Dépouillements

Vapor phase deposition using a plasma spray process / von Niessen, Konstantin in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 07 p. Titre : Vapor phase deposition using a plasma spray process Type de document : texte imprimé Auteurs : von Niessen, Konstantin, Auteur ; Gindrat, Malko, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Tubines à gaz Langues : Anglais (eng) Mots-clés : Crystal  microstructure  Engines  Jets  Plasma  arc  sprayed  coatings  Plasma  deposition  Thermal  barrier  coatings  Turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco AG (Switzerland) to deposit coatings out of the vapor phase. PS-PVD is developed on the basis of the well established low pressure plasma spraying technology. In comparison to conventional vacuum plasma spraying and low pressure plasma spraying, these new processes use a high energy plasma gun operated at a work pressure below 2 mbar. This leads to unconventional plasma jet characteristics, which can be used to obtain specific and unique coatings. An important new feature of PS-PVD is the possibility to deposit a coating not only by melting the feed stock material, which builds up a layer from liquid splats, but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional PVD technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and electron beam-physical vapor deposition (EB-PVD) coatings. In contrast to EB-PVD, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume. Due to the forced gas stream of the plasma jet, complex shaped parts like multi-airfoil turbine vanes can be coated with columnar thermal barrier coatings using PS-PVD. Even shadowed areas and areas, which are not in the line-of-sight to the coating source, can be coated homogeneously. This paper reports on the progress made by Sulzer Metco to develop a thermal spray process to produce coatings out of the vapor phase. Columnar thermal barrier coatings made of yttria stabilized zircona are optimized to serve in a turbine engine. This includes coating properties like strain tolerance and erosion resistance but also the coverage of multiple air foils. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Vapor phase deposition using a plasma spray process [texte imprimé] / von Niessen, Konstantin, Auteur ; Gindrat, Malko, Auteur . - 2011 . - 07 p. Tubines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 07 p. Mots-clés : Crystal  microstructure  Engines  Jets  Plasma  arc  sprayed  coatings  Plasma  deposition  Thermal  barrier  coatings  Turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco AG (Switzerland) to deposit coatings out of the vapor phase. PS-PVD is developed on the basis of the well established low pressure plasma spraying technology. In comparison to conventional vacuum plasma spraying and low pressure plasma spraying, these new processes use a high energy plasma gun operated at a work pressure below 2 mbar. This leads to unconventional plasma jet characteristics, which can be used to obtain specific and unique coatings. An important new feature of PS-PVD is the possibility to deposit a coating not only by melting the feed stock material, which builds up a layer from liquid splats, but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional PVD technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and electron beam-physical vapor deposition (EB-PVD) coatings. In contrast to EB-PVD, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume. Due to the forced gas stream of the plasma jet, complex shaped parts like multi-airfoil turbine vanes can be coated with columnar thermal barrier coatings using PS-PVD. Even shadowed areas and areas, which are not in the line-of-sight to the coating source, can be coated homogeneously. This paper reports on the progress made by Sulzer Metco to develop a thermal spray process to produce coatings out of the vapor phase. Columnar thermal barrier coatings made of yttria stabilized zircona are optimized to serve in a turbine engine. This includes coating properties like strain tolerance and erosion resistance but also the coverage of multiple air foils. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

The impact of density ratio on the liquid core dynamics of a turbulent liquid jet injected into a crossflow / Marcus Herrmann in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 09 p. Titre : The impact of density ratio on the liquid core dynamics of a turbulent liquid jet injected into a crossflow Type de document : texte imprimé Auteurs : Marcus Herrmann, Auteur ; Arienti, Marco, Auteur ; Marios Soteriou, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Bending  Dissociation  Flow  simulation  Gas  turbines  Jets  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Atomizing liquids by injecting them into crossflows is a common approach in gas turbines and augmentors. Much of our current understanding of the processes resulting in atomization of the jets, the resulting jet penetration and spray drop size distribution have been obtained by performing laboratory experiments at ambient conditions. Yet, operating conditions under which jets in crossflows atomize can be far different from ambient. Hence, several dimensionless groups have been identified that are believed to determine jet penetration and resulting drop size distribution. These are usually the jet and crossflow Weber and Reynolds numbers and the momentum flux ratio. In this paper, we aim to answer the question of whether an additional dimensionless group, the liquid to gas density ratio must be matched. We perform detailed simulations of the primary atomization region using the refined level set grid (RLSG) method to track the motion of the liquid/gas phase interface. We employ a balanced force, interface projected curvature method to ensure high accuracy of the surface tension forces, use a multiscale approach to transfer broken off, small scale nearly spherical drops into a Lagrangian point particle description allowing for full two-way coupling and continued secondary atomization, and employ a dynamic Smagorinsky large eddy simulation (LES) approach in the single phase regions of the flow to describe turbulence. We present simulation results for a turbulent liquid jet (q=6.6, We=330, and Re=14,000) injected into a gaseous crossflow (Re=740,000) analyzed under ambient conditions (density ratio 816) experimentally by Brown and McDonnell [2006, “Near Field Behavior of a Liquid Jet in a Crossflow,” Proceedings of the ILASS Americas, 19th Annual Conference on Liquid Atomization and Spray Systems]. We compare simulation results obtained using a liquid to gas density ratio of 10 and 100. The results show that the increase in density ratio causes a noticeable increase in liquid core penetration with reduced bending and spreading in the transverse directions. The post-primary atomization spray penetrates further in both the jet and transverse direction. Results further show that the penetration correlations for the windward side trajectory commonly reported in the literature strongly depend on the value of threshold probability used to identify the leading edge. Correlations based on penetration of the jet's liquid core center of mass, on the other hand, can provide a less ambiguous measure of jet penetration. Finally, the increase in density ratio results in a decrease in wavelength of the most dominant feature associated with a traveling wave along the jet as determined by proper orthogonal decomposition. DEWEY : 620.1 ISSN : 0742-9795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] The impact of density ratio on the liquid core dynamics of a turbulent liquid jet injected into a crossflow [texte imprimé] / Marcus Herrmann, Auteur ; Arienti, Marco, Auteur ; Marios Soteriou, Auteur . - 2011 . - 09 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 09 p. Mots-clés : Bending  Dissociation  Flow  simulation  Gas  turbines  Jets  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Atomizing liquids by injecting them into crossflows is a common approach in gas turbines and augmentors. Much of our current understanding of the processes resulting in atomization of the jets, the resulting jet penetration and spray drop size distribution have been obtained by performing laboratory experiments at ambient conditions. Yet, operating conditions under which jets in crossflows atomize can be far different from ambient. Hence, several dimensionless groups have been identified that are believed to determine jet penetration and resulting drop size distribution. These are usually the jet and crossflow Weber and Reynolds numbers and the momentum flux ratio. In this paper, we aim to answer the question of whether an additional dimensionless group, the liquid to gas density ratio must be matched. We perform detailed simulations of the primary atomization region using the refined level set grid (RLSG) method to track the motion of the liquid/gas phase interface. We employ a balanced force, interface projected curvature method to ensure high accuracy of the surface tension forces, use a multiscale approach to transfer broken off, small scale nearly spherical drops into a Lagrangian point particle description allowing for full two-way coupling and continued secondary atomization, and employ a dynamic Smagorinsky large eddy simulation (LES) approach in the single phase regions of the flow to describe turbulence. We present simulation results for a turbulent liquid jet (q=6.6, We=330, and Re=14,000) injected into a gaseous crossflow (Re=740,000) analyzed under ambient conditions (density ratio 816) experimentally by Brown and McDonnell [2006, “Near Field Behavior of a Liquid Jet in a Crossflow,” Proceedings of the ILASS Americas, 19th Annual Conference on Liquid Atomization and Spray Systems]. We compare simulation results obtained using a liquid to gas density ratio of 10 and 100. The results show that the increase in density ratio causes a noticeable increase in liquid core penetration with reduced bending and spreading in the transverse directions. The post-primary atomization spray penetrates further in both the jet and transverse direction. Results further show that the penetration correlations for the windward side trajectory commonly reported in the literature strongly depend on the value of threshold probability used to identify the leading edge. Correlations based on penetration of the jet's liquid core center of mass, on the other hand, can provide a less ambiguous measure of jet penetration. Finally, the increase in density ratio results in a decrease in wavelength of the most dominant feature associated with a traveling wave along the jet as determined by proper orthogonal decomposition. DEWEY : 620.1 ISSN : 0742-9795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

Describing function analysis of limit cycles in a multiple flame combustor / Frédéric Boudy in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 08 p. Titre : Describing function analysis of limit cycles in a multiple flame combustor Type de document : texte imprimé Auteurs : Frédéric Boudy, Auteur ; Daniel Durox, Auteur ; Thierry Schuller, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Chemically  reactive  flow  Combustion  Flames  Flow  instability  Fluid  oscillations  Functional  analysis  Laminar  flow  Pipe  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A recently developed nonlinear flame describing function (FDF) is used to analyze combustion instabilities in a system where the feeding manifold has a variable size and where the flame is confined by quartz tubes of variable length. Self-sustained combustion oscillations are observed when the geometry is changed. The regimes of oscillation are characterized at the limit cycle and also during the onset of oscillations. The theoretical predictions of the oscillation frequencies and levels are obtained using the FDF. This generalizes the concept of flame transfer function by including dependence on the frequency and level of oscillation. Predictions are compared with experimental results for two different lengths of the confinement tube. These results are, in turn, used to predict most of the experimentally observed phenomena and in particular, the correct oscillation levels and frequencies at limit cycles. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Describing function analysis of limit cycles in a multiple flame combustor [texte imprimé] / Frédéric Boudy, Auteur ; Daniel Durox, Auteur ; Thierry Schuller, Auteur . - 2011 . - 08 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 08 p. Mots-clés : Chemically  reactive  flow  Combustion  Flames  Flow  instability  Fluid  oscillations  Functional  analysis  Laminar  flow  Pipe  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A recently developed nonlinear flame describing function (FDF) is used to analyze combustion instabilities in a system where the feeding manifold has a variable size and where the flame is confined by quartz tubes of variable length. Self-sustained combustion oscillations are observed when the geometry is changed. The regimes of oscillation are characterized at the limit cycle and also during the onset of oscillations. The theoretical predictions of the oscillation frequencies and levels are obtained using the FDF. This generalizes the concept of flame transfer function by including dependence on the frequency and level of oscillation. Predictions are compared with experimental results for two different lengths of the confinement tube. These results are, in turn, used to predict most of the experimentally observed phenomena and in particular, the correct oscillation levels and frequencies at limit cycles. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

Methane oxycombustion for low CO2 cycles / A. Amato in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 09 p. Titre : Methane oxycombustion for low CO2 cycles : blowoff measurements and analysis Type de document : texte imprimé Auteurs : A. Amato, Auteur ; B. Hudak, Auteur ; P. D'Carlo, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Oxyfuel  Carbon  dioxide  Blowoff  Carbon  capture Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Increasing concerns about climate change have encouraged interest in zero-CO2 emission hydrocarbon combustion techniques. In one approach, nitrogen is removed from the combustion air and replaced with another diluent, typically carbon dioxide or steam. In this way, formation of nitrogen oxides is prevented and the exhaust stream can be separated into concentrated CO2 and water by a simple condensation process. The concentrated CO2 stream can then be sequestered or used for enhanced oil recovery. Burning fuels in an O2/CO2 diluent raises new combustion opportunities and challenges for both emissions and operability: this study focuses on the latter aspect. CH4/O2/CO2 flames have slower chemical kinetics than methane-air flames and as such, flame stability is more problematic as they are easier to blow off. This issue was investigated experimentally by characterizing the stability boundaries of a swirl stabilized combustor. Near stoichiometric CO2 and N2 diluted methane/oxygen flames were considered and compared with lean methane/air flames. Numerical modeling of chemical kinetics was also performed to analyze the dependence of laminar flame speeds and extinction strain rates upon dilution by different species and to develop correlations for blowoff boundaries. Finally, blowoff trends at high pressure were extrapolated from atmospheric pressure data to simulate conditions closer to those of gas turbines. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Methane oxycombustion for low CO2 cycles : blowoff measurements and analysis [texte imprimé] / A. Amato, Auteur ; B. Hudak, Auteur ; P. D'Carlo, Auteur . - 2011 . - 09 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 09 p. Mots-clés : Oxyfuel  Carbon  dioxide  Blowoff  Carbon  capture Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Increasing concerns about climate change have encouraged interest in zero-CO2 emission hydrocarbon combustion techniques. In one approach, nitrogen is removed from the combustion air and replaced with another diluent, typically carbon dioxide or steam. In this way, formation of nitrogen oxides is prevented and the exhaust stream can be separated into concentrated CO2 and water by a simple condensation process. The concentrated CO2 stream can then be sequestered or used for enhanced oil recovery. Burning fuels in an O2/CO2 diluent raises new combustion opportunities and challenges for both emissions and operability: this study focuses on the latter aspect. CH4/O2/CO2 flames have slower chemical kinetics than methane-air flames and as such, flame stability is more problematic as they are easier to blow off. This issue was investigated experimentally by characterizing the stability boundaries of a swirl stabilized combustor. Near stoichiometric CO2 and N2 diluted methane/oxygen flames were considered and compared with lean methane/air flames. Numerical modeling of chemical kinetics was also performed to analyze the dependence of laminar flame speeds and extinction strain rates upon dilution by different species and to develop correlations for blowoff boundaries. Finally, blowoff trends at high pressure were extrapolated from atmospheric pressure data to simulate conditions closer to those of gas turbines. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

Measurement and simulation of turbulent mixing in a jet in crossflow / Flavio Cesar Cunha Galeazzo in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 10 p. Titre : Measurement and simulation of turbulent mixing in a jet in crossflow Type de document : texte imprimé Auteurs : Flavio Cesar Cunha Galeazzo, Auteur ; Donnert, Georg, Auteur ; Peter Habisreuther, Auteur Année de publication : 2011 Article en page(s) : 10 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Combustion  Computational  fluid  dynamics  Flow  measurement  Flow  simulation  Gas  turbines  Jets  Navier-Stokes  equations  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Computational fluid dynamics (CFD) has an important role in current research. While large eddy simulations (LES) are now common practice in academia, Reynolds-averaged Navier–Stokes (RANS) simulations are still very common in the industry. Using RANS allows faster simulations, however, the choice of the turbulence model has a bigger impact on the results. An important influence of the turbulence modeling is the description of turbulent mixing. Experience has shown that often inaccurate simulations of combustion processes originate from an inadequate description of the mixing field. A simple turbulent flow and mixing configuration of major theoretical and practical importance is the jet in crossflow (JIC). Due to its good fuel-air mixing capability over a small distance, JIC is favored by gas turbine manufacturers. As the design of the mixing process is the key to creating stable low NOx combustion systems, reliable predictive tools and detailed understanding of this basic system are still demanded. Therefore, the current study has re-investigated the JIC configuration under engine relevant conditions both experimentally and numerically using the most sophisticated tools available today. The combination of planar particle image velocimetry and laser induced fluorescence was used to measure the turbulent velocity and concentration fields as well as to determine the correlations of the Reynolds stress tensor [overline u[sub i][sup [prime]]u[sub j][sup [prime]]] and the Reynolds flux vector [overline u[sub i][sup [prime]]c[sup [prime]]]. Boundary conditions were determined using laser Doppler velocimetry. The comparisons between the measurements and simulation using RANS and LES showed that the mean velocity field was well described using the SST turbulence model. However, the Reynolds stresses and more so, the Reynolds fluxes deviate substantially from the measured data. The systematic variation of the turbulent Schmidt number reveals the limited influence of this parameter indicating that the basic modeling is amiss. The results of the LES simulation using the standard Smagorinsky model were found to provide much better agreement with the experiments also in the description of turbulent mixing. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Measurement and simulation of turbulent mixing in a jet in crossflow [texte imprimé] / Flavio Cesar Cunha Galeazzo, Auteur ; Donnert, Georg, Auteur ; Peter Habisreuther, Auteur . - 2011 . - 10 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 10 p. Mots-clés : Combustion  Computational  fluid  dynamics  Flow  measurement  Flow  simulation  Gas  turbines  Jets  Navier-Stokes  equations  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Computational fluid dynamics (CFD) has an important role in current research. While large eddy simulations (LES) are now common practice in academia, Reynolds-averaged Navier–Stokes (RANS) simulations are still very common in the industry. Using RANS allows faster simulations, however, the choice of the turbulence model has a bigger impact on the results. An important influence of the turbulence modeling is the description of turbulent mixing. Experience has shown that often inaccurate simulations of combustion processes originate from an inadequate description of the mixing field. A simple turbulent flow and mixing configuration of major theoretical and practical importance is the jet in crossflow (JIC). Due to its good fuel-air mixing capability over a small distance, JIC is favored by gas turbine manufacturers. As the design of the mixing process is the key to creating stable low NOx combustion systems, reliable predictive tools and detailed understanding of this basic system are still demanded. Therefore, the current study has re-investigated the JIC configuration under engine relevant conditions both experimentally and numerically using the most sophisticated tools available today. The combination of planar particle image velocimetry and laser induced fluorescence was used to measure the turbulent velocity and concentration fields as well as to determine the correlations of the Reynolds stress tensor [overline u[sub i][sup [prime]]u[sub j][sup [prime]]] and the Reynolds flux vector [overline u[sub i][sup [prime]]c[sup [prime]]]. Boundary conditions were determined using laser Doppler velocimetry. The comparisons between the measurements and simulation using RANS and LES showed that the mean velocity field was well described using the SST turbulence model. However, the Reynolds stresses and more so, the Reynolds fluxes deviate substantially from the measured data. The systematic variation of the turbulent Schmidt number reveals the limited influence of this parameter indicating that the basic modeling is amiss. The results of the LES simulation using the standard Smagorinsky model were found to provide much better agreement with the experiments also in the description of turbulent mixing. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

Hot streak migration in a turbine stage / Altug M. Basol in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 10 p. Titre : Hot streak migration in a turbine stage : integrated design to improve aerothermal performance Type de document : texte imprimé Auteurs : Altug M. Basol, Auteur ; Philipp Jenny, Auteur ; Mohamed Ibrahim, Auteur Année de publication : 2011 Article en page(s) : 10 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Rotors  Stators  Turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Hot streaks can cause localized hot spots on the blade surfaces in a high pressure turbine, increasing the heat load locally and even leading to material loss in regions such as the rotor blade tip. This study explores numerically the effect of the hot streak's clocking position at the stator inlet on the rotor blade heat load and on the tip in particular. The inlet boundary conditions are taken from the hot streak experiment conducted in the axial turbine facility “LISA” at ETH Zurich. Using a particle tracking tool, in conjunction with time resolved simulations, a detailed analysis of the migration pattern of the hot streak is performed and the underlying mechanisms are discussed. The effect of clocking the hot streak from midpitch to the stator pressure side and in the opposite direction is examined. By clocking this particular hot streak even 10% of the stator pitch toward the pressure side up to 24 K reduction in the rotor blade tip adiabatic wall temperatures could be achieved under realistic engine conditions. Finally, based on the observations made, the implications for an integrated combustor-turbine design strategy are discussed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Hot streak migration in a turbine stage : integrated design to improve aerothermal performance [texte imprimé] / Altug M. Basol, Auteur ; Philipp Jenny, Auteur ; Mohamed Ibrahim, Auteur . - 2011 . - 10 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 10 p. Mots-clés : Rotors  Stators  Turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Hot streaks can cause localized hot spots on the blade surfaces in a high pressure turbine, increasing the heat load locally and even leading to material loss in regions such as the rotor blade tip. This study explores numerically the effect of the hot streak's clocking position at the stator inlet on the rotor blade heat load and on the tip in particular. The inlet boundary conditions are taken from the hot streak experiment conducted in the axial turbine facility “LISA” at ETH Zurich. Using a particle tracking tool, in conjunction with time resolved simulations, a detailed analysis of the migration pattern of the hot streak is performed and the underlying mechanisms are discussed. The effect of clocking the hot streak from midpitch to the stator pressure side and in the opposite direction is examined. By clocking this particular hot streak even 10% of the stator pitch toward the pressure side up to 24 K reduction in the rotor blade tip adiabatic wall temperatures could be achieved under realistic engine conditions. Finally, based on the observations made, the implications for an integrated combustor-turbine design strategy are discussed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

Study of a two-phase flow pump and separator system / François Gruselle in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 08 p. Titre : Study of a two-phase flow pump and separator system Type de document : texte imprimé Auteurs : François Gruselle, Auteur ; Johan Steimes, Auteur ; Patrick Hendrick, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Two-phase  flow  Separation  Pumping  Experiments  CFD  simulations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The Aero-Thermo-Mechanics (ATM) Department of ULB (Université Libre de Bruxelles) is developing an original system to pump and separate a two-phase flow. Many applications need to extract a certain phase of a multiphase flow: oil extraction, flow in nuclear pumps, flow in aircraft lubrication systems, pulp and paper processing, etc. The main objective of this study is to obtain a lightweight, compact, and efficient system that can both extract the gas of a two-phase flow and increase the pressure of the liquid phase. Prototypes with different designs were first tested at ULB on a specific test bench using water and air. The current prototype is a kind of axial-centrifugal pump. The axial part is used to separate the two phases of the flow and to collect, in the centrifugal part, the liquid phase only. The test results of the water-air prototypes have allowed to identify the key design and working parameters for efficient separation and pumping. A theoretical model has also been developed to describe the behavior of these prototypes. After successful tests with water-air mixtures, the technology has been implemented for a hot oil-air mixture. The tests with oil-air mixtures are performed on the aeroengine lubrication system test bench that the ATM Department developed and continues developing for other projects. At the same time, the flow field in the pump and separator system is being studied with commercial computational fluid dynamics software packages. Several two-phase flow models are considered for this particular application. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Study of a two-phase flow pump and separator system [texte imprimé] / François Gruselle, Auteur ; Johan Steimes, Auteur ; Patrick Hendrick, Auteur . - 2011 . - 08 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 08 p. Mots-clés : Two-phase  flow  Separation  Pumping  Experiments  CFD  simulations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The Aero-Thermo-Mechanics (ATM) Department of ULB (Université Libre de Bruxelles) is developing an original system to pump and separate a two-phase flow. Many applications need to extract a certain phase of a multiphase flow: oil extraction, flow in nuclear pumps, flow in aircraft lubrication systems, pulp and paper processing, etc. The main objective of this study is to obtain a lightweight, compact, and efficient system that can both extract the gas of a two-phase flow and increase the pressure of the liquid phase. Prototypes with different designs were first tested at ULB on a specific test bench using water and air. The current prototype is a kind of axial-centrifugal pump. The axial part is used to separate the two phases of the flow and to collect, in the centrifugal part, the liquid phase only. The test results of the water-air prototypes have allowed to identify the key design and working parameters for efficient separation and pumping. A theoretical model has also been developed to describe the behavior of these prototypes. After successful tests with water-air mixtures, the technology has been implemented for a hot oil-air mixture. The tests with oil-air mixtures are performed on the aeroengine lubrication system test bench that the ATM Department developed and continues developing for other projects. At the same time, the flow field in the pump and separator system is being studied with commercial computational fluid dynamics software packages. Several two-phase flow models are considered for this particular application. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

Thermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part I: measurements / Luis San Andrés in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 10 p. Titre : Thermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part I: measurements Type de document : texte imprimé Auteurs : Luis San Andrés, Auteur ; Ryu, Keun, Auteur ; Tae Ho Kim, Auteur Année de publication : 2011 Article en page(s) : 10 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Cooling  Gas  turbines  Machine  bearings  Rotors  Shafts  Temperature  measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Implementation of gas foil bearings (GFBs) into micro gas turbines requires careful thermal management with accurate measurements verifying model predictions. This two-part paper presents test data and analytical results for a test rotor and GFB system operating hot (157°C maximum rotor outer diameter (OD) temperature). Part I details the test rig and measurements of bearing temperatures and rotor dynamic motions obtained in a hollow rotor supported on a pair of second generation GFBs, each consisting of a single top foil (38.14 mm inner diameter) uncoated for high temperature operation and five bump strip support layers. An electric cartridge (maximum of 360°C) loosely installed inside the rotor (1.065 kg, 38.07 mm OD, and 4.8 mm thick) is a heat source warming the rotor-bearing system. While coasting down from 30 krpm to rest, large elapsed times (50–70 s) demonstrate rotor airborne operation, near friction free, and while traversing the system critical speed at ~13 krpm, the rotor peak motion amplitude decreases as the system temperature increases. In tests conducted at a fixed rotor speed of 30 krpm, while the shaft heats, a cooling gas stream of increasing strength is set to manage the temperatures in the bearings and rotor. The effect of the cooling flow, if turbulent in character, is most distinctive at the highest heater temperature. For operation at a lower heater temperature condition, however, the cooling flow stream demonstrates a very limited effectiveness. The measurements demonstrate the reliable performance of the rotor-GFB system when operating hot. The test results, along with full disclosure on the materials and geometry of the test bearings and rotor, serve to benchmark a predictive tool. A companion paper (Part II) compares the measured bearing temperatures and the rotor response amplitudes to predictions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Thermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part I: measurements [texte imprimé] / Luis San Andrés, Auteur ; Ryu, Keun, Auteur ; Tae Ho Kim, Auteur . - 2011 . - 10 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 10 p. Mots-clés : Cooling  Gas  turbines  Machine  bearings  Rotors  Shafts  Temperature  measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Implementation of gas foil bearings (GFBs) into micro gas turbines requires careful thermal management with accurate measurements verifying model predictions. This two-part paper presents test data and analytical results for a test rotor and GFB system operating hot (157°C maximum rotor outer diameter (OD) temperature). Part I details the test rig and measurements of bearing temperatures and rotor dynamic motions obtained in a hollow rotor supported on a pair of second generation GFBs, each consisting of a single top foil (38.14 mm inner diameter) uncoated for high temperature operation and five bump strip support layers. An electric cartridge (maximum of 360°C) loosely installed inside the rotor (1.065 kg, 38.07 mm OD, and 4.8 mm thick) is a heat source warming the rotor-bearing system. While coasting down from 30 krpm to rest, large elapsed times (50–70 s) demonstrate rotor airborne operation, near friction free, and while traversing the system critical speed at ~13 krpm, the rotor peak motion amplitude decreases as the system temperature increases. In tests conducted at a fixed rotor speed of 30 krpm, while the shaft heats, a cooling gas stream of increasing strength is set to manage the temperatures in the bearings and rotor. The effect of the cooling flow, if turbulent in character, is most distinctive at the highest heater temperature. For operation at a lower heater temperature condition, however, the cooling flow stream demonstrates a very limited effectiveness. The measurements demonstrate the reliable performance of the rotor-GFB system when operating hot. The test results, along with full disclosure on the materials and geometry of the test bearings and rotor, serve to benchmark a predictive tool. A companion paper (Part II) compares the measured bearing temperatures and the rotor response amplitudes to predictions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

Thermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part II: predictions versus test data / Luis San Andrés in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 08 p. Titre : Thermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part II: predictions versus test data Type de document : texte imprimé Auteurs : Luis San Andrés, Auteur ; Ryu, Keun, Auteur ; Tae Ho Kim, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Gas  turbines  Heat  transfer  Machine  bearings  Rotors  Shafts  Thermal  expansion  Thermal  management  (packaging)  Thermoelasticity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Implementation of gas foil bearings (GFBs) in microgas turbines relies on physics based computational models anchored to test data. This two-part paper presents test data and analytical results for a test rotor and GFB system operating hot. A companion paper (Part I) describes a test rotor-GFB system operating hot to 157°C rotor OD temperature, presents measurements of rotor dynamic response and temperatures in the bearings and rotor, and includes a cooling gas stream condition to manage the system temperatures. The second part briefs on a thermoelastohydrodynamic (TEHD) model for GFBs performance and presents predictions of the thermal energy transport and forced response, static and dynamic, in the tested gas foil bearing system. The model considers the heat flow from the rotor into the bearing cartridges and also the thermal expansion of the shaft and bearing cartridge and shaft centrifugal growth due to rotation. Predictions show that bearings' ID temperatures increase linearly with rotor speed and shaft temperature. Large cooling flow rates, in excess of 100 l/min, reduce significantly the temperatures in the bearings and rotor. Predictions, agreeing well with recorded temperatures given in Part I, also reproduce the radial gradient of temperature between the hot shaft and the bearings ID, largest (37°C/mm) for the strongest cooling stream (150 l/min). The shaft thermal growth, more significant as the temperature grows, reduces the bearings operating clearances and also the minimum film thickness, in particular, at the highest rotor speed (30 krpm). A rotor finite element structural model and GFB force coefficients from the TEHD model are used to predict the test system critical speeds and damping ratios for operation at increasing shaft temperatures. In general, predictions of the rotor imbalance show good agreement with shaft motion measurements acquired during rotor speed coastdown tests. As the shaft temperature increases, the rotor peak motion amplitudes decrease and the system rigid-mode critical speed increases. The computational tool, benchmarked by the measurements, furthers the application of GFBs in high temperature oil-free rotating machinery. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Thermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part II: predictions versus test data [texte imprimé] / Luis San Andrés, Auteur ; Ryu, Keun, Auteur ; Tae Ho Kim, Auteur . - 2011 . - 08 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 08 p. Mots-clés : Gas  turbines  Heat  transfer  Machine  bearings  Rotors  Shafts  Thermal  expansion  Thermal  management  (packaging)  Thermoelasticity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Implementation of gas foil bearings (GFBs) in microgas turbines relies on physics based computational models anchored to test data. This two-part paper presents test data and analytical results for a test rotor and GFB system operating hot. A companion paper (Part I) describes a test rotor-GFB system operating hot to 157°C rotor OD temperature, presents measurements of rotor dynamic response and temperatures in the bearings and rotor, and includes a cooling gas stream condition to manage the system temperatures. The second part briefs on a thermoelastohydrodynamic (TEHD) model for GFBs performance and presents predictions of the thermal energy transport and forced response, static and dynamic, in the tested gas foil bearing system. The model considers the heat flow from the rotor into the bearing cartridges and also the thermal expansion of the shaft and bearing cartridge and shaft centrifugal growth due to rotation. Predictions show that bearings' ID temperatures increase linearly with rotor speed and shaft temperature. Large cooling flow rates, in excess of 100 l/min, reduce significantly the temperatures in the bearings and rotor. Predictions, agreeing well with recorded temperatures given in Part I, also reproduce the radial gradient of temperature between the hot shaft and the bearings ID, largest (37°C/mm) for the strongest cooling stream (150 l/min). The shaft thermal growth, more significant as the temperature grows, reduces the bearings operating clearances and also the minimum film thickness, in particular, at the highest rotor speed (30 krpm). A rotor finite element structural model and GFB force coefficients from the TEHD model are used to predict the test system critical speeds and damping ratios for operation at increasing shaft temperatures. In general, predictions of the rotor imbalance show good agreement with shaft motion measurements acquired during rotor speed coastdown tests. As the shaft temperature increases, the rotor peak motion amplitudes decrease and the system rigid-mode critical speed increases. The computational tool, benchmarked by the measurements, furthers the application of GFBs in high temperature oil-free rotating machinery. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

Direct outer ring cooling of a high speed jet engine mainshaft ball bearing / Gloeckner, Peter in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 07 p. Titre : Direct outer ring cooling of a high speed jet engine mainshaft ball bearing : experimental investigation results Type de document : texte imprimé Auteurs : Gloeckner, Peter, Auteur ; Dullenkopf, Klaus, Auteur ; Michael Flouros, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Aerospace  propulsion  Aircraft  Ball  bearings  Cooling  Jet  engines  Shafts Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Operating conditions in high speed mainshaft ball bearings applied in new aircraft propulsion systems require enhanced bearing designs and materials. Rotational speeds, loads, demands on higher thrust capability, and reliability have increased continuously over the last years. A consequence of these increasing operating conditions are increased bearing temperatures. A state of the art jet engine high speed ball bearing has been modified with an oil channel in the outer diameter of the bearing. This oil channel provides direct cooling of the outer ring. Rig testing under typical flight conditions has been performed to investigate the cooling efficiency of the outer ring oil channel. In this paper, the experimental results including bearing temperature distribution, power dissipation, and bearing oil pumping and the impact on oil mass and parasitic power loss reduction are presented. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Direct outer ring cooling of a high speed jet engine mainshaft ball bearing : experimental investigation results [texte imprimé] / Gloeckner, Peter, Auteur ; Dullenkopf, Klaus, Auteur ; Michael Flouros, Auteur . - 2011 . - 07 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 07 p. Mots-clés : Aerospace  propulsion  Aircraft  Ball  bearings  Cooling  Jet  engines  Shafts Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Operating conditions in high speed mainshaft ball bearings applied in new aircraft propulsion systems require enhanced bearing designs and materials. Rotational speeds, loads, demands on higher thrust capability, and reliability have increased continuously over the last years. A consequence of these increasing operating conditions are increased bearing temperatures. A state of the art jet engine high speed ball bearing has been modified with an oil channel in the outer diameter of the bearing. This oil channel provides direct cooling of the outer ring. Rig testing under typical flight conditions has been performed to investigate the cooling efficiency of the outer ring oil channel. In this paper, the experimental results including bearing temperature distribution, power dissipation, and bearing oil pumping and the impact on oil mass and parasitic power loss reduction are presented. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

Real-time IMEP estimation and control using an in-cylinder pressure sensor for a common-rail direct injection diesel engine / Oh, Seungsuk in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 09 p. Titre : Real-time IMEP estimation and control using an in-cylinder pressure sensor for a common-rail direct injection diesel engine Type de document : texte imprimé Auteurs : Oh, Seungsuk, Auteur ; Junsoo Kim, Auteur ; Oh, Byounggul, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Cylinder  pressure  Indicated  mean  effective  pressure  (IMEP)  estimation  Difference  pressure  integral  (DPI)  Torque  control Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An in-cylinder pressure-based control method is capable of improving engine performance, as well as reducing harmful emissions. However, this method is difficult to be implemented in a conventional engine management system due to the excessive data acquisition and long computation time. In this study, we propose a real-time indicated mean effective pressure (IMEP) estimation method using cylinder pressure in a common-rail direct injection diesel engine. In this method, difference pressure integral (DPI) was applied to the estimation. The DPI requires only 180 pressure data points during one engine cycle from top dead center to bottom dead center when pressure data are captured at every crank angle. Therefore, the IMEP can be estimated in real time. To further reduce the computational load, the IMEP was also estimated using DPI at 2 deg, 3 deg, and 4 deg crank angle resolutions. Furthermore, based on the estimated IMEP, we controlled IMEP using a radial basis function network and linear feedback controller. As a result of the study, successful estimation and control were demonstrated through engine experiments. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Real-time IMEP estimation and control using an in-cylinder pressure sensor for a common-rail direct injection diesel engine [texte imprimé] / Oh, Seungsuk, Auteur ; Junsoo Kim, Auteur ; Oh, Byounggul, Auteur . - 2011 . - 09 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 09 p. Mots-clés : Cylinder  pressure  Indicated  mean  effective  pressure  (IMEP)  estimation  Difference  pressure  integral  (DPI)  Torque  control Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An in-cylinder pressure-based control method is capable of improving engine performance, as well as reducing harmful emissions. However, this method is difficult to be implemented in a conventional engine management system due to the excessive data acquisition and long computation time. In this study, we propose a real-time indicated mean effective pressure (IMEP) estimation method using cylinder pressure in a common-rail direct injection diesel engine. In this method, difference pressure integral (DPI) was applied to the estimation. The DPI requires only 180 pressure data points during one engine cycle from top dead center to bottom dead center when pressure data are captured at every crank angle. Therefore, the IMEP can be estimated in real time. To further reduce the computational load, the IMEP was also estimated using DPI at 2 deg, 3 deg, and 4 deg crank angle resolutions. Furthermore, based on the estimated IMEP, we controlled IMEP using a radial basis function network and linear feedback controller. As a result of the study, successful estimation and control were demonstrated through engine experiments. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

Thermodynamic optimization of advanced steam power plants retrofitted for oxy-coal combustion / M. V. J. J. Suresh in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 12 p. Titre : Thermodynamic optimization of advanced steam power plants retrofitted for oxy-coal combustion Type de document : texte imprimé Auteurs : M. V. J. J. Suresh, Auteur ; K. S. Reddy, Auteur ; Ajit Kumar Kolar, Auteur Année de publication : 2011 Article en page(s) : 12 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Energy  High  ash  coal  Supercritical  Air-coal  combustion  Oxy-coal  combustion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Thermodynamic optimization of power plants based on supercritical (SupC) and ultrasupercritical (USC) steam parameters is reported in this article. The objective is to compute the maximum attainable power plant efficiency in Indian climatic conditions using high ash (HA) indigenous coal. A unit size of 800 MWe presently under development in India is considered for energy and exergy analysis of power plants. Commercially established steam turbine parameters are used for the optimization of SupC power plant, whereas advanced steam turbine parameters currently under research and development are used for the optimization of USC power plant. The plant energy efficiency of the optimized SupC and USC power plant based on air-coal combustion (ACC) show considerable increases of 2.8 and 5.2% points, respectively compared with the current SupC ACC power plant (reference plant) being commissioned in India. The increases in plant exergy efficiency for the same power plants are 2.6 and 4.8% points and the corresponding CO2 reductions are about 6 and 11%, respectively. The maximum possible plant energy efficiency in Indian climatic conditions using HA Indian coal is about 42.7% (USC power plant). The effect of low ash coal on plant energy and exergy efficiencies compared with HA coal is also presented. Further, the effect of oxy-coal combustion (OCC) on the plant energy and exergy efficiencies compared with the ACC is studied for the double reheat SupC and USC power plants to account for the impact of CO2 capture. A significant reduction of 8.8 and 6.6% points in plant energy efficiency is observed for SupC and USC OCC power plants, respectively compared with the reference SupC ACC power plant. DEWEY : 620.1 ISSN : 0472-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Thermodynamic optimization of advanced steam power plants retrofitted for oxy-coal combustion [texte imprimé] / M. V. J. J. Suresh, Auteur ; K. S. Reddy, Auteur ; Ajit Kumar Kolar, Auteur . - 2011 . - 12 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 12 p. Mots-clés : Energy  High  ash  coal  Supercritical  Air-coal  combustion  Oxy-coal  combustion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Thermodynamic optimization of power plants based on supercritical (SupC) and ultrasupercritical (USC) steam parameters is reported in this article. The objective is to compute the maximum attainable power plant efficiency in Indian climatic conditions using high ash (HA) indigenous coal. A unit size of 800 MWe presently under development in India is considered for energy and exergy analysis of power plants. Commercially established steam turbine parameters are used for the optimization of SupC power plant, whereas advanced steam turbine parameters currently under research and development are used for the optimization of USC power plant. The plant energy efficiency of the optimized SupC and USC power plant based on air-coal combustion (ACC) show considerable increases of 2.8 and 5.2% points, respectively compared with the current SupC ACC power plant (reference plant) being commissioned in India. The increases in plant exergy efficiency for the same power plants are 2.6 and 4.8% points and the corresponding CO2 reductions are about 6 and 11%, respectively. The maximum possible plant energy efficiency in Indian climatic conditions using HA Indian coal is about 42.7% (USC power plant). The effect of low ash coal on plant energy and exergy efficiencies compared with HA coal is also presented. Further, the effect of oxy-coal combustion (OCC) on the plant energy and exergy efficiencies compared with the ACC is studied for the double reheat SupC and USC power plants to account for the impact of CO2 capture. A significant reduction of 8.8 and 6.6% points in plant energy efficiency is observed for SupC and USC OCC power plants, respectively compared with the reference SupC ACC power plant. DEWEY : 620.1 ISSN : 0472-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

A consolidated model for the turbine operation of centrifugal pumps / Punit Singh in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 09 p. Titre : A consolidated model for the turbine operation of centrifugal pumps Type de document : texte imprimé Auteurs : Punit Singh, Auteur ; Franz Nestmann, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Pump  as  turbine  Prediction  Selection  Evaluation  Cordier  line  Uncertainty  analysis  Acceptance  criterion  Optimization Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A consolidated model for the turbine operation of centrifugal pumps comprising accurate prediction, optimum selection, and rigorous evaluation has been the primary need and the most challenging tasks for the industry to deal with. This paper introduces a consolidated model that is developed from experimental results of different pump shapes (20–80 rpm) and turbomachine fundamentals directly resulting in the parsimony feature of the model. The model also creates a new basis for dealing with uncertainties. The prediction model segment of the consolidated model requires only the pump shape and size as input parameters for bringing out the complete turbine characteristics. The selection model segment, on the other hand, requires the site head and flow as fixed input parameters and turbine speed as the control parameter to prescribe suitable pumps available in the market. The evaluation model segment compares the absolute turbine characteristics of the suitable pumps and recommends the most suitable pump for the given site. The model also includes an acceptance criterion that relates the deviation of the “pump as turbine” operating parameters with the site parameters, and it is very useful at the evaluation stage. The features of the consolidated model are illustrated with two case studies, which highlight the importance of evaluation in addition to the prediction and basic selection of pumps operating as turbines. In order to increase the accuracy and robustness of the model, the paper recommends an optimization routine stage on the existing model that comprises results of more pump shapes (obtained through field projects or extended laboratory work). The optimization procedure suggested would come a long way to provide a lasting solution for the search of a reliable pump as turbine model. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] A consolidated model for the turbine operation of centrifugal pumps [texte imprimé] / Punit Singh, Auteur ; Franz Nestmann, Auteur . - 2011 . - 09 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 09 p. Mots-clés : Pump  as  turbine  Prediction  Selection  Evaluation  Cordier  line  Uncertainty  analysis  Acceptance  criterion  Optimization Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A consolidated model for the turbine operation of centrifugal pumps comprising accurate prediction, optimum selection, and rigorous evaluation has been the primary need and the most challenging tasks for the industry to deal with. This paper introduces a consolidated model that is developed from experimental results of different pump shapes (20–80 rpm) and turbomachine fundamentals directly resulting in the parsimony feature of the model. The model also creates a new basis for dealing with uncertainties. The prediction model segment of the consolidated model requires only the pump shape and size as input parameters for bringing out the complete turbine characteristics. The selection model segment, on the other hand, requires the site head and flow as fixed input parameters and turbine speed as the control parameter to prescribe suitable pumps available in the market. The evaluation model segment compares the absolute turbine characteristics of the suitable pumps and recommends the most suitable pump for the given site. The model also includes an acceptance criterion that relates the deviation of the “pump as turbine” operating parameters with the site parameters, and it is very useful at the evaluation stage. The features of the consolidated model are illustrated with two case studies, which highlight the importance of evaluation in addition to the prediction and basic selection of pumps operating as turbines. In order to increase the accuracy and robustness of the model, the paper recommends an optimization routine stage on the existing model that comprises results of more pump shapes (obtained through field projects or extended laboratory work). The optimization procedure suggested would come a long way to provide a lasting solution for the search of a reliable pump as turbine model. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

HTR-TN achievements and prospects for future developments / Dominique Hittner in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 09 p. Titre : HTR-TN achievements and prospects for future developments Type de document : texte imprimé Auteurs : Dominique Hittner, Auteur ; Carmen Angulo, Auteur ; Virginie Basini, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Fission  reactors  Heat  transfer Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : It is already 10 years since the (European) High Temperature Reactor Technology Network (HTR-TN) launched a program for development of HTR technology, which expanded through three successive Euratom framework programs, with many projects in line with the network strategy. Widely relying in the beginning on the legacy of the former European HTR developments (DRAGON, AVR, THTR, etc.) that it contributed to safeguard, this program led to advances in HTR/VHTR technologies and produced significant results, which can contribute to the international cooperation through Euratom involvement in the Generation IV International Forum (GIF). the main achievements of the European program, performed in complement to efforts made in several European countries and other GIF partners, are presented: they concern the validation of computer codes (reactor physics, as well as system transient analysis from normal operation to air ingress accident and fuel performance in normal and accident conditions), materials (metallic materials for vessel, direct cycle turbines and intermediate heat exchanger, graphite, etc.), component development, fuel manufacturing and irradiation behavior, and specific HTR waste management (fuel and graphite). Key experiments have been performed or are still ongoing, like irradiation of graphite and of fuel material (PYCASSO experiment), high burn-up fuel PIE, safety test and isotopic analysis, IHX mock-up thermohydraulic test in helium atmosphere, air ingress experiment for a block type core, etc. Now HTR-TN partners consider that it is time for Europe to go a step forward toward industrial demonstration. In line with the orientations of the “Strategic Energy Technology Plan (SET-Plan)” recently issued by the European Commission that promotes a strategy for development of low-carbon energy technologies and mentions Generation IV nuclear systems as part of key technologies, HTR-TN proposes to launch a program for extending the contribution of nuclear energy to industrial process heat applications addressing (1) the development of a flexible HTR that can be coupled to many different process heat and cogeneration applications with very versatile requirements, (2) the development of coupling technologies for such coupling, (3) the possible adaptations of process heat applications required for nuclear coupling, and (4) the integration and optimization of the whole coupled system. As a preliminary step for this ambitious program, HTR-TN endeavors to create a strategic partnership between nuclear industry and R&D and process heat user industries. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] HTR-TN achievements and prospects for future developments [texte imprimé] / Dominique Hittner, Auteur ; Carmen Angulo, Auteur ; Virginie Basini, Auteur . - 2011 . - 09 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 09 p. Mots-clés : Fission  reactors  Heat  transfer Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : It is already 10 years since the (European) High Temperature Reactor Technology Network (HTR-TN) launched a program for development of HTR technology, which expanded through three successive Euratom framework programs, with many projects in line with the network strategy. Widely relying in the beginning on the legacy of the former European HTR developments (DRAGON, AVR, THTR, etc.) that it contributed to safeguard, this program led to advances in HTR/VHTR technologies and produced significant results, which can contribute to the international cooperation through Euratom involvement in the Generation IV International Forum (GIF). the main achievements of the European program, performed in complement to efforts made in several European countries and other GIF partners, are presented: they concern the validation of computer codes (reactor physics, as well as system transient analysis from normal operation to air ingress accident and fuel performance in normal and accident conditions), materials (metallic materials for vessel, direct cycle turbines and intermediate heat exchanger, graphite, etc.), component development, fuel manufacturing and irradiation behavior, and specific HTR waste management (fuel and graphite). Key experiments have been performed or are still ongoing, like irradiation of graphite and of fuel material (PYCASSO experiment), high burn-up fuel PIE, safety test and isotopic analysis, IHX mock-up thermohydraulic test in helium atmosphere, air ingress experiment for a block type core, etc. Now HTR-TN partners consider that it is time for Europe to go a step forward toward industrial demonstration. In line with the orientations of the “Strategic Energy Technology Plan (SET-Plan)” recently issued by the European Commission that promotes a strategy for development of low-carbon energy technologies and mentions Generation IV nuclear systems as part of key technologies, HTR-TN proposes to launch a program for extending the contribution of nuclear energy to industrial process heat applications addressing (1) the development of a flexible HTR that can be coupled to many different process heat and cogeneration applications with very versatile requirements, (2) the development of coupling technologies for such coupling, (3) the possible adaptations of process heat applications required for nuclear coupling, and (4) the integration and optimization of the whole coupled system. As a preliminary step for this ambitious program, HTR-TN endeavors to create a strategic partnership between nuclear industry and R&D and process heat user industries. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

The study on abrasive water jet for predicting the cutting performance and monitoring the cutting situation in the water / Yasuyuki Nakamura in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 03 p. Titre : The study on abrasive water jet for predicting the cutting performance and monitoring the cutting situation in the water Type de document : texte imprimé Auteurs : Yasuyuki Nakamura, Auteur ; Kazuya Sano, Auteur ; Yoshitugu Morishita, Auteur Année de publication : 2011 Article en page(s) : 03 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : High-pressure  techniques  Water  jet  cutting Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The abrasive water jet (AWJ), is to shoot the abrasive mixed with high-pressure water to the material for cutting, can cut most materials, such as metals and concretes in water with long stand-off means the length from the cutting head to the material for cutting. On the other hand, AWJ is required to reduce an amount of the abrasive because it becomes the waste. It is also difficult to monitor the cutting condition by any visual methods such as a TV camera in the water becoming cloudy by both used abrasive and cut metal grit. For solving these issues, some cutting tests were conducted and (1) it was possible to predict an optimal supply rate of abrasive by considering the conservation of momentum between the water jet and the abrasive. (2) It was also possible to judge whether the material could be cut successfully or not by detecting the change in the frequency characteristics of vibration or sound caused during the cutting process. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] The study on abrasive water jet for predicting the cutting performance and monitoring the cutting situation in the water [texte imprimé] / Yasuyuki Nakamura, Auteur ; Kazuya Sano, Auteur ; Yoshitugu Morishita, Auteur . - 2011 . - 03 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 03 p. Mots-clés : High-pressure  techniques  Water  jet  cutting Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The abrasive water jet (AWJ), is to shoot the abrasive mixed with high-pressure water to the material for cutting, can cut most materials, such as metals and concretes in water with long stand-off means the length from the cutting head to the material for cutting. On the other hand, AWJ is required to reduce an amount of the abrasive because it becomes the waste. It is also difficult to monitor the cutting condition by any visual methods such as a TV camera in the water becoming cloudy by both used abrasive and cut metal grit. For solving these issues, some cutting tests were conducted and (1) it was possible to predict an optimal supply rate of abrasive by considering the conservation of momentum between the water jet and the abrasive. (2) It was also possible to judge whether the material could be cut successfully or not by detecting the change in the frequency characteristics of vibration or sound caused during the cutting process. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

An investigation of air-cooled steam condenser performance under windy conditions using computational fluid dynamics / M. T. F. Owen in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 04 p. Titre : An investigation of air-cooled steam condenser performance under windy conditions using computational fluid dynamics Type de document : texte imprimé Auteurs : M. T. F. Owen, Auteur ; D. G. Kröger, Auteur Année de publication : 2011 Article en page(s) : 04 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Air-cooled  steam  condenser  CFD  modeling  Wind  effects Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The development of an efficient and reliable method of evaluating the performance of an air-cooled steam condenser (ACC) under windy conditions using computational fluid dynamics (CFD) is presented. A two-step modeling approach is employed as a result of computational limitations. The numerical ACC model developed in this study makes use of the pressure jump fan model, among other approximations, in an attempt to minimize the computational expense of the performance evaluation. The accuracy of the numerical model is verified through a comparison of the numerical results to test data collected during full-scale tests carried out on an operational ACC. Good correlation is achieved between the numerical results and test data. The effect of wind on ACC performance at El Dorado Power Plant (Nevada, USA) is investigated. It is found that reduced fan performance due to distorted flow at the inlet of the upstream fans is the primary contributor to the reduction in ACC performance associated with increased wind speed in this case. The model developed in this study has the potential to allow for the evaluation of large ACC installations and provides a reliable platform from which further investigations into improving ACC performance under windy conditions can be carried out. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] An investigation of air-cooled steam condenser performance under windy conditions using computational fluid dynamics [texte imprimé] / M. T. F. Owen, Auteur ; D. G. Kröger, Auteur . - 2011 . - 04 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 04 p. Mots-clés : Air-cooled  steam  condenser  CFD  modeling  Wind  effects Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The development of an efficient and reliable method of evaluating the performance of an air-cooled steam condenser (ACC) under windy conditions using computational fluid dynamics (CFD) is presented. A two-step modeling approach is employed as a result of computational limitations. The numerical ACC model developed in this study makes use of the pressure jump fan model, among other approximations, in an attempt to minimize the computational expense of the performance evaluation. The accuracy of the numerical model is verified through a comparison of the numerical results to test data collected during full-scale tests carried out on an operational ACC. Good correlation is achieved between the numerical results and test data. The effect of wind on ACC performance at El Dorado Power Plant (Nevada, USA) is investigated. It is found that reduced fan performance due to distorted flow at the inlet of the upstream fans is the primary contributor to the reduction in ACC performance associated with increased wind speed in this case. The model developed in this study has the potential to allow for the evaluation of large ACC installations and provides a reliable platform from which further investigations into improving ACC performance under windy conditions can be carried out. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

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