Dépouillements

Spray in crossflow / Eugene Lubarsky in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 09 p. Titre : Spray in crossflow : dependence on weber number Type de document : texte imprimé Auteurs : Eugene Lubarsky, Auteur ; Jonathan R. Reichel, Auteur ; Ben T. Zinn, Auteur Année de publication : 2010 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Computational  fluid  dynamics  Diameter  measurement  Drops  Fuel  systems  Jets  Mach  number  Orifices  (mechanical)  Shear  flow  Sprays  Velocity  measurement  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper describes an experimental investigation of the spray created by Jet A fuel injection from a plate containing sharp edged orifice 0.018 in. (457 µm) in diameter and L/D ratio of 10 into the crossflow of preheated air (555 K) at elevated pressure in the test section (4 atm) and liquid to air momentum flux ratio of 40. A two component phase Doppler particle analyzer was used for measuring the characteristics of the spray. The Weber number of the spray in crossflow was varied between 33 and 2020 and the effect of Weber number on spray properties was investigated. It was seen that the shear breakup mechanism dominates at Weber number greater than about 300. Droplets' diameters were found to be in the range of 15–30 µm for higher values of Weber numbers, while larger droplets (100–200 µm) were observed at Weber number of 33. Larger droplets were observed at the periphery of the spray. The droplet velocities and diameters were measured in a plane 30 mm downstream of the orifice along the centerline of the spray at an incoming airflow Mach number of 0.2. The droplets reach a maximum of 90% of the flow velocity at this location. The velocity of the droplets in the directions perpendicular to the airflow direction is higher at the periphery of the spray possibly due to the presence of larger droplets there. The rms values of the droplet velocities are highest slightly off the centerline of the spray due to the presence of vortices and shear layers around the liquid jet. The data presented here improve the understanding of spray formation processes, and provide benchmark data for computational fluid dynamics (CFD) code validation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Spray in crossflow : dependence on weber number [texte imprimé] / Eugene Lubarsky, Auteur ; Jonathan R. Reichel, Auteur ; Ben T. Zinn, Auteur . - 2010 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 09 p. Mots-clés : Computational  fluid  dynamics  Diameter  measurement  Drops  Fuel  systems  Jets  Mach  number  Orifices  (mechanical)  Shear  flow  Sprays  Velocity  measurement  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper describes an experimental investigation of the spray created by Jet A fuel injection from a plate containing sharp edged orifice 0.018 in. (457 µm) in diameter and L/D ratio of 10 into the crossflow of preheated air (555 K) at elevated pressure in the test section (4 atm) and liquid to air momentum flux ratio of 40. A two component phase Doppler particle analyzer was used for measuring the characteristics of the spray. The Weber number of the spray in crossflow was varied between 33 and 2020 and the effect of Weber number on spray properties was investigated. It was seen that the shear breakup mechanism dominates at Weber number greater than about 300. Droplets' diameters were found to be in the range of 15–30 µm for higher values of Weber numbers, while larger droplets (100–200 µm) were observed at Weber number of 33. Larger droplets were observed at the periphery of the spray. The droplet velocities and diameters were measured in a plane 30 mm downstream of the orifice along the centerline of the spray at an incoming airflow Mach number of 0.2. The droplets reach a maximum of 90% of the flow velocity at this location. The velocity of the droplets in the directions perpendicular to the airflow direction is higher at the periphery of the spray possibly due to the presence of larger droplets there. The rms values of the droplet velocities are highest slightly off the centerline of the spray due to the presence of vortices and shear layers around the liquid jet. The data presented here improve the understanding of spray formation processes, and provide benchmark data for computational fluid dynamics (CFD) code validation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Effect of flame structure on the flame transfer function in a premixed gas turbine combustor / Daesik Kim in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Titre : Effect of flame structure on the flame transfer function in a premixed gas turbine combustor Type de document : texte imprimé Auteurs : Daesik Kim, Auteur ; Jong Guen Lee, Auteur ; Bryan D. Quay, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Gas  turbines  Transfer  functions Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The flame transfer function in a premixed gas turbine combustor is experimentally determined. The fuel (natural gas) is premixed with air upstream of a choked inlet to the combustor. Therefore, the input to the flame transfer function is the imposed velocity fluctuations of the fuel/air mixture without equivalence ratio fluctuations. The inlet-velocity fluctuations are achieved by a variable-speed siren over the forcing frequency of 75–280 Hz and measured using a hot-wire anemometer at the inlet to the combustor. The output function (heat release) is determined using chemiluminescence measurement from the whole flame. Flame images are recorded to understand how the flame structure plays a role in the global heat release response of flame to the inlet-velocity perturbation. The results show that the gain and phase of the flame transfer function depend on flame structure as well as the frequency and magnitude of inlet-velocity modulation and can be generalized in terms of the relative length scale of flame to convection length scale of inlet-velocity perturbation, which is represented by a Strouhal number. Nonlinear flame response is characterized by a periodic vortex shedding from shear layer, and the nonlinearity occurs at lower magnitude of inlet-velocity fluctuation as the modulation frequency increases. However, for a given modulation frequency, the flame structure does not affect the magnitude of inlet-velocity fluctuation at which the nonlinear flame response starts to appear. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Effect of flame structure on the flame transfer function in a premixed gas turbine combustor [texte imprimé] / Daesik Kim, Auteur ; Jong Guen Lee, Auteur ; Bryan D. Quay, Auteur . - 2010 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Mots-clés : Combustion  Gas  turbines  Transfer  functions Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The flame transfer function in a premixed gas turbine combustor is experimentally determined. The fuel (natural gas) is premixed with air upstream of a choked inlet to the combustor. Therefore, the input to the flame transfer function is the imposed velocity fluctuations of the fuel/air mixture without equivalence ratio fluctuations. The inlet-velocity fluctuations are achieved by a variable-speed siren over the forcing frequency of 75–280 Hz and measured using a hot-wire anemometer at the inlet to the combustor. The output function (heat release) is determined using chemiluminescence measurement from the whole flame. Flame images are recorded to understand how the flame structure plays a role in the global heat release response of flame to the inlet-velocity perturbation. The results show that the gain and phase of the flame transfer function depend on flame structure as well as the frequency and magnitude of inlet-velocity modulation and can be generalized in terms of the relative length scale of flame to convection length scale of inlet-velocity perturbation, which is represented by a Strouhal number. Nonlinear flame response is characterized by a periodic vortex shedding from shear layer, and the nonlinearity occurs at lower magnitude of inlet-velocity fluctuation as the modulation frequency increases. However, for a given modulation frequency, the flame structure does not affect the magnitude of inlet-velocity fluctuation at which the nonlinear flame response starts to appear. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Determination of the instantaneous fuel flow rate out of a fuel nozzle / Tongxun Yi in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Titre : Determination of the instantaneous fuel flow rate out of a fuel nozzle Type de document : texte imprimé Auteurs : Tongxun Yi, Auteur ; Domenic A. Santavicca, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Acoustic  waves  Combustion  Fuel  systems  Nozzles  Time-varying  systems  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Reported is a practical method for accurate and fast determination of the instantaneous fuel flow rate out of a fuel injector. Both gaseous and liquid fuels are considered. Unsteady fuel flow rates introduced into a combustor can be caused by both self-excited pressure pulsations and fuel modulations. During combustion instability, the air flow rate into a combustor also varies in response to pressure pulsations. Accurate determination of the instantaneous fuel and air flow rates is important for both modeling and control of combustion instability. The developed method is based on the acoustic wave theory and pressure measurements at two locations upstream of a fuel injector. This method bypasses the complexities and nonlinearities of fuel actuators and fuel nozzles, and works for systems with slow-time-varying characteristics. Acoustic impedance of a gaseous fuel nozzle is found to be a function of multivariables, including the forcing frequency, the acoustic oscillation intensity, and the mean fuel flow rate. Thus, it is not an intrinsic property of the fuel injector alone. In the present study, sharp tubing bending with almost zero radii is found to have minimal effects on the distribution of 1D acoustic wave. This is probably because vortex shedding and recirculation at tubing corners do not alter the globally 1D characteristics of acoustic wave distribution. Different from the traditional two-microphone method, which determines the acoustic velocity at the middle locations of the two microphones, the present method allows the acoustic velocity, the acoustic mass flux, and the specific acoustic impedance to be determined along the fuel tubing or an air pipe. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Determination of the instantaneous fuel flow rate out of a fuel nozzle [texte imprimé] / Tongxun Yi, Auteur ; Domenic A. Santavicca, Auteur . - 2010 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Mots-clés : Acoustic  waves  Combustion  Fuel  systems  Nozzles  Time-varying  systems  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Reported is a practical method for accurate and fast determination of the instantaneous fuel flow rate out of a fuel injector. Both gaseous and liquid fuels are considered. Unsteady fuel flow rates introduced into a combustor can be caused by both self-excited pressure pulsations and fuel modulations. During combustion instability, the air flow rate into a combustor also varies in response to pressure pulsations. Accurate determination of the instantaneous fuel and air flow rates is important for both modeling and control of combustion instability. The developed method is based on the acoustic wave theory and pressure measurements at two locations upstream of a fuel injector. This method bypasses the complexities and nonlinearities of fuel actuators and fuel nozzles, and works for systems with slow-time-varying characteristics. Acoustic impedance of a gaseous fuel nozzle is found to be a function of multivariables, including the forcing frequency, the acoustic oscillation intensity, and the mean fuel flow rate. Thus, it is not an intrinsic property of the fuel injector alone. In the present study, sharp tubing bending with almost zero radii is found to have minimal effects on the distribution of 1D acoustic wave. This is probably because vortex shedding and recirculation at tubing corners do not alter the globally 1D characteristics of acoustic wave distribution. Different from the traditional two-microphone method, which determines the acoustic velocity at the middle locations of the two microphones, the present method allows the acoustic velocity, the acoustic mass flux, and the specific acoustic impedance to be determined along the fuel tubing or an air pipe. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Ignition and flame speed kinetics of two natural gas blends with high levels of heavier hydrocarbons / Gilles Bourque in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 11 p. Titre : Ignition and flame speed kinetics of two natural gas blends with high levels of heavier hydrocarbons Type de document : texte imprimé Auteurs : Gilles Bourque, Auteur ; Darren Healy, Auteur ; Henry Curran, Auteur Année de publication : 2010 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Fuel  Gas  turbines  Ignition  Laminar  flow  Natural  gas  technology  Reaction  kinetics  theory Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : High-pressure experiments and chemical kinetics modeling were performed to generate a database and a chemical kinetic model that can characterize the combustion chemistry of methane-based fuel blends containing significant levels of heavy hydrocarbons (up to 37.5% by volume). Ignition delay times were measured in two different shock tubes and in a rapid compression machine at pressures up to 34 atm and temperatures from 740 K to 1660 K. Laminar flame speeds were also measured at pressures up to 4 atm using a high-pressure vessel with optical access. Two different fuel blends containing ethane, propane, n-butane, and n-pentane added to methane were studied at equivalence ratios varying from lean (0.3) to rich (2.0). This paper represents the most comprehensive set of experimental ignition and laminar flame speed data available in the open literature for CH4/C2H6/C3H8/C4H10/C5H12 fuel blends with significant levels of C2+ hydrocarbons. Using these data, a detailed chemical kinetics model based on current and recent work by the authors was compiled and refined. The predictions of the model are very good over the entire range of ignition delay times, considering the fact that the data set is so thorough. Nonetheless, some improvements to the model can still be made with respect to ignition times at the lowest temperatures and for the laminar flame speeds at pressures above 1 atm and at rich conditions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Ignition and flame speed kinetics of two natural gas blends with high levels of heavier hydrocarbons [texte imprimé] / Gilles Bourque, Auteur ; Darren Healy, Auteur ; Henry Curran, Auteur . - 2010 . - 11 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 11 p. Mots-clés : Combustion  Fuel  Gas  turbines  Ignition  Laminar  flow  Natural  gas  technology  Reaction  kinetics  theory Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : High-pressure experiments and chemical kinetics modeling were performed to generate a database and a chemical kinetic model that can characterize the combustion chemistry of methane-based fuel blends containing significant levels of heavy hydrocarbons (up to 37.5% by volume). Ignition delay times were measured in two different shock tubes and in a rapid compression machine at pressures up to 34 atm and temperatures from 740 K to 1660 K. Laminar flame speeds were also measured at pressures up to 4 atm using a high-pressure vessel with optical access. Two different fuel blends containing ethane, propane, n-butane, and n-pentane added to methane were studied at equivalence ratios varying from lean (0.3) to rich (2.0). This paper represents the most comprehensive set of experimental ignition and laminar flame speed data available in the open literature for CH4/C2H6/C3H8/C4H10/C5H12 fuel blends with significant levels of C2+ hydrocarbons. Using these data, a detailed chemical kinetics model based on current and recent work by the authors was compiled and refined. The predictions of the model are very good over the entire range of ignition delay times, considering the fact that the data set is so thorough. Nonetheless, some improvements to the model can still be made with respect to ignition times at the lowest temperatures and for the laminar flame speeds at pressures above 1 atm and at rich conditions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Emission characteristics of a premixed cyclic-periodical-mixing combustor operated with hydrogen-natural gas fuel mixtures / Jochen R. Brückner-Kalb in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 08 p. Titre : Emission characteristics of a premixed cyclic-periodical-mixing combustor operated with hydrogen-natural gas fuel mixtures Type de document : texte imprimé Auteurs : Jochen R. Brückner-Kalb, Auteur ; Michael Krösser, Auteur ; Christoph Hirsch, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Chemical  reactors  Combustion  Flames  Fuel  Ignition  Natural  gas  technology Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The concept of the cyclic periodical mixing combustion process (Kalb, and Sattelmayer, 2004, “Lean Blowout Limit and NOx-Production of a Premixed Sub-ppm-NOx Burner With Periodic Flue Gas Recirculation,” Proceedings of the ASME Turbo Expo 2004, Paper No. GT2004-53410; Kalb, and Sattelmayer, 2006, “Lean Blowout Limit and NOx-Production of a Premixed Sub-ppm-NOx Burner With Periodic Recirculation of Combustion Products,” ASME J. Eng. Gas Turbines Power, 128(2), pp. 247–254) for the extension of the lean blowout limit had been implemented in an atmospheric experimental combustor for testing with both external perfect (Brückner-Kalb, Hirsch, and Sattelmayer, 2006, “Operation Characteristics of a Premixed Sub-ppm NOx Burner With Periodical Recirculation of Combustion Products,” Proceedings of the ASME Turbo Expo 2006, Paper No. GT2006-90072) and technical (Brückner-Kalb, Napravnik, Hirsch, and Sattelmayer, 2007, “Development of a Fuel-Air Premixer for a Sub-ppm NOx Burner,” Proceedings of the ASME Turbo Expo 2007, Paper No. GT2007-27779) premixing of reactants. It had been tested with natural gas and has now been tested with a mixture of 70%vol of hydrogen and 30%vol of natural gas (98% CH4) as fuel. With natural gas the NOx emissions are unaffected by the limited technical premixing quality, as long as the air preheat is in the design range of the premixers (Brückner-Kalb, Napravnik, Hirsch, and Sattelmayer, 2007, “Development of a Fuel-Air Premixer for a Sub-ppm NOx Burner,” Proceedings of the ASME Turbo Expo 2007, Paper No. GT2007-27779). Then, for adiabatic flame temperatures of up to 1630 K NOx emissions are below 1 ppm(v) with CO emissions below 8 ppm(v) in the whole operation range of the test combustor (15% O2, dry). With the “70%volH2−30%volCH4” mixture the NOx emissions increase by nearly one order of magnitude. Then, NOx emissions below 7 ppm(v) (15% O2, dry) are achieved for adiabatic flame temperatures of up to 1600 K. They approach the 1 ppm(v) level only for flame temperatures below 1450 K. CO emissions are below 4 ppm(v). The reason for the increase in the NOx emissions is the higher reactivity of the mixture, which leads to earlier ignition in zones of still elevated unmixedness of reactants near the premixer-injector exits. This effect was investigated by chemical reactor network simulations analyzing a pressure effect and an additional chemical effect of hydrogen combustion on NOx formation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Emission characteristics of a premixed cyclic-periodical-mixing combustor operated with hydrogen-natural gas fuel mixtures [texte imprimé] / Jochen R. Brückner-Kalb, Auteur ; Michael Krösser, Auteur ; Christoph Hirsch, Auteur . - 2010 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 08 p. Mots-clés : Chemical  reactors  Combustion  Flames  Fuel  Ignition  Natural  gas  technology Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The concept of the cyclic periodical mixing combustion process (Kalb, and Sattelmayer, 2004, “Lean Blowout Limit and NOx-Production of a Premixed Sub-ppm-NOx Burner With Periodic Flue Gas Recirculation,” Proceedings of the ASME Turbo Expo 2004, Paper No. GT2004-53410; Kalb, and Sattelmayer, 2006, “Lean Blowout Limit and NOx-Production of a Premixed Sub-ppm-NOx Burner With Periodic Recirculation of Combustion Products,” ASME J. Eng. Gas Turbines Power, 128(2), pp. 247–254) for the extension of the lean blowout limit had been implemented in an atmospheric experimental combustor for testing with both external perfect (Brückner-Kalb, Hirsch, and Sattelmayer, 2006, “Operation Characteristics of a Premixed Sub-ppm NOx Burner With Periodical Recirculation of Combustion Products,” Proceedings of the ASME Turbo Expo 2006, Paper No. GT2006-90072) and technical (Brückner-Kalb, Napravnik, Hirsch, and Sattelmayer, 2007, “Development of a Fuel-Air Premixer for a Sub-ppm NOx Burner,” Proceedings of the ASME Turbo Expo 2007, Paper No. GT2007-27779) premixing of reactants. It had been tested with natural gas and has now been tested with a mixture of 70%vol of hydrogen and 30%vol of natural gas (98% CH4) as fuel. With natural gas the NOx emissions are unaffected by the limited technical premixing quality, as long as the air preheat is in the design range of the premixers (Brückner-Kalb, Napravnik, Hirsch, and Sattelmayer, 2007, “Development of a Fuel-Air Premixer for a Sub-ppm NOx Burner,” Proceedings of the ASME Turbo Expo 2007, Paper No. GT2007-27779). Then, for adiabatic flame temperatures of up to 1630 K NOx emissions are below 1 ppm(v) with CO emissions below 8 ppm(v) in the whole operation range of the test combustor (15% O2, dry). With the “70%volH2−30%volCH4” mixture the NOx emissions increase by nearly one order of magnitude. Then, NOx emissions below 7 ppm(v) (15% O2, dry) are achieved for adiabatic flame temperatures of up to 1600 K. They approach the 1 ppm(v) level only for flame temperatures below 1450 K. CO emissions are below 4 ppm(v). The reason for the increase in the NOx emissions is the higher reactivity of the mixture, which leads to earlier ignition in zones of still elevated unmixedness of reactants near the premixer-injector exits. This effect was investigated by chemical reactor network simulations analyzing a pressure effect and an additional chemical effect of hydrogen combustion on NOx formation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Flame transfer functions for liquid-fueled swirl-stabilized turbulent lean direct fuel injection combustion / Tongxun Yi in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 06 p. Titre : Flame transfer functions for liquid-fueled swirl-stabilized turbulent lean direct fuel injection combustion Type de document : texte imprimé Auteurs : Tongxun Yi, Auteur ; Domenic A. Santavicca, Auteur Année de publication : 2010 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Flames  Fuel  systems  Internal  combustion  engines  Nozzles  Valves Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Heat release rate responses to inlet fuel modulations, i.e., the flame transfer function (FTF), are measured for a turbulent, liquid-fueled, swirl-stabilized lean direct fuel injection combustor. Fuel modulations are achieved using a motor-driven rotary fuel valve designed specially for this purpose, which is capable of fuel modulations of up to 1 kHz. Small-amplitude fuel modulations, typically below 2.0% of the mean fuel, are applied in this study. There is almost no change in FTFs at different fuel-modulation amplitudes, implying that the derived FTFs are linear and that the induced heat release rate oscillations mainly respond to variations in the instantaneous fuel flow rate rather than in the droplet size and distribution. The gain and phases of the FTFs at different air flow rates and preheat temperatures are examined. The instantaneous fuel flow rate is determined from pressure measurements upstream of a fuel nozzle. Applications of the FTF to modeling and control of combustion instability and lean blowout are discussed. DEWEY : 620.1 ISSN : 0742-479 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Flame transfer functions for liquid-fueled swirl-stabilized turbulent lean direct fuel injection combustion [texte imprimé] / Tongxun Yi, Auteur ; Domenic A. Santavicca, Auteur . - 2010 . - 06 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 06 p. Mots-clés : Combustion  Flames  Fuel  systems  Internal  combustion  engines  Nozzles  Valves Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Heat release rate responses to inlet fuel modulations, i.e., the flame transfer function (FTF), are measured for a turbulent, liquid-fueled, swirl-stabilized lean direct fuel injection combustor. Fuel modulations are achieved using a motor-driven rotary fuel valve designed specially for this purpose, which is capable of fuel modulations of up to 1 kHz. Small-amplitude fuel modulations, typically below 2.0% of the mean fuel, are applied in this study. There is almost no change in FTFs at different fuel-modulation amplitudes, implying that the derived FTFs are linear and that the induced heat release rate oscillations mainly respond to variations in the instantaneous fuel flow rate rather than in the droplet size and distribution. The gain and phases of the FTFs at different air flow rates and preheat temperatures are examined. The instantaneous fuel flow rate is determined from pressure measurements upstream of a fuel nozzle. Applications of the FTF to modeling and control of combustion instability and lean blowout are discussed. DEWEY : 620.1 ISSN : 0742-479 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

A sparse estimation approach to fault isolation / Borguet, S. in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Titre : A sparse estimation approach to fault isolation Type de document : texte imprimé Auteurs : Borguet, S., Auteur ; O. Léonard, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  testing  Jet  engines  Least  mean  squares  methods  Quadratic  programming Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Least-squares-based methods are very popular in the jet engine community for health monitoring purposes. In most practical situations, the number of health parameters exceeds the number of measurements, making the estimation problem underdetermined. To address this issue, regularization adds a penalty term on the deviations of the health parameters. Generally, this term imposes a quadratic penalization on these deviations. A side effect of this technique is a relatively poor isolation capability. The latter feature can be improved by recognizing that abrupt faults impact at most one or two component(s) simultaneously. This translates mathematically into the search for a sparse solution. The present contribution reports the development of a fault isolation tool favoring sparse solutions. It is very efficiently implemented in the form of a quadratic program. As a validation procedure, the resulting algorithm is applied to a variety of fault conditions simulated with a generic commercial turbofan model. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] A sparse estimation approach to fault isolation [texte imprimé] / Borguet, S., Auteur ; O. Léonard, Auteur . - 2010 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Mots-clés : Aerospace  testing  Jet  engines  Least  mean  squares  methods  Quadratic  programming Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Least-squares-based methods are very popular in the jet engine community for health monitoring purposes. In most practical situations, the number of health parameters exceeds the number of measurements, making the estimation problem underdetermined. To address this issue, regularization adds a penalty term on the deviations of the health parameters. Generally, this term imposes a quadratic penalization on these deviations. A side effect of this technique is a relatively poor isolation capability. The latter feature can be improved by recognizing that abrupt faults impact at most one or two component(s) simultaneously. This translates mathematically into the search for a sparse solution. The present contribution reports the development of a fault isolation tool favoring sparse solutions. It is very efficiently implemented in the form of a quadratic program. As a validation procedure, the resulting algorithm is applied to a variety of fault conditions simulated with a generic commercial turbofan model. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

A parametric thermodynamic evaluation of high performance gas turbine based power cycles / Rakesh K. Bhargava in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 14 p. Titre : A parametric thermodynamic evaluation of high performance gas turbine based power cycles Type de document : texte imprimé Auteurs : Rakesh K. Bhargava, Auteur ; Michele Bianchi, Auteur ; Stefano Campanari, Auteur Année de publication : 2010 Article en page(s) : 14 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Brayton  cycle  Fuel  cell  power  plants  Gas  turbine  power  stations  Gas  turbines  Solid  oxide  fuel  cells  Steam  power  stations  Thermodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper discusses the gas turbine performance enhancement approach that has gained a lot of momentum in recent years in which modified Brayton cycles are used with humidification or water/steam injection, termed “wet cycles,” or with fuel cells, obtaining “hybrid cycles.” The investigated high performance cycles include intercooled steam-injected gas turbine cycle, recuperated water injection cycle, humidified air turbine cycle, and cascaded humidified advanced turbine cycle, Brayton cycle with high temperature fuel cells (molten carbonate fuel cells or solid oxide fuel cells), and their combinations with the modified Brayton cycles. Most of these systems, with a few exceptions, have not yet become commercially available as more development work is required. The results presented show that the cycle efficiency achievable with the aforementioned high performance systems can be comparable or better than a combined cycle system, a currently commercially available power generation system having maximum cycle efficiency. The main emphasis of this paper is to provide a detailed parametric thermodynamic cycle analysis, using uniform design parameters and assumptions, of the above mentioned cycles and discuss their comparative performance including advantages and limitations. The performance of these cycles is also compared with the already developed and commercially available gas turbines without water/steam injection features, called “dry cycles.” In addition, a brief review of the available literature of the identified high performance complex gas turbine cycles is also included in this paper. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] A parametric thermodynamic evaluation of high performance gas turbine based power cycles [texte imprimé] / Rakesh K. Bhargava, Auteur ; Michele Bianchi, Auteur ; Stefano Campanari, Auteur . - 2010 . - 14 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 14 p. Mots-clés : Brayton  cycle  Fuel  cell  power  plants  Gas  turbine  power  stations  Gas  turbines  Solid  oxide  fuel  cells  Steam  power  stations  Thermodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper discusses the gas turbine performance enhancement approach that has gained a lot of momentum in recent years in which modified Brayton cycles are used with humidification or water/steam injection, termed “wet cycles,” or with fuel cells, obtaining “hybrid cycles.” The investigated high performance cycles include intercooled steam-injected gas turbine cycle, recuperated water injection cycle, humidified air turbine cycle, and cascaded humidified advanced turbine cycle, Brayton cycle with high temperature fuel cells (molten carbonate fuel cells or solid oxide fuel cells), and their combinations with the modified Brayton cycles. Most of these systems, with a few exceptions, have not yet become commercially available as more development work is required. The results presented show that the cycle efficiency achievable with the aforementioned high performance systems can be comparable or better than a combined cycle system, a currently commercially available power generation system having maximum cycle efficiency. The main emphasis of this paper is to provide a detailed parametric thermodynamic cycle analysis, using uniform design parameters and assumptions, of the above mentioned cycles and discuss their comparative performance including advantages and limitations. The performance of these cycles is also compared with the already developed and commercially available gas turbines without water/steam injection features, called “dry cycles.” In addition, a brief review of the available literature of the identified high performance complex gas turbine cycles is also included in this paper. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Manufacturing optimization for bondcoat/thermal barrier coating systems / Hans-Peter Bossmann in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Titre : Manufacturing optimization for bondcoat/thermal barrier coating systems Type de document : texte imprimé Auteurs : Hans-Peter Bossmann, Auteur ; Sharath Bachegowda, Auteur ; Alexander Schnell, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Design  of  experiments  Gas  turbines  Plasma  arc  spraying  Thermal  barrier  coatings Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A reliable lifetime prediction rule for bondcoat/thermal barrier coating (BC/TBC) coated parts in gas turbine operation is necessary to determine remnant service life. The specimens investigated were coated with MCrAlY plus yttria partially stabilized zirconia applied by vacuum plasma spraying and atmospheric plasma spraying processes, respectively. The performances of these laboratory specimens were statistically assessed, combining long term oxidation testing with thermal cycling, thus superimposing thermomechanical loading on the laboratory specimens to more accurately represent engine conditions. A design of experiment (DOE) approach was used for manufacturing optimization of the BC/TBC system. The life of the coating system is influenced by several manufacturing parameters such as BC thickness, BC roughness, TBC thickness, TBC porosity, and TBC stiffness. Specimens with a suitable variation in these parameters were produced to ensure a balanced test matrix of fractional factorial DOE. Based on results derived from laboratory testing the specifically tailored parts, first and second order effects of manufacturing parameters on lifetime were quantified. The findings revealed that the second order effects (the interaction of manufacturing parameters) were more important on the lifetime of the BC/TBC system than the corresponding first order effect (single parameter). For instance, the variation in BC thickness or BC roughness led to a scatter of lifetimes of 10% and 60%, respectively, whereas their interaction resulted in a scatter of lifetime of 150% for the same range of coating parameters. Further examples of such pairings are also demonstrated. Finally, a lifetime prediction for three quality classes (high, medium, and low qualities) has been demonstrated. The difference in achievable lifetime highlights the importance of manufacturing parameters in determining the life of the BC/TBC system. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Manufacturing optimization for bondcoat/thermal barrier coating systems [texte imprimé] / Hans-Peter Bossmann, Auteur ; Sharath Bachegowda, Auteur ; Alexander Schnell, Auteur . - 2010 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Mots-clés : Design  of  experiments  Gas  turbines  Plasma  arc  spraying  Thermal  barrier  coatings Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A reliable lifetime prediction rule for bondcoat/thermal barrier coating (BC/TBC) coated parts in gas turbine operation is necessary to determine remnant service life. The specimens investigated were coated with MCrAlY plus yttria partially stabilized zirconia applied by vacuum plasma spraying and atmospheric plasma spraying processes, respectively. The performances of these laboratory specimens were statistically assessed, combining long term oxidation testing with thermal cycling, thus superimposing thermomechanical loading on the laboratory specimens to more accurately represent engine conditions. A design of experiment (DOE) approach was used for manufacturing optimization of the BC/TBC system. The life of the coating system is influenced by several manufacturing parameters such as BC thickness, BC roughness, TBC thickness, TBC porosity, and TBC stiffness. Specimens with a suitable variation in these parameters were produced to ensure a balanced test matrix of fractional factorial DOE. Based on results derived from laboratory testing the specifically tailored parts, first and second order effects of manufacturing parameters on lifetime were quantified. The findings revealed that the second order effects (the interaction of manufacturing parameters) were more important on the lifetime of the BC/TBC system than the corresponding first order effect (single parameter). For instance, the variation in BC thickness or BC roughness led to a scatter of lifetimes of 10% and 60%, respectively, whereas their interaction resulted in a scatter of lifetime of 150% for the same range of coating parameters. Further examples of such pairings are also demonstrated. Finally, a lifetime prediction for three quality classes (high, medium, and low qualities) has been demonstrated. The difference in achievable lifetime highlights the importance of manufacturing parameters in determining the life of the BC/TBC system. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Effects of coating thickness, test temperature, and coating hardness on the erosion resistance of steam turbine blades / Shun-sen Wang in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Titre : Effects of coating thickness, test temperature, and coating hardness on the erosion resistance of steam turbine blades Type de document : texte imprimé Auteurs : Shun-sen Wang, Auteur ; Guan-wei Liu, Auteur ; Jing-ru Mao, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Blades  Chromium  compounds  Hardness  Ion  plating  Protective  coatings  Steam  turbines  Thermal  spraying  Wear  resistance Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper experimentally examines the influence of coating thickness, test temperature, coating hardness, and defects on the erosion resistance of boride coatings, ion plating CrN coatings, and thermal spraying coatings. The results demonstrate that the erosion rate of coating can be reduced effectively by improving coating hardness and thickness with the absence of the cracks of coating during the coating process. In comparison with thermal spraying coatings, boride coatings and ion plating CrN coatings are more suitable for protecting steam turbine blades from solid particle erosion due to higher erosion resistance. However, blades cannot be protected effectively when coating is thinner than a critical value thetacrit. Based on our results, it is recommended that the protective coating for the steam turbine blade should be thicker than 0.02 mm. In addition, the effect of temperature on erosion resistance of the coating is strongly dependent on the properties of transition layer between coating and substrate material. For the coating without pinholes or pores in the transition layer, the variation in erosion rate with temperature is consistent with that of uncoated substrate material. However, the erosion rate of coating descends with the elevation of test temperature when a lot of pinholes or pores are produced in the transition layer. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Effects of coating thickness, test temperature, and coating hardness on the erosion resistance of steam turbine blades [texte imprimé] / Shun-sen Wang, Auteur ; Guan-wei Liu, Auteur ; Jing-ru Mao, Auteur . - 2010 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Mots-clés : Blades  Chromium  compounds  Hardness  Ion  plating  Protective  coatings  Steam  turbines  Thermal  spraying  Wear  resistance Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper experimentally examines the influence of coating thickness, test temperature, coating hardness, and defects on the erosion resistance of boride coatings, ion plating CrN coatings, and thermal spraying coatings. The results demonstrate that the erosion rate of coating can be reduced effectively by improving coating hardness and thickness with the absence of the cracks of coating during the coating process. In comparison with thermal spraying coatings, boride coatings and ion plating CrN coatings are more suitable for protecting steam turbine blades from solid particle erosion due to higher erosion resistance. However, blades cannot be protected effectively when coating is thinner than a critical value thetacrit. Based on our results, it is recommended that the protective coating for the steam turbine blade should be thicker than 0.02 mm. In addition, the effect of temperature on erosion resistance of the coating is strongly dependent on the properties of transition layer between coating and substrate material. For the coating without pinholes or pores in the transition layer, the variation in erosion rate with temperature is consistent with that of uncoated substrate material. However, the erosion rate of coating descends with the elevation of test temperature when a lot of pinholes or pores are produced in the transition layer. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Role of platinum in thermal barrier coatings used in gas turbine blade applications / H. M. Tawancy in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 06 p. Titre : Role of platinum in thermal barrier coatings used in gas turbine blade applications Type de document : texte imprimé Auteurs : H. M. Tawancy, Auteur ; Luai M. Al Hadhrami, Auteur Année de publication : 2010 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aluminium  compounds  Blades  Diffusion  Electroplating  Gas  turbines  Oxidation  Platinum  Superalloys  Thermal  barrier  coatings Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Current technology of thermal barrier coating systems used in gas turbine blade applications relies on the use of a metallic bond coat, which has a twofold function: (i) it develops a thin layer of aluminum oxide enhancing the adhesion of the ceramic top coat and (ii) it provides an additional resistance to oxidation. It was the objective of this study to develop an understanding of the role of platinum in bond coats of the diffusion-type deposited on a nickel-based superalloy. Two Pt-containing bond coats were included in the study: (i) a platinum-aluminide and (ii) a bond coat formed by interdiffusion between an electroplated layer of platinum and the superalloy substrate. In both cases, the top ceramic coat was yttria-stabilized zirconia. For reference purposes, a simple aluminide bond coat free of Pt was also included in the study. Thermal exposure tests at 1150°C with a 24 h cycling period at room temperature were used to compare the coating performance. Microstructural features were characterized by various electron-optical techniques. Experimental results indicated that Pt acts as a “cleanser” of the oxide-bond coat interface by decelerating the kinetics of interdiffusion between the bond coat and superalloy substrate. This was found to promote selective oxidation of Al resulting in a purer Al2O3 scale of a slower growth rate increasing its effectiveness as “glue” holding the ceramic top coat to the underlying metallic substrate. However, the exact effect of Pt was found to be a function of the state of its presence within the outermost coating layer. Of the two bond coats studied, a surface layer of Pt-rich gamma prime phase (L12 superlattice) was found to provide longer coating life in comparison with a mixture of PtAl2 and beta phase. This could be related to the effectiveness of gamma prime phase as a sink for titanium minimizing its detrimental effect on the adherence of aluminum oxide. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Role of platinum in thermal barrier coatings used in gas turbine blade applications [texte imprimé] / H. M. Tawancy, Auteur ; Luai M. Al Hadhrami, Auteur . - 2010 . - 06 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 06 p. Mots-clés : Aluminium  compounds  Blades  Diffusion  Electroplating  Gas  turbines  Oxidation  Platinum  Superalloys  Thermal  barrier  coatings Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Current technology of thermal barrier coating systems used in gas turbine blade applications relies on the use of a metallic bond coat, which has a twofold function: (i) it develops a thin layer of aluminum oxide enhancing the adhesion of the ceramic top coat and (ii) it provides an additional resistance to oxidation. It was the objective of this study to develop an understanding of the role of platinum in bond coats of the diffusion-type deposited on a nickel-based superalloy. Two Pt-containing bond coats were included in the study: (i) a platinum-aluminide and (ii) a bond coat formed by interdiffusion between an electroplated layer of platinum and the superalloy substrate. In both cases, the top ceramic coat was yttria-stabilized zirconia. For reference purposes, a simple aluminide bond coat free of Pt was also included in the study. Thermal exposure tests at 1150°C with a 24 h cycling period at room temperature were used to compare the coating performance. Microstructural features were characterized by various electron-optical techniques. Experimental results indicated that Pt acts as a “cleanser” of the oxide-bond coat interface by decelerating the kinetics of interdiffusion between the bond coat and superalloy substrate. This was found to promote selective oxidation of Al resulting in a purer Al2O3 scale of a slower growth rate increasing its effectiveness as “glue” holding the ceramic top coat to the underlying metallic substrate. However, the exact effect of Pt was found to be a function of the state of its presence within the outermost coating layer. Of the two bond coats studied, a surface layer of Pt-rich gamma prime phase (L12 superlattice) was found to provide longer coating life in comparison with a mixture of PtAl2 and beta phase. This could be related to the effectiveness of gamma prime phase as a sink for titanium minimizing its detrimental effect on the adherence of aluminum oxide. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Micro gas turbine recuperator / Mario L. Ferrari in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 08 p. Titre : Micro gas turbine recuperator : steady-state and transient experimental investigation Type de document : texte imprimé Auteurs : Mario L. Ferrari, Auteur ; Matteo Pascenti, Auteur ; Loredana Magistri, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Gas  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The aim of this work is the experimental analysis of a primary-surface recuperator, operating in a 100 kW micro gas turbine, as in a standard recuperated cycle. These tests, performed in both steady-state and transient conditions, have been carried out using the micro gas turbine test rig, developed by the Thermochemical Power Group at the University of Genova, Italy. Even if this facility has mainly been designed for hybrid system emulations, it is possible to exploit the plant for component tests, such as experimental studies on recuperators. The valves installed in the rig make it possible to operate the plant in the standard recuperated configuration, and the facility has been equipped with new probes essential for this kind of tests. A wide-ranging analysis of the recuperator performance has been carried out with the machine, operating in stand-alone configuration, or connected to the electrical grid, to test different control strategy influences. Particular attention has been given to tests performed at different electrical load values and with different mass flow rates through the recuperator ducts. The final section of this paper reports the transient analysis carried out on this recuperator. The attention is mainly focused on thermal transient performance of the component, showing the effects of both temperature and flow steps. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Micro gas turbine recuperator : steady-state and transient experimental investigation [texte imprimé] / Mario L. Ferrari, Auteur ; Matteo Pascenti, Auteur ; Loredana Magistri, Auteur . - 2010 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 08 p. Mots-clés : Gas  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The aim of this work is the experimental analysis of a primary-surface recuperator, operating in a 100 kW micro gas turbine, as in a standard recuperated cycle. These tests, performed in both steady-state and transient conditions, have been carried out using the micro gas turbine test rig, developed by the Thermochemical Power Group at the University of Genova, Italy. Even if this facility has mainly been designed for hybrid system emulations, it is possible to exploit the plant for component tests, such as experimental studies on recuperators. The valves installed in the rig make it possible to operate the plant in the standard recuperated configuration, and the facility has been equipped with new probes essential for this kind of tests. A wide-ranging analysis of the recuperator performance has been carried out with the machine, operating in stand-alone configuration, or connected to the electrical grid, to test different control strategy influences. Particular attention has been given to tests performed at different electrical load values and with different mass flow rates through the recuperator ducts. The final section of this paper reports the transient analysis carried out on this recuperator. The attention is mainly focused on thermal transient performance of the component, showing the effects of both temperature and flow steps. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Comparison of three microturbine primary surface recuperator alloys / Wendy J. Matthews in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 06 p. Titre : Comparison of three microturbine primary surface recuperator alloys Type de document : texte imprimé Auteurs : Wendy J. Matthews, Auteur ; Karren L. More, Auteur ; Larry R. Walker, Auteur Année de publication : 2010 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Austenitic  stainless  steel  Chromium  alloys  Combustion  Costing  Creep  Iron  alloys  Manganese  alloys  Materials  testing  Nickel  alloys  Niobium  alloys  Oxidation  Solid  solution  hardening  Turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Extensive work performed by Capstone Turbine Corporation, Oak Ridge National Laboratory, and various others has shown that the traditional primary surface recuperator alloy, type 347 stainless steel, is unsuitable for applications above 650°C (~1200°F). Numerous studies have shown that the presence of water vapor greatly accelerates the oxidation rate of type 347 stainless steel at temperatures above 650°C (~1200°F). Water vapor is present as a product of combustion in the microturbine exhaust, making it necessary to find replacement alloys for type 347 stainless steel that will meet the long life requirements of microturbine primary surface recuperators. It has been well established over the past few years that alloys with higher chromium and nickel contents than type 347 stainless steel have much greater oxidation resistance in the microturbine environment. One such alloy that has replaced type 347 stainless steel in primary surface recuperators is Haynes Alloy HR-120 (Haynes and HR-120 are trademarks of Haynes International, Inc.), a solid-solution-strengthened alloy with nominally 33 wt % Fe, 37 wt % Ni and 25 wt % Cr. Unfortunately, while HR-120 is significantly more oxidation resistant in the microturbine environment, it is also a much more expensive alloy. In the interest of cost reduction, other candidate primary surface recuperator alloys are being investigated as possible alternatives to type 347 stainless steel. An initial rainbow recuperator test has been performed at Capstone to compare the oxidation resistance of type 347 stainless steel, HR-120, and the Allegheny Ludlum austenitic alloy AL 20–25+Nb (AL 20–25+Nb is a trademark of ATI Properties, Inc. and is licensed to Allegheny Ludlum Corporation). Evaluation of surface oxide scale formation and associated alloy depletion and other compositional changes has been carried out at Oak Ridge National Laboratory. The results of this initial rainbow test will be presented and discussed in this paper. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Comparison of three microturbine primary surface recuperator alloys [texte imprimé] / Wendy J. Matthews, Auteur ; Karren L. More, Auteur ; Larry R. Walker, Auteur . - 2010 . - 06 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 06 p. Mots-clés : Austenitic  stainless  steel  Chromium  alloys  Combustion  Costing  Creep  Iron  alloys  Manganese  alloys  Materials  testing  Nickel  alloys  Niobium  alloys  Oxidation  Solid  solution  hardening  Turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Extensive work performed by Capstone Turbine Corporation, Oak Ridge National Laboratory, and various others has shown that the traditional primary surface recuperator alloy, type 347 stainless steel, is unsuitable for applications above 650°C (~1200°F). Numerous studies have shown that the presence of water vapor greatly accelerates the oxidation rate of type 347 stainless steel at temperatures above 650°C (~1200°F). Water vapor is present as a product of combustion in the microturbine exhaust, making it necessary to find replacement alloys for type 347 stainless steel that will meet the long life requirements of microturbine primary surface recuperators. It has been well established over the past few years that alloys with higher chromium and nickel contents than type 347 stainless steel have much greater oxidation resistance in the microturbine environment. One such alloy that has replaced type 347 stainless steel in primary surface recuperators is Haynes Alloy HR-120 (Haynes and HR-120 are trademarks of Haynes International, Inc.), a solid-solution-strengthened alloy with nominally 33 wt % Fe, 37 wt % Ni and 25 wt % Cr. Unfortunately, while HR-120 is significantly more oxidation resistant in the microturbine environment, it is also a much more expensive alloy. In the interest of cost reduction, other candidate primary surface recuperator alloys are being investigated as possible alternatives to type 347 stainless steel. An initial rainbow recuperator test has been performed at Capstone to compare the oxidation resistance of type 347 stainless steel, HR-120, and the Allegheny Ludlum austenitic alloy AL 20–25+Nb (AL 20–25+Nb is a trademark of ATI Properties, Inc. and is licensed to Allegheny Ludlum Corporation). Evaluation of surface oxide scale formation and associated alloy depletion and other compositional changes has been carried out at Oak Ridge National Laboratory. The results of this initial rainbow test will be presented and discussed in this paper. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Nonlinear dynamic analysis and experiment verification of rotor-ball bearings-support-stator coupling system for aeroengine with rubbing coupling faults / G. Chen in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 09 p. Titre : Nonlinear dynamic analysis and experiment verification of rotor-ball bearings-support-stator coupling system for aeroengine with rubbing coupling faults Type de document : texte imprimé Auteurs : G. Chen, Auteur ; C. G. Li, Auteur ; D. Y. Wang, Auteur Année de publication : 2010 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  engines  Ball  bearings  Rotors  Stators Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this paper, a new rotor-ball bearings-support-stator coupling system dynamic model with rubbing coupling faults is established for practical aeroengine. In the model, the rubbing fault is modeled, the stator motion is considered, the flexible support and squeeze film damper are established, and the nonlinear factors of ball bearing, such as the clearance of the bearing, the nonlinear Hertzian contact force between balls and races, and the varying compliance vibration because of the periodical variety of the contact position between balls and races, are modeled. The numerical integral method is used to obtain the system responses, the effect of support stiffness on rotor responses is studied using a vibration amplitude-rotating speed plot, and the characteristics of the rubbing fault is analyzed using a 3D cascade plot. An aeroengine tester with a stator is established to carry out the rubbing fault experiments, the simulation results from the rotor-ball bearings-support-stator coupling model are compared with the experimental results, and the consistency of the results show fully the effectiveness of the new rotor-ball bearings-support-stator coupling model with rubbing fault. DEWEY : 62.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Nonlinear dynamic analysis and experiment verification of rotor-ball bearings-support-stator coupling system for aeroengine with rubbing coupling faults [texte imprimé] / G. Chen, Auteur ; C. G. Li, Auteur ; D. Y. Wang, Auteur . - 2010 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 09 p. Mots-clés : Aerospace  engines  Ball  bearings  Rotors  Stators Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this paper, a new rotor-ball bearings-support-stator coupling system dynamic model with rubbing coupling faults is established for practical aeroengine. In the model, the rubbing fault is modeled, the stator motion is considered, the flexible support and squeeze film damper are established, and the nonlinear factors of ball bearing, such as the clearance of the bearing, the nonlinear Hertzian contact force between balls and races, and the varying compliance vibration because of the periodical variety of the contact position between balls and races, are modeled. The numerical integral method is used to obtain the system responses, the effect of support stiffness on rotor responses is studied using a vibration amplitude-rotating speed plot, and the characteristics of the rubbing fault is analyzed using a 3D cascade plot. An aeroengine tester with a stator is established to carry out the rubbing fault experiments, the simulation results from the rotor-ball bearings-support-stator coupling model are compared with the experimental results, and the consistency of the results show fully the effectiveness of the new rotor-ball bearings-support-stator coupling model with rubbing fault. DEWEY : 62.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Onset of (1/2)X vibration and its prevention / John J. Yu in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 10 p. Titre : Onset of (1/2)X vibration and its prevention Type de document : texte imprimé Auteurs : John J. Yu, Auteur Année de publication : 2010 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Turbomachinery  Vibrations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper discusses real cases on three different machines where subsynchronous vibration occurred suddenly at a frequency exactly equal to one-half ((1/2)X) of the operational speed of 3600 rpm. In two cases, vibration amplitude increased from around 2 mils (51 µm) pp to over 12 mils (305 µm) pp, causing the machine to trip unexpectedly. The (1/2)X vibration was even sustained during shutdown at speed below 3600 rpm after trip. Unlike other reported experimental results, shaft orbit measured by proximity probes was fairly circular and dominantly composed of the (1/2)X component without significant components at multiple orders of the (1/2)X. The onset of the subsynchronous (1/2)X vibration was sometimes triggered by changes in bearing lube oil temperature and supply pressure, which would typically be believed to be caused by oil whirl that could occur at close to the (1/2)X frequency. An upward shift in shaft centerline plot was observed to occur prior to the onset of the subsynchronous vibration. The (1/2)X vibration was successfully prevented by changing bearing clearance or adjustment of bearing oil temperature and supply pressure. Parametric excitation analysis on (1/2)X vibration is also given in this paper. The main purpose of this paper, unlike previously published papers on analytical or experimental results, is to show shaft orbital and centerline plots as well as spectrum data due to the (1/2)X vibration, including effects of operating conditions in real rotating machines. DEWEY : 62.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Onset of (1/2)X vibration and its prevention [texte imprimé] / John J. Yu, Auteur . - 2010 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 10 p. Mots-clés : Turbomachinery  Vibrations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper discusses real cases on three different machines where subsynchronous vibration occurred suddenly at a frequency exactly equal to one-half ((1/2)X) of the operational speed of 3600 rpm. In two cases, vibration amplitude increased from around 2 mils (51 µm) pp to over 12 mils (305 µm) pp, causing the machine to trip unexpectedly. The (1/2)X vibration was even sustained during shutdown at speed below 3600 rpm after trip. Unlike other reported experimental results, shaft orbit measured by proximity probes was fairly circular and dominantly composed of the (1/2)X component without significant components at multiple orders of the (1/2)X. The onset of the subsynchronous (1/2)X vibration was sometimes triggered by changes in bearing lube oil temperature and supply pressure, which would typically be believed to be caused by oil whirl that could occur at close to the (1/2)X frequency. An upward shift in shaft centerline plot was observed to occur prior to the onset of the subsynchronous vibration. The (1/2)X vibration was successfully prevented by changing bearing clearance or adjustment of bearing oil temperature and supply pressure. Parametric excitation analysis on (1/2)X vibration is also given in this paper. The main purpose of this paper, unlike previously published papers on analytical or experimental results, is to show shaft orbital and centerline plots as well as spectrum data due to the (1/2)X vibration, including effects of operating conditions in real rotating machines. DEWEY : 62.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

An experimental and modeling study of HCCI combustion using n-heptane / Hongsheng Guo in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 10 p. Titre : An experimental and modeling study of HCCI combustion using n-heptane Type de document : texte imprimé Auteurs : Hongsheng Guo, Auteur ; W. Stuart Neill, Auteur ; Wally Chippior, Auteur Année de publication : 2010 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Internal  combustion  engines  Numerical  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Homogeneous charge compression ignition (HCCI) is an advanced low-temperature combustion technology being considered for internal combustion engines due to its potential for high fuel conversion efficiency and extremely low emissions of particulate matter and oxides of nitrogen (NOx). In its simplest form, HCCI combustion involves the auto-ignition of a homogeneous mixture of fuel, air, and diluents at low to moderate temperatures and high pressure. Previous research has indicated that fuel chemistry has a strong impact on HCCI combustion. This paper reports the preliminary results of an experimental and modeling study of HCCI combustion using n-heptane, a volatile hydrocarbon with well known fuel chemistry. A Co-operative Fuel Research (CFR) engine was modified by the addition of a port fuel injection system to produce a homogeneous fuel-air mixture in the intake manifold, which contributed to a stable and repeatable HCCI combustion process. Detailed experiments were performed to explore the effects of critical engine parameters such as intake temperature, compression ratio, air/fuel ratio, engine speed, turbocharging, and intake mixture throttling on HCCI combustion. The influence of these parameters on the phasing of the low-temperature reaction, main combustion stage, and negative temperature coefficient delay period are presented and discussed. A single-zone numerical simulation with detailed fuel chemistry was developed and validated. The simulations show good agreement with the experimental data and capture important combustion phase trends as engine parameters are varied. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] An experimental and modeling study of HCCI combustion using n-heptane [texte imprimé] / Hongsheng Guo, Auteur ; W. Stuart Neill, Auteur ; Wally Chippior, Auteur . - 2010 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 10 p. Mots-clés : Internal  combustion  engines  Numerical  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Homogeneous charge compression ignition (HCCI) is an advanced low-temperature combustion technology being considered for internal combustion engines due to its potential for high fuel conversion efficiency and extremely low emissions of particulate matter and oxides of nitrogen (NOx). In its simplest form, HCCI combustion involves the auto-ignition of a homogeneous mixture of fuel, air, and diluents at low to moderate temperatures and high pressure. Previous research has indicated that fuel chemistry has a strong impact on HCCI combustion. This paper reports the preliminary results of an experimental and modeling study of HCCI combustion using n-heptane, a volatile hydrocarbon with well known fuel chemistry. A Co-operative Fuel Research (CFR) engine was modified by the addition of a port fuel injection system to produce a homogeneous fuel-air mixture in the intake manifold, which contributed to a stable and repeatable HCCI combustion process. Detailed experiments were performed to explore the effects of critical engine parameters such as intake temperature, compression ratio, air/fuel ratio, engine speed, turbocharging, and intake mixture throttling on HCCI combustion. The influence of these parameters on the phasing of the low-temperature reaction, main combustion stage, and negative temperature coefficient delay period are presented and discussed. A single-zone numerical simulation with detailed fuel chemistry was developed and validated. The simulations show good agreement with the experimental data and capture important combustion phase trends as engine parameters are varied. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Experimental study on effects of nozzle hole geometry on achieving low diesel engine emissions / Prashanth K. Karra in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 10 p. Titre : Experimental study on effects of nozzle hole geometry on achieving low diesel engine emissions Type de document : texte imprimé Auteurs : Prashanth K. Karra, Auteur ; Song-Charng Kong, Auteur Année de publication : 2010 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air  pollution  Diesel  engines  Nozzles Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three injectors with different nozzle geometries were tested in a multicylinder diesel engine with a high-pressure common-rail injection system. Various injection pressures were tested along with exhaust gas recirculation to achieve low NOx and soot emissions. The injectors used in the study included a six-hole nozzle, a ten-hole nozzle, and a six-hole convergent nozzle with a K-factor of 3. All three injectors had the same flow numbers. All three injectors tested were effective in reducing NOx and soot emissions at appropriate conditions. It was found that low temperature combustion can be achieved by using high levels of exhaust gas recirculation with late injection timings. High injection pressures significantly reduced soot emissions at conventional injection timings. The effect of injection pressure was not significant at retarded injection timings, i.e., 5 ATDC. The convergent nozzle was found to produce higher soot emissions compared with the straight-hole nozzle under the same injection conditions. Effects of the convergent nozzle on NOx emissions and fuel consumption were not significant. The small nozzle size in the ten-hole injector can generate smaller fuel drops and lead to better atomization. The ten-hole injector appeared to have better air utilization and resulted in significant reductions in NOx and soot emissions over a wide range of operating conditions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Experimental study on effects of nozzle hole geometry on achieving low diesel engine emissions [texte imprimé] / Prashanth K. Karra, Auteur ; Song-Charng Kong, Auteur . - 2010 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 10 p. Mots-clés : Air  pollution  Diesel  engines  Nozzles Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three injectors with different nozzle geometries were tested in a multicylinder diesel engine with a high-pressure common-rail injection system. Various injection pressures were tested along with exhaust gas recirculation to achieve low NOx and soot emissions. The injectors used in the study included a six-hole nozzle, a ten-hole nozzle, and a six-hole convergent nozzle with a K-factor of 3. All three injectors had the same flow numbers. All three injectors tested were effective in reducing NOx and soot emissions at appropriate conditions. It was found that low temperature combustion can be achieved by using high levels of exhaust gas recirculation with late injection timings. High injection pressures significantly reduced soot emissions at conventional injection timings. The effect of injection pressure was not significant at retarded injection timings, i.e., 5 ATDC. The convergent nozzle was found to produce higher soot emissions compared with the straight-hole nozzle under the same injection conditions. Effects of the convergent nozzle on NOx emissions and fuel consumption were not significant. The small nozzle size in the ten-hole injector can generate smaller fuel drops and lead to better atomization. The ten-hole injector appeared to have better air utilization and resulted in significant reductions in NOx and soot emissions over a wide range of operating conditions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Computationally efficient whole-engine model of a cummins 2007 turbocharged diesel engine / Kulkarni, Anup M. in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 09 p. Titre : Computationally efficient whole-engine model of a cummins 2007 turbocharged diesel engine Type de document : texte imprimé Auteurs : Kulkarni, Anup M., Auteur ; Shaver, Gregory. M., Auteur ; Sriram S. Popuri, Auteur Année de publication : 2010 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air  pollution  Closed  loop  systems  Combustion  Compressors  Diesel  engines  Exhaust  systems  Fuel  systems  Open  loop  systems  Shapes  (structures) Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper describes an accurate, flexible, and computationally efficient whole engine model incorporating a multizone, quasidimension combustion submodel for a 6.7-l six-cylinder turbocharged diesel engine with cooled exhaust gas recirculation (EGR), cooled air, and multiple fuel injections. The engine performance and NOx emissions predicative capability of the model is demonstrated at 22 engine operating conditions. The only model inputs are physical engine control module “control actions,” including injection rates, injection timings, EGR valve position, and variable geometry turbocharger rack position. The model is run using both “open” and “closed” loop control strategies for air/EGR path control, in both cases achieving very good correlation with experimental data. Model outputs include in-cylinder pressure and heat release, torque, combustion timing, brake specific fuel consumption, EGR flow rate, air flow rate, exhaust and intake pressure, and NOx emissions. The model predicts engine performance and emissions with average absolute errors within 5% and 18%, respectively, of true values with “open-loop” air/EGR control, and within 5% and 11% with “closed-loop” air/EGR control. In addition, accurate prediction of the coupling of the in-cylinder combustion and emission-production processes with the boosted, cooled air/EGR gas dynamics is a key characteristic of the model. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Computationally efficient whole-engine model of a cummins 2007 turbocharged diesel engine [texte imprimé] / Kulkarni, Anup M., Auteur ; Shaver, Gregory. M., Auteur ; Sriram S. Popuri, Auteur . - 2010 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 09 p. Mots-clés : Air  pollution  Closed  loop  systems  Combustion  Compressors  Diesel  engines  Exhaust  systems  Fuel  systems  Open  loop  systems  Shapes  (structures) Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper describes an accurate, flexible, and computationally efficient whole engine model incorporating a multizone, quasidimension combustion submodel for a 6.7-l six-cylinder turbocharged diesel engine with cooled exhaust gas recirculation (EGR), cooled air, and multiple fuel injections. The engine performance and NOx emissions predicative capability of the model is demonstrated at 22 engine operating conditions. The only model inputs are physical engine control module “control actions,” including injection rates, injection timings, EGR valve position, and variable geometry turbocharger rack position. The model is run using both “open” and “closed” loop control strategies for air/EGR path control, in both cases achieving very good correlation with experimental data. Model outputs include in-cylinder pressure and heat release, torque, combustion timing, brake specific fuel consumption, EGR flow rate, air flow rate, exhaust and intake pressure, and NOx emissions. The model predicts engine performance and emissions with average absolute errors within 5% and 18%, respectively, of true values with “open-loop” air/EGR control, and within 5% and 11% with “closed-loop” air/EGR control. In addition, accurate prediction of the coupling of the in-cylinder combustion and emission-production processes with the boosted, cooled air/EGR gas dynamics is a key characteristic of the model. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

A convective mass transfer model for predicting vapor formation within the cooling system of an internal combustion engine after shutdown / Rocco Piccione in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 10 p. Titre : A convective mass transfer model for predicting vapor formation within the cooling system of an internal combustion engine after shutdown Type de document : texte imprimé Auteurs : Rocco Piccione, Auteur ; Antonio Vulcano, Auteur ; Sergio Bova, Auteur Année de publication : 2010 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Automotive  components  Cooling  Internal  combustion  engines  Mass  transfer  Pumps  Shafts  Thermodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In the usual liquid cooling system of an internal combustion engine a centrifugal pump is driven by the crankshaft and imposes a coolant flow, which transfers heat from the engine walls to the radiator. Therefore, as the engine is switched-off, the coolant flow also stops, while metal temperature may be particularly high after a period of high load operation; coolant vaporization in the cylinder head passages may occur in these conditions, with a pressure increase inside the cooling circuit. A numerical dynamic model was developed to predict this phenomenon, often called after-boiling among engine manufacturers. The model structure includes thermodynamic equations to compute heat transfer as well as mass transfer equations to determine the vaporized mass of the coolant, which occurs in cylinder head passages and the vapor condensation within the radiator. The developed mathematical model was validated against test data carried out on a production four-stroke spark-ignition engine, and simulation results show good agreement with experimental data. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] A convective mass transfer model for predicting vapor formation within the cooling system of an internal combustion engine after shutdown [texte imprimé] / Rocco Piccione, Auteur ; Antonio Vulcano, Auteur ; Sergio Bova, Auteur . - 2010 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 10 p. Mots-clés : Automotive  components  Cooling  Internal  combustion  engines  Mass  transfer  Pumps  Shafts  Thermodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In the usual liquid cooling system of an internal combustion engine a centrifugal pump is driven by the crankshaft and imposes a coolant flow, which transfers heat from the engine walls to the radiator. Therefore, as the engine is switched-off, the coolant flow also stops, while metal temperature may be particularly high after a period of high load operation; coolant vaporization in the cylinder head passages may occur in these conditions, with a pressure increase inside the cooling circuit. A numerical dynamic model was developed to predict this phenomenon, often called after-boiling among engine manufacturers. The model structure includes thermodynamic equations to compute heat transfer as well as mass transfer equations to determine the vaporized mass of the coolant, which occurs in cylinder head passages and the vapor condensation within the radiator. The developed mathematical model was validated against test data carried out on a production four-stroke spark-ignition engine, and simulation results show good agreement with experimental data. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Measurement of flow phenomena in a lower plenum model of a prismatic gas-cooled reactor / Hugh M. McIlroy, Jr. in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Titre : Measurement of flow phenomena in a lower plenum model of a prismatic gas-cooled reactor Type de document : texte imprimé Auteurs : Hugh M. McIlroy, Jr., Auteur ; Mc Eligot, Donald M., Auteur ; Robert J. Pink, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Chemical  reactors  Confined  flow  Flow  measurement  Jets  Refractive  index  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Mean-velocity-field and turbulence data are presented that measure turbulent flow phenomena in an approximately 1:7 scale model of a region of the lower plenum of a typical prismatic gas-cooled reactor similar to a General Atomics gas-turbine-modular helium reactor design. The data were obtained in the Matched-Index-of-Refraction (MIR) Facility at Idaho National Laboratory (INL) and are offered for assessing computational fluid dynamics software. This experiment has been selected as the first standard problem endorsed by the Generation IV International Forum. Results concentrate on the region of the lower plenum near its far reflector wall (away from the outlet duct). The flow in the lower plenum consists of multiple jets injected into a confined cross flow—with obstructions. The model consists of a row of full circular posts along its centerline with half-posts on the two parallel walls to approximate geometry scaled to that expected from the staggered parallel rows of posts in the reactor design. The model is fabricated from clear, fused quartz to match the refractive-index of the working fluid so that optical techniques may be employed for the measurements. The benefit of the MIR technique is that it permits optical measurements to determine flow characteristics in complex passages in and around objects to be obtained without locating intrusive transducers that will disturb the flow field and without distortion of the optical paths. An advantage of the INL system is its large size, leading to improved spatial and temporal resolutions compared with similar facilities at smaller scales. A three-dimensional particle image velocimetry system was used to collect the data. Inlet-jet Reynolds numbers (based on the jet diameter and the time-mean bulk velocity) are approximately 4300 and 12,400. Uncertainty analyses and a discussion of the standard problem are included. The measurements reveal developing, nonuniform, turbulent flow in the inlet jets and complicated flow patterns in the model lower plenum. Data include three-dimensional vector plots, data displays along the coordinate planes (slices), and presentations that describe the component flows at specific regions in the model. Information on inlet conditions is also presented. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Measurement of flow phenomena in a lower plenum model of a prismatic gas-cooled reactor [texte imprimé] / Hugh M. McIlroy, Jr., Auteur ; Mc Eligot, Donald M., Auteur ; Robert J. Pink, Auteur . - 2010 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 07 p. Mots-clés : Chemical  reactors  Confined  flow  Flow  measurement  Jets  Refractive  index  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Mean-velocity-field and turbulence data are presented that measure turbulent flow phenomena in an approximately 1:7 scale model of a region of the lower plenum of a typical prismatic gas-cooled reactor similar to a General Atomics gas-turbine-modular helium reactor design. The data were obtained in the Matched-Index-of-Refraction (MIR) Facility at Idaho National Laboratory (INL) and are offered for assessing computational fluid dynamics software. This experiment has been selected as the first standard problem endorsed by the Generation IV International Forum. Results concentrate on the region of the lower plenum near its far reflector wall (away from the outlet duct). The flow in the lower plenum consists of multiple jets injected into a confined cross flow—with obstructions. The model consists of a row of full circular posts along its centerline with half-posts on the two parallel walls to approximate geometry scaled to that expected from the staggered parallel rows of posts in the reactor design. The model is fabricated from clear, fused quartz to match the refractive-index of the working fluid so that optical techniques may be employed for the measurements. The benefit of the MIR technique is that it permits optical measurements to determine flow characteristics in complex passages in and around objects to be obtained without locating intrusive transducers that will disturb the flow field and without distortion of the optical paths. An advantage of the INL system is its large size, leading to improved spatial and temporal resolutions compared with similar facilities at smaller scales. A three-dimensional particle image velocimetry system was used to collect the data. Inlet-jet Reynolds numbers (based on the jet diameter and the time-mean bulk velocity) are approximately 4300 and 12,400. Uncertainty analyses and a discussion of the standard problem are included. The measurements reveal developing, nonuniform, turbulent flow in the inlet jets and complicated flow patterns in the model lower plenum. Data include three-dimensional vector plots, data displays along the coordinate planes (slices), and presentations that describe the component flows at specific regions in the model. Information on inlet conditions is also presented. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

Extrapolation and curve-fitting of calibration data for differential pressure flow meters / David R. Keyser in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 04 p. Titre : Extrapolation and curve-fitting of calibration data for differential pressure flow meters Type de document : texte imprimé Auteurs : David R. Keyser, Auteur ; Jeffrey R. Friedman, Auteur Année de publication : 2010 Article en page(s) : 04 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Calibration  Curve  fitting  Extrapolation  Flow  measurement  Flowmeters  Nozzles  Orifices  (mechanical)  Regression  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Performance test codes require primary mass-flow accuracies that in many applications require laboratory quality calibration of differential pressure meters. It is also true that many performance tests are conducted at Reynolds numbers and flows well above the laboratories' capacities, and sound extrapolation methods had to be developed. Statistical curve fits and regression analyses by themselves, absent fluid-dynamic foundations, are not valid procedures for extrapolation. The ASME PTC 19.5-2004 discharge coefficient equations reproduced in this paper for nozzles, orifices, and venturis are suitable for use whenever calibration data are to be applied in a flow measurement and/or extrapolated to higher Reynolds numbers as necessary. The equations may also be used for uncalibrated differential pressure meters by using nominal values. It is necessary to note that the metering runs must be manufactured with dimensions, tolerances, smoothness, etc., and installed in strict accordance with ASME PTC 19.5 for these equations to be valid. Note that for compressible flow, the value of the expansion factor term in the PTC 19.5 equation must be the one corresponding to the published PTC 19.5 equation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] Extrapolation and curve-fitting of calibration data for differential pressure flow meters [texte imprimé] / David R. Keyser, Auteur ; Jeffrey R. Friedman, Auteur . - 2010 . - 04 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 04 p. Mots-clés : Calibration  Curve  fitting  Extrapolation  Flow  measurement  Flowmeters  Nozzles  Orifices  (mechanical)  Regression  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Performance test codes require primary mass-flow accuracies that in many applications require laboratory quality calibration of differential pressure meters. It is also true that many performance tests are conducted at Reynolds numbers and flows well above the laboratories' capacities, and sound extrapolation methods had to be developed. Statistical curve fits and regression analyses by themselves, absent fluid-dynamic foundations, are not valid procedures for extrapolation. The ASME PTC 19.5-2004 discharge coefficient equations reproduced in this paper for nozzles, orifices, and venturis are suitable for use whenever calibration data are to be applied in a flow measurement and/or extrapolated to higher Reynolds numbers as necessary. The equations may also be used for uncalibrated differential pressure meters by using nominal values. It is necessary to note that the metering runs must be manufactured with dimensions, tolerances, smoothness, etc., and installed in strict accordance with ASME PTC 19.5 for these equations to be valid. Note that for compressible flow, the value of the expansion factor term in the PTC 19.5 equation must be the one corresponding to the published PTC 19.5 equation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

A micro gas turbine based test rig for educational purposes / Mario L. Ferrari in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 05 p. Titre : A micro gas turbine based test rig for educational purposes Type de document : texte imprimé Auteurs : Mario L. Ferrari, Auteur ; Matteo Pascenti, Auteur ; Loredana Magistri, Auteur Année de publication : 2010 Article en page(s) : 05 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cogeneration  Compressors  Educational  courses  Flow  control  Gas  turbines  Power  engineering  education  Power  grids  Student  experiments Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The Thermochemical Power Group of the University of Genoa, Italy, has developed a new “Gas Turbine” laboratory to introduce undergraduate students to the Gas Turbines and Innovative Cycles course, and Ph.D.s to advanced experimental activities in the same field. In the laboratory a general-purpose experimental rig, based on a modified commercial 100 kW recuperated micro gas turbine, was installed and fully instrumented. One of the main objectives of the laboratory is to provide both students and researchers with several experimental possibilities to obtain data related to the gas turbine steady-state, transient, and dynamic performance, including the effect of interaction between the turbomachines (especially the compressor), and more complex innovative gas turbine cycle configurations, such as recuperated, humid air, and hybrid (with high temperature fuel cells). The facility was partially funded by two Integrated Projects of the EU VI Framework Program (Felicitas and LARGE-SOFC) and the Italian Government (PRIN project), and it was designed with a high flexibility approach including: flow control management, cogenerative and trigenerative applications, downstream compressor volume variation, grid-connected or stand-alone operations, recuperated or simple cycles, and room temperature control. The paper also shows, as an example of the possibilities offered by the rig, experimental data obtained by both Master and Ph.D. students. The tests presented here are essential for understanding commercial gas turbines and microturbine performance, control strategy development, and theoretical model validation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...] [article] A micro gas turbine based test rig for educational purposes [texte imprimé] / Mario L. Ferrari, Auteur ; Matteo Pascenti, Auteur ; Loredana Magistri, Auteur . - 2010 . - 05 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 2 (Fevrier 2010) . - 05 p. Mots-clés : Cogeneration  Compressors  Educational  courses  Flow  control  Gas  turbines  Power  engineering  education  Power  grids  Student  experiments Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The Thermochemical Power Group of the University of Genoa, Italy, has developed a new “Gas Turbine” laboratory to introduce undergraduate students to the Gas Turbines and Innovative Cycles course, and Ph.D.s to advanced experimental activities in the same field. In the laboratory a general-purpose experimental rig, based on a modified commercial 100 kW recuperated micro gas turbine, was installed and fully instrumented. One of the main objectives of the laboratory is to provide both students and researchers with several experimental possibilities to obtain data related to the gas turbine steady-state, transient, and dynamic performance, including the effect of interaction between the turbomachines (especially the compressor), and more complex innovative gas turbine cycle configurations, such as recuperated, humid air, and hybrid (with high temperature fuel cells). The facility was partially funded by two Integrated Projects of the EU VI Framework Program (Felicitas and LARGE-SOFC) and the Italian Government (PRIN project), and it was designed with a high flexibility approach including: flow control management, cogenerative and trigenerative applications, downstream compressor volume variation, grid-connected or stand-alone operations, recuperated or simple cycles, and room temperature control. The paper also shows, as an example of the possibilities offered by the rig, experimental data obtained by both Master and Ph.D. students. The tests presented here are essential for understanding commercial gas turbines and microturbine performance, control strategy development, and theoretical model validation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000002 [...]

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