Dépouillements

Understanding ice crystal accretion and shedding phenomenon in jet engines using a rig test / Jeanne G. Mason in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 08 p. Titre : Understanding ice crystal accretion and shedding phenomenon in jet engines using a rig test Type de document : texte imprimé Auteurs : Jeanne G. Mason, Auteur ; Philip Chow, Auteur ; Dan M. Fuleki, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerodynamics  Aerospace  industry  Freezing  Jet  engines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The aviation industry has now connected a number of engine power-loss events to the ingestion of atmospheric ice crystals. Ice crystals are believed to penetrate to and eventually accrete on surfaces in the engine core where local air temperatures are warmer than freezing. Research aimed at understanding the accretion and shedding of ice crystals within the engine is being conducted industrywide. Although this specific icing condition is readily produced inside an operating engine, rig testing is the preferred research tool because it has the advantage of good visibility of the ice accretion process and easy access for video documentation. This paper presents one of the first efforts to simulate the warm air/cold ice conditions occurring inside the engine core using a test rig. The test section contains geometry simulating the transition duct between the low and high compressors in a typical jet engine and an airfoil simulating the engine strut connecting the inner and outer surfaces. Test results showed ice formed on the airfoil and other surfaces in the test section at air temperatures warmer than freezing. However, when both the air and surface temperatures were held below freezing, the injected ice did not melt and no ice accretion was observed. Ice only formed on the airfoil when mixed-phase conditions (liquid and ice) were produced, by introducing the ice into a warm airflow. This test concludes that a rig-level ice crystal icing test is feasible and capable of producing ice accretion in a simulated engine environment. As it was the first test of its kind, reporting of these preliminary test results are expected to benefit future experimenters. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Understanding ice crystal accretion and shedding phenomenon in jet engines using a rig test [texte imprimé] / Jeanne G. Mason, Auteur ; Philip Chow, Auteur ; Dan M. Fuleki, Auteur . - 2012 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 08 p. Mots-clés : Aerodynamics  Aerospace  industry  Freezing  Jet  engines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The aviation industry has now connected a number of engine power-loss events to the ingestion of atmospheric ice crystals. Ice crystals are believed to penetrate to and eventually accrete on surfaces in the engine core where local air temperatures are warmer than freezing. Research aimed at understanding the accretion and shedding of ice crystals within the engine is being conducted industrywide. Although this specific icing condition is readily produced inside an operating engine, rig testing is the preferred research tool because it has the advantage of good visibility of the ice accretion process and easy access for video documentation. This paper presents one of the first efforts to simulate the warm air/cold ice conditions occurring inside the engine core using a test rig. The test section contains geometry simulating the transition duct between the low and high compressors in a typical jet engine and an airfoil simulating the engine strut connecting the inner and outer surfaces. Test results showed ice formed on the airfoil and other surfaces in the test section at air temperatures warmer than freezing. However, when both the air and surface temperatures were held below freezing, the injected ice did not melt and no ice accretion was observed. Ice only formed on the airfoil when mixed-phase conditions (liquid and ice) were produced, by introducing the ice into a warm airflow. This test concludes that a rig-level ice crystal icing test is feasible and capable of producing ice accretion in a simulated engine environment. As it was the first test of its kind, reporting of these preliminary test results are expected to benefit future experimenters. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

LES predictions of noise emissions from a low-bypass ratio military gas turbine engine / N. Sinha in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 10 p. Titre : LES predictions of noise emissions from a low-bypass ratio military gas turbine engine Type de document : texte imprimé Auteurs : N. Sinha, Auteur ; J. Erwin, Auteur ; C. Kannepalli, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aeroacoustics  Boundary  layer  turbulence  Engines  Flow  simulation  Gas  turbines  Jets  Military  aircraft  Navier-Stokes  equations  Nozzles  Propulsion  Shear  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A practical framework for predicting jet structure and noise from military aircraft is described, which is developmental and has been examined for some fundamental jet flow problems. The framework currently utilizes Reynolds-averaged Navier Stokes (RANS) methodology for geometrically complex internal propulsive flowpaths and large eddy simulation (LES) methodology for the jet structure downstream of the nozzle exit. Temporal data from the LES solution is stored on a flared-cylindrical surface surrounding the jet, to be used for noise propagation to the farfield. Earlier applications of RANS methodology combined with the use of analogy-based jet noise codes proved inadequate due to the inability of the noise codes to treat complex 3D flows, such as those associated with multiple nozzles and/or with varied jet noise reduction concepts. Restricting the use of LES (or RANS/LES), methodology to free shear flows remedies the severe grid resolution issues that would be encountered with utilization of LES for modeling internal propulsive flows. The issue of “adequately” initiating the LES solution from a RANS solution profile just downstream of the nozzle exit has been the focus of our exploratory studies and is clearly more complex than standard procedures, such as recycling and rescaling techniques used for simple wall bounded flows. Approaches examined are discussed and unified RANS/LES solutions for several flows are described. The application of this framework to more complex flows requires no fundamental modifications as will also be discussed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] LES predictions of noise emissions from a low-bypass ratio military gas turbine engine [texte imprimé] / N. Sinha, Auteur ; J. Erwin, Auteur ; C. Kannepalli, Auteur . - 2012 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 10 p. Mots-clés : Aeroacoustics  Boundary  layer  turbulence  Engines  Flow  simulation  Gas  turbines  Jets  Military  aircraft  Navier-Stokes  equations  Nozzles  Propulsion  Shear  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A practical framework for predicting jet structure and noise from military aircraft is described, which is developmental and has been examined for some fundamental jet flow problems. The framework currently utilizes Reynolds-averaged Navier Stokes (RANS) methodology for geometrically complex internal propulsive flowpaths and large eddy simulation (LES) methodology for the jet structure downstream of the nozzle exit. Temporal data from the LES solution is stored on a flared-cylindrical surface surrounding the jet, to be used for noise propagation to the farfield. Earlier applications of RANS methodology combined with the use of analogy-based jet noise codes proved inadequate due to the inability of the noise codes to treat complex 3D flows, such as those associated with multiple nozzles and/or with varied jet noise reduction concepts. Restricting the use of LES (or RANS/LES), methodology to free shear flows remedies the severe grid resolution issues that would be encountered with utilization of LES for modeling internal propulsive flows. The issue of “adequately” initiating the LES solution from a RANS solution profile just downstream of the nozzle exit has been the focus of our exploratory studies and is clearly more complex than standard procedures, such as recycling and rescaling techniques used for simple wall bounded flows. Approaches examined are discussed and unified RANS/LES solutions for several flows are described. The application of this framework to more complex flows requires no fundamental modifications as will also be discussed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Influence of transversal acoustic excitation of the burner approach flow on the flame structure / Martin Hauser in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 08 p. Titre : Influence of transversal acoustic excitation of the burner approach flow on the flame structure Type de document : texte imprimé Auteurs : Martin Hauser, Auteur ; Manuel Lorenz, Auteur ; Thomas Sattelmayer, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Acoustics  Electric  power  generation  Engines  Flames  Gas  turbines  Oscillations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Modern large gas turbines for power generation have multiple burners, which are distributed around the circumference of the engine and which generate flames in combustors of either annular or can-annular geometry. In both cases, considering only the axial modes has proven to be insufficient for the assessment of the thermoacoustic stability. An adequate analysis requires consideration of the circumferential acoustic coupling generated by the acoustic field in the upstream and downstream annuli and the open passages between the cans, respectively. As in annular combustors, the particularly critical eigenmodes with low frequencies are predominantly of circumferential nature; the stability of annular combustors is often governed by the onset of circumferential acoustic oscillations. To determine the influence of these circumferential acoustic modes on the dynamic flame behavior, a new single burner test rig was developed. The unique acoustic properties of the test rig allow the exposure of a single swirl burner to a two-dimensional acoustic field that resembles the circumferential mode in an annular combustor. Measurements were performed for axial as well as transversal excitation of the burner and the combination of both. To investigate the dynamic flame structure, phase-resolved flame images have been evaluated in terms of amplitude and phase distribution. Under transversal excitation, the flame structure becomes highly asymmetrical. A region of higher OH* intensity is generated in the combustion chamber, which rotates with the excitation frequency. From phase-resolved particle image velocimetry (PIV) measurements of the isothermal flow, it is concluded that the transversal excitation modulates the swirl generation leading to an asymmetrical velocity distribution in the burner nozzle and the combustion chamber. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Influence of transversal acoustic excitation of the burner approach flow on the flame structure [texte imprimé] / Martin Hauser, Auteur ; Manuel Lorenz, Auteur ; Thomas Sattelmayer, Auteur . - 2012 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 08 p. Mots-clés : Acoustics  Electric  power  generation  Engines  Flames  Gas  turbines  Oscillations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Modern large gas turbines for power generation have multiple burners, which are distributed around the circumference of the engine and which generate flames in combustors of either annular or can-annular geometry. In both cases, considering only the axial modes has proven to be insufficient for the assessment of the thermoacoustic stability. An adequate analysis requires consideration of the circumferential acoustic coupling generated by the acoustic field in the upstream and downstream annuli and the open passages between the cans, respectively. As in annular combustors, the particularly critical eigenmodes with low frequencies are predominantly of circumferential nature; the stability of annular combustors is often governed by the onset of circumferential acoustic oscillations. To determine the influence of these circumferential acoustic modes on the dynamic flame behavior, a new single burner test rig was developed. The unique acoustic properties of the test rig allow the exposure of a single swirl burner to a two-dimensional acoustic field that resembles the circumferential mode in an annular combustor. Measurements were performed for axial as well as transversal excitation of the burner and the combination of both. To investigate the dynamic flame structure, phase-resolved flame images have been evaluated in terms of amplitude and phase distribution. Under transversal excitation, the flame structure becomes highly asymmetrical. A region of higher OH* intensity is generated in the combustion chamber, which rotates with the excitation frequency. From phase-resolved particle image velocimetry (PIV) measurements of the isothermal flow, it is concluded that the transversal excitation modulates the swirl generation leading to an asymmetrical velocity distribution in the burner nozzle and the combustion chamber. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Stall warning in a low-speed axial fan by visualization of sound signals / Anthony G. Sheard in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 10 p. Titre : Stall warning in a low-speed axial fan by visualization of sound signals Type de document : texte imprimé Auteurs : Anthony G. Sheard, Auteur ; Alessandro Corsini, Auteur ; Stefano Bianchi, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerodynamics  Failure  (mechanical)  Fans  Flow  visualisation  Risk  analysis  Waveform  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This study describes the development of a novel stall-detection methodology for low-speed axial-flow fans. Because aerodynamic stall is a major potential cause of mechanical failure in axial fans, effective stall-detection techniques have had wide application for many years. However, aerodynamic stall does not always result in mechanical failure. A subsonic fan can sometimes operate at low speeds in an aerodynamically stalled condition without incurring mechanical failure. To differentiate between aerodynamic stall conditions that constitute a mechanical risk and those that do not, the stall-detection methodology in the present study utilizes a symmetrized dot pattern (SDP) technique that is capable of differentiating between stall conditions. This paper describes a stall-detections criterion based on a SDP visual waveform analysis and develops a stall-warning methodology based on that analysis. This study presents an analysis of measured acoustic and structural data across nine aerodynamic operating conditions represented in a 3×3 matrix. The matrix is a combination of (i) three speeds (full-, half-, and quarter-speed) and (ii) three operational states (stable operation, incipient stall, and rotating stall). The matrix of SDPs and structural data are used to differentiate critical stall conditions (those that will lead to mechanical failure of the fan) from noncritical ones (those that will not result in mechanical failure), thus providing a basis for an intelligent stall-warning methodology. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Stall warning in a low-speed axial fan by visualization of sound signals [texte imprimé] / Anthony G. Sheard, Auteur ; Alessandro Corsini, Auteur ; Stefano Bianchi, Auteur . - 2012 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 10 p. Mots-clés : Aerodynamics  Failure  (mechanical)  Fans  Flow  visualisation  Risk  analysis  Waveform  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This study describes the development of a novel stall-detection methodology for low-speed axial-flow fans. Because aerodynamic stall is a major potential cause of mechanical failure in axial fans, effective stall-detection techniques have had wide application for many years. However, aerodynamic stall does not always result in mechanical failure. A subsonic fan can sometimes operate at low speeds in an aerodynamically stalled condition without incurring mechanical failure. To differentiate between aerodynamic stall conditions that constitute a mechanical risk and those that do not, the stall-detection methodology in the present study utilizes a symmetrized dot pattern (SDP) technique that is capable of differentiating between stall conditions. This paper describes a stall-detections criterion based on a SDP visual waveform analysis and develops a stall-warning methodology based on that analysis. This study presents an analysis of measured acoustic and structural data across nine aerodynamic operating conditions represented in a 3×3 matrix. The matrix is a combination of (i) three speeds (full-, half-, and quarter-speed) and (ii) three operational states (stable operation, incipient stall, and rotating stall). The matrix of SDPs and structural data are used to differentiate critical stall conditions (those that will lead to mechanical failure of the fan) from noncritical ones (those that will not result in mechanical failure), thus providing a basis for an intelligent stall-warning methodology. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Novel high-performing single-pressure combined cycle with CO2 capture / Nikolett Sipöcz in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 08 p. Titre : Novel high-performing single-pressure combined cycle with CO2 capture Type de document : texte imprimé Auteurs : Nikolett Sipöcz, Auteur ; Klas Jonshagen, Auteur ; Mohsen Assadi, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air  pollution  control  climate  mitigation  Cogeneration  Heat  recovery  Power  generation  economics  Power  markets Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The European electric power industry has undergone considerable changes over the past two decades as a result of more stringent laws concerning environmental protection along with the deregulation and liberalization of the electric power market. However, the pressure to deliver solutions in regard to the issue of climate change has increased dramatically in the last few years and has given rise to the possibility that future natural gas-fired combined cycle (NGCC) plants will also be subject to CO2 capture requirements. At the same time, the interest in combined cycles with their high efficiency, low capital costs, and complexity has grown as a consequence of addressing new challenges posed by the need to operate according to market demand in order to be economically viable. Considering that these challenges will also be imposed on new natural gas-fired power plants in the foreseeable future, this study presents a new process concept for natural gas combined cycle power plants with CO2 capture. The simulation tool IPSEpro is used to model a 400 MW single-pressure NGCC with post-combustion CO2 capture using an amine-based absorption process with monoethanolamine. To improve the costs of capture, the gas turbine GE 109FB is utilizing exhaust gas recirculation, thereby, increasing the CO2 content in the gas turbine working fluid to almost double that of conventional operating gas turbines. In addition, the concept advantageously uses approximately 20% less steam for solvent regeneration by utilizing preheated water extracted from heat recovery steam generator. The further recovery of heat from exhaust gases for water preheating by use of an increased economizer flow results in an outlet stack temperature comparable to those achieved in combined cycle plants with multiple-pressure levels. As a result, overall power plant efficiency as high as that achieved for a triple-pressure reheated NGCC with corresponding CO2 removal facility is attained. The concept, thus, provides a more cost-efficient option to triple-pressure combined cycles since the number of heat exchangers, boilers, etc., is reduced considerably. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Novel high-performing single-pressure combined cycle with CO2 capture [texte imprimé] / Nikolett Sipöcz, Auteur ; Klas Jonshagen, Auteur ; Mohsen Assadi, Auteur . - 2012 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 08 p. Mots-clés : Air  pollution  control  climate  mitigation  Cogeneration  Heat  recovery  Power  generation  economics  Power  markets Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The European electric power industry has undergone considerable changes over the past two decades as a result of more stringent laws concerning environmental protection along with the deregulation and liberalization of the electric power market. However, the pressure to deliver solutions in regard to the issue of climate change has increased dramatically in the last few years and has given rise to the possibility that future natural gas-fired combined cycle (NGCC) plants will also be subject to CO2 capture requirements. At the same time, the interest in combined cycles with their high efficiency, low capital costs, and complexity has grown as a consequence of addressing new challenges posed by the need to operate according to market demand in order to be economically viable. Considering that these challenges will also be imposed on new natural gas-fired power plants in the foreseeable future, this study presents a new process concept for natural gas combined cycle power plants with CO2 capture. The simulation tool IPSEpro is used to model a 400 MW single-pressure NGCC with post-combustion CO2 capture using an amine-based absorption process with monoethanolamine. To improve the costs of capture, the gas turbine GE 109FB is utilizing exhaust gas recirculation, thereby, increasing the CO2 content in the gas turbine working fluid to almost double that of conventional operating gas turbines. In addition, the concept advantageously uses approximately 20% less steam for solvent regeneration by utilizing preheated water extracted from heat recovery steam generator. The further recovery of heat from exhaust gases for water preheating by use of an increased economizer flow results in an outlet stack temperature comparable to those achieved in combined cycle plants with multiple-pressure levels. As a result, overall power plant efficiency as high as that achieved for a triple-pressure reheated NGCC with corresponding CO2 removal facility is attained. The concept, thus, provides a more cost-efficient option to triple-pressure combined cycles since the number of heat exchangers, boilers, etc., is reduced considerably. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Importance of auxiliary power consumption for combined cycle performance / S. Can Gülen in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 10 P. Titre : Importance of auxiliary power consumption for combined cycle performance Type de document : texte imprimé Auteurs : S. Can Gülen, Auteur Année de publication : 2012 Article en page(s) : 10 P. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combined  cycle  power  stations  Gas  turbine  power  stations  Power  consumption Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The key product of a combined cycle power plant is electric power generated for industrial, commercial, and residential customers. In that sense, the key performance metric that establishes the pecking order among thousands of existing, new, old, and planned power plants is the thermal efficiency. This is a ratio of net electric power generated by the plant to its rate of fuel consumption in the gas turbine combustors and, if applicable, heat recovery boiler duct burners. The term in the numerator of that simple ratio is subject to myriad ambiguities and/or misunderstandings resulting primarily from the lack of a standardized definition agreed upon by all major players. More precisely, it is the lack of a standardized definition of the plant auxiliary power consumption (or load) that must be subtracted from the generator output of all turbines in the plant, which then determines the net contribution of that power plant to the electric grid. For a combined cycle power plant, the key contributor to the plant's auxiliary power load is the heat rejection system. In particular, any statement of combined cycle power plant thermal efficiency that does not specify the steam turbine exhaust pressure and the exhaust steam cooling system to achieve that pressure at the site ambient and loading conditions is subject to conjecture. Furthermore, for an assessment of the realism associated with the two in terms of economic and mechanical design feasibility, it is necessary to know the steam turbine exhaust end size and configuration. Using fundamental design principles, this paper provides a precise definition of the plant auxiliary load and quantifies its ramification on the plant's net thermal efficiency. In addition, four standard auxiliary load levels are quantitatively defined based on a rigorous study of heat rejection system design considerations with a second-law perspective. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Importance of auxiliary power consumption for combined cycle performance [texte imprimé] / S. Can Gülen, Auteur . - 2012 . - 10 P. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 10 P. Mots-clés : Combined  cycle  power  stations  Gas  turbine  power  stations  Power  consumption Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The key product of a combined cycle power plant is electric power generated for industrial, commercial, and residential customers. In that sense, the key performance metric that establishes the pecking order among thousands of existing, new, old, and planned power plants is the thermal efficiency. This is a ratio of net electric power generated by the plant to its rate of fuel consumption in the gas turbine combustors and, if applicable, heat recovery boiler duct burners. The term in the numerator of that simple ratio is subject to myriad ambiguities and/or misunderstandings resulting primarily from the lack of a standardized definition agreed upon by all major players. More precisely, it is the lack of a standardized definition of the plant auxiliary power consumption (or load) that must be subtracted from the generator output of all turbines in the plant, which then determines the net contribution of that power plant to the electric grid. For a combined cycle power plant, the key contributor to the plant's auxiliary power load is the heat rejection system. In particular, any statement of combined cycle power plant thermal efficiency that does not specify the steam turbine exhaust pressure and the exhaust steam cooling system to achieve that pressure at the site ambient and loading conditions is subject to conjecture. Furthermore, for an assessment of the realism associated with the two in terms of economic and mechanical design feasibility, it is necessary to know the steam turbine exhaust end size and configuration. Using fundamental design principles, this paper provides a precise definition of the plant auxiliary load and quantifies its ramification on the plant's net thermal efficiency. In addition, four standard auxiliary load levels are quantitatively defined based on a rigorous study of heat rejection system design considerations with a second-law perspective. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Influence of titanium in nickel-base superalloys on the performance of thermal barrier coatings utilizing gamma−gamma[prime] platinum bond coats / H. M. Tawancy in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 06 p. Titre : Influence of titanium in nickel-base superalloys on the performance of thermal barrier coatings utilizing gamma−gamma[prime] platinum bond coats Type de document : texte imprimé Auteurs : H. M. Tawancy, Auteur ; Luai M. Al Hadhrami, Auteur Année de publication : 2012 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Adhesion  Aluminium  alloys  Coating  techniques  Electron  optics  Nickel  alloys  Titanium  alloys Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Titanium is a key element in nickel-base superalloys needed with aluminum to achieve the desired volume fraction of the strengthening gamma[prime]-phase. However, depending upon its concentration, titanium can degrade the adherence of aluminum oxide by forming TiO2 particles near the oxide-metal interface. This effect is extended to thermal barrier coating systems where in this case, the bond coat replaces the superalloy as the underlying substrate. Noting that the onset of failure of thermal barrier coating systems coincides with the first spall of the thermally grown oxide, titanium level in the superalloy can have an important effect on the useful life of the coating. Therefore, this study was undertaken to examine the effect of titanium on the performance of a thermal barrier coating system. Included in the study were two Ni-base superalloys with similar chemical composition except for the Ti content and a Pt-containing bond coat consisting of gamma[prime]+gamma-phases all top coated with zirconia stabilized by 7 wt % yttria. Coating performance was evaluated from thermal exposure tests at 1150°C with a 24 h cycling period to room temperature. Various electron-optical techniques were used to characterize the microstructure. The coating system on the low-Ti alloy was found to outperform that on the high-Ti alloy. However, for both alloys, failure was observed to occur by loss of adhesion between the thermally grown oxide and underlying bond coat. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Influence of titanium in nickel-base superalloys on the performance of thermal barrier coatings utilizing gamma−gamma[prime] platinum bond coats [texte imprimé] / H. M. Tawancy, Auteur ; Luai M. Al Hadhrami, Auteur . - 2012 . - 06 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 06 p. Mots-clés : Adhesion  Aluminium  alloys  Coating  techniques  Electron  optics  Nickel  alloys  Titanium  alloys Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Titanium is a key element in nickel-base superalloys needed with aluminum to achieve the desired volume fraction of the strengthening gamma[prime]-phase. However, depending upon its concentration, titanium can degrade the adherence of aluminum oxide by forming TiO2 particles near the oxide-metal interface. This effect is extended to thermal barrier coating systems where in this case, the bond coat replaces the superalloy as the underlying substrate. Noting that the onset of failure of thermal barrier coating systems coincides with the first spall of the thermally grown oxide, titanium level in the superalloy can have an important effect on the useful life of the coating. Therefore, this study was undertaken to examine the effect of titanium on the performance of a thermal barrier coating system. Included in the study were two Ni-base superalloys with similar chemical composition except for the Ti content and a Pt-containing bond coat consisting of gamma[prime]+gamma-phases all top coated with zirconia stabilized by 7 wt % yttria. Coating performance was evaluated from thermal exposure tests at 1150°C with a 24 h cycling period to room temperature. Various electron-optical techniques were used to characterize the microstructure. The coating system on the low-Ti alloy was found to outperform that on the high-Ti alloy. However, for both alloys, failure was observed to occur by loss of adhesion between the thermally grown oxide and underlying bond coat. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Computational evaluation of adhesion and mechanical properties of nanolayered erosion-resistant coatings for gas turbines / Mariusz Bielawski in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 07 p. Titre : Computational evaluation of adhesion and mechanical properties of nanolayered erosion-resistant coatings for gas turbines Type de document : texte imprimé Auteurs : Mariusz Bielawski, Auteur ; Kuiying Chen, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Adhesion  Brittleness  Density  functional  theory  Elastic  constants  Fracture  mechanics  Fracture  toughness  Gas  turbines  Protective  coatings  Shear  modulus  Transition  metals  Young's  modulus Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A computational method to evaluate fracture toughness of prospective erosion-resistant coatings using a combination of first-principles density functional theory (DFT) calculations and fracture mechanics is proposed. Elastic coefficients C11, C12, and C44, the ideal work of adhesion Wad, bulk modulus B, shear modulus G, and Young's modulus E of transition metal nitrides with a cubic structure such as TiN, CrN, ZrN, VN, and HfN are calculated. Both the G/B ratio and Cauchy pressure C12−C44 indicate brittle behavior for TiN, ZrN, and HfN and more metallic behavior for CrN and VN. The fracture toughness KIC and interfacial fracture toughness KICInt for bilayer combinations of these five nitrides is calculated along the [100] and [110] directions. The largest KIC value is obtained for HfN (2.14 MPa m1/2) in (100) orientation and for TiN (2.16 MPa m1/2) in (110) orientation. The lowest fracture toughness, in both orientations, is found for CrN. Among ten coherent interfaces of the five investigated nitrides the largest value of interfacial fracture toughness KICInt=3.24 MPa m1/2 is recorded for the HfN/TiN interface in the (110) orientation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Computational evaluation of adhesion and mechanical properties of nanolayered erosion-resistant coatings for gas turbines [texte imprimé] / Mariusz Bielawski, Auteur ; Kuiying Chen, Auteur . - 2012 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 07 p. Mots-clés : Adhesion  Brittleness  Density  functional  theory  Elastic  constants  Fracture  mechanics  Fracture  toughness  Gas  turbines  Protective  coatings  Shear  modulus  Transition  metals  Young's  modulus Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A computational method to evaluate fracture toughness of prospective erosion-resistant coatings using a combination of first-principles density functional theory (DFT) calculations and fracture mechanics is proposed. Elastic coefficients C11, C12, and C44, the ideal work of adhesion Wad, bulk modulus B, shear modulus G, and Young's modulus E of transition metal nitrides with a cubic structure such as TiN, CrN, ZrN, VN, and HfN are calculated. Both the G/B ratio and Cauchy pressure C12−C44 indicate brittle behavior for TiN, ZrN, and HfN and more metallic behavior for CrN and VN. The fracture toughness KIC and interfacial fracture toughness KICInt for bilayer combinations of these five nitrides is calculated along the [100] and [110] directions. The largest KIC value is obtained for HfN (2.14 MPa m1/2) in (100) orientation and for TiN (2.16 MPa m1/2) in (110) orientation. The lowest fracture toughness, in both orientations, is found for CrN. Among ten coherent interfaces of the five investigated nitrides the largest value of interfacial fracture toughness KICInt=3.24 MPa m1/2 is recorded for the HfN/TiN interface in the (110) orientation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

An experimental system for assessing combustor durability / Nagaraja S. Rudrapatna in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 06 p. Titre : An experimental system for assessing combustor durability Type de document : texte imprimé Auteurs : Nagaraja S. Rudrapatna, Auteur ; Benjamin H. Peterson, Auteur ; Daniel Greving, Auteur Année de publication : 2012 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cobalt  alloys  Combustion  equipment  Creep  Durability  Failure  analysis  Gas  turbines  Nickel  alloys  Thermal  barrier  coatings  Thermal  stress  cracking Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Modern gas turbine combustors are made of high temperature alloys, employ effusion cooling, and are protected by a thermal barrier coating (TBC). Gas turbine combustor failure modes, such as TBC spallation, cracking, and distortion resulting from oxidation, creep, and thermal fatigue, are driven by hot spot peak temperature and the associated thermal gradient. Standard material characterization tests, such as creep, oxidation, and low cycle fatigue are indicators of a material's potential performance but they neither fully represent the combustor geometric/material system nor fully represent the thermal fatigue conditions a combustor is subjected to during engine operation. Combustor rig tests and/or engine cyclic endurance tests to determine the suitability of new material systems for combustors are time-consuming and costly. Therefore, a simple yet efficient test method for screening material systems under representative combustor conditions is needed. An experimental system has been developed to fill this gap. This paper discusses the configured specimen geometry, test methodology, observed test results, and a comparison with typical failure modes observed in combustors. DEWEY : 620.1 ISSN : 0742-4794 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] An experimental system for assessing combustor durability [texte imprimé] / Nagaraja S. Rudrapatna, Auteur ; Benjamin H. Peterson, Auteur ; Daniel Greving, Auteur . - 2012 . - 06 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 06 p. Mots-clés : Cobalt  alloys  Combustion  equipment  Creep  Durability  Failure  analysis  Gas  turbines  Nickel  alloys  Thermal  barrier  coatings  Thermal  stress  cracking Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Modern gas turbine combustors are made of high temperature alloys, employ effusion cooling, and are protected by a thermal barrier coating (TBC). Gas turbine combustor failure modes, such as TBC spallation, cracking, and distortion resulting from oxidation, creep, and thermal fatigue, are driven by hot spot peak temperature and the associated thermal gradient. Standard material characterization tests, such as creep, oxidation, and low cycle fatigue are indicators of a material's potential performance but they neither fully represent the combustor geometric/material system nor fully represent the thermal fatigue conditions a combustor is subjected to during engine operation. Combustor rig tests and/or engine cyclic endurance tests to determine the suitability of new material systems for combustors are time-consuming and costly. Therefore, a simple yet efficient test method for screening material systems under representative combustor conditions is needed. An experimental system has been developed to fill this gap. This paper discusses the configured specimen geometry, test methodology, observed test results, and a comparison with typical failure modes observed in combustors. DEWEY : 620.1 ISSN : 0742-4794 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Development of a 3 kW microturbine for CHP applications / W. P. J. Visser in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 08 p. Titre : Development of a 3 kW microturbine for CHP applications Type de document : texte imprimé Auteurs : W. P. J. Visser, Auteur ; S. A. Shakariyants, Auteur ; M. Oostveen, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air  pollution  control  Carbon  compounds  Cogeneration  Distributed  power  generation  Turbogenerators Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Combined heat and power (CHP) concepts for small-scale distributed power generation offer significant potential for saving energy and reducing CO2 emissions. Microturbines are an interesting candidate for small CHP systems with advantages in terms of performance, size, noise, and costs. MTT is developing a 3 kW recuperated microturbine for micro CHP applications for large households and for truck combined APU-heating systems. To minimize costs, off-the-shelf automotive turbocharger technology has been used for the turbomachinery. During recent years, turbocharger turbomachinery performance and efficiencies have significantly increased, even for very small sizes. At the same time, efficient high-speed motor-generators have become available at relatively low prices. The development of a concept demonstrator started in May 2008. This program phase included a cycle analysis and component selection study around off-the-shelf turbomachinery, design of a custom combustor, recuperator and generator, and a test program. In this paper, results of the cycle definition, conceptual design and component matching study are presented. Next, the development of a detailed performance model is described and performance prediction results are given. Also, results of the test program and test analysis work are presented. Finally, from the conclusion of the demonstrator phase an outlook is given on the prototype design and performance, which will be the next phase of the development program. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Development of a 3 kW microturbine for CHP applications [texte imprimé] / W. P. J. Visser, Auteur ; S. A. Shakariyants, Auteur ; M. Oostveen, Auteur . - 2012 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 08 p. Mots-clés : Air  pollution  control  Carbon  compounds  Cogeneration  Distributed  power  generation  Turbogenerators Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Combined heat and power (CHP) concepts for small-scale distributed power generation offer significant potential for saving energy and reducing CO2 emissions. Microturbines are an interesting candidate for small CHP systems with advantages in terms of performance, size, noise, and costs. MTT is developing a 3 kW recuperated microturbine for micro CHP applications for large households and for truck combined APU-heating systems. To minimize costs, off-the-shelf automotive turbocharger technology has been used for the turbomachinery. During recent years, turbocharger turbomachinery performance and efficiencies have significantly increased, even for very small sizes. At the same time, efficient high-speed motor-generators have become available at relatively low prices. The development of a concept demonstrator started in May 2008. This program phase included a cycle analysis and component selection study around off-the-shelf turbomachinery, design of a custom combustor, recuperator and generator, and a test program. In this paper, results of the cycle definition, conceptual design and component matching study are presented. Next, the development of a detailed performance model is described and performance prediction results are given. Also, results of the test program and test analysis work are presented. Finally, from the conclusion of the demonstrator phase an outlook is given on the prototype design and performance, which will be the next phase of the development program. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Primary surface recuperator alloy oxidation / Wendy J. Matthews in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 05 p. Titre : Primary surface recuperator alloy oxidation : a comparison of accelerated engine testing to field operation Type de document : texte imprimé Auteurs : Wendy J. Matthews, Auteur ; Karren L. More, Auteur ; Larry R. Walker, Auteur Année de publication : 2012 Article en page(s) : 05 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Alloys  Chromium  alloys  Gas  turbines  Heat  exchangers  Iron  alloys  Life  testing  Nickel  alloys  Oxidation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The Capstone C65 Microturbine primary surface recuperator (PSR) core has been manufactured from Haynes alloy HR-120 since 2005 (Microturbine is a registered trademark of Capstone Turbine Corporation; Haynes and HR-120 are trademarks of Haynes International, Inc.). When exposed to the harsh operating environment of the microturbine PSR, HR-120 forms a protective oxide scale that is resistant to the effects of the water vapor present in the exhaust gas. Long-term accelerated microturbine testing with samples in a modified PSR with a removable aft dome is ongoing at an elevated turbine exit temperature (TET) ~100°F higher than normal operation. The elevated TET test engine is operated at steady-state conditions, and the engine is shut down at predetermined intervals for sample removal. Material characterization of the elevated TET samples has been carried out by Capstone Turbine Corporation in collaboration with Oak Ridge National Laboratory. The surface oxide scale formation and associated alloy compositional changes have been evaluated for elevated TET samples with operating lives ranging from ~1800 h to ~26,500 h. In addition, field-operated HR-120 recuperators have been sectioned and samples have been evaluated for operating lives ranging from ~5500 h to ~18,000 h. Results from the microstructural and compositional analyses of both the long-term steady-state elevated TET HR-120 samples and the field-operated HR-120 recuperator samples will be presented and compared. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Primary surface recuperator alloy oxidation : a comparison of accelerated engine testing to field operation [texte imprimé] / Wendy J. Matthews, Auteur ; Karren L. More, Auteur ; Larry R. Walker, Auteur . - 2012 . - 05 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 05 p. Mots-clés : Alloys  Chromium  alloys  Gas  turbines  Heat  exchangers  Iron  alloys  Life  testing  Nickel  alloys  Oxidation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The Capstone C65 Microturbine primary surface recuperator (PSR) core has been manufactured from Haynes alloy HR-120 since 2005 (Microturbine is a registered trademark of Capstone Turbine Corporation; Haynes and HR-120 are trademarks of Haynes International, Inc.). When exposed to the harsh operating environment of the microturbine PSR, HR-120 forms a protective oxide scale that is resistant to the effects of the water vapor present in the exhaust gas. Long-term accelerated microturbine testing with samples in a modified PSR with a removable aft dome is ongoing at an elevated turbine exit temperature (TET) ~100°F higher than normal operation. The elevated TET test engine is operated at steady-state conditions, and the engine is shut down at predetermined intervals for sample removal. Material characterization of the elevated TET samples has been carried out by Capstone Turbine Corporation in collaboration with Oak Ridge National Laboratory. The surface oxide scale formation and associated alloy compositional changes have been evaluated for elevated TET samples with operating lives ranging from ~1800 h to ~26,500 h. In addition, field-operated HR-120 recuperators have been sectioned and samples have been evaluated for operating lives ranging from ~5500 h to ~18,000 h. Results from the microstructural and compositional analyses of both the long-term steady-state elevated TET HR-120 samples and the field-operated HR-120 recuperator samples will be presented and compared. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Design and performance prediction of hybrid air foil thrust bearings / Donghyun Lee in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 13 p. Titre : Design and performance prediction of hybrid air foil thrust bearings Type de document : texte imprimé Auteurs : Donghyun Lee, Auteur ; Daejong Kim, Auteur Année de publication : 2012 Article en page(s) : 13 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  components  Aerospace  engines  Damping  Design  engineering  Elasticity  Finite  difference  methods  Friction  Hydrostatics  Machine  bearings  Orifices  (mechanical)  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Air foil bearings (AFBs) have been recognized as the most promising for oil-free turbomachinery. However, the applications of AFBs to the relatively large turbomachinery have many technical challenges due to limited load capacity and wear during start/stops. A hybrid air foil bearing (HAFB), which combines the benefits of AFB and hydrostatic air bearing, was introduced earlier by the authors, and the experimental studies showed much larger load capacity at low speeds and much lesser friction torque during start/stop than hydrodynamic counterpart. The benefit of HAFB was recognized through the experimental studies, and the concept of hybrid operation was further developed to thrust air foil bearings. This paper presents novel design features of the hybrid air foil thrust bearing (HAFTB) with radially arranged bump foils and preformed Rayleigh step contour, and presents simulated static and dynamic characteristics of the HAFTB. A 2D thin plate equation in cylindrical coordinate was solved with the finite difference method for the prediction of the top foil deflection. Parametric studies were performed to evaluate the effect of various design parameters on the static and dynamic performances of HAFTB. At low speeds, a design with orifice located at the center of land region showed the highest load capacity, while a design with orifice located near the leading edge of land region showed the highest load capacity at high speeds. Direct and coupled bearing coefficients were also calculated for various operating conditions. The direct stiffness increases with supply pressure but the direct damping decreases with supply pressure. In addition, typical hardening effect of gas film accompanying increase of stiffness and decrease of damping was predicted in high frequency excitations. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Design and performance prediction of hybrid air foil thrust bearings [texte imprimé] / Donghyun Lee, Auteur ; Daejong Kim, Auteur . - 2012 . - 13 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 13 p. Mots-clés : Aerospace  components  Aerospace  engines  Damping  Design  engineering  Elasticity  Finite  difference  methods  Friction  Hydrostatics  Machine  bearings  Orifices  (mechanical)  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Air foil bearings (AFBs) have been recognized as the most promising for oil-free turbomachinery. However, the applications of AFBs to the relatively large turbomachinery have many technical challenges due to limited load capacity and wear during start/stops. A hybrid air foil bearing (HAFB), which combines the benefits of AFB and hydrostatic air bearing, was introduced earlier by the authors, and the experimental studies showed much larger load capacity at low speeds and much lesser friction torque during start/stop than hydrodynamic counterpart. The benefit of HAFB was recognized through the experimental studies, and the concept of hybrid operation was further developed to thrust air foil bearings. This paper presents novel design features of the hybrid air foil thrust bearing (HAFTB) with radially arranged bump foils and preformed Rayleigh step contour, and presents simulated static and dynamic characteristics of the HAFTB. A 2D thin plate equation in cylindrical coordinate was solved with the finite difference method for the prediction of the top foil deflection. Parametric studies were performed to evaluate the effect of various design parameters on the static and dynamic performances of HAFTB. At low speeds, a design with orifice located at the center of land region showed the highest load capacity, while a design with orifice located near the leading edge of land region showed the highest load capacity at high speeds. Direct and coupled bearing coefficients were also calculated for various operating conditions. The direct stiffness increases with supply pressure but the direct damping decreases with supply pressure. In addition, typical hardening effect of gas film accompanying increase of stiffness and decrease of damping was predicted in high frequency excitations. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Remaining technical challenges and future plans for oil-free turbomachinery / Christopher DellaCorte in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 07 p. Titre : Remaining technical challenges and future plans for oil-free turbomachinery Type de document : texte imprimé Auteurs : Christopher DellaCorte, Auteur ; Robert J. Bruckner, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  engines  Aerospace  propulsion  Compressors  Gas  turbines  Lubricants Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The application of oil-free technologies (foil gas bearings, solid lubricants, and advanced analysis and predictive modeling tools) to advanced turbomachinery has been underway for several decades. During that time, full commercialization has occurred in aircraft air cycle machines, turbocompressors, cryocoolers, and ever-larger microturbines. Emerging products in the automotive sector (turbochargers and superchargers) indicate that a high volume serial production of foil bearings is imminent. The demonstration of foil bearings in auxiliary power units and select locations in propulsion gas turbines illustrates that such technology also has a place in these future systems. Foil bearing designs, predictive tools, and advanced solid lubricants that can satisfy anticipated requirements have been reported, but a major question remains regarding the scalability of foil bearings to ever-larger sizes to support heavier rotors. In this paper, the technological history, primary physics, engineering practicalities, and existing experimental and experiential database for scaling foil bearings are reviewed, and the major remaining technical challenges are identified DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Remaining technical challenges and future plans for oil-free turbomachinery [texte imprimé] / Christopher DellaCorte, Auteur ; Robert J. Bruckner, Auteur . - 2012 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 07 p. Mots-clés : Aerospace  engines  Aerospace  propulsion  Compressors  Gas  turbines  Lubricants Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The application of oil-free technologies (foil gas bearings, solid lubricants, and advanced analysis and predictive modeling tools) to advanced turbomachinery has been underway for several decades. During that time, full commercialization has occurred in aircraft air cycle machines, turbocompressors, cryocoolers, and ever-larger microturbines. Emerging products in the automotive sector (turbochargers and superchargers) indicate that a high volume serial production of foil bearings is imminent. The demonstration of foil bearings in auxiliary power units and select locations in propulsion gas turbines illustrates that such technology also has a place in these future systems. Foil bearing designs, predictive tools, and advanced solid lubricants that can satisfy anticipated requirements have been reported, but a major question remains regarding the scalability of foil bearings to ever-larger sizes to support heavier rotors. In this paper, the technological history, primary physics, engineering practicalities, and existing experimental and experiential database for scaling foil bearings are reviewed, and the major remaining technical challenges are identified DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

A methodology for predicting the response of blades with nonlinear coatings / Sergio Filippi in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 07 p. Titre : A methodology for predicting the response of blades with nonlinear coatings Type de document : texte imprimé Auteurs : Sergio Filippi, Auteur ; Peter J. Torvik, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Benchmark  testing  Blades  Corrosion  resistance  Engines  Finite  element  analysis  Gas  turbines  Thermal  barrier  coatings  Young's  modulus Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Ceramic coatings applied by air plasma spray or electron beam techniques as thermal barrier coatings or to improve the erosion or corrosion resistance of blades in gas turbine engines are found to add damping to the system. However, such coatings display nonlinear mechanical properties in that the Young's modulus and the measure of damping are dependent on the amplitude of cyclic strain. To account for the coating nonlinearity, a new methodology for predicting blade response was developed and applied to an actual component coated with a titania-alumina blend ceramic infiltrated with a viscoelastic material. Resonant frequencies, mode shapes, and the forced response of a one blade segment of an integrated disk from a fan stage rotor were computed and compared with results from bench tests. Predicted frequencies agreed satisfactorily with measured values; predicted and observed values of system damping agreed to within 10%. The results of these comparisons are taken to indicate that it is possible to use laboratory-determined material properties together with an iterative finite element analysis to obtain satisfactory predictions of the response of an actual blade with a nonlinear coating. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] A methodology for predicting the response of blades with nonlinear coatings [texte imprimé] / Sergio Filippi, Auteur ; Peter J. Torvik, Auteur . - 2012 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 07 p. Mots-clés : Benchmark  testing  Blades  Corrosion  resistance  Engines  Finite  element  analysis  Gas  turbines  Thermal  barrier  coatings  Young's  modulus Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Ceramic coatings applied by air plasma spray or electron beam techniques as thermal barrier coatings or to improve the erosion or corrosion resistance of blades in gas turbine engines are found to add damping to the system. However, such coatings display nonlinear mechanical properties in that the Young's modulus and the measure of damping are dependent on the amplitude of cyclic strain. To account for the coating nonlinearity, a new methodology for predicting blade response was developed and applied to an actual component coated with a titania-alumina blend ceramic infiltrated with a viscoelastic material. Resonant frequencies, mode shapes, and the forced response of a one blade segment of an integrated disk from a fan stage rotor were computed and compared with results from bench tests. Predicted frequencies agreed satisfactorily with measured values; predicted and observed values of system damping agreed to within 10%. The results of these comparisons are taken to indicate that it is possible to use laboratory-determined material properties together with an iterative finite element analysis to obtain satisfactory predictions of the response of an actual blade with a nonlinear coating. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Rotordynamic force prediction of centrifugal compressor impellers using computational fluid dynamics / J. Jeffrey Moore in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 10 p. Titre : Rotordynamic force prediction of centrifugal compressor impellers using computational fluid dynamics Type de document : texte imprimé Auteurs : J. Jeffrey Moore, Auteur ; David L. Ransom, Auteur ; Flavia Viana, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerodynamics  Compressors  Computational  fluid  dynamics  Impellers  Production  equipment  Rotors Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The energy industry depends on centrifugal compressors to produce, process, reinject, and transport many different gases. Centrifugal compressors use one or more impellers to impart momentum to the flowing gas and, thereby, produce an increase in pressure through diffusion. As the operating pressure in a compressor increases, the fluid-rotor interaction at the seals and impellers become more important. Also, the new generation of megascale liquefied natural gas compressors is dependent on accurate assessment of these forces. The aerodynamic forces and cross-coupled stiffness from the impellers cannot be accurately predicted with traditional methods and must be estimated with semiempirical formulations. The result of these inaccuracies is a potential for compressor designs that can experience unexpected, dangerous, and damaging instabilities and subsynchronous vibrations. The current investigation is intended to advance the state of the art to achieve an improved, physics-based method of predicted aerodynamic destabilizing cross-coupling forces on centrifugal compressor impellers using computational fluid dynamics (CFD). CFD was employed in this study to predict the impeller-fluid interaction forces, which gives rise to the aerodynamic cross coupling. The procedure utilized in this study was developed by Moore and Palazzolo (2002, “Rotordynamic Force Prediction of Centrifugal Impeller Shroud Passages Using Computational Fluid Dynamic Techniques With Combined Primary Secondary Flow Model,” ASME J. Eng. Gas Turbines Power, 123, pp. 910–918), which applied the method to liquid pump impellers. Their results showed good correlation to test data. Unfortunately, no such data exist for centrifugal compressors. Therefore, in order to validate the present model, comparisons will be made to predict the instability of an industrial centrifugal compressor. A parametric CFD study is then presented leading to a new analytical expression for predicting the cross-coupled stiffness for centrifugal impellers. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Rotordynamic force prediction of centrifugal compressor impellers using computational fluid dynamics [texte imprimé] / J. Jeffrey Moore, Auteur ; David L. Ransom, Auteur ; Flavia Viana, Auteur . - 2012 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 10 p. Mots-clés : Aerodynamics  Compressors  Computational  fluid  dynamics  Impellers  Production  equipment  Rotors Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The energy industry depends on centrifugal compressors to produce, process, reinject, and transport many different gases. Centrifugal compressors use one or more impellers to impart momentum to the flowing gas and, thereby, produce an increase in pressure through diffusion. As the operating pressure in a compressor increases, the fluid-rotor interaction at the seals and impellers become more important. Also, the new generation of megascale liquefied natural gas compressors is dependent on accurate assessment of these forces. The aerodynamic forces and cross-coupled stiffness from the impellers cannot be accurately predicted with traditional methods and must be estimated with semiempirical formulations. The result of these inaccuracies is a potential for compressor designs that can experience unexpected, dangerous, and damaging instabilities and subsynchronous vibrations. The current investigation is intended to advance the state of the art to achieve an improved, physics-based method of predicted aerodynamic destabilizing cross-coupling forces on centrifugal compressor impellers using computational fluid dynamics (CFD). CFD was employed in this study to predict the impeller-fluid interaction forces, which gives rise to the aerodynamic cross coupling. The procedure utilized in this study was developed by Moore and Palazzolo (2002, “Rotordynamic Force Prediction of Centrifugal Impeller Shroud Passages Using Computational Fluid Dynamic Techniques With Combined Primary Secondary Flow Model,” ASME J. Eng. Gas Turbines Power, 123, pp. 910–918), which applied the method to liquid pump impellers. Their results showed good correlation to test data. Unfortunately, no such data exist for centrifugal compressors. Therefore, in order to validate the present model, comparisons will be made to predict the instability of an industrial centrifugal compressor. A parametric CFD study is then presented leading to a new analytical expression for predicting the cross-coupled stiffness for centrifugal impellers. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

On thermal performance of seawater cooling towers / Mostafa H. Sharqawy in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 07 p. Titre : On thermal performance of seawater cooling towers Type de document : texte imprimé Auteurs : Mostafa H. Sharqawy, Auteur ; John H. Lienhard, V, Auteur ; Syed M. Zubair, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cooling  towers  Seawater  Surface  tension  Thermal  conductivity  Viscosity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Seawater cooling towers have been used since the 1970s in power generation and other industries, so as to reduce the consumption of freshwater. The salts in seawater are known to create a number of operational problems, including salt deposition, packing blockage, corrosion, and certain environmental impacts from salt drift and blowdown return. In addition, the salinity of seawater affects the thermophysical properties that govern the thermal performance of cooling towers, including vapor pressure, density, specific heat, viscosity, thermal conductivity, and surface tension. In this paper, the thermal performance of seawater cooling towers is investigated using a detailed model of a counterflow wet cooling tower. The model takes into consideration the coupled heat and mass transfer processes and does not make any of the conventional Merkel approximations. In addition, the model incorporates the most up-to-date seawater properties in the literature. The model governing equations are solved numerically, and its validity is checked against the available data in the literature. Based on the results of the model, a correction factor that characterizes the degradation of the cooling tower effectiveness as a function of seawater salinity and temperature approach is presented for performance evaluation purposes. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] On thermal performance of seawater cooling towers [texte imprimé] / Mostafa H. Sharqawy, Auteur ; John H. Lienhard, V, Auteur ; Syed M. Zubair, Auteur . - 2012 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 07 p. Mots-clés : Cooling  towers  Seawater  Surface  tension  Thermal  conductivity  Viscosity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Seawater cooling towers have been used since the 1970s in power generation and other industries, so as to reduce the consumption of freshwater. The salts in seawater are known to create a number of operational problems, including salt deposition, packing blockage, corrosion, and certain environmental impacts from salt drift and blowdown return. In addition, the salinity of seawater affects the thermophysical properties that govern the thermal performance of cooling towers, including vapor pressure, density, specific heat, viscosity, thermal conductivity, and surface tension. In this paper, the thermal performance of seawater cooling towers is investigated using a detailed model of a counterflow wet cooling tower. The model takes into consideration the coupled heat and mass transfer processes and does not make any of the conventional Merkel approximations. In addition, the model incorporates the most up-to-date seawater properties in the literature. The model governing equations are solved numerically, and its validity is checked against the available data in the literature. Based on the results of the model, a correction factor that characterizes the degradation of the cooling tower effectiveness as a function of seawater salinity and temperature approach is presented for performance evaluation purposes. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Examination of initialization and geometric details on the results of CFD simulations of diesel engines / Michael J. Bergin in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 04 p. Titre : Examination of initialization and geometric details on the results of CFD simulations of diesel engines Type de document : texte imprimé Auteurs : Michael J. Bergin, Auteur ; Ettore Musu, Auteur ; Sage Kokjohn, Auteur Année de publication : 2012 Article en page(s) : 04 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Computational  fluid  dynamics  Diesel  engines  Flow  simulation  Swirling  flow  Torque  Valves Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Computational fluid dynamic simulations using the AVL FIRE and KIVA 3V codes were performed to examine commonly accepted techniques and assumptions used when simulating direct injection diesel engines. Simulations of a steady-state impulse swirl meter validated the commonly used practice of evaluating the swirl ratio of diesel engines by integrating the valve flow and torque history over discrete valve lift values. The results indicate the simulations capture the complex interactions occurring in the ports, cylinder, and honeycomb cell impulse swirl meter. Geometric details of engines due to valve recesses in the cylinder head and piston cannot be reproduced axisymmetrically. The commonly adopted axisymmetric assumption for an engine with a centrally located injector was tested by comparing the swirl and emissions history for a noncombusting and a double injection low temperature combustion case with varying geometric fidelity. Consideration of the detailed engine geometry including valve recesses in the piston altered the swirl history such that the peak swirl ratio at TDC decreased by approximately 10% compared with the simplified no-recess geometry. An analog to the detailed geometry of the full 3D geometry was included in the axisymmetric geometry by including a groove in the cylinder head of the mesh. The corresponding emissions predictions of the combusting cases showed greater sensitivity to the altered swirl history as the air-fuel ratio was decreased. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Examination of initialization and geometric details on the results of CFD simulations of diesel engines [texte imprimé] / Michael J. Bergin, Auteur ; Ettore Musu, Auteur ; Sage Kokjohn, Auteur . - 2012 . - 04 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 4 (Avril 2011) . - 04 p. Mots-clés : Combustion  Computational  fluid  dynamics  Diesel  engines  Flow  simulation  Swirling  flow  Torque  Valves Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Computational fluid dynamic simulations using the AVL FIRE and KIVA 3V codes were performed to examine commonly accepted techniques and assumptions used when simulating direct injection diesel engines. Simulations of a steady-state impulse swirl meter validated the commonly used practice of evaluating the swirl ratio of diesel engines by integrating the valve flow and torque history over discrete valve lift values. The results indicate the simulations capture the complex interactions occurring in the ports, cylinder, and honeycomb cell impulse swirl meter. Geometric details of engines due to valve recesses in the cylinder head and piston cannot be reproduced axisymmetrically. The commonly adopted axisymmetric assumption for an engine with a centrally located injector was tested by comparing the swirl and emissions history for a noncombusting and a double injection low temperature combustion case with varying geometric fidelity. Consideration of the detailed engine geometry including valve recesses in the piston altered the swirl history such that the peak swirl ratio at TDC decreased by approximately 10% compared with the simplified no-recess geometry. An analog to the detailed geometry of the full 3D geometry was included in the axisymmetric geometry by including a groove in the cylinder head of the mesh. The corresponding emissions predictions of the combusting cases showed greater sensitivity to the altered swirl history as the air-fuel ratio was decreased. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

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