ; Eduardo Manuel Dias Lopes, Auteur ; Vicente Maneta, 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° 5 (Mai 2010) . - 07 p. Mots-clés : Alloy  steel  Boilers  Combined  cycle  power  stations  Finite  element  analysis  Heat  recovery  Martensitic  steel Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Demand for power is growing everyday, mainly due to emerging economies in countries such as China, Russia, India, and Brazil. During the last 50 years steam pressure and temperature in power plants have been continuously raised to improve thermal efficiency. Recent efforts to improve efficiency leads to the development of a new generation of heat recovery steam generator, where the Benson once-through technology is applied to improve the thermal efficiency. The main purpose of this paper is to analyze the mechanical behavior of a high pressure superheater manifold by applying finite element modeling and a finite element analysis with the objective of analyzing stress propagation, leading to the study of damage mechanism, e.g., uniaxial fatigue, uniaxial creep for life prediction. The objective of this paper is also to analyze the mechanical properties of the new high temperature resistant materials in the market such as 2Cr Bainitic steels (T/P23 and T/P24) and also the 9–12Cr Martensitic steels (T/P91, T/P92, E911, and P/T122). For this study the design rules for construction of power boilers to define the geometry of the HPSH manifold were applied. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Computational design of corrosion-resistant Fe–Cr–Ni–Al nanocoatings for power generation / K. S. Chan in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 09 p. Titre : Computational design of corrosion-resistant Fe–Cr–Ni–Al nanocoatings for power generation Type de document : texte imprimé Auteurs : K. S. Chan, Auteur ; W. Liang, Auteur ; N. S. Cheruvu, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aluminium  compounds  Chromium  compounds  Corrosion  protective  coatings  Corrosion  resistance  Gas  turbines  Iron  compounds  Mechanical  engineering  computing  Nanostructured  materials  Nickel  compounds  Phase  diagrams  Steam  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A computational approach has been undertaken to design and assess potential Fe–Cr–Ni–Al systems to produce stable nanostructured corrosion-resistant coatings that form a protective, continuous scale of alumina or chromia at elevated temperatures. The phase diagram computation was modeled using the THERMO-CALC® software and database (Thermo-Calc® Software, 2007, THERMO-CALC for Windows Version 4, Thermo-Calc Software AB, Stockholm, Sweden; Thermo-Calc® Software, 2007, TCFE5, Version 5, Thermo-Calc Software AB, Stockholm, Sweden) to generate pseudoternary Fe–Cr–Ni–Al phase diagrams to help identify compositional ranges without the undesirable brittle phases. The computational modeling of the grain growth process, sintering of voids and interface toughness determination by indentation, assessed microstructural stability, and durability of the nanocoatings fabricated by a magnetron-sputtering process. Interdiffusion of Al, Cr, and Ni was performed using the DICTRA® diffusion code (Thermo-Calc Software®, DICTRA, Version 24, 2007, Version 25, 2008, Thermo-Calc Software AB, Stockholm, Sweden) to maximize the long-term stability of the nanocoatings. The computational results identified a new series of Fe–Cr–Ni–Al coatings that maintain long-term stability and a fine-grained microstructure at elevated temperatures. The formation of brittle sigma-phase in Fe–Cr–Ni–Al alloys is suppressed for Al contents in excess of 4 wt %. The grain growth modeling indicated that the columnar-grained structure with a high percentage of low-angle grain boundaries is resistant to grain growth. Sintering modeling indicated that the initial relative density of as-processed magnetron-sputtered coatings could achieve full density after a short thermal exposure or heat-treatment. The interface toughness computation indicated that the Fe–Cr–Ni–Al nanocoatings exhibit high interface toughness in the range of 52–366 J/m2. The interdiffusion modeling using the DICTRA software package indicated that inward diffusion could result in substantial to moderate Al and Cr losses from the nanocoating to the substrate during long-term thermal exposures. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Computational design of corrosion-resistant Fe–Cr–Ni–Al nanocoatings for power generation [texte imprimé] / K. S. Chan, Auteur ; W. Liang, Auteur ; N. S. Cheruvu, 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° 5 (Mai 2010) . - 09 p. Mots-clés : Aluminium  compounds  Chromium  compounds  Corrosion  protective  coatings  Corrosion  resistance  Gas  turbines  Iron  compounds  Mechanical  engineering  computing  Nanostructured  materials  Nickel  compounds  Phase  diagrams  Steam  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A computational approach has been undertaken to design and assess potential Fe–Cr–Ni–Al systems to produce stable nanostructured corrosion-resistant coatings that form a protective, continuous scale of alumina or chromia at elevated temperatures. The phase diagram computation was modeled using the THERMO-CALC® software and database (Thermo-Calc® Software, 2007, THERMO-CALC for Windows Version 4, Thermo-Calc Software AB, Stockholm, Sweden; Thermo-Calc® Software, 2007, TCFE5, Version 5, Thermo-Calc Software AB, Stockholm, Sweden) to generate pseudoternary Fe–Cr–Ni–Al phase diagrams to help identify compositional ranges without the undesirable brittle phases. The computational modeling of the grain growth process, sintering of voids and interface toughness determination by indentation, assessed microstructural stability, and durability of the nanocoatings fabricated by a magnetron-sputtering process. Interdiffusion of Al, Cr, and Ni was performed using the DICTRA® diffusion code (Thermo-Calc Software®, DICTRA, Version 24, 2007, Version 25, 2008, Thermo-Calc Software AB, Stockholm, Sweden) to maximize the long-term stability of the nanocoatings. The computational results identified a new series of Fe–Cr–Ni–Al coatings that maintain long-term stability and a fine-grained microstructure at elevated temperatures. The formation of brittle sigma-phase in Fe–Cr–Ni–Al alloys is suppressed for Al contents in excess of 4 wt %. The grain growth modeling indicated that the columnar-grained structure with a high percentage of low-angle grain boundaries is resistant to grain growth. Sintering modeling indicated that the initial relative density of as-processed magnetron-sputtered coatings could achieve full density after a short thermal exposure or heat-treatment. The interface toughness computation indicated that the Fe–Cr–Ni–Al nanocoatings exhibit high interface toughness in the range of 52–366 J/m2. The interdiffusion modeling using the DICTRA software package indicated that inward diffusion could result in substantial to moderate Al and Cr losses from the nanocoating to the substrate during long-term thermal exposures. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

A cyclic life prediction approach for directionally solidified nickel superalloys / Roland Mücke in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 07 p. Titre : A cyclic life prediction approach for directionally solidified nickel superalloys Type de document : texte imprimé Auteurs : Roland Mücke, Auteur ; Piyawan Woratat, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Blades  Creep  fracture  Fracture  toughness  Gas  turbines  Remaining  life  assessment  Superalloys Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The performance of heavy duty gas turbines is closely related to the material capability of the components of the first turbine stage. In modern gas turbines single crystal (SX) and directionally solidified (DS) nickel superalloys are applied, which, compared with their conventionally cast version, hold a higher cyclic life and a significantly improved creep rupture strength. SX and DS nickel superalloys feature a significant directional dependence of the material properties. To fully exploit the material capability, the anisotropy needs to be accounted for in both the constitutive and lifing model. In this context, the paper addresses a cyclic life prediction procedure for DS materials with transverse isotropic material symmetry. Thereby, the well-known local approaches to fatigue life prediction of isotropic materials under uniaxial loading are extended toward materials with transverse isotropic properties under multiaxial load conditions. As part of the proposed methodology, a Hill type function is utilized for describing the anisotropic failure behavior. The coefficients of the Hill surface are determined from the actual multiaxial loading, material symmetry, and anisotropic fatigue strength of the material. In this paper we first characterize the anisotropy of DS superalloys. We then present the general mathematical framework of the proposed lifing procedure. Later we discuss a validation of the cyclic life model by comparing the measured and predicted fatigue lives of the test specimens. Finally, the proposed method is applied to the cyclic life prediction of a gas turbine blade. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] A cyclic life prediction approach for directionally solidified nickel superalloys [texte imprimé] / Roland Mücke, Auteur ; Piyawan Woratat, 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° 5 (Mai 2010) . - 07 p. Mots-clés : Blades  Creep  fracture  Fracture  toughness  Gas  turbines  Remaining  life  assessment  Superalloys Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The performance of heavy duty gas turbines is closely related to the material capability of the components of the first turbine stage. In modern gas turbines single crystal (SX) and directionally solidified (DS) nickel superalloys are applied, which, compared with their conventionally cast version, hold a higher cyclic life and a significantly improved creep rupture strength. SX and DS nickel superalloys feature a significant directional dependence of the material properties. To fully exploit the material capability, the anisotropy needs to be accounted for in both the constitutive and lifing model. In this context, the paper addresses a cyclic life prediction procedure for DS materials with transverse isotropic material symmetry. Thereby, the well-known local approaches to fatigue life prediction of isotropic materials under uniaxial loading are extended toward materials with transverse isotropic properties under multiaxial load conditions. As part of the proposed methodology, a Hill type function is utilized for describing the anisotropic failure behavior. The coefficients of the Hill surface are determined from the actual multiaxial loading, material symmetry, and anisotropic fatigue strength of the material. In this paper we first characterize the anisotropy of DS superalloys. We then present the general mathematical framework of the proposed lifing procedure. Later we discuss a validation of the cyclic life model by comparing the measured and predicted fatigue lives of the test specimens. Finally, the proposed method is applied to the cyclic life prediction of a gas turbine blade. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Overcoming of a resonance stall and the minimization of amplitudes in the transient resonance of a vibratory machine by the phase modulation method / J. Michalczyk in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 07 p. Titre : Overcoming of a resonance stall and the minimization of amplitudes in the transient resonance of a vibratory machine by the phase modulation method Type de document : texte imprimé Auteurs : J. Michalczyk, Auteur ; L. Bednarski, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Angular  velocity  control  Electric  motors  Minimisation  Phase  modulation  Resonance  Vibration  control  Vibrations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The present paper elucidates the difficulties faced in the practical implementation of phase modulation methods in the form that was presented by Wang et al. and in the actual systems where the motor driving moment is the control value. A more general model, which takes into consideration the impact of machine vibrations on the rotor angular velocity, was developed. The modification of the phase modulation method is also proposed. The usefulness of such an approach for shaping the transient resonance of the machines with an unbalanced rotor is proven by means of a simulation and an experiment. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Overcoming of a resonance stall and the minimization of amplitudes in the transient resonance of a vibratory machine by the phase modulation method [texte imprimé] / J. Michalczyk, Auteur ; L. Bednarski, 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° 5 (Mai 2010) . - 07 p. Mots-clés : Angular  velocity  control  Electric  motors  Minimisation  Phase  modulation  Resonance  Vibration  control  Vibrations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The present paper elucidates the difficulties faced in the practical implementation of phase modulation methods in the form that was presented by Wang et al. and in the actual systems where the motor driving moment is the control value. A more general model, which takes into consideration the impact of machine vibrations on the rotor angular velocity, was developed. The modification of the phase modulation method is also proposed. The usefulness of such an approach for shaping the transient resonance of the machines with an unbalanced rotor is proven by means of a simulation and an experiment. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

An active auxiliary bearing control strategy to reduce the onset of asynchronous periodic contact modes in rotor/magnetic bearing systems / Iain S. Cade in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 09 p. Titre : An active auxiliary bearing control strategy to reduce the onset of asynchronous periodic contact modes in rotor/magnetic bearing systems Type de document : texte imprimé Auteurs : Iain S. Cade, Auteur ; Sahinkaya, M. Necip, Auteur ; Burrows, Clifford R., Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Machine  control  Magnetic  bearings  Rotors Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : To prevent rotor/stator contact in a rotor/magnetic bearing system, auxiliary bearings may be located along the shaft and at the magnetic bearings. Rotor responses after a contact event may include periodic trapped modes where repeated contact may lead to highly localized thermal stresses. This paper considers an active auxiliary bearing system with a control strategy designed to limit the trapped contact modes in a rotor/magnetic bearing system that are induced by rotor unbalance. The controller is evaluated from a system model and its responses to short duration contact events. An active auxiliary bearing model is introduced to the system where the dynamic response of the bearing is dependent on the controller. From a harmonic decomposition of rotor/bearing contact, dynamic controllers are sought, which limit the numbers of possible periodic solutions for a given rotor unbalance and operating speed. A case study is performed considering a simple two degree of freedom system with passive and active auxiliary bearings. Recovery of a rotor trapped in an asynchronous contact mode is shown with variation of the auxiliary bearing controller parameters. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] An active auxiliary bearing control strategy to reduce the onset of asynchronous periodic contact modes in rotor/magnetic bearing systems [texte imprimé] / Iain S. Cade, Auteur ; Sahinkaya, M. Necip, Auteur ; Burrows, Clifford R., 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° 5 (Mai 2010) . - 09 p. Mots-clés : Machine  control  Magnetic  bearings  Rotors Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : To prevent rotor/stator contact in a rotor/magnetic bearing system, auxiliary bearings may be located along the shaft and at the magnetic bearings. Rotor responses after a contact event may include periodic trapped modes where repeated contact may lead to highly localized thermal stresses. This paper considers an active auxiliary bearing system with a control strategy designed to limit the trapped contact modes in a rotor/magnetic bearing system that are induced by rotor unbalance. The controller is evaluated from a system model and its responses to short duration contact events. An active auxiliary bearing model is introduced to the system where the dynamic response of the bearing is dependent on the controller. From a harmonic decomposition of rotor/bearing contact, dynamic controllers are sought, which limit the numbers of possible periodic solutions for a given rotor unbalance and operating speed. A case study is performed considering a simple two degree of freedom system with passive and active auxiliary bearings. Recovery of a rotor trapped in an asynchronous contact mode is shown with variation of the auxiliary bearing controller parameters. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

The numerical and experimental characteristics of multimode dry-friction whip and whirl / Jason C. Wilkes in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 09 p. Titre : The numerical and experimental characteristics of multimode dry-friction whip and whirl Type de document : texte imprimé Auteurs : Jason C. Wilkes, Auteur ; Childs, Dara W., Auteur ; Benjamin J. Dyck, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Abrasion  Finite  element  analysis  Friction  Rotors  Stators  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The nature of dry-friction whip and whirl is investigated through experimental and numerical methods. A test rig was designed and constructed to demonstrate and record the character of multimode dry-friction whip and whirl. These tests examined steady-state whip and whirl characteristics for a variety of rub materials and clearances. A simulation model was constructed using tapered Timoshenko beam finite elements to form multiple-degree-of-freedom rotor and stator models. These models were reduced by component mode synthesis to discard high-frequency modes while retaining physical coordinates at the rub location to model rotor-stator interaction using a nonlinear contact model with Coulomb friction. Simulations were performed for specific test cases, and compared against experimental data; these comparisons are favorable. Experimental data analysis showed multiple whirl and whip regions, despite claims of previous investigators that these regions are predicted analytically but not produced in simulations or experiments. Spectral analysis illustrates the presence of harmonic sidebands that accompany the fundamental whirl solution. These sidebands are more evident in whip, and can excite higher-frequency whirl solutions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] The numerical and experimental characteristics of multimode dry-friction whip and whirl [texte imprimé] / Jason C. Wilkes, Auteur ; Childs, Dara W., Auteur ; Benjamin J. Dyck, 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° 5 (Mai 2010) . - 09 p. Mots-clés : Abrasion  Finite  element  analysis  Friction  Rotors  Stators  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The nature of dry-friction whip and whirl is investigated through experimental and numerical methods. A test rig was designed and constructed to demonstrate and record the character of multimode dry-friction whip and whirl. These tests examined steady-state whip and whirl characteristics for a variety of rub materials and clearances. A simulation model was constructed using tapered Timoshenko beam finite elements to form multiple-degree-of-freedom rotor and stator models. These models were reduced by component mode synthesis to discard high-frequency modes while retaining physical coordinates at the rub location to model rotor-stator interaction using a nonlinear contact model with Coulomb friction. Simulations were performed for specific test cases, and compared against experimental data; these comparisons are favorable. Experimental data analysis showed multiple whirl and whip regions, despite claims of previous investigators that these regions are predicted analytically but not produced in simulations or experiments. Spectral analysis illustrates the presence of harmonic sidebands that accompany the fundamental whirl solution. These sidebands are more evident in whip, and can excite higher-frequency whirl solutions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Forced response of mistuned bladed disks in gas flow / Evgeny Petrov in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 10 p. Titre : Forced response of mistuned bladed disks in gas flow : a comparative study of predictions and full-scale experimental results Type de document : texte imprimé Auteurs : Evgeny Petrov, Auteur ; Luca Di Mare, Auteur ; Holger Hennings, Auteur Année de publication : 2011 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerodynamics  Blades  Computational  fluid  dynamics  Damping  Discs  (structures)  Gas  turbines  Shock  absorbers Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An integrated experimental-numerical study of forced response for a mistuned bladed disk has been performed. A full chain for the predictive forced response analysis has been developed including data exchange between the computational fluid dynamics code and a code for the prediction of the nonlinear forced response for a bladed disk. The experimental measurements are performed at a full-scale single stage test rig with excitation by aerodynamic forces from gas flow. The numerical modeling approaches and the test rig setup are discussed. Comparison of experimentally measured and predicted values of blade resonance frequencies and response levels for a mistuned bladed disk without dampers is performed. A good correspondence between frequencies at which individual blades have maximum response levels is achieved. The effects of structural damping and underplatform damper parameters on amplitudes and resonance frequencies of the bladed disk are explored. It is shown that the underplatform damper significantly reduces scatters in values of the individual blade frequencies and maximum forced response levels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Forced response of mistuned bladed disks in gas flow : a comparative study of predictions and full-scale experimental results [texte imprimé] / Evgeny Petrov, Auteur ; Luca Di Mare, Auteur ; Holger Hennings, Auteur . - 2011 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 10 p. Mots-clés : Aerodynamics  Blades  Computational  fluid  dynamics  Damping  Discs  (structures)  Gas  turbines  Shock  absorbers Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An integrated experimental-numerical study of forced response for a mistuned bladed disk has been performed. A full chain for the predictive forced response analysis has been developed including data exchange between the computational fluid dynamics code and a code for the prediction of the nonlinear forced response for a bladed disk. The experimental measurements are performed at a full-scale single stage test rig with excitation by aerodynamic forces from gas flow. The numerical modeling approaches and the test rig setup are discussed. Comparison of experimentally measured and predicted values of blade resonance frequencies and response levels for a mistuned bladed disk without dampers is performed. A good correspondence between frequencies at which individual blades have maximum response levels is achieved. The effects of structural damping and underplatform damper parameters on amplitudes and resonance frequencies of the bladed disk are explored. It is shown that the underplatform damper significantly reduces scatters in values of the individual blade frequencies and maximum forced response levels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Eddy current damping / Jacob Laborenz in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 07 p. Titre : Eddy current damping : a concept study for steam turbine blading Type de document : texte imprimé Auteurs : Jacob Laborenz, Auteur ; Christian Siewert, Auteur ; Lars Panning, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Blades  Damping  Fatigue  Steam  turbines  Vibrations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In gas and steam turbine applications a common approach to prevent the blades from high cycle fatigue failures due to high vibration amplitudes is the usage of friction damping elements. Besides the intended amplitude reduction this procedure also features some possibly unwanted side effects like a shift in resonance frequencies due to stiffening effects caused by the contact. Thus, as an alternative an eddy current based noncontacting damping concept for the application in turbomachinery is investigated. In this paper two different types of eddy current dampers are considered. Theoretical models for both are established by applying electromagnetic-mechanical theory. The theoretical models are compared with forced response measurements that are performed at a stationary test rig. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Eddy current damping : a concept study for steam turbine blading [texte imprimé] / Jacob Laborenz, Auteur ; Christian Siewert, Auteur ; Lars Panning, 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° 5 (Mai 2010) . - 07 p. Mots-clés : Blades  Damping  Fatigue  Steam  turbines  Vibrations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In gas and steam turbine applications a common approach to prevent the blades from high cycle fatigue failures due to high vibration amplitudes is the usage of friction damping elements. Besides the intended amplitude reduction this procedure also features some possibly unwanted side effects like a shift in resonance frequencies due to stiffening effects caused by the contact. Thus, as an alternative an eddy current based noncontacting damping concept for the application in turbomachinery is investigated. In this paper two different types of eddy current dampers are considered. Theoretical models for both are established by applying electromagnetic-mechanical theory. The theoretical models are compared with forced response measurements that are performed at a stationary test rig. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Assessment of multiobjective genetic algorithms with different niching strategies and regression methods for engine optimization and design / Yu Shi in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 09 p. Titre : Assessment of multiobjective genetic algorithms with different niching strategies and regression methods for engine optimization and design Type de document : texte imprimé Auteurs : Yu Shi, Auteur ; Rolf D. Reitz, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Design  of  experiments  Engines  Genetic  algorithms  Radial  basis  function  networks  Regression  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In a previous study (Shi, Y., and Reitz, R. D., 2008, “Assessment of Optimization Methodologies to Study the Effects of Bowl Geometry, Spray Targeting and Swirl Ratio for a Heavy-Duty Diesel Engine Operated at High-Load,” SAE Paper No. 2008-01-0949), nondominated sorting genetic algorithm II (NSGA II) (Deb, K., Pratap, A., Agarwal, S., and Meyarivan, T., 2002, “A Fast and Elitist Multiobjective Genetic Algorithm: NSGA-II,” IEEE Trans. Evol. Comput., 6, pp. 182–197) performed better than other popular multiobjective genetic algorithms (MOGAs) in engine optimization that sought optimal combinations of the piston bowl geometry, spray targeting, and swirl ratio. NSGA II is further studied in this paper using different niching strategies that are applied to the objective space and design space, which diversify the optimal objectives and design parameters, accordingly. Convergence and diversity metrics are defined to assess the performance of NSGA II using different niching strategies. It was found that use of design niching achieved more diversified results with respect to design parameters, as expected. Regression was then conducted on the design data sets that were obtained from the optimizations with two niching strategies. Four regression methods, including K-nearest neighbors (KNs), kriging (KR), neural networks (NNs), and radial basis functions (RBFs), were compared. The results showed that the data set obtained from optimization with objective niching provided a more fitted learning space for the regression methods. KNs and KR outperformed the other two methods with respect to prediction accuracy. Furthermore, a log transformation to the objective space improved the prediction accuracy for the KN, KR, and NN methods, except the RBF method. The results indicate that it is appropriate to use a regression tool to partly replace the actual CFD evaluation tool in engine optimization designs using the genetic algorithm. This hybrid mode saves computational resources (processors) without losing optimal accuracy. A design of experiment (DoE) method (the optimal Latin hypercube method) was also used to generate a data set for the regression processes. However, the predicted results were much less reliable than the results that were learned using the dynamically increasing data sets from the NSGA II generations. Applying the dynamical learning strategy during the optimization processes allows computationally expensive CFD evaluations to be partly replaced by evaluations using the regression techniques. The present study demonstrates the feasibility of applying the hybrid mode to engine optimization problems, and the conclusions can also extend to other optimization studies (numerical or experimental) that feature time-consuming evaluations and have highly nonlinear objective spaces. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Assessment of multiobjective genetic algorithms with different niching strategies and regression methods for engine optimization and design [texte imprimé] / Yu Shi, Auteur ; Rolf D. Reitz, 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° 5 (Mai 2010) . - 09 p. Mots-clés : Design  of  experiments  Engines  Genetic  algorithms  Radial  basis  function  networks  Regression  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In a previous study (Shi, Y., and Reitz, R. D., 2008, “Assessment of Optimization Methodologies to Study the Effects of Bowl Geometry, Spray Targeting and Swirl Ratio for a Heavy-Duty Diesel Engine Operated at High-Load,” SAE Paper No. 2008-01-0949), nondominated sorting genetic algorithm II (NSGA II) (Deb, K., Pratap, A., Agarwal, S., and Meyarivan, T., 2002, “A Fast and Elitist Multiobjective Genetic Algorithm: NSGA-II,” IEEE Trans. Evol. Comput., 6, pp. 182–197) performed better than other popular multiobjective genetic algorithms (MOGAs) in engine optimization that sought optimal combinations of the piston bowl geometry, spray targeting, and swirl ratio. NSGA II is further studied in this paper using different niching strategies that are applied to the objective space and design space, which diversify the optimal objectives and design parameters, accordingly. Convergence and diversity metrics are defined to assess the performance of NSGA II using different niching strategies. It was found that use of design niching achieved more diversified results with respect to design parameters, as expected. Regression was then conducted on the design data sets that were obtained from the optimizations with two niching strategies. Four regression methods, including K-nearest neighbors (KNs), kriging (KR), neural networks (NNs), and radial basis functions (RBFs), were compared. The results showed that the data set obtained from optimization with objective niching provided a more fitted learning space for the regression methods. KNs and KR outperformed the other two methods with respect to prediction accuracy. Furthermore, a log transformation to the objective space improved the prediction accuracy for the KN, KR, and NN methods, except the RBF method. The results indicate that it is appropriate to use a regression tool to partly replace the actual CFD evaluation tool in engine optimization designs using the genetic algorithm. This hybrid mode saves computational resources (processors) without losing optimal accuracy. A design of experiment (DoE) method (the optimal Latin hypercube method) was also used to generate a data set for the regression processes. However, the predicted results were much less reliable than the results that were learned using the dynamically increasing data sets from the NSGA II generations. Applying the dynamical learning strategy during the optimization processes allows computationally expensive CFD evaluations to be partly replaced by evaluations using the regression techniques. The present study demonstrates the feasibility of applying the hybrid mode to engine optimization problems, and the conclusions can also extend to other optimization studies (numerical or experimental) that feature time-consuming evaluations and have highly nonlinear objective spaces. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

A numerical investigation of transient flow and cavitation within minisac and valve-covered orifice diesel injector nozzles / Won Geun Lee in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 08 p. Titre : A numerical investigation of transient flow and cavitation within minisac and valve-covered orifice diesel injector nozzles Type de document : texte imprimé Auteurs : Won Geun Lee, Auteur ; Rolf D. Reitz, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cavitation  Confined  flow  Diesel  engines  Fuel  systems  Needles  Nozzles  Numerical  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Cavitating flow within diesel injector passages has been investigated numerically using the homogeneous equilibrium model (HEM), which uses the barotropic assumption and the variable speed of sound of the mixture. To apply the HEM, the KIVA-3V code was modified to implement a generalized equation of state, and injector needle movement is simulated by the arbitrary Lagrangian-Eulerian (ALE) approach and the snapper algorithm. It is demonstrated that the model can predict the effect of nozzle passage geometry on the flow structure and cavitation. The model is able to reproduce the transient fuel injection rate as a function of the needle lift profile. Special interest is focused on the transient behavior during the nozzle closing period, which shows that the fast decrease in flow rate can increase the cavitation in the nozzle passage. The effects of the pressure difference and environment pressure on cavitation augmentation at the end-of-injection were also investigated. Flow characteristics due to different shapes of the nozzle flow passage in axisymmetric single hole nozzles and multihole nozzle configurations (minisac and valve-covered orifice eight-hole nozzles) were compared with emphasis on the end-of-injection period. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] A numerical investigation of transient flow and cavitation within minisac and valve-covered orifice diesel injector nozzles [texte imprimé] / Won Geun Lee, Auteur ; Rolf D. Reitz, 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° 5 (Mai 2010) . - 08 p. Mots-clés : Cavitation  Confined  flow  Diesel  engines  Fuel  systems  Needles  Nozzles  Numerical  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Cavitating flow within diesel injector passages has been investigated numerically using the homogeneous equilibrium model (HEM), which uses the barotropic assumption and the variable speed of sound of the mixture. To apply the HEM, the KIVA-3V code was modified to implement a generalized equation of state, and injector needle movement is simulated by the arbitrary Lagrangian-Eulerian (ALE) approach and the snapper algorithm. It is demonstrated that the model can predict the effect of nozzle passage geometry on the flow structure and cavitation. The model is able to reproduce the transient fuel injection rate as a function of the needle lift profile. Special interest is focused on the transient behavior during the nozzle closing period, which shows that the fast decrease in flow rate can increase the cavitation in the nozzle passage. The effects of the pressure difference and environment pressure on cavitation augmentation at the end-of-injection were also investigated. Flow characteristics due to different shapes of the nozzle flow passage in axisymmetric single hole nozzles and multihole nozzle configurations (minisac and valve-covered orifice eight-hole nozzles) were compared with emphasis on the end-of-injection period. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

A study on an automatically variable intake exhaust injection timing turbocharging system for diesel engines / Shiyou Yang in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 07 p. Titre : A study on an automatically variable intake exhaust injection timing turbocharging system for diesel engines Type de document : texte imprimé Auteurs : Shiyou Yang, Auteur ; Kangyao Deng, Auteur ; Yi Cui, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Compressors  Diesel  engines  Exhaust  systems  Finite  volume  methods  Fuel  systems  Intake  systems  (machines) Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A new turbocharging system, named automatically variable intake exhaust injection timing (AVIEIT), is proposed. Its main purpose is to improve the performance of low-speed high torque operating conditions and improve the economy of high-speed operating conditions for high-speed supercharged intercooled diesel engines. The principle of the AVIEIT turbocharging system is presented. A control mechanism for the proposed AVIEIT system used for a truck diesel engine is introduced. An engine simulation code has been developed. In this code, a zero-dimensional in-cylinder combustion model, a one-dimensional finite volume method-total variation diminishing model for unsteady gas flow in the intake and exhaust manifolds, and a turbocharger model are used. The developed code is used to simulate the performances of diesel engines using the AVIEIT system. Simulations of a military use diesel engine “12V150” and a truck diesel engine “D6114” using the AVIEIT system have been performed. Simulation results show that the in-cylinder charge air amount of the diesel engine with the AVIEIT system is increased at low-speed high torque operating conditions, and the fuel economy is improved at high-speed operating conditions. In order to test the idea of the AVIEIT system, an experiment on a truck diesel engine D6114 equipped with an AVIEIT control mechanism has been finished. The experiment results show that the AVIEIT system can improve the economy of high-speed operating conditions. Both the simulation and experiment results suggest that the AVIEIT system has the potential to replace the waste-gate and variable geometry turbocharger turbocharging systems. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] A study on an automatically variable intake exhaust injection timing turbocharging system for diesel engines [texte imprimé] / Shiyou Yang, Auteur ; Kangyao Deng, Auteur ; Yi Cui, 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° 5 (Mai 2010) . - 07 p. Mots-clés : Combustion  Compressors  Diesel  engines  Exhaust  systems  Finite  volume  methods  Fuel  systems  Intake  systems  (machines) Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A new turbocharging system, named automatically variable intake exhaust injection timing (AVIEIT), is proposed. Its main purpose is to improve the performance of low-speed high torque operating conditions and improve the economy of high-speed operating conditions for high-speed supercharged intercooled diesel engines. The principle of the AVIEIT turbocharging system is presented. A control mechanism for the proposed AVIEIT system used for a truck diesel engine is introduced. An engine simulation code has been developed. In this code, a zero-dimensional in-cylinder combustion model, a one-dimensional finite volume method-total variation diminishing model for unsteady gas flow in the intake and exhaust manifolds, and a turbocharger model are used. The developed code is used to simulate the performances of diesel engines using the AVIEIT system. Simulations of a military use diesel engine “12V150” and a truck diesel engine “D6114” using the AVIEIT system have been performed. Simulation results show that the in-cylinder charge air amount of the diesel engine with the AVIEIT system is increased at low-speed high torque operating conditions, and the fuel economy is improved at high-speed operating conditions. In order to test the idea of the AVIEIT system, an experiment on a truck diesel engine D6114 equipped with an AVIEIT control mechanism has been finished. The experiment results show that the AVIEIT system can improve the economy of high-speed operating conditions. Both the simulation and experiment results suggest that the AVIEIT system has the potential to replace the waste-gate and variable geometry turbocharger turbocharging systems. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

In-cylinder flow computational fluid dynamics analysis of a four-valve spark ignition engine / Damian E. Ramajo in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 10 p. Titre : In-cylinder flow computational fluid dynamics analysis of a four-valve spark ignition engine : comparison between steady and dynamic tests Type de document : texte imprimé Auteurs : Damian E. Ramajo, Auteur ; Norberto M. Nigro, Auteur Année de publication : 2011 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Computational  fluid  dynamics  Engine  cylinders  Ignition  Internal  combustion  engines  Sparks  Turbulence  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Numerical and experimental techniques were applied in order to study the in-cylinder flow field in a commercial four-valve per cylinder spark ignition engine. Investigation was aimed at analyzing the generation and evolution of tumble-vortex structures during the intake and compression strokes, and the capacity of this engine to promote turbulence enhancement during tumble degradation at the end of the compression stroke. For these purposes, three different approaches were analyzed. First, steady flow rig tests were experimentally carried out, and then reproduced by computational fluid dynamics (CFD). Once CFD was assessed, cold dynamic simulations of the full engine cycle were performed for several engine speeds (1500 rpm, 3000 rpm, and 4500 rpm). Steady and cold dynamic results were compared in order to assess the feasibility of the former to quantify the in-cylinder flow. After that, combustion was incorporated by means of a homogeneous heat source, and dynamic boundary conditions were introduced in order to approach real engine conditions. The combustion model estimates the burning rate as a function of some averaged in-cylinder flow variables (temperature, pressure, turbulent intensity, and piston position). Results were employed to characterize the in-cylinder flow field of the engine and to establish similarities and differences between the three performed tests that are currently used to estimate the engine mean flow characteristics (steady flow rig, and cold and real dynamic simulations). DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] In-cylinder flow computational fluid dynamics analysis of a four-valve spark ignition engine : comparison between steady and dynamic tests [texte imprimé] / Damian E. Ramajo, Auteur ; Norberto M. Nigro, Auteur . - 2011 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 10 p. Mots-clés : Computational  fluid  dynamics  Engine  cylinders  Ignition  Internal  combustion  engines  Sparks  Turbulence  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Numerical and experimental techniques were applied in order to study the in-cylinder flow field in a commercial four-valve per cylinder spark ignition engine. Investigation was aimed at analyzing the generation and evolution of tumble-vortex structures during the intake and compression strokes, and the capacity of this engine to promote turbulence enhancement during tumble degradation at the end of the compression stroke. For these purposes, three different approaches were analyzed. First, steady flow rig tests were experimentally carried out, and then reproduced by computational fluid dynamics (CFD). Once CFD was assessed, cold dynamic simulations of the full engine cycle were performed for several engine speeds (1500 rpm, 3000 rpm, and 4500 rpm). Steady and cold dynamic results were compared in order to assess the feasibility of the former to quantify the in-cylinder flow. After that, combustion was incorporated by means of a homogeneous heat source, and dynamic boundary conditions were introduced in order to approach real engine conditions. The combustion model estimates the burning rate as a function of some averaged in-cylinder flow variables (temperature, pressure, turbulent intensity, and piston position). Results were employed to characterize the in-cylinder flow field of the engine and to establish similarities and differences between the three performed tests that are currently used to estimate the engine mean flow characteristics (steady flow rig, and cold and real dynamic simulations). DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Computational study of a high-expansion ratio radial organic rankine cycle turbine stator / John Harinck in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 06 p. Titre : Computational study of a high-expansion ratio radial organic rankine cycle turbine stator Type de document : texte imprimé Auteurs : John Harinck, Auteur ; Teemu Turunen-Saaresti, Auteur ; Piero Colonna, Auteur Année de publication : 2011 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Computational  fluid  dynamics  Mechanical  engineering  computing  Nozzles  Stators  Thermodynamics  Turbogenerators  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : There is a growing interest in organic Rankine cycle (ORC) turbogenerators because they are suitable as sustainable energy converters. ORC turbogenerators can efficiently utilize external heat sources at low to medium temperature in the small to medium power range. ORC turbines typically operate at very high pressure ratio and expand the organic working fluid in the dense-gas thermodynamic region, thus requiring computational fluid dynamics (CFD) solvers coupled with accurate thermodynamic models for their performance assessment and design. This article presents a comparative numerical study on the simulated flow field generated by a stator nozzle of an existing high-expansion ratio radial ORC turbine with toluene as working fluid. The analysis covers the influence on the simulated flow fields of the real-gas flow solvers: FLUENT, FINFLO, and ZFLOW, of two turbulence models and of two accurate thermodynamic models of the fluid. The results show that FLUENT is by far the most dissipative flow solver, resulting in large differences in all flow quantities and appreciably lower predictions of the isentropic nozzle efficiency. If the combination of the k−omega turbulence model and FINFLO solver is adopted, a shock-induced separation bubble appears in the calculated results. The bubble affects, in particular, the variation in the flow velocity and angle along the stator outlet. The accurate thermodynamic models by Lemmon and Span (2006, “Short Fundamental Equations of State for 20 Industrial Fluids,” J. Chem. Eng. Data, 51(3), pp. 785–850) and Goodwin (1989, “Toluene Thermophysical Properties From 178 to 800 K at Pressures to 1000 Bar,” J. Phys. Chem. Ref. Data, 18(4), pp. 1565–1636) lead to small differences in the flow field, especially if compared with the large deviations that would be present if the flow were simulated based on the ideal gas law. However, the older and less accurate thermodynamic model by Goodwin does differ significantly from the more accurate Lemmon–Span thermodynamic model in its prediction of the specific enthalpy difference, which leads to a considerably different value for the specific work and stator isentropic efficiency. The above differences point to a need for experimental validation of flow solvers in real-gas conditions, if CFD tools are to be applied for performance improvements of high-expansion ratio turbines operating partly in the real-gas regime. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Computational study of a high-expansion ratio radial organic rankine cycle turbine stator [texte imprimé] / John Harinck, Auteur ; Teemu Turunen-Saaresti, Auteur ; Piero Colonna, 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° 5 (Mai 2010) . - 06 p. Mots-clés : Computational  fluid  dynamics  Mechanical  engineering  computing  Nozzles  Stators  Thermodynamics  Turbogenerators  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : There is a growing interest in organic Rankine cycle (ORC) turbogenerators because they are suitable as sustainable energy converters. ORC turbogenerators can efficiently utilize external heat sources at low to medium temperature in the small to medium power range. ORC turbines typically operate at very high pressure ratio and expand the organic working fluid in the dense-gas thermodynamic region, thus requiring computational fluid dynamics (CFD) solvers coupled with accurate thermodynamic models for their performance assessment and design. This article presents a comparative numerical study on the simulated flow field generated by a stator nozzle of an existing high-expansion ratio radial ORC turbine with toluene as working fluid. The analysis covers the influence on the simulated flow fields of the real-gas flow solvers: FLUENT, FINFLO, and ZFLOW, of two turbulence models and of two accurate thermodynamic models of the fluid. The results show that FLUENT is by far the most dissipative flow solver, resulting in large differences in all flow quantities and appreciably lower predictions of the isentropic nozzle efficiency. If the combination of the k−omega turbulence model and FINFLO solver is adopted, a shock-induced separation bubble appears in the calculated results. The bubble affects, in particular, the variation in the flow velocity and angle along the stator outlet. The accurate thermodynamic models by Lemmon and Span (2006, “Short Fundamental Equations of State for 20 Industrial Fluids,” J. Chem. Eng. Data, 51(3), pp. 785–850) and Goodwin (1989, “Toluene Thermophysical Properties From 178 to 800 K at Pressures to 1000 Bar,” J. Phys. Chem. Ref. Data, 18(4), pp. 1565–1636) lead to small differences in the flow field, especially if compared with the large deviations that would be present if the flow were simulated based on the ideal gas law. However, the older and less accurate thermodynamic model by Goodwin does differ significantly from the more accurate Lemmon–Span thermodynamic model in its prediction of the specific enthalpy difference, which leads to a considerably different value for the specific work and stator isentropic efficiency. The above differences point to a need for experimental validation of flow solvers in real-gas conditions, if CFD tools are to be applied for performance improvements of high-expansion ratio turbines operating partly in the real-gas regime. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Laser beam welding of open-porous metallic foams for application in cooling structures of combined cycle power plants / Uwe Reisgen in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 05 p. Titre : Laser beam welding of open-porous metallic foams for application in cooling structures of combined cycle power plants Type de document : texte imprimé Auteurs : Uwe Reisgen, Auteur ; Simon Olschok, Auteur ; Stefan Longerich, Auteur Année de publication : 2011 Article en page(s) : 05 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combined  cycle  power  stations  Cooling  Laser  beam  welding  Laser  sintering  Metal  foams  Multilayers  Porous  materials  Powder  metallurgy Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Within the Collaborative Research Centre 561, “Thermally highly loaded, porous and cooled multilayer systems for combined cycle power plants,” open-porous and high-temperature stable Ni-based structures are being developed for the requirements of effusion cooling. A two-dimensional cooling strategy for the walls of combustion chambers, which allows the outflow of the cooling medium over the complete wall area of the combustion chamber, could be realized by an open-porous metallic foam structure. The open-porous metallic foam is produced by the “slip reaction foam sintering” process, a powder metallurgical process. To join several foams to assemble structural elements, laser beam welding has been used. Different joining strategies have been examined to find out the most suitable method to join these foams. In this paper, the process setups, settings of the different strategies, and results of trials (seam geometry and strength tests) are discussed. The need for graded structures to combine the essential permeability and adequate weldability is also shown. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Laser beam welding of open-porous metallic foams for application in cooling structures of combined cycle power plants [texte imprimé] / Uwe Reisgen, Auteur ; Simon Olschok, Auteur ; Stefan Longerich, Auteur . - 2011 . - 05 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 05 p. Mots-clés : Combined  cycle  power  stations  Cooling  Laser  beam  welding  Laser  sintering  Metal  foams  Multilayers  Porous  materials  Powder  metallurgy Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Within the Collaborative Research Centre 561, “Thermally highly loaded, porous and cooled multilayer systems for combined cycle power plants,” open-porous and high-temperature stable Ni-based structures are being developed for the requirements of effusion cooling. A two-dimensional cooling strategy for the walls of combustion chambers, which allows the outflow of the cooling medium over the complete wall area of the combustion chamber, could be realized by an open-porous metallic foam structure. The open-porous metallic foam is produced by the “slip reaction foam sintering” process, a powder metallurgical process. To join several foams to assemble structural elements, laser beam welding has been used. Different joining strategies have been examined to find out the most suitable method to join these foams. In this paper, the process setups, settings of the different strategies, and results of trials (seam geometry and strength tests) are discussed. The need for graded structures to combine the essential permeability and adequate weldability is also shown. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

Technical brief: Predictions of flow field for circular-disk bluff-body stabilized flame investigated by large eddy simulation and experiments / Peiqing Guo in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 06 p. Titre : Technical brief: Predictions of flow field for circular-disk bluff-body stabilized flame investigated by large eddy simulation and experiments Type de document : texte imprimé Auteurs : Peiqing Guo, Auteur ; Shusheng Zang, Auteur ; Bing Ge, Auteur Année de publication : 2011 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Flames  Flow  instability  Flow  simulation  Flow  visualisation  Turbulence  Velocity  measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The objective of the current work is to shed light on simulating the flow features of nonpremixed flame stabilized by a circular-disk bluff-body with large eddy simulation technique. Two subgrid scale (SGS) models (Smagorinsky and Germano), combined with a constrained chemical equilibrium model, are applied to simulate this turbulent flame. Validation is made through the particle image velocimetry measurements. The comparison between the numerical simulation and experimental data shows that both models perform well and reproduce most of the significant features of the bluff-body flame, while the Germano SGS model performs better in prediction of turbulent fluctuations. These investigations show that it is possible to describe such flows with relatively simple turbulence and combustion models with moderate grids. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] Technical brief: Predictions of flow field for circular-disk bluff-body stabilized flame investigated by large eddy simulation and experiments [texte imprimé] / Peiqing Guo, Auteur ; Shusheng Zang, Auteur ; Bing Ge, 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° 5 (Mai 2010) . - 06 p. Mots-clés : Combustion  Flames  Flow  instability  Flow  simulation  Flow  visualisation  Turbulence  Velocity  measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The objective of the current work is to shed light on simulating the flow features of nonpremixed flame stabilized by a circular-disk bluff-body with large eddy simulation technique. Two subgrid scale (SGS) models (Smagorinsky and Germano), combined with a constrained chemical equilibrium model, are applied to simulate this turbulent flame. Validation is made through the particle image velocimetry measurements. The comparison between the numerical simulation and experimental data shows that both models perform well and reproduce most of the significant features of the bluff-body flame, while the Germano SGS model performs better in prediction of turbulent fluctuations. These investigations show that it is possible to describe such flows with relatively simple turbulence and combustion models with moderate grids. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]

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