Dépouillements

An investigation into the effects of highly transient flight maneuvers with heat and mass transfer on the T-38 air force trainer inlet / Alan Hale in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 10 p. Titre : An investigation into the effects of highly transient flight maneuvers with heat and mass transfer on the T-38 air force trainer inlet Type de document : texte imprimé Auteurs : Alan Hale, Auteur ; Andrew Hughes, Auteur ; Jim Sirbaugh, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  propulsion  Aircraft  testing  Boundary  layers  Computational  fluid  dynamics  Cooling  Distortion  Jet  engines  Mass  transfer  Military  aircraft  Nozzles  Supersonic  flow  Thermal  energy  storage Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The T-38 talon currently serves as the primary United States Air Force trainer for fighter aircraft. This supersonic trainer was developed in the 1960s but continues to be used today as the result of various modernization programs throughout its service life. The latest propulsion modernization program focused on improved takeoff performance of the T-38's inlets, improved reliability of the twin J85 afterburning turbojet engines, and reduced drag with an improved exhaust nozzle design. The T-38's inlet includes bleed holes upstream of the engine face to provide cooling airflow from the inlet to the engine bay. However, at various flight conditions, the bay air is pressurized relative to the inlet, resulting in reverse flow of hot engine bay air into the inlet. This reverse flow causes total temperature distortion that may reduce the engine stability margin. Partial inlet instrumentation of the left engine was used to estimate the total temperature distortion associated with reverse flow, however, flight testing of highly transient maneuvers revealed levels of total temperature distortion greater than that predicted for reverse flow alone. This discovery led to the hypothesis that thermal energy storage of the aluminum inlet during transient flight maneuvers resulted in increased temperature distortion at the engine face. Flight data analysis demonstrated the need for a near-real-time thermal inlet distortion analysis capability. A two-dimensional (2D) transient axisymmetric heat and mass transfer model was developed through the use of a lumped-parameter boundary-layer model to simulate the inlet flow and determine the time-dependent inlet duct heat transfer. This model was validated with transient 2D computational fluid dynamics and two flight maneuvers. The analysis of flight maneuvers revealed that in the absence of engine bay air re-ingestion, the time lag associated with the heating and cooling of the inlet walls generates radial temperature distortion, which has the effect of reducing engine stability margin up to 5.44% for the maneuvers analyzed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] An investigation into the effects of highly transient flight maneuvers with heat and mass transfer on the T-38 air force trainer inlet [texte imprimé] / Alan Hale, Auteur ; Andrew Hughes, Auteur ; Jim Sirbaugh, Auteur . - 2012 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 10 p. Mots-clés : Aerospace  propulsion  Aircraft  testing  Boundary  layers  Computational  fluid  dynamics  Cooling  Distortion  Jet  engines  Mass  transfer  Military  aircraft  Nozzles  Supersonic  flow  Thermal  energy  storage Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The T-38 talon currently serves as the primary United States Air Force trainer for fighter aircraft. This supersonic trainer was developed in the 1960s but continues to be used today as the result of various modernization programs throughout its service life. The latest propulsion modernization program focused on improved takeoff performance of the T-38's inlets, improved reliability of the twin J85 afterburning turbojet engines, and reduced drag with an improved exhaust nozzle design. The T-38's inlet includes bleed holes upstream of the engine face to provide cooling airflow from the inlet to the engine bay. However, at various flight conditions, the bay air is pressurized relative to the inlet, resulting in reverse flow of hot engine bay air into the inlet. This reverse flow causes total temperature distortion that may reduce the engine stability margin. Partial inlet instrumentation of the left engine was used to estimate the total temperature distortion associated with reverse flow, however, flight testing of highly transient maneuvers revealed levels of total temperature distortion greater than that predicted for reverse flow alone. This discovery led to the hypothesis that thermal energy storage of the aluminum inlet during transient flight maneuvers resulted in increased temperature distortion at the engine face. Flight data analysis demonstrated the need for a near-real-time thermal inlet distortion analysis capability. A two-dimensional (2D) transient axisymmetric heat and mass transfer model was developed through the use of a lumped-parameter boundary-layer model to simulate the inlet flow and determine the time-dependent inlet duct heat transfer. This model was validated with transient 2D computational fluid dynamics and two flight maneuvers. The analysis of flight maneuvers revealed that in the absence of engine bay air re-ingestion, the time lag associated with the heating and cooling of the inlet walls generates radial temperature distortion, which has the effect of reducing engine stability margin up to 5.44% for the maneuvers analyzed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Modeling wall film formation and breakup using an integrated interface-tracking/discrete-phase approach / M. Arienti in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 07 p. Titre : Modeling wall film formation and breakup using an integrated interface-tracking/discrete-phase approach Type de document : texte imprimé Auteurs : M. Arienti, Auteur ; L. Wang, Auteur ; M. Corn, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Channel  flow  Combustion  Computational  fluid  dynamics  Jets  Liquid  films  Numerical  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : We propose a computationally tractable model for film formation and breakup based on data from experiments and direct numerical simulations. This work is a natural continuation of previous studies where primary atomization was modeled based on local flow information from a relatively low-resolution tracking of the liquid interface [Arienti and Soteriou, 2007, “Dynamics of Pulsed Jet in Crossflow,” ASME Paper No. GT2007-27816]. The submodels for film formation proposed here are supported by direct numerical simulations obtained with the refined level set grid method [Herrmann, 2008, “A Balanced Force Refined Level Set Grid Method for Two-Phase Flows on Unstructured Flow Solver Grids,” J. Comput. Phys., 227, pp. 2674–2706]. The overall approach is validated by a carefully designed experiment [Shedd et al., 2009, “Liquid Jet Breakup by an Impinging Air Jet,” Forty-Seventh AIAA Aerospace Sciences Meeting. Paper No. AIAA-2009-0998], where the liquid jet is crossflow-atomized in a rectangular channel so that a film forms on the wall opposite to the injection orifice. The film eventually breaks up at the downstream exit of the channel. Comparisons with phase Doppler particle analyzer data and with nonintrusive film thickness point measurements complete this study. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Modeling wall film formation and breakup using an integrated interface-tracking/discrete-phase approach [texte imprimé] / M. Arienti, Auteur ; L. Wang, Auteur ; M. Corn, Auteur . - 2012 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 07 p. Mots-clés : Channel  flow  Combustion  Computational  fluid  dynamics  Jets  Liquid  films  Numerical  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : We propose a computationally tractable model for film formation and breakup based on data from experiments and direct numerical simulations. This work is a natural continuation of previous studies where primary atomization was modeled based on local flow information from a relatively low-resolution tracking of the liquid interface [Arienti and Soteriou, 2007, “Dynamics of Pulsed Jet in Crossflow,” ASME Paper No. GT2007-27816]. The submodels for film formation proposed here are supported by direct numerical simulations obtained with the refined level set grid method [Herrmann, 2008, “A Balanced Force Refined Level Set Grid Method for Two-Phase Flows on Unstructured Flow Solver Grids,” J. Comput. Phys., 227, pp. 2674–2706]. The overall approach is validated by a carefully designed experiment [Shedd et al., 2009, “Liquid Jet Breakup by an Impinging Air Jet,” Forty-Seventh AIAA Aerospace Sciences Meeting. Paper No. AIAA-2009-0998], where the liquid jet is crossflow-atomized in a rectangular channel so that a film forms on the wall opposite to the injection orifice. The film eventually breaks up at the downstream exit of the channel. Comparisons with phase Doppler particle analyzer data and with nonintrusive film thickness point measurements complete this study. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Measurements of density pulsations in the outlet nozzle of a combustion chamber by rayleigh-scattering searching entropy waves / Anne Rausch in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 09 p. Titre : Measurements of density pulsations in the outlet nozzle of a combustion chamber by rayleigh-scattering searching entropy waves Type de document : texte imprimé Auteurs : Anne Rausch, Auteur ; Andre Fischer, Auteur ; Holger Konle, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Density  measurement  Fluid  dynamics  Nozzles  Optical  variables  measurement  Rayleigh  scattering  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The development of measurement techniques, which enable temporal and spatial highly resolved density investigations even in harsh environments, is essential. Rayleigh scattering is a noninvasive optical measurement technique permitting such investigations. A Rayleigh-scattering measurement system is set up, providing a new insight into fluid mechanical processes in turbomachines. In this paper, Rayleigh scattering is used for the detection of density oscillations in the optical accessible convergent-divergent outlet nozzle of a small scale combustion test rig at various power consumptions and equivalence ratios. Until now, this part of the combustion chamber is sparsely investigated due to the challenging measurement conditions. The temporal density oscillation inside the nozzle can be shown up to 4 kHz as well as its spatial distribution. Systematic errors of the setup are investigated. Spectra of pressure and density oscillations are compared. Measurements with nonreacting air flow are conducted to study flow induced density fluctuations. Entropy noise related correlations between density and pressure fluctuations are found. Therewith, the builtup Rayleigh-scattering system enables investigations of the presumed region of indirect noise generation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Measurements of density pulsations in the outlet nozzle of a combustion chamber by rayleigh-scattering searching entropy waves [texte imprimé] / Anne Rausch, Auteur ; Andre Fischer, Auteur ; Holger Konle, Auteur . - 2012 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 09 p. Mots-clés : Density  measurement  Fluid  dynamics  Nozzles  Optical  variables  measurement  Rayleigh  scattering  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The development of measurement techniques, which enable temporal and spatial highly resolved density investigations even in harsh environments, is essential. Rayleigh scattering is a noninvasive optical measurement technique permitting such investigations. A Rayleigh-scattering measurement system is set up, providing a new insight into fluid mechanical processes in turbomachines. In this paper, Rayleigh scattering is used for the detection of density oscillations in the optical accessible convergent-divergent outlet nozzle of a small scale combustion test rig at various power consumptions and equivalence ratios. Until now, this part of the combustion chamber is sparsely investigated due to the challenging measurement conditions. The temporal density oscillation inside the nozzle can be shown up to 4 kHz as well as its spatial distribution. Systematic errors of the setup are investigated. Spectra of pressure and density oscillations are compared. Measurements with nonreacting air flow are conducted to study flow induced density fluctuations. Entropy noise related correlations between density and pressure fluctuations are found. Therewith, the builtup Rayleigh-scattering system enables investigations of the presumed region of indirect noise generation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Performance model “Zooming” for in-depth component fault diagnosis / N. Aretakis in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 11 p. Titre : Performance model “Zooming” for in-depth component fault diagnosis Type de document : texte imprimé Auteurs : N. Aretakis, Auteur ; I. Roumeliotis, Auteur ; K. Mathioudakis, Auteur Année de publication : 2012 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Compressors  Engines  Fault  location  Gas  turbines  Maintenance  engineering Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A method giving the possibility for a more detailed gas path component fault diagnosis by exploiting the “zooming” feature of current performance modeling techniques is presented. A diagnostic engine performance model is the main tool that points to the faulty engine component. A diagnostic component model is then used to identify the fault. The method is demonstrated on the case of compressor faults. A 1D model based on the “stage stacking” approach is used to “zoom” into the compressors, supporting a 0D engine model. A first level diagnosis determines the deviation of overall compressor performance parameters while zooming calculations allow a localization of the faulty stages of a multistage compressor. The possibility to derive more detailed information with no additional measurement data is established by the incorporation of empirical knowledge on the type of faults that are usually encountered in practice. Although the approach is based on known individual diagnostic methods, it is demonstrated that the integrated formulation provides not only higher effectiveness but also additional fault identification capabilities. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Performance model “Zooming” for in-depth component fault diagnosis [texte imprimé] / N. Aretakis, Auteur ; I. Roumeliotis, Auteur ; K. Mathioudakis, Auteur . - 2012 . - 11 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 11 p. Mots-clés : Compressors  Engines  Fault  location  Gas  turbines  Maintenance  engineering Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A method giving the possibility for a more detailed gas path component fault diagnosis by exploiting the “zooming” feature of current performance modeling techniques is presented. A diagnostic engine performance model is the main tool that points to the faulty engine component. A diagnostic component model is then used to identify the fault. The method is demonstrated on the case of compressor faults. A 1D model based on the “stage stacking” approach is used to “zoom” into the compressors, supporting a 0D engine model. A first level diagnosis determines the deviation of overall compressor performance parameters while zooming calculations allow a localization of the faulty stages of a multistage compressor. The possibility to derive more detailed information with no additional measurement data is established by the incorporation of empirical knowledge on the type of faults that are usually encountered in practice. Although the approach is based on known individual diagnostic methods, it is demonstrated that the integrated formulation provides not only higher effectiveness but also additional fault identification capabilities. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Chemical looping combustion using the direct combustion of liquid metal in a gas turbine based cycle / Niall R. McGlashan in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 13 p. Titre : Chemical looping combustion using the direct combustion of liquid metal in a gas turbine based cycle Type de document : texte imprimé Auteurs : Niall R. McGlashan, Auteur ; Peter R. N. Childs, Auteur ; Andrew L. Heyes, Auteur Année de publication : 2012 Article en page(s) : 13 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Gas  turbines  Heat  exchangers  Latent  heat  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A combined cycle gas-turbine generating power and hydrogen is proposed and evaluated. The cycle embodies chemical looping combustion (CLC) and uses a Na based oxygen carrier. In operation, a stoichiometric excess of liquid Na is injected directly into the combustion chamber of a gas-turbine cycle, where it is burnt in compressed O2 produced in an external air separation unit (ASU). The resulting combustion chamber exit stream consists of hot Na vapor and this is expanded in a turbine. Liquid Na2O oxide is also generated in the combustion process but this can be separated, readily, from the Na vapor and collects in a pool at the bottom of the reactor. To regenerate liquid Na from Na2O, and hence complete the chemical loop, a reduction reactor (the reducer) is fed with three streams: the hot Na2O from the oxidizer, the Na vapor (plus some entrained wetness) exiting a Na-turbine, and a stream of solid fuel, which is assumed to be pure carbon for simplicity. The sensible heat content of the liquid Na2O and latent and sensible heat of the Na vapor provide the heat necessary to drive the endothermic reduction reaction and ensure the reducer is externally adiabatic. The exit gas from the reducer consists of almost pure CO, which can be used to generate byproduct H2 using the water-gas shift reaction. A mass and energy balance of the system is conducted assuming reactions reach equilibrium. The analysis allows for losses associated with turbomachinery; heat exchangers are assumed to operate with a finite approach temperature. However, pressure losses in equipment and pipework are assumed negligible—a reasonable assumption for this type of analysis that will still yield meaningful data. The analysis confirms that the combustion chamber exit temperature is limited by both first and second law considerations to a value suitable for a practical gas-turbine. The analysis also shows that the overall efficiency of the cycle, under optimum conditions and taking into account the work necessary to drive the ASU, can exceed 75%. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Chemical looping combustion using the direct combustion of liquid metal in a gas turbine based cycle [texte imprimé] / Niall R. McGlashan, Auteur ; Peter R. N. Childs, Auteur ; Andrew L. Heyes, Auteur . - 2012 . - 13 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 13 p. Mots-clés : Combustion  Gas  turbines  Heat  exchangers  Latent  heat  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A combined cycle gas-turbine generating power and hydrogen is proposed and evaluated. The cycle embodies chemical looping combustion (CLC) and uses a Na based oxygen carrier. In operation, a stoichiometric excess of liquid Na is injected directly into the combustion chamber of a gas-turbine cycle, where it is burnt in compressed O2 produced in an external air separation unit (ASU). The resulting combustion chamber exit stream consists of hot Na vapor and this is expanded in a turbine. Liquid Na2O oxide is also generated in the combustion process but this can be separated, readily, from the Na vapor and collects in a pool at the bottom of the reactor. To regenerate liquid Na from Na2O, and hence complete the chemical loop, a reduction reactor (the reducer) is fed with three streams: the hot Na2O from the oxidizer, the Na vapor (plus some entrained wetness) exiting a Na-turbine, and a stream of solid fuel, which is assumed to be pure carbon for simplicity. The sensible heat content of the liquid Na2O and latent and sensible heat of the Na vapor provide the heat necessary to drive the endothermic reduction reaction and ensure the reducer is externally adiabatic. The exit gas from the reducer consists of almost pure CO, which can be used to generate byproduct H2 using the water-gas shift reaction. A mass and energy balance of the system is conducted assuming reactions reach equilibrium. The analysis allows for losses associated with turbomachinery; heat exchangers are assumed to operate with a finite approach temperature. However, pressure losses in equipment and pipework are assumed negligible—a reasonable assumption for this type of analysis that will still yield meaningful data. The analysis confirms that the combustion chamber exit temperature is limited by both first and second law considerations to a value suitable for a practical gas-turbine. The analysis also shows that the overall efficiency of the cycle, under optimum conditions and taking into account the work necessary to drive the ASU, can exceed 75%. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Effects of swirl velocities from fan assemblies mounted on lifting surfaces / Alexandros Terzis in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 09 p. Titre : Effects of swirl velocities from fan assemblies mounted on lifting surfaces Type de document : texte imprimé Auteurs : Alexandros Terzis, Auteur ; Charilaos Kazakos, Auteur ; Nikolaos Papadopoulos, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aircraft  Blades  Fans  Jets  Vehicle  dynamics  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The penetration of a jet of fluid into a traversal moving stream is a basic configuration of a wide range of engineering applications, such as film cooling and V/STOL aircrafts. This investigation examines experimentally the effect of blowing ratio of fans in crossflow, and numerically, the effect of the swirl velocity of jets in crossflow, downstream of the injection hole. The experimental results indicated an agreement with typically straight jets in crossflow (no vorticity), illustrating that the trace of the jet, remains close to the wall and subsequently enhance cooling at low blowing ratios in the case of turbine blade applications. However, the rotation of the jet results in an imparity between the two parts of the counter rotating vortex pair and as a consequence, the injected fluid not only bends in the direction of the main stream but also diverts in the direction of the rotation in order to conserve its angular momentum. The induction of the swirl velocity on the injected jet destructs one of the two parts of the kidney vortex, which entrains fluid from the crossflow to the jet promoting the mixing between the two fluids while the trace of a swirled jet remains closer to the wall downstream of the injection hole. Finally, the use of contrarotating jet or fan configurations reduces the wall shear stress in a very great extent, leading to better thermal protection of turbine blades, as well as cancels out the yaw torques of each fan separately, resulting in better flight control of typical lift surface. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Effects of swirl velocities from fan assemblies mounted on lifting surfaces [texte imprimé] / Alexandros Terzis, Auteur ; Charilaos Kazakos, Auteur ; Nikolaos Papadopoulos, Auteur . - 2012 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 09 p. Mots-clés : Aircraft  Blades  Fans  Jets  Vehicle  dynamics  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The penetration of a jet of fluid into a traversal moving stream is a basic configuration of a wide range of engineering applications, such as film cooling and V/STOL aircrafts. This investigation examines experimentally the effect of blowing ratio of fans in crossflow, and numerically, the effect of the swirl velocity of jets in crossflow, downstream of the injection hole. The experimental results indicated an agreement with typically straight jets in crossflow (no vorticity), illustrating that the trace of the jet, remains close to the wall and subsequently enhance cooling at low blowing ratios in the case of turbine blade applications. However, the rotation of the jet results in an imparity between the two parts of the counter rotating vortex pair and as a consequence, the injected fluid not only bends in the direction of the main stream but also diverts in the direction of the rotation in order to conserve its angular momentum. The induction of the swirl velocity on the injected jet destructs one of the two parts of the kidney vortex, which entrains fluid from the crossflow to the jet promoting the mixing between the two fluids while the trace of a swirled jet remains closer to the wall downstream of the injection hole. Finally, the use of contrarotating jet or fan configurations reduces the wall shear stress in a very great extent, leading to better thermal protection of turbine blades, as well as cancels out the yaw torques of each fan separately, resulting in better flight control of typical lift surface. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Effect of simulated combustor temperature nonuniformity on HP vane and end wall heat transfer: / Imran Qureshi in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 13 p. Titre : Effect of simulated combustor temperature nonuniformity on HP vane and end wall heat transfer: : an experimental and computational investigation Type de document : texte imprimé Auteurs : Imran Qureshi, Auteur ; Arrigo Beretta, Auteur ; Thomas Povey, Auteur Année de publication : 2012 Article en page(s) : 13 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Computational  fluid  dynamics  Gas  turbines  Heat  transfer  Nozzles  Test  facilities Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents experimental measurements and computational predictions of surface and end wall heat transfer for a high-pressure (HP) nozzle guide vane operating as part of a full HP turbine stage in an annular rotating turbine facility, with and without inlet temperature distortion (hot streaks). A detailed aerodynamic survey of the vane surface is also presented. The test turbine was the unshrouded MT1 turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough, UK. This is a short-duration facility, which simulates engine-representative M, Re, nondimensional speed, and gas-to-wall temperature ratio at the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation combustor simulator, capable of simulating well-defined, aggressive temperature profiles in both the radial and circumferential directions. This work forms part of the pan-European research program, TATEF II. Measurements of HP vane and end wall heat transfer obtained with inlet temperature distortion are compared with results for uniform inlet conditions. Steady and unsteady computational fluid dynamics (CFD) predictions have also been conducted on vane and end wall surfaces using the Rolls-Royce CFD code HYDRA to complement the analysis of experimental results. The heat transfer measurements presented in this paper are the first of their kind in that the temperature distortion is representative of an extreme cycle point, and was simulated with good periodicity and with well-defined boundary conditions in the test turbine. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Effect of simulated combustor temperature nonuniformity on HP vane and end wall heat transfer: : an experimental and computational investigation [texte imprimé] / Imran Qureshi, Auteur ; Arrigo Beretta, Auteur ; Thomas Povey, Auteur . - 2012 . - 13 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 13 p. Mots-clés : Combustion  Computational  fluid  dynamics  Gas  turbines  Heat  transfer  Nozzles  Test  facilities Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents experimental measurements and computational predictions of surface and end wall heat transfer for a high-pressure (HP) nozzle guide vane operating as part of a full HP turbine stage in an annular rotating turbine facility, with and without inlet temperature distortion (hot streaks). A detailed aerodynamic survey of the vane surface is also presented. The test turbine was the unshrouded MT1 turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough, UK. This is a short-duration facility, which simulates engine-representative M, Re, nondimensional speed, and gas-to-wall temperature ratio at the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation combustor simulator, capable of simulating well-defined, aggressive temperature profiles in both the radial and circumferential directions. This work forms part of the pan-European research program, TATEF II. Measurements of HP vane and end wall heat transfer obtained with inlet temperature distortion are compared with results for uniform inlet conditions. Steady and unsteady computational fluid dynamics (CFD) predictions have also been conducted on vane and end wall surfaces using the Rolls-Royce CFD code HYDRA to complement the analysis of experimental results. The heat transfer measurements presented in this paper are the first of their kind in that the temperature distortion is representative of an extreme cycle point, and was simulated with good periodicity and with well-defined boundary conditions in the test turbine. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

An immersed particle heat exchanger for externally fired and heat recovery gas turbines / Luciano Andrea Catalano in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 07 p. Titre : An immersed particle heat exchanger for externally fired and heat recovery gas turbines Type de document : texte imprimé Auteurs : Luciano Andrea Catalano, Auteur ; Fabio De Bellis, Auteur ; Riccardo Amirante, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Computational  fluid  dynamics  Gas  turbines  Heat  exchangers  Heat  recovery  Heat  transfer Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Designing and manufacturing high-efficiency heat exchangers is usually considered a limiting factor in the development of gas turbines employing either heat recovery Joule–Brayton cycles or external combustion. In this work, an innovative heat exchanger is proposed, modeled, and partially tested to validate the developed numerical model employed for its design. The heat exchanger is based on an intermediate medium (aluminum oxide Al2O3) flowing in countercurrent through an hot stream of gas. In this process, heat can be absorbed from the hot gas, temporarily stored, and then similarly released in a second pipe, where a cold stream is warmed up. A flow of alumina particles with very small diameter (of the order of hundreds of microns) can be employed to enhance the heat transfer. Experimental tests demonstrate that simple one-dimensional steady equations, also neglecting conduction in the particles, can be effectively employed to simulate the flow in the vertical part of the pipe, namely, to compute the pipe length required to achieve a prescribed heat exchange. On the other side, full three-dimensional computational fluid dynamics simulations have been performed to demonstrate that a more thorough gas flow and particle displacement analysis is needed to avoid a bad distribution of alumina particles and, thus, to achieve high thermal efficiency. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] An immersed particle heat exchanger for externally fired and heat recovery gas turbines [texte imprimé] / Luciano Andrea Catalano, Auteur ; Fabio De Bellis, Auteur ; Riccardo Amirante, Auteur . - 2012 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 07 p. Mots-clés : Computational  fluid  dynamics  Gas  turbines  Heat  exchangers  Heat  recovery  Heat  transfer Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Designing and manufacturing high-efficiency heat exchangers is usually considered a limiting factor in the development of gas turbines employing either heat recovery Joule–Brayton cycles or external combustion. In this work, an innovative heat exchanger is proposed, modeled, and partially tested to validate the developed numerical model employed for its design. The heat exchanger is based on an intermediate medium (aluminum oxide Al2O3) flowing in countercurrent through an hot stream of gas. In this process, heat can be absorbed from the hot gas, temporarily stored, and then similarly released in a second pipe, where a cold stream is warmed up. A flow of alumina particles with very small diameter (of the order of hundreds of microns) can be employed to enhance the heat transfer. Experimental tests demonstrate that simple one-dimensional steady equations, also neglecting conduction in the particles, can be effectively employed to simulate the flow in the vertical part of the pipe, namely, to compute the pipe length required to achieve a prescribed heat exchange. On the other side, full three-dimensional computational fluid dynamics simulations have been performed to demonstrate that a more thorough gas flow and particle displacement analysis is needed to avoid a bad distribution of alumina particles and, thus, to achieve high thermal efficiency. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Identification of structural stiffness and energy dissipation parameters in a second generation foil bearing: / Luis San Andrés in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 09 p. Titre : Identification of structural stiffness and energy dissipation parameters in a second generation foil bearing: : effect of shaft temperature Type de document : texte imprimé Auteurs : Luis San Andrés, Auteur ; Ryu, Keun, Auteur ; Tae Ho Kim, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Damping  Gas  turbines  Machine  bearings  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Established high temperature operation of gas foil bearings (GFB) is of great interest for gas turbine applications. The effects of (high) shaft temperature on the structural stiffness and mechanical energy dissipation parameters of a foil bearing (FB) must be assessed experimentally. Presently, a hollow shaft warmed by an electric heater holds a floating second generation FB that is loaded dynamically by an electromagnetic shaker. In tests with the shaft temperature up to 184°C, the measurements of dynamic load and ensuing FB deflection render the bearing structural parameters, stiffness and damping, as a function of excitation frequency and amplitude of motion. The identified FB stiffness and viscous damping coefficients increase with shaft temperature due to an increase in the FB assembly interference or preload. The bearing material structural loss factor best representing mechanical energy dissipation decreases slightly with shaft temperature while increasing with excitation frequency. Separate static load measurements on the bearing also make evident the preload of the test bearing-shaft system at room temperature. The loss factor obtained from the area inside the hysteresis loop of the static load versus the deflection curve agrees remarkably with the loss factor obtained from the dynamic load measurements. The static procedure offers substantial savings in cost and time to determine the energy dissipation characteristics of foil bearings. Post-test inspection of the FB reveals sustained wear at the locations, where the bumps contact the top foil and the bearing sleeve inner surface, thus, evidences the bearing energy dissipation by dry friction. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Identification of structural stiffness and energy dissipation parameters in a second generation foil bearing: : effect of shaft temperature [texte imprimé] / Luis San Andrés, Auteur ; Ryu, Keun, Auteur ; Tae Ho Kim, Auteur . - 2012 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 09 p. Mots-clés : Damping  Gas  turbines  Machine  bearings  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Established high temperature operation of gas foil bearings (GFB) is of great interest for gas turbine applications. The effects of (high) shaft temperature on the structural stiffness and mechanical energy dissipation parameters of a foil bearing (FB) must be assessed experimentally. Presently, a hollow shaft warmed by an electric heater holds a floating second generation FB that is loaded dynamically by an electromagnetic shaker. In tests with the shaft temperature up to 184°C, the measurements of dynamic load and ensuing FB deflection render the bearing structural parameters, stiffness and damping, as a function of excitation frequency and amplitude of motion. The identified FB stiffness and viscous damping coefficients increase with shaft temperature due to an increase in the FB assembly interference or preload. The bearing material structural loss factor best representing mechanical energy dissipation decreases slightly with shaft temperature while increasing with excitation frequency. Separate static load measurements on the bearing also make evident the preload of the test bearing-shaft system at room temperature. The loss factor obtained from the area inside the hysteresis loop of the static load versus the deflection curve agrees remarkably with the loss factor obtained from the dynamic load measurements. The static procedure offers substantial savings in cost and time to determine the energy dissipation characteristics of foil bearings. Post-test inspection of the FB reveals sustained wear at the locations, where the bumps contact the top foil and the bearing sleeve inner surface, thus, evidences the bearing energy dissipation by dry friction. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

A test rig for noncontact traveling wave excitation of a bladed disk with underplatform dampers / Teresa Berruti in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 08 p. Titre : A test rig for noncontact traveling wave excitation of a bladed disk with underplatform dampers Type de document : texte imprimé Auteurs : Teresa Berruti, Auteur ; Christian M. Firrone, Auteur ; Muzio M. Gola, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Blades  Discs  (structures)  Electromagnets  Frequency  response  Friction  Numerical  analysis  Steam  turbines  Vibration  control Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a static test rig called “Octopus” designed for the validation of numerical models aimed at calculating the nonlinear dynamic response of a bladed disk with underplatform dampers (UPDs). The test rig supports a bladed disk on a fixture and each UPD is pressed against the blade platforms by wires pulled by dead weights. Both excitation system and response measurement system are noncontacting. This paper features the design and the setup of the noncontacting excitation generated by electromagnets placed under each blade. A traveling wave excitation is generated according to a desired engine order by shifting the phase of the harmonic force of one electromagnet with respect to the contiguous exciters. Since the friction phenomenon generated by UPDs introduces nonlinearities on the forced response, the amplitude of the exciting force must be kept constant at a known value on every blade during step-sine test to calculate frequency response functions. The issue of the force control is therefore addressed since the performance of the electromagnet changes with frequency. The system calibration procedure and the estimated errors on the generated force are also presented. Examples of experimental tests that can be performed on a dummy integral bladed disk (blisk) mounted on the rig are described in the end. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] A test rig for noncontact traveling wave excitation of a bladed disk with underplatform dampers [texte imprimé] / Teresa Berruti, Auteur ; Christian M. Firrone, Auteur ; Muzio M. Gola, Auteur . - 2012 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 08 p. Mots-clés : Blades  Discs  (structures)  Electromagnets  Frequency  response  Friction  Numerical  analysis  Steam  turbines  Vibration  control Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a static test rig called “Octopus” designed for the validation of numerical models aimed at calculating the nonlinear dynamic response of a bladed disk with underplatform dampers (UPDs). The test rig supports a bladed disk on a fixture and each UPD is pressed against the blade platforms by wires pulled by dead weights. Both excitation system and response measurement system are noncontacting. This paper features the design and the setup of the noncontacting excitation generated by electromagnets placed under each blade. A traveling wave excitation is generated according to a desired engine order by shifting the phase of the harmonic force of one electromagnet with respect to the contiguous exciters. Since the friction phenomenon generated by UPDs introduces nonlinearities on the forced response, the amplitude of the exciting force must be kept constant at a known value on every blade during step-sine test to calculate frequency response functions. The issue of the force control is therefore addressed since the performance of the electromagnet changes with frequency. The system calibration procedure and the estimated errors on the generated force are also presented. Examples of experimental tests that can be performed on a dummy integral bladed disk (blisk) mounted on the rig are described in the end. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Impact of screens around bearings on the flow and heat transfer in the vent and scavenge oil pipes in bearing chambers / Michael Flouros in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 10 p. Titre : Impact of screens around bearings on the flow and heat transfer in the vent and scavenge oil pipes in bearing chambers Type de document : texte imprimé Auteurs : Michael Flouros, Auteur ; Francois Cottier, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  engines  Aircraft  Computational  fluid  dynamics  Heat  transfer  Machine  bearings  Pipe  flow  Temperature  distribution  Two-phase  flow  Vents  (mechanical  components) Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The aim of this paper is to investigate, first, the effects of screens introduced around bearings and, second, the use of protruded instead of flush installed vent pipes. The investigation focuses on the air and oil flow distributions and on the heat transfer in the scavenge and the vent pipes in an aeroengine bearing chamber. The flow distribution has an impact on the pipe's wall temperature distribution with the likelihood of generating hot spots. High temperatures may cause substantial effects on the health of the lubrication system. Problems may range from oil quality degradation to oil self ignition. A steady state CFD analysis of the heat transfer involving the two-phase air and oil flow in these pipes is performed using the ANSYS CFX package. It was demonstrated that whereas screens around bearings reduce the parasitic losses and vent protrusion reduces the oil flow to the air/oil separator, however, due to the oil flow distribution the thermal effects may lead to high material temperatures and to malfunctions in the engine's lube system. En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Impact of screens around bearings on the flow and heat transfer in the vent and scavenge oil pipes in bearing chambers [texte imprimé] / Michael Flouros, Auteur ; Francois Cottier, Auteur . - 2012 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 10 p. Mots-clés : Aerospace  engines  Aircraft  Computational  fluid  dynamics  Heat  transfer  Machine  bearings  Pipe  flow  Temperature  distribution  Two-phase  flow  Vents  (mechanical  components) Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The aim of this paper is to investigate, first, the effects of screens introduced around bearings and, second, the use of protruded instead of flush installed vent pipes. The investigation focuses on the air and oil flow distributions and on the heat transfer in the scavenge and the vent pipes in an aeroengine bearing chamber. The flow distribution has an impact on the pipe's wall temperature distribution with the likelihood of generating hot spots. High temperatures may cause substantial effects on the health of the lubrication system. Problems may range from oil quality degradation to oil self ignition. A steady state CFD analysis of the heat transfer involving the two-phase air and oil flow in these pipes is performed using the ANSYS CFX package. It was demonstrated that whereas screens around bearings reduce the parasitic losses and vent protrusion reduces the oil flow to the air/oil separator, however, due to the oil flow distribution the thermal effects may lead to high material temperatures and to malfunctions in the engine's lube system. En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Effect of mass transfer on the performance of selective catalytic reduction (SCR) systems / Nimrod Kapas in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 09 p. Titre : Effect of mass transfer on the performance of selective catalytic reduction (SCR) systems Type de document : texte imprimé Auteurs : Nimrod Kapas, Auteur ; Tariq Shamim, Auteur ; Paul Laing, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air  pollution  control  Diesel  engines  Mass  transfer  Nitrogen  compounds  Surface  chemistry Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a computational investigation of the effect of mass transfer on the performance of selective catalytic reduction (SCR) catalysts, which are employed to reduce NOx emissions from diesel engines. The paper employs a single-channel based, one-dimensional, isothermal model. The heterogeneous surface chemistry is modeled by considering standard and fast SCR mechanisms, and the mass transfer rate is described by using a one-dimensional film model and dimensionless Sherwood (Sh) number. The paper investigates the effect of Sh numbers on the catalyst conversion performance at various temperatures and space velocities. The results show that the effect of the Sh number on the SCR catalyst performance is temperature dependent and is more pronounced at high space velocities. In general, higher Sh numbers lead to increased conversion efficiencies. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Effect of mass transfer on the performance of selective catalytic reduction (SCR) systems [texte imprimé] / Nimrod Kapas, Auteur ; Tariq Shamim, Auteur ; Paul Laing, Auteur . - 2012 . - 09 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 09 p. Mots-clés : Air  pollution  control  Diesel  engines  Mass  transfer  Nitrogen  compounds  Surface  chemistry Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a computational investigation of the effect of mass transfer on the performance of selective catalytic reduction (SCR) catalysts, which are employed to reduce NOx emissions from diesel engines. The paper employs a single-channel based, one-dimensional, isothermal model. The heterogeneous surface chemistry is modeled by considering standard and fast SCR mechanisms, and the mass transfer rate is described by using a one-dimensional film model and dimensionless Sherwood (Sh) number. The paper investigates the effect of Sh numbers on the catalyst conversion performance at various temperatures and space velocities. The results show that the effect of the Sh number on the SCR catalyst performance is temperature dependent and is more pronounced at high space velocities. In general, higher Sh numbers lead to increased conversion efficiencies. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Experimental investigation of thermal load in high speed direct injection diesel engine under the control of various engine performance parameters / Jeonghoon Lee in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 08 p. Titre : Experimental investigation of thermal load in high speed direct injection diesel engine under the control of various engine performance parameters Type de document : texte imprimé Auteurs : Jeonghoon Lee, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Diesel  engines  Engine  cylinders  Exhaust  systems  Fuel  systems  Thermodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Multiple injection strategies are being widely utilized to reduce the vibration, noise, and particle emission in diesel engines. A considerable amount of research related to attempts to increase the maximum power and to reduce vibration, noise, and particulate matters has been done. However, investigations of various performance parameters in terms of the thermal load in high speed direct injection engines are rarely to be found despite the fact that the relationship between these parameters and the reliability of the engine is important for mass production. Hence, the thermal load imposed on the cylinder head and cylinder block of a four-cylinder diesel engine was investigated under the most severe test conditions, at the rated speed and with a full load, by changing the performance parameters such as the main injection timing, the fuel pressure in the common rail, the boost pressure, the exhaust gas recirculation, the fuel quantity of the pilot injection, the timing of the pilot injection, the fuel quantity of the postinjection, and the timing of postinjection. Experimental results showed that the main injection timing among other parameters was the parameter that influenced the thermal load most at the rated engine speed and under a full load condition. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Experimental investigation of thermal load in high speed direct injection diesel engine under the control of various engine performance parameters [texte imprimé] / Jeonghoon Lee, Auteur . - 2012 . - 08 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 08 p. Mots-clés : Diesel  engines  Engine  cylinders  Exhaust  systems  Fuel  systems  Thermodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Multiple injection strategies are being widely utilized to reduce the vibration, noise, and particle emission in diesel engines. A considerable amount of research related to attempts to increase the maximum power and to reduce vibration, noise, and particulate matters has been done. However, investigations of various performance parameters in terms of the thermal load in high speed direct injection engines are rarely to be found despite the fact that the relationship between these parameters and the reliability of the engine is important for mass production. Hence, the thermal load imposed on the cylinder head and cylinder block of a four-cylinder diesel engine was investigated under the most severe test conditions, at the rated speed and with a full load, by changing the performance parameters such as the main injection timing, the fuel pressure in the common rail, the boost pressure, the exhaust gas recirculation, the fuel quantity of the pilot injection, the timing of the pilot injection, the fuel quantity of the postinjection, and the timing of postinjection. Experimental results showed that the main injection timing among other parameters was the parameter that influenced the thermal load most at the rated engine speed and under a full load condition. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Understanding ignition delay effects with pure component fuels in a single-cylinder diesel engine / Caton, Patrick A. in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 11 p. Titre : Understanding ignition delay effects with pure component fuels in a single-cylinder diesel engine Type de document : texte imprimé Auteurs : Caton, Patrick A., Auteur ; Leonard J. Hamilton, Auteur ; Jim S. Cowart, Auteur Année de publication : 2012 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Diesel  engines  Ignition  Surface  tension  Viscosity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In order to better understand how future candidate diesel fuels may affect combustion characteristics in diesel engines, 21 pure component hydrocarbon fuels were tested in a single-cylinder diesel engine. These pure component fuels included normal alkanes (C6–C16), normal primary alkenes (C6–C18), isoalkanes, cycloalkanes/-enes, and aromatic species. In addition, seven fuel blends were tested, including commercial diesel fuel, U.S. Navy JP-5 aviation fuel, and five Fischer–Tropsch synthetic fuels. Ignition delay was used as a primary combustion metric for each fuel, and the ignition delay period was analyzed from the perspective of the physical delay period followed by the chemical delay period. While fuel properties could not strictly be varied independently of each other, several ignition delay correlations with respect to physical properties were suggested. In general, longer ignition delays were observed for component fuels with lower liquid fuel density, kinematic viscosity, and liquid-air surface tension. Longer ignition delay was also observed for component fuels with higher fuel volatility, as measured by boiling point and vapor pressure. Experimental data show two regimes of operation: For a carbon chain length of 12 or greater, there is little variation in ignition delay for the tested fuels. For shorter chain lengths, a fuel molecular structure is very important. Carbon chain length was used as a scaling variable with an empirical factor to collapse the ignition delay onto a single trend line. Companion detailed kinetic modeling was pursued on the lightest fuel species set (C6) since this fuel set possessed the greatest ignition delay differences. The kinetic model gives a chemical ignition delay time, which, together with the measured experimental ignition delay, suggests that the physical and chemical delay period have comparable importance. However, the calculated chemical delay periods capture the general variation in the overall ignition delay and could be used to predict the ignition delay of possible future synthetic diesel fuels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Understanding ignition delay effects with pure component fuels in a single-cylinder diesel engine [texte imprimé] / Caton, Patrick A., Auteur ; Leonard J. Hamilton, Auteur ; Jim S. Cowart, Auteur . - 2012 . - 11 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 11 p. Mots-clés : Diesel  engines  Ignition  Surface  tension  Viscosity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In order to better understand how future candidate diesel fuels may affect combustion characteristics in diesel engines, 21 pure component hydrocarbon fuels were tested in a single-cylinder diesel engine. These pure component fuels included normal alkanes (C6–C16), normal primary alkenes (C6–C18), isoalkanes, cycloalkanes/-enes, and aromatic species. In addition, seven fuel blends were tested, including commercial diesel fuel, U.S. Navy JP-5 aviation fuel, and five Fischer–Tropsch synthetic fuels. Ignition delay was used as a primary combustion metric for each fuel, and the ignition delay period was analyzed from the perspective of the physical delay period followed by the chemical delay period. While fuel properties could not strictly be varied independently of each other, several ignition delay correlations with respect to physical properties were suggested. In general, longer ignition delays were observed for component fuels with lower liquid fuel density, kinematic viscosity, and liquid-air surface tension. Longer ignition delay was also observed for component fuels with higher fuel volatility, as measured by boiling point and vapor pressure. Experimental data show two regimes of operation: For a carbon chain length of 12 or greater, there is little variation in ignition delay for the tested fuels. For shorter chain lengths, a fuel molecular structure is very important. Carbon chain length was used as a scaling variable with an empirical factor to collapse the ignition delay onto a single trend line. Companion detailed kinetic modeling was pursued on the lightest fuel species set (C6) since this fuel set possessed the greatest ignition delay differences. The kinetic model gives a chemical ignition delay time, which, together with the measured experimental ignition delay, suggests that the physical and chemical delay period have comparable importance. However, the calculated chemical delay periods capture the general variation in the overall ignition delay and could be used to predict the ignition delay of possible future synthetic diesel fuels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Gas-to-liquid sprays at different injection and ambient conditions / Dung Ngoc Nguyen in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 10 p. Titre : Gas-to-liquid sprays at different injection and ambient conditions Type de document : texte imprimé Auteurs : Dung Ngoc Nguyen, Auteur ; Hiroaki Ishida, Auteur ; Masahiro Shioji, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Nozzles  Sprays Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Alternative fuels exhibit potential as a clean fuel and suitable to address problems of energy security and environmental pollution. The main objective of this research was to provide the fundamental data of ignition delay and combustion characteristics for gas-to-liquid (GTL) fuels. Experiments were carried out in a constant-volume vessel under diesel-engine conditions to study the effects of various injection and ambient conditions on ignition and combustion characteristics. The results showed that all tested fuels exhibited similar ignition-delay trends: Ignition delay increased as ambient temperature, ambient pressure, and oxygen concentration decreased. The result of changing injection pressures and nozzle-hole diameters did not significantly affect ignition-delay values for all tested fuels. The variation in ignition-delay values was small at temperatures higher than 700 K but large at temperatures less than 700 K. In addition, the result showed that GTL fuels with high cetane number corresponded to shorter ignition delay and smoother heat-release rate than those for gas-oil (conventional diesel fuel) at the same temperature, pressure, and oxygen concentration. The blend GTL fuel improved ignition quality and combustion than that of gas-oil. Shadowgraph images showed that GTL fuels exhibited shorter spray penetration and mixed with the hot air quicker than gas-oil. In addition, GTL fuels showed suitability for premixed charge compression-ignition operations owing to ignitability at low temperature. The obtained results provide useful information for finding the optimal conditions for the design and control of diesel engines fuelled by synthetic GTL fuels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Gas-to-liquid sprays at different injection and ambient conditions [texte imprimé] / Dung Ngoc Nguyen, Auteur ; Hiroaki Ishida, Auteur ; Masahiro Shioji, Auteur . - 2012 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 10 p. Mots-clés : Nozzles  Sprays Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Alternative fuels exhibit potential as a clean fuel and suitable to address problems of energy security and environmental pollution. The main objective of this research was to provide the fundamental data of ignition delay and combustion characteristics for gas-to-liquid (GTL) fuels. Experiments were carried out in a constant-volume vessel under diesel-engine conditions to study the effects of various injection and ambient conditions on ignition and combustion characteristics. The results showed that all tested fuels exhibited similar ignition-delay trends: Ignition delay increased as ambient temperature, ambient pressure, and oxygen concentration decreased. The result of changing injection pressures and nozzle-hole diameters did not significantly affect ignition-delay values for all tested fuels. The variation in ignition-delay values was small at temperatures higher than 700 K but large at temperatures less than 700 K. In addition, the result showed that GTL fuels with high cetane number corresponded to shorter ignition delay and smoother heat-release rate than those for gas-oil (conventional diesel fuel) at the same temperature, pressure, and oxygen concentration. The blend GTL fuel improved ignition quality and combustion than that of gas-oil. Shadowgraph images showed that GTL fuels exhibited shorter spray penetration and mixed with the hot air quicker than gas-oil. In addition, GTL fuels showed suitability for premixed charge compression-ignition operations owing to ignitability at low temperature. The obtained results provide useful information for finding the optimal conditions for the design and control of diesel engines fuelled by synthetic GTL fuels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Lubricant-derived ash properties and their effects on diesel particulate filter pressure-drop performance / Alexander Sappok in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 12 p. Titre : Lubricant-derived ash properties and their effects on diesel particulate filter pressure-drop performance Type de document : texte imprimé Auteurs : Alexander Sappok, Auteur ; Victor W. Wong, Auteur Année de publication : 2012 Article en page(s) : 12 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Additives  Engines  Exhaust  systems  Fuel  economy  Lubricants  Petroleum Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Diesel particulate filters (DPFs) have seen widespread use in on- and off-road applications as an effective means for meeting increasingly stringent particle emission regulations. Over time, incombustible material or ash, primarily derived from metallic additives in the engine lubricant, accumulates in the DPF. Ash accumulation leads to increased flow restriction and an associated increase in pressure-drop across the particulate filter, negatively impacting engine performance and fuel economy and eventually requiring periodic filter service or replacement. While the adverse effects of ash accumulation on DPF performance are well known, the underlying mechanisms controlling these effects are not. The results of this work show ash accumulation and distribution in the DPF as a dynamic process with each stage of ash accumulation altering the filter's pressure-drop response. Through a combined approach employing targeted experiments and comparison with the existing knowledge base, this work further demonstrates the significant effect ash deposits have on DPF pressure-drop sensitivity to soot accumulation. Ash deposits reduce the available filtration area, resulting in locally elevated soot loads and higher exhaust gas velocities through the filter, altering the conditions under which the soot is deposited and ultimately controlling the filter's pressure-drop characteristics. In this study, a novel accelerated ash loading system was employed to generate the ash and load the DPFs under carefully controlled exhaust conditions. The ash loading system was coupled to the exhaust of a Cummins ISB diesel engine, allowing for accelerated ash loading and DPF performance evaluation with realistic exhaust conditions. Following DPF performance evaluation, the filters were subjected to a detailed post-mortem analysis in which key ash properties were measured and quantified. The experimental results, coupled with the ash property measurements, provide additional insight into the underlying physical mechanisms controlling ash properties, ash/soot interactions, and their effects on DPF performance. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Lubricant-derived ash properties and their effects on diesel particulate filter pressure-drop performance [texte imprimé] / Alexander Sappok, Auteur ; Victor W. Wong, Auteur . - 2012 . - 12 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 12 p. Mots-clés : Additives  Engines  Exhaust  systems  Fuel  economy  Lubricants  Petroleum Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Diesel particulate filters (DPFs) have seen widespread use in on- and off-road applications as an effective means for meeting increasingly stringent particle emission regulations. Over time, incombustible material or ash, primarily derived from metallic additives in the engine lubricant, accumulates in the DPF. Ash accumulation leads to increased flow restriction and an associated increase in pressure-drop across the particulate filter, negatively impacting engine performance and fuel economy and eventually requiring periodic filter service or replacement. While the adverse effects of ash accumulation on DPF performance are well known, the underlying mechanisms controlling these effects are not. The results of this work show ash accumulation and distribution in the DPF as a dynamic process with each stage of ash accumulation altering the filter's pressure-drop response. Through a combined approach employing targeted experiments and comparison with the existing knowledge base, this work further demonstrates the significant effect ash deposits have on DPF pressure-drop sensitivity to soot accumulation. Ash deposits reduce the available filtration area, resulting in locally elevated soot loads and higher exhaust gas velocities through the filter, altering the conditions under which the soot is deposited and ultimately controlling the filter's pressure-drop characteristics. In this study, a novel accelerated ash loading system was employed to generate the ash and load the DPFs under carefully controlled exhaust conditions. The ash loading system was coupled to the exhaust of a Cummins ISB diesel engine, allowing for accelerated ash loading and DPF performance evaluation with realistic exhaust conditions. Following DPF performance evaluation, the filters were subjected to a detailed post-mortem analysis in which key ash properties were measured and quantified. The experimental results, coupled with the ash property measurements, provide additional insight into the underlying physical mechanisms controlling ash properties, ash/soot interactions, and their effects on DPF performance. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

Model-based actuator trajectories optimization for a diesel engine using a direct method / Michael Benz in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 3 (Mars 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 11 p. Titre : Model-based actuator trajectories optimization for a diesel engine using a direct method Type de document : texte imprimé Auteurs : Michael Benz, Auteur ; Markus Hehn, Auteur ; Christopher H. Onder, Auteur Année de publication : 2012 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Actuators  Air  pollution  control  Diesel  engines  Feedforward  Fuel  systems  Optimisation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper proposes a novel optimization method that allows a reduction in the pollutant emission of diesel engines during transient operation. The key idea is to synthesize optimal actuator commands using reliable models of the engine system and powerful numerical optimization methods. The engine model includes a mean-value engine model for the dynamics of the gas paths, including the turbocharger of the fuel injection, and of the torque generation. The pollutant formation is modeled using an extended quasi-static modeling approach. The optimization substantially changes the input signals, such that the engine model is enabled to extrapolate all relevant outputs beyond the regular operating area. A feedforward controller for the injected fuel mass is used to eliminate the nonlinear path constraints during the optimization. The model is validated using experimental data obtained on a transient engine test bench. A direct single shooting method is found to be most effective for the numerical optimization. The results show a significant potential for reducing the pollutant emissions during transient operation of the engine. The optimized input trajectories derived assist the design of sophisticated engine control systems. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Model-based actuator trajectories optimization for a diesel engine using a direct method [texte imprimé] / Michael Benz, Auteur ; Markus Hehn, Auteur ; Christopher H. Onder, Auteur . - 2012 . - 11 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 3 (Mars 2011) . - 11 p. Mots-clés : Actuators  Air  pollution  control  Diesel  engines  Feedforward  Fuel  systems  Optimisation Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper proposes a novel optimization method that allows a reduction in the pollutant emission of diesel engines during transient operation. The key idea is to synthesize optimal actuator commands using reliable models of the engine system and powerful numerical optimization methods. The engine model includes a mean-value engine model for the dynamics of the gas paths, including the turbocharger of the fuel injection, and of the torque generation. The pollutant formation is modeled using an extended quasi-static modeling approach. The optimization substantially changes the input signals, such that the engine model is enabled to extrapolate all relevant outputs beyond the regular operating area. A feedforward controller for the injected fuel mass is used to eliminate the nonlinear path constraints during the optimization. The model is validated using experimental data obtained on a transient engine test bench. A direct single shooting method is found to be most effective for the numerical optimization. The results show a significant potential for reducing the pollutant emissions during transient operation of the engine. The optimized input trajectories derived assist the design of sophisticated engine control systems. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

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