Dépouillements

Instability control by premixed pilot flames / Peter Albrecht in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 08 p. Titre : Instability control by premixed pilot flames Type de document : texte imprimé Auteurs : Peter Albrecht, Auteur ; Stefanie Bade, Auteur ; Arnaud Lacarelle, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Flames Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Premixed flames of swirl-stabilized combustors (displaced half-cone) are susceptible to thermo-acoustic instabilities, which should be avoided under all operating conditions in order to guarantee a long service life for both stationary and aircraft gas turbines. The source of this unstable flame behavior can be found in a transition of the premix flame structure between two stationary conditions that can be easily excited by fuel fluctuations, coherent structures within the flow, and other mechanisms. Pilot flames can alleviate this issue either by improving the dynamic stability directly or by sustaining the main combustion process at operating points where instabilities are unlikely. In the present study, the impact of two different premixed pilot injections on the combustion stability is investigated. One of the pilot injector (pilot flame injector) was located upstream of the recirculation zone at the apex of the burner. The second one was a pilot ring placed at the burner outlet on the dump plane. A noticeable feature of the pilot injector was that an ignition device allowed for creating pilot premixed flames. The present investigation showed that these premixed pilot flames were able to suppress instabilities over a wider fuel/air ratio range than the conventional premixed pilot injection alone. Furthermore, it was possible to prevent instabilities and maintain the flame burning near the lean blowout when a percentage of the fuel was premixed with air and injected through the pilot ring. NOx emissions were significantly reduced. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Instability control by premixed pilot flames [texte imprimé] / Peter Albrecht, Auteur ; Stefanie Bade, Auteur ; Arnaud Lacarelle, 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° 4 (Avril 2010) . - 08 p. Mots-clés : Combustion  Flames Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Premixed flames of swirl-stabilized combustors (displaced half-cone) are susceptible to thermo-acoustic instabilities, which should be avoided under all operating conditions in order to guarantee a long service life for both stationary and aircraft gas turbines. The source of this unstable flame behavior can be found in a transition of the premix flame structure between two stationary conditions that can be easily excited by fuel fluctuations, coherent structures within the flow, and other mechanisms. Pilot flames can alleviate this issue either by improving the dynamic stability directly or by sustaining the main combustion process at operating points where instabilities are unlikely. In the present study, the impact of two different premixed pilot injections on the combustion stability is investigated. One of the pilot injector (pilot flame injector) was located upstream of the recirculation zone at the apex of the burner. The second one was a pilot ring placed at the burner outlet on the dump plane. A noticeable feature of the pilot injector was that an ignition device allowed for creating pilot premixed flames. The present investigation showed that these premixed pilot flames were able to suppress instabilities over a wider fuel/air ratio range than the conventional premixed pilot injection alone. Furthermore, it was possible to prevent instabilities and maintain the flame burning near the lean blowout when a percentage of the fuel was premixed with air and injected through the pilot ring. NOx emissions were significantly reduced. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Characterization of forced flame response of swirl-stabilized turbulent lean-premixed flames in a gas turbine combustor / Kyu Tae Kim in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 08 p. Titre : Characterization of forced flame response of swirl-stabilized turbulent lean-premixed flames in a gas turbine combustor Type de document : texte imprimé Auteurs : Kyu Tae Kim, Auteur ; Jong Guen Lee, Auteur ; Hyung Ju Lee, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Chemiluminescence  Combustion  Flames  Gas  turbines  Heat  transfer  Swirling  flow  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Flame transfer function measurements of turbulent premixed flames are made in a model lean-premixed, swirl-stabilized, gas turbine combustor. OH*, CH*, and CO2* chemiluminescence emissions are measured to determine heat release oscillation from a whole flame, and the two-microphone technique is used to measure inlet velocity fluctuation. 2D CH* chemiluminescence imaging is used to characterize the flame shape: the flame length (LCH* max) and flame angle (alpha). Using H2-natural gas composite fuels, XH2=0.00–0.60, a very short flame is obtained and hydrogen enrichment of natural gas is found to have a significant impact on the flame structure and flame attachment points. For a pure natural gas flame, the flames exhibit a “V” structure, whereas H2-enriched natural gas flames have an “M” structure. Results show that the gain of M flames is much smaller than that of V flames. Similar to results of analytic and experimental investigations on the flame transfer function of laminar premixed flames, it shows that the dynamics of a turbulent premixed flame is governed by three relevant parameters: the Strouhal number (St=LCH* max/Lconv), the flame length (LCH* max), and the flame angle (alpha). Two flames with the same flame shape exhibit very similar forced responses, regardless of their inlet flow conditions. This is significant because the forced flame response of a highly turbulent, practical gas turbine combustor can be quantitatively generalized using the nondimensional parameters, which collapse all relevant input conditions into the flame shape and the Strouhal number. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Characterization of forced flame response of swirl-stabilized turbulent lean-premixed flames in a gas turbine combustor [texte imprimé] / Kyu Tae Kim, Auteur ; Jong Guen Lee, Auteur ; Hyung Ju Lee, 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° 4 (Avril 2010) . - 08 p. Mots-clés : Chemiluminescence  Combustion  Flames  Gas  turbines  Heat  transfer  Swirling  flow  Turbulence Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Flame transfer function measurements of turbulent premixed flames are made in a model lean-premixed, swirl-stabilized, gas turbine combustor. OH*, CH*, and CO2* chemiluminescence emissions are measured to determine heat release oscillation from a whole flame, and the two-microphone technique is used to measure inlet velocity fluctuation. 2D CH* chemiluminescence imaging is used to characterize the flame shape: the flame length (LCH* max) and flame angle (alpha). Using H2-natural gas composite fuels, XH2=0.00–0.60, a very short flame is obtained and hydrogen enrichment of natural gas is found to have a significant impact on the flame structure and flame attachment points. For a pure natural gas flame, the flames exhibit a “V” structure, whereas H2-enriched natural gas flames have an “M” structure. Results show that the gain of M flames is much smaller than that of V flames. Similar to results of analytic and experimental investigations on the flame transfer function of laminar premixed flames, it shows that the dynamics of a turbulent premixed flame is governed by three relevant parameters: the Strouhal number (St=LCH* max/Lconv), the flame length (LCH* max), and the flame angle (alpha). Two flames with the same flame shape exhibit very similar forced responses, regardless of their inlet flow conditions. This is significant because the forced flame response of a highly turbulent, practical gas turbine combustor can be quantitatively generalized using the nondimensional parameters, which collapse all relevant input conditions into the flame shape and the Strouhal number. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Time scale model for the prediction of the onset of flame flashback driven by combustion induced vortex breakdown / M. Konle in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 06 p. Titre : Time scale model for the prediction of the onset of flame flashback driven by combustion induced vortex breakdown Type de document : texte imprimé Auteurs : M. Konle, Auteur ; T. Sattelmayer, Auteur Année de publication : 2010 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Combustion  equipment  Flames  Gas  turbines  Numerical  analysis  Quenching  (thermal)  Turbulence  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Flame flashback driven by combustion induced vortex breakdown (CIVB) represents one of the most severe reliability problems of modern gas turbines with swirl stabilized combustors. Former experimental investigations of this topic with a 500 kW burner delivered a model for the prediction of the CIVB occurrence for moderate to high mass flow rates. This model is based on a time scale comparison. The characteristic time scales were chosen following the idea that quenching at the flame tip is the dominating effect preventing upstream flame propagation in the center of the vortex flow. Additional numerical investigations showed that the relative position of the flame regarding the recirculation zone influences the interaction of the flame and flow field. The recent analysis on turbulence and chemical reaction of data acquired with high speed measurement techniques applied during the CIVB driven flame propagation by the authors lead to the extension of the prediction model. As the corrugated flame regimes at the flame tip prevails at low to moderate mass flow rates, a more precise prediction in this range of mass flow rates is achieved using a characteristic burnout time taub~1/Sl for the reactive volume. This paper presents first this new idea, confirms it then with numerical as well as experimental data, and extends finally the former model to a prediction tool that can be applied in the full mass flow range of swirl burners. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Time scale model for the prediction of the onset of flame flashback driven by combustion induced vortex breakdown [texte imprimé] / M. Konle, Auteur ; T. Sattelmayer, 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° 4 (Avril 2010) . - 06 p. Mots-clés : Combustion  Combustion  equipment  Flames  Gas  turbines  Numerical  analysis  Quenching  (thermal)  Turbulence  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Flame flashback driven by combustion induced vortex breakdown (CIVB) represents one of the most severe reliability problems of modern gas turbines with swirl stabilized combustors. Former experimental investigations of this topic with a 500 kW burner delivered a model for the prediction of the CIVB occurrence for moderate to high mass flow rates. This model is based on a time scale comparison. The characteristic time scales were chosen following the idea that quenching at the flame tip is the dominating effect preventing upstream flame propagation in the center of the vortex flow. Additional numerical investigations showed that the relative position of the flame regarding the recirculation zone influences the interaction of the flame and flow field. The recent analysis on turbulence and chemical reaction of data acquired with high speed measurement techniques applied during the CIVB driven flame propagation by the authors lead to the extension of the prediction model. As the corrugated flame regimes at the flame tip prevails at low to moderate mass flow rates, a more precise prediction in this range of mass flow rates is achieved using a characteristic burnout time taub~1/Sl for the reactive volume. This paper presents first this new idea, confirms it then with numerical as well as experimental data, and extends finally the former model to a prediction tool that can be applied in the full mass flow range of swirl burners. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Jet engine health signal denoising using optimally weighted recursive median filters / Payuna Uday in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 08 p. Titre : Jet engine health signal denoising using optimally weighted recursive median filters Type de document : texte imprimé Auteurs : Payuna Uday, Auteur ; Ranjan Ganguli, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Acoustic  signal  processing  Condition  monitoring  Jet  engines  Median  filters  Noise  abatement  Recursive  filters  Signal  denoising Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The removal of noise and outliers from health signals is an important problem in jet engine health monitoring. Typically, health signals are time series of damage indicators, which can be sensor measurements or features derived from such measurements. Sharp or sudden changes in health signals can represent abrupt faults and long term deterioration in the system is typical of gradual faults. Simple linear filters tend to smooth out the sharp trend shifts in jet engine signals and are also not good for outlier removal. We propose new optimally designed nonlinear weighted recursive median filters for noise removal from typical health signals of jet engines. Signals for abrupt and gradual faults and with transient data are considered. Numerical results are obtained for a jet engine and show that preprocessing of health signals using the proposed filter significantly removes Gaussian noise and outliers and could therefore greatly improve the accuracy of diagnostic systems. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Jet engine health signal denoising using optimally weighted recursive median filters [texte imprimé] / Payuna Uday, Auteur ; Ranjan Ganguli, 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° 4 (Avril 2010) . - 08 p. Mots-clés : Acoustic  signal  processing  Condition  monitoring  Jet  engines  Median  filters  Noise  abatement  Recursive  filters  Signal  denoising Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The removal of noise and outliers from health signals is an important problem in jet engine health monitoring. Typically, health signals are time series of damage indicators, which can be sensor measurements or features derived from such measurements. Sharp or sudden changes in health signals can represent abrupt faults and long term deterioration in the system is typical of gradual faults. Simple linear filters tend to smooth out the sharp trend shifts in jet engine signals and are also not good for outlier removal. We propose new optimally designed nonlinear weighted recursive median filters for noise removal from typical health signals of jet engines. Signals for abrupt and gradual faults and with transient data are considered. Numerical results are obtained for a jet engine and show that preprocessing of health signals using the proposed filter significantly removes Gaussian noise and outliers and could therefore greatly improve the accuracy of diagnostic systems. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

A fault diagnosis method for industrial gas turbines using bayesian data analysis / Young K. Lee in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 06 p. Titre : A fault diagnosis method for industrial gas turbines using bayesian data analysis Type de document : texte imprimé Auteurs : Young K. Lee, Auteur ; Dimitri N. Mavris, Auteur ; Vitali V. Volovoi, Auteur Année de publication : 2010 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Compressors  Cost  reduction  Data  analysis  Fault  diagnosis  Flow  sensors  Gas  turbines  Maintenance  engineering Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents an offline fault diagnosis method for industrial gas turbines in a steady-state. Fault diagnosis plays an important role in the efforts for gas turbine owners to shift from preventive maintenance to predictive maintenance, and consequently to reduce the maintenance cost. Ever since its birth, numerous techniques have been researched in this field, yet none of them is completely better than the others and perfectly solves the problem. Fault diagnosis is a challenging problem because there are numerous fault situations that can possibly happen to a gas turbine, and multiple faults may occur in multiple components of the gas turbine simultaneously. An algorithm tailored to one fault situation may not perform well in other fault situations. A general algorithm that performs well in overall fault situations tends to compromise its accuracy in the individual fault situation. In addition to the issue of generality versus accuracy, another challenging aspect of fault diagnosis is that, data used in diagnosis contain errors. The data is comprised of measurements obtained from gas turbines. Measurements contain random errors and often systematic errors like sensor biases as well. In this paper, to maintain the generality and the accuracy together, multiple Bayesian models tailored to various fault situations are implemented in one hierarchical model. The fault situations include single faults occurring in a component, and multiple faults occurring in more than one component. In addition to faults occurring in the components of a gas turbine, sensor biases are explicitly included in the multiple models so that the magnitude of a bias, if any, can be estimated as well. Results from these multiple Bayesian models are averaged according to how much each model is supported by data. Gibbs sampling is used for the calculation of the Bayesian models. The presented method is applied to fault diagnosis of a gas turbine that is equipped with a faulty compressor and a biased fuel flow sensor. The presented method successfully diagnoses the magnitudes of the compressor fault and the fuel flow sensor bias with limited amount of data. It is also shown that averaging multiple models gives rise to more accurate and less uncertain results than using a single general model. By averaging multiple models, based on various fault situations, fault diagnosis can be general yet accurate. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] A fault diagnosis method for industrial gas turbines using bayesian data analysis [texte imprimé] / Young K. Lee, Auteur ; Dimitri N. Mavris, Auteur ; Vitali V. Volovoi, 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° 4 (Avril 2010) . - 06 p. Mots-clés : Compressors  Cost  reduction  Data  analysis  Fault  diagnosis  Flow  sensors  Gas  turbines  Maintenance  engineering Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents an offline fault diagnosis method for industrial gas turbines in a steady-state. Fault diagnosis plays an important role in the efforts for gas turbine owners to shift from preventive maintenance to predictive maintenance, and consequently to reduce the maintenance cost. Ever since its birth, numerous techniques have been researched in this field, yet none of them is completely better than the others and perfectly solves the problem. Fault diagnosis is a challenging problem because there are numerous fault situations that can possibly happen to a gas turbine, and multiple faults may occur in multiple components of the gas turbine simultaneously. An algorithm tailored to one fault situation may not perform well in other fault situations. A general algorithm that performs well in overall fault situations tends to compromise its accuracy in the individual fault situation. In addition to the issue of generality versus accuracy, another challenging aspect of fault diagnosis is that, data used in diagnosis contain errors. The data is comprised of measurements obtained from gas turbines. Measurements contain random errors and often systematic errors like sensor biases as well. In this paper, to maintain the generality and the accuracy together, multiple Bayesian models tailored to various fault situations are implemented in one hierarchical model. The fault situations include single faults occurring in a component, and multiple faults occurring in more than one component. In addition to faults occurring in the components of a gas turbine, sensor biases are explicitly included in the multiple models so that the magnitude of a bias, if any, can be estimated as well. Results from these multiple Bayesian models are averaged according to how much each model is supported by data. Gibbs sampling is used for the calculation of the Bayesian models. The presented method is applied to fault diagnosis of a gas turbine that is equipped with a faulty compressor and a biased fuel flow sensor. The presented method successfully diagnoses the magnitudes of the compressor fault and the fuel flow sensor bias with limited amount of data. It is also shown that averaging multiple models gives rise to more accurate and less uncertain results than using a single general model. By averaging multiple models, based on various fault situations, fault diagnosis can be general yet accurate. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Experimental analysis of a waveguide pressure measuring system / Matthew A. White in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 07 p. Titre : Experimental analysis of a waveguide pressure measuring system Type de document : texte imprimé Auteurs : Matthew A. White, Auteur ; Manuj Dhingra, Auteur ; J. V. R. Prasad, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  engines  Blades  Compressors  Frequency  response  Gas  turbines  Pressure  measurement  Pressure  transducers  Probes Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An infinite-line probe is commonly used to measure unsteady pressure in high-temperature environments while protecting the pressure transducer. In this study, an existing theoretical model is used to derive the response of a waveguide pressure measuring system. An ambient temperature centrifugal compressor rig acts as an experimental source of fluctuating pressure. The compressor is operated at different discrete rotational speeds, and the blade-passing frequencies are used to obtain frequency response data. In the experiments, pressure waves attenuated at a rate faster than that predicted by the theoretical model for a 0.322 m (12 in.) sensor offset. Furthermore, the decay in the magnitude of the pressure oscillations accelerated at blade-passing frequencies above 9 kHz. A unique contribution of this study is to show that whereas the experimentally observed overall attenuation is broadly consistent with the theoretical predictions, pressure oscillations corresponding to individual blade passages may be disproportionally attenuated. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Experimental analysis of a waveguide pressure measuring system [texte imprimé] / Matthew A. White, Auteur ; Manuj Dhingra, Auteur ; J. V. R. Prasad, 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° 4 (Avril 2010) . - 07 p. Mots-clés : Aerospace  engines  Blades  Compressors  Frequency  response  Gas  turbines  Pressure  measurement  Pressure  transducers  Probes Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An infinite-line probe is commonly used to measure unsteady pressure in high-temperature environments while protecting the pressure transducer. In this study, an existing theoretical model is used to derive the response of a waveguide pressure measuring system. An ambient temperature centrifugal compressor rig acts as an experimental source of fluctuating pressure. The compressor is operated at different discrete rotational speeds, and the blade-passing frequencies are used to obtain frequency response data. In the experiments, pressure waves attenuated at a rate faster than that predicted by the theoretical model for a 0.322 m (12 in.) sensor offset. Furthermore, the decay in the magnitude of the pressure oscillations accelerated at blade-passing frequencies above 9 kHz. A unique contribution of this study is to show that whereas the experimentally observed overall attenuation is broadly consistent with the theoretical predictions, pressure oscillations corresponding to individual blade passages may be disproportionally attenuated. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Application of cost matrices and cost curves to enhance diagnostic health management metrics for gas turbine engines / Craig R. Davison in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 08 p. Titre : Application of cost matrices and cost curves to enhance diagnostic health management metrics for gas turbine engines Type de document : texte imprimé Auteurs : Craig R. Davison, Auteur ; Chris Drummond, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  engines  Aircraft  Condition  monitoring  Costing  Fault  diagnosis  Gas  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Statistically based metrics, incorporating operating costs, for gas turbine engine diagnostic systems are required to evaluate competing products fairly and to establish a convincing business case. Diagnostic algorithm validation often includes engine testing with implanted faults. The implantation rate is rarely, if ever, representative of the true fault occurrence rate and the sample size is very small. Costs related to diagnostic outcomes have a significant effect on the utility of a given algorithm and need to be incorporated into the assessment. Techniques for assessing diagnostics are drawn from the literature and modified for application to gas turbine applications. The techniques are modified with computational experiments and the application demonstrated through examples. New techniques are compared to the traditional methods and the advantages presented. A technique is presented to convert a confusion matrix with a non-representative fault distribution to one representative of the expected distribution. The small sample size associated with fault implantation studies requires a confidence interval on the results to provide valid comparisons and a method for calculating confidence intervals, including on zero entries, is presented. Receiver operating characteristic (ROC) curves evaluate diagnostic system performance across a range of threshold settings. This allows an algorithm's ability to be assessed over a range of possible usage. Cost curves are analogous to ROC curves but offer several advantages. The techniques for applying cost curves to diagnostic algorithms are presented and their advantages over ROC curves are outlined. This paper provides techniques for more informed comparison of diagnostic algorithms, possibly preventing incorrect assessment due to small sample sizes. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Application of cost matrices and cost curves to enhance diagnostic health management metrics for gas turbine engines [texte imprimé] / Craig R. Davison, Auteur ; Chris Drummond, 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° 4 (Avril 2010) . - 08 p. Mots-clés : Aerospace  engines  Aircraft  Condition  monitoring  Costing  Fault  diagnosis  Gas  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Statistically based metrics, incorporating operating costs, for gas turbine engine diagnostic systems are required to evaluate competing products fairly and to establish a convincing business case. Diagnostic algorithm validation often includes engine testing with implanted faults. The implantation rate is rarely, if ever, representative of the true fault occurrence rate and the sample size is very small. Costs related to diagnostic outcomes have a significant effect on the utility of a given algorithm and need to be incorporated into the assessment. Techniques for assessing diagnostics are drawn from the literature and modified for application to gas turbine applications. The techniques are modified with computational experiments and the application demonstrated through examples. New techniques are compared to the traditional methods and the advantages presented. A technique is presented to convert a confusion matrix with a non-representative fault distribution to one representative of the expected distribution. The small sample size associated with fault implantation studies requires a confidence interval on the results to provide valid comparisons and a method for calculating confidence intervals, including on zero entries, is presented. Receiver operating characteristic (ROC) curves evaluate diagnostic system performance across a range of threshold settings. This allows an algorithm's ability to be assessed over a range of possible usage. Cost curves are analogous to ROC curves but offer several advantages. The techniques for applying cost curves to diagnostic algorithms are presented and their advantages over ROC curves are outlined. This paper provides techniques for more informed comparison of diagnostic algorithms, possibly preventing incorrect assessment due to small sample sizes. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Gas turbine performance and health status estimation using adaptive gas path analysis / Y. G. Li in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 09 p. Titre : Gas turbine performance and health status estimation using adaptive gas path analysis Type de document : texte imprimé Auteurs : Y. G. Li, Auteur Année de publication : 2010 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  engines  Aerospace  testing  Compressors  Condition  monitoring  Gas  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In gas turbine operations, engine performance and health status are very important information for engine operators. Such engine performance is normally represented by engine airflow rate, compressor pressure ratios, compressor isentropic efficiencies, turbine entry temperature, turbine isentropic efficiencies, etc., while the engine health status is represented by compressor and turbine efficiency indices and flow capacity indices. However, these crucial performance and health information cannot be directly measured and therefore are not easily available. In this research, a novel Adaptive Gas Path Analysis (Adaptive GPA) approach has been developed to estimate actual engine performance and gas path component health status by using gas path measurements, such as gas path pressures, temperatures, shaft rotational speeds, fuel flow rate, etc. Two steps are included in the Adaptive GPA approach, the first step is the estimation of degraded engine performance status by a novel application of a performance adaptation method, and the second step is the estimation of engine health status at component level by using a new diagnostic method introduced in this paper, based on the information obtained in the first step. The developed Adaptive GPA approach has been tested in four test cases where the performance and degradation of a model gas turbine engine similar to Rolls-Royce aero engine Avon-300 have been analyzed. The case studies have shown that the developed novel linear and nonlinear Adaptive GPA approaches can accurately and quickly estimate the degraded engine performance and predict the degradation of major engine gas path components with the existence of measurement noise. The test cases have also shown that the calculation time required by the approach is short enough for its potential online applications. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Gas turbine performance and health status estimation using adaptive gas path analysis [texte imprimé] / Y. G. Li, 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° 4 (Avril 2010) . - 09 p. Mots-clés : Aerospace  engines  Aerospace  testing  Compressors  Condition  monitoring  Gas  turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In gas turbine operations, engine performance and health status are very important information for engine operators. Such engine performance is normally represented by engine airflow rate, compressor pressure ratios, compressor isentropic efficiencies, turbine entry temperature, turbine isentropic efficiencies, etc., while the engine health status is represented by compressor and turbine efficiency indices and flow capacity indices. However, these crucial performance and health information cannot be directly measured and therefore are not easily available. In this research, a novel Adaptive Gas Path Analysis (Adaptive GPA) approach has been developed to estimate actual engine performance and gas path component health status by using gas path measurements, such as gas path pressures, temperatures, shaft rotational speeds, fuel flow rate, etc. Two steps are included in the Adaptive GPA approach, the first step is the estimation of degraded engine performance status by a novel application of a performance adaptation method, and the second step is the estimation of engine health status at component level by using a new diagnostic method introduced in this paper, based on the information obtained in the first step. The developed Adaptive GPA approach has been tested in four test cases where the performance and degradation of a model gas turbine engine similar to Rolls-Royce aero engine Avon-300 have been analyzed. The case studies have shown that the developed novel linear and nonlinear Adaptive GPA approaches can accurately and quickly estimate the degraded engine performance and predict the degradation of major engine gas path components with the existence of measurement noise. The test cases have also shown that the calculation time required by the approach is short enough for its potential online applications. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Maximization of the profit of a complex combined-cycle cogeneration plant using a professional process simulator / Leonardo S. Vieira in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 10 p. Titre : Maximization of the profit of a complex combined-cycle cogeneration plant using a professional process simulator Type de document : texte imprimé Auteurs : Leonardo S. Vieira, Auteur ; Carlos F. Matt, Auteur ; Vanessa G. Guedes, Auteur Année de publication : 2010 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cogeneration  Combined  cycle  power  stations  Optimisation  Power  generation  economics  Power  system  management  Profitability  Thermodynamic  properties Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The high cost of energy resources has driven a strong and continued quest for their optimal utilization. In this context, modern thermoeconomic optimization techniques have been developed to analyze and design improved energy systems, leading to a better compromise between energetic efficiency and cost. Thermoeconomic optimization can be parametric (plant configuration is fixed), applicable both at the design phase or operation phase of a system, or structural (plant configuration may vary). In practice, mathematical thermoeconomic optimization may be accomplished in two ways: (i) the conventional way, which manipulates all pertinent equations simultaneously or (ii) integrated with a professional process simulator, such that the equations are manipulated separately. In the latter case, the simulator deals with the thermodynamic property and balance equations, while an external optimization routine, linked to the simulator, deals with the economic equations and objective function. In this work, a previous implementation of an integrated approach for parametric mathematical thermoeconomic optimization of complex thermal systems is applied to an actual combined-cycle cogeneration plant located in the outskirts of the city of Rio de Janeiro in Brazil. The plant contains more than 60 thermal components, including two gas turbines, one steam turbine, and two heat recovery steam generators. Several hundred variables are required to simulate the plant at one operational steady-state. The plant produces 380 MW of power nominally, and exports a mass flow rate between 200 tons/h and 400 tons/h of superheated process steam, at 45 bars and 404°C, to a neighboring refinery. The simulator is the THERMOFLEX software, which interfaces with the Microsoft Excel program. The optimization routine is written in the Visual Basic for Applications language and is based on Powell's method. The cogeneration plant operates subjected to time-changing economic scenarios, because of varying fuel, electricity, and steam prices. Thus, to manage the plant, it is necessary to vary the operational state appropriately as the economic parameters change. For a prescribed economic scenario, previous work determined the minimum operational cost, when a fixed contracted hourly-rate of process steam was to be exported, while a variable amount of electrical power was produced. In this paper, a broader optimization problem is formulated and solved, for which the objective is to maximize the plant profit under different economic scenarios. It is shown that the optimal operating conditions depend on the economic parameters, and do not necessarily imply maximum efficiency. The integrated optimization approach proves effective, robust, and helpful for optimal plant management. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Maximization of the profit of a complex combined-cycle cogeneration plant using a professional process simulator [texte imprimé] / Leonardo S. Vieira, Auteur ; Carlos F. Matt, Auteur ; Vanessa G. Guedes, 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° 4 (Avril 2010) . - 10 p. Mots-clés : Cogeneration  Combined  cycle  power  stations  Optimisation  Power  generation  economics  Power  system  management  Profitability  Thermodynamic  properties Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The high cost of energy resources has driven a strong and continued quest for their optimal utilization. In this context, modern thermoeconomic optimization techniques have been developed to analyze and design improved energy systems, leading to a better compromise between energetic efficiency and cost. Thermoeconomic optimization can be parametric (plant configuration is fixed), applicable both at the design phase or operation phase of a system, or structural (plant configuration may vary). In practice, mathematical thermoeconomic optimization may be accomplished in two ways: (i) the conventional way, which manipulates all pertinent equations simultaneously or (ii) integrated with a professional process simulator, such that the equations are manipulated separately. In the latter case, the simulator deals with the thermodynamic property and balance equations, while an external optimization routine, linked to the simulator, deals with the economic equations and objective function. In this work, a previous implementation of an integrated approach for parametric mathematical thermoeconomic optimization of complex thermal systems is applied to an actual combined-cycle cogeneration plant located in the outskirts of the city of Rio de Janeiro in Brazil. The plant contains more than 60 thermal components, including two gas turbines, one steam turbine, and two heat recovery steam generators. Several hundred variables are required to simulate the plant at one operational steady-state. The plant produces 380 MW of power nominally, and exports a mass flow rate between 200 tons/h and 400 tons/h of superheated process steam, at 45 bars and 404°C, to a neighboring refinery. The simulator is the THERMOFLEX software, which interfaces with the Microsoft Excel program. The optimization routine is written in the Visual Basic for Applications language and is based on Powell's method. The cogeneration plant operates subjected to time-changing economic scenarios, because of varying fuel, electricity, and steam prices. Thus, to manage the plant, it is necessary to vary the operational state appropriately as the economic parameters change. For a prescribed economic scenario, previous work determined the minimum operational cost, when a fixed contracted hourly-rate of process steam was to be exported, while a variable amount of electrical power was produced. In this paper, a broader optimization problem is formulated and solved, for which the objective is to maximize the plant profit under different economic scenarios. It is shown that the optimal operating conditions depend on the economic parameters, and do not necessarily imply maximum efficiency. The integrated optimization approach proves effective, robust, and helpful for optimal plant management. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

The analysis of heat transfer in automotive turbochargers / Nick Baines in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010)

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 08 p. Titre : The analysis of heat transfer in automotive turbochargers Type de document : texte imprimé Auteurs : Nick Baines, Auteur ; Karl D. Wygant, Auteur ; Antonis Dris, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Automobile  industry  Heat  transfer  Turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Heat transfers in an automotive turbocharger comprise significant energy flows, but are rarely measured or accounted for in any turbocharger performance assessment. Existing measurements suggest that the difference in turbine efficiency calculated in the conventional way, by means of the fluid temperature change, under adiabatic conditions differs considerably from the usual diabatic test conditions, particularly at low turbine pressure ratio. In the work described in this paper, three commercial turbochargers were extensively instrumented with thermocouples on all accessible external and internal surfaces in order to make comprehensive temperature surveys. The turbochargers were run at ranges of turbine inlet temperature and external ventilation. Adiabatic tests were also carried out to serve as a reference condition. Based on the temperature measurements, the internal heat fluxes from the turbine gas to the turbocharger structure and from there to the lubricating oil and the compressor, and the external heat fluxes to the environment were calculated. A one-dimensional heat transfer network model of the turbocharger was demonstrated to be able to simulate the heat fluxes to good accuracy, and the heat transfer coefficients required were ultimately found to be mostly independent of the turbochargers tested. DEWEY : 620.1 ISSN : 0742-4795 [article] The analysis of heat transfer in automotive turbochargers [texte imprimé] / Nick Baines, Auteur ; Karl D. Wygant, Auteur ; Antonis Dris, 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° 4 (Avril 2010) . - 08 p. Mots-clés : Automobile  industry  Heat  transfer  Turbines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Heat transfers in an automotive turbocharger comprise significant energy flows, but are rarely measured or accounted for in any turbocharger performance assessment. Existing measurements suggest that the difference in turbine efficiency calculated in the conventional way, by means of the fluid temperature change, under adiabatic conditions differs considerably from the usual diabatic test conditions, particularly at low turbine pressure ratio. In the work described in this paper, three commercial turbochargers were extensively instrumented with thermocouples on all accessible external and internal surfaces in order to make comprehensive temperature surveys. The turbochargers were run at ranges of turbine inlet temperature and external ventilation. Adiabatic tests were also carried out to serve as a reference condition. Based on the temperature measurements, the internal heat fluxes from the turbine gas to the turbocharger structure and from there to the lubricating oil and the compressor, and the external heat fluxes to the environment were calculated. A one-dimensional heat transfer network model of the turbocharger was demonstrated to be able to simulate the heat fluxes to good accuracy, and the heat transfer coefficients required were ultimately found to be mostly independent of the turbochargers tested. DEWEY : 620.1 ISSN : 0742-4795

Identification of squeeze film damper force coefficients from multiple-frequency noncircular journal motions / Adolfo Delgado in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 09 p. Titre : Identification of squeeze film damper force coefficients from multiple-frequency noncircular journal motions Type de document : texte imprimé Auteurs : Adolfo Delgado, Auteur ; Luis San Andrés, Auteur Année de publication : 2010 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Damping  Machine  bearings  Parameter  estimation  Rotors Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In rotor-bearing systems, squeeze film dampers (SFDs) provide structural isolation, reduce amplitudes of rotor response to imbalance, and in some instances, increase the system threshold speed of instability. SFDs are typically installed at the bearing supports, either in series or in parallel. In multispool engines, SFDs are located in the interface between rotating shafts. These intershaft dampers must ameliorate complex rotor motions of various whirl frequencies arising from the low speed and the high speed rotors. The paper presents experiments to characterize the forced response of an open ends SFD subject to dynamic loads with multiple frequencies, as in a jet engine intershaft damper. The test rig comprises of a stationary journal and a flexibly supported housing that holds the test damper and instrumentation. The open ends SFD is 127 mm in diameter, 25.4 mm film land length, and has a radial clearance of 0.125 mm. The damper is lubricated with ISO VG 2 oil at room temperature (24°C, feed pressure 31 kPa). In the experiments, two orthogonally positioned shakers deliver forces to the test damper that produce controlled amplitude motions with two whirl frequencies, one fixed and the other one varying over a specified range that includes the test system natural frequency. The test data collected, forces and motions versus time, are converted into the frequency domain for parameter identification. The identified viscous damping coefficients are strong functions of the amplitude of journal motion, lying within predictions from classical formulas for circular centered orbits and small amplitude motions about an eccentric journal position. The damper inertia coefficients agree well with predictions derived from a fluid flow model that includes the effect of the feed groove. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Identification of squeeze film damper force coefficients from multiple-frequency noncircular journal motions [texte imprimé] / Adolfo Delgado, Auteur ; Luis San Andrés, 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° 4 (Avril 2010) . - 09 p. Mots-clés : Damping  Machine  bearings  Parameter  estimation  Rotors Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In rotor-bearing systems, squeeze film dampers (SFDs) provide structural isolation, reduce amplitudes of rotor response to imbalance, and in some instances, increase the system threshold speed of instability. SFDs are typically installed at the bearing supports, either in series or in parallel. In multispool engines, SFDs are located in the interface between rotating shafts. These intershaft dampers must ameliorate complex rotor motions of various whirl frequencies arising from the low speed and the high speed rotors. The paper presents experiments to characterize the forced response of an open ends SFD subject to dynamic loads with multiple frequencies, as in a jet engine intershaft damper. The test rig comprises of a stationary journal and a flexibly supported housing that holds the test damper and instrumentation. The open ends SFD is 127 mm in diameter, 25.4 mm film land length, and has a radial clearance of 0.125 mm. The damper is lubricated with ISO VG 2 oil at room temperature (24°C, feed pressure 31 kPa). In the experiments, two orthogonally positioned shakers deliver forces to the test damper that produce controlled amplitude motions with two whirl frequencies, one fixed and the other one varying over a specified range that includes the test system natural frequency. The test data collected, forces and motions versus time, are converted into the frequency domain for parameter identification. The identified viscous damping coefficients are strong functions of the amplitude of journal motion, lying within predictions from classical formulas for circular centered orbits and small amplitude motions about an eccentric journal position. The damper inertia coefficients agree well with predictions derived from a fluid flow model that includes the effect of the feed groove. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Testing and calibration procedures for mistuning identification and traveling wave excitation of blisks / Darren E. Holland in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 09 p. Titre : Testing and calibration procedures for mistuning identification and traveling wave excitation of blisks Type de document : texte imprimé Auteurs : Darren E. Holland, Auteur ; Matthew P. Castanier, Auteur ; Ceccio, Steven L., Auteur Année de publication : 2010 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Blades  Calibration  Discs  (structures)  Finite  element  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this work, an integrated testing and calibration procedure is presented for performing mistuning identification (ID) and traveling wave excitation (TWE) of one-piece bladed disks (blisks). The procedure yields accurate results while also being highly efficient and is comprised of three basic phases. First, selected modes from a tuned blisk finite element model are used to determine a minimal set of measurement degrees of freedom (and locations) that will work well for mistuning ID. Second, a testing procedure is presented that allows the mistuning to be identified from relatively few vibration response measurements. A numerical validation is used to investigate the convergence of the mistuning ID results to a prescribed mistuning pattern using the proposed approach and alternative testing strategies. Third, a method is derived to iteratively calibrate the excitation applied to each blade so that differences among the blade excitation magnitudes can be minimized for a single blade excitation, and also the excitation phases can be accurately set to achieve the desired traveling wave excitation. The calibration algorithm uses the principle of reciprocity and involves solving a least-squares problem to reduce the effects of measurement noise and uncertainty. Because the TWE calibration procedure re-uses the data collected during the mistuning ID, the overall procedure is integrated and efficient. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Testing and calibration procedures for mistuning identification and traveling wave excitation of blisks [texte imprimé] / Darren E. Holland, Auteur ; Matthew P. Castanier, Auteur ; Ceccio, Steven L., 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° 4 (Avril 2010) . - 09 p. Mots-clés : Blades  Calibration  Discs  (structures)  Finite  element  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this work, an integrated testing and calibration procedure is presented for performing mistuning identification (ID) and traveling wave excitation (TWE) of one-piece bladed disks (blisks). The procedure yields accurate results while also being highly efficient and is comprised of three basic phases. First, selected modes from a tuned blisk finite element model are used to determine a minimal set of measurement degrees of freedom (and locations) that will work well for mistuning ID. Second, a testing procedure is presented that allows the mistuning to be identified from relatively few vibration response measurements. A numerical validation is used to investigate the convergence of the mistuning ID results to a prescribed mistuning pattern using the proposed approach and alternative testing strategies. Third, a method is derived to iteratively calibrate the excitation applied to each blade so that differences among the blade excitation magnitudes can be minimized for a single blade excitation, and also the excitation phases can be accurately set to achieve the desired traveling wave excitation. The calibration algorithm uses the principle of reciprocity and involves solving a least-squares problem to reduce the effects of measurement noise and uncertainty. Because the TWE calibration procedure re-uses the data collected during the mistuning ID, the overall procedure is integrated and efficient. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Rotordynamic force coefficients of a hybrid brush seal / Luis San Andrés in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 07 p. Titre : Rotordynamic force coefficients of a hybrid brush seal : measurements and predictions Type de document : texte imprimé Auteurs : Luis San Andrés, Auteur ; José Baker, Auteur ; Adolfo Delgado, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  engines  Damping  Distortion  Elasticity  Friction  Gas  turbines  Hydrodynamics  Rotors  Seals  (stoppers)  Shafts  Wear Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Brush seals effectively control leakage in air breathing engines, albeit only applied for relatively low-pressure differentials. Hybrid brush seals (HBS) are an alternative to resolve poor reliability resulting from bristle tip wear while also allowing for reverse shaft rotation operations. A HBS incorporates pads contacting the shaft on assembly; and which under rotor spinning, lift off due to the generation of a hydrodynamic pressure. The ensuing gas film prevents intermittent contact, reducing wear, and thermal distortions. This paper presents rotordynamic measurements conducted on a test rig for evaluation of HBS technology. Single frequency shaker loads are exerted on a test rotor holding a hybrid brush seal, and measurements of rotor displacements follow for operating conditions with increasing gas supply pressures and two rotor speeds. A frequency domain identification method delivers the test system stiffness and damping coefficients. The HBS stiffness coefficients are not affected by rotor speed though the seal viscous damping shows a strong frequency dependency. The identified HBS direct stiffness decreases ~15% as the supply/discharge pressure increases Pr=1.7–2.4. The HBS cross-coupled stiffnesses are insignificant, at least one order of magnitude smaller than the direct stiffnesses. A structural loss factor (gamma) and dry-friction coefficient (µ) represent the energy dissipated in a HBS by the bristle-to-bristle and bristle-to-pad interactions. Predictions of HBS stiffness and damping coefficients correlate well with the test derived parameters. Both model predictions and test results show the dramatic reduction in the seal equivalent viscous damping coefficients as the excitation whirl frequency increases. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Rotordynamic force coefficients of a hybrid brush seal : measurements and predictions [texte imprimé] / Luis San Andrés, Auteur ; José Baker, Auteur ; Adolfo Delgado, 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° 4 (Avril 2010) . - 07 p. Mots-clés : Aerospace  engines  Damping  Distortion  Elasticity  Friction  Gas  turbines  Hydrodynamics  Rotors  Seals  (stoppers)  Shafts  Wear Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Brush seals effectively control leakage in air breathing engines, albeit only applied for relatively low-pressure differentials. Hybrid brush seals (HBS) are an alternative to resolve poor reliability resulting from bristle tip wear while also allowing for reverse shaft rotation operations. A HBS incorporates pads contacting the shaft on assembly; and which under rotor spinning, lift off due to the generation of a hydrodynamic pressure. The ensuing gas film prevents intermittent contact, reducing wear, and thermal distortions. This paper presents rotordynamic measurements conducted on a test rig for evaluation of HBS technology. Single frequency shaker loads are exerted on a test rotor holding a hybrid brush seal, and measurements of rotor displacements follow for operating conditions with increasing gas supply pressures and two rotor speeds. A frequency domain identification method delivers the test system stiffness and damping coefficients. The HBS stiffness coefficients are not affected by rotor speed though the seal viscous damping shows a strong frequency dependency. The identified HBS direct stiffness decreases ~15% as the supply/discharge pressure increases Pr=1.7–2.4. The HBS cross-coupled stiffnesses are insignificant, at least one order of magnitude smaller than the direct stiffnesses. A structural loss factor (gamma) and dry-friction coefficient (µ) represent the energy dissipated in a HBS by the bristle-to-bristle and bristle-to-pad interactions. Predictions of HBS stiffness and damping coefficients correlate well with the test derived parameters. Both model predictions and test results show the dramatic reduction in the seal equivalent viscous damping coefficients as the excitation whirl frequency increases. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Thermohydrodynamic analysis of bump type gas foil bearings / Luis San Andrés in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 10 p. Titre : Thermohydrodynamic analysis of bump type gas foil bearings : a model anchored to test data Type de document : texte imprimé Auteurs : Luis San Andrés, Auteur ; Tae Ho Kim, Auteur Année de publication : 2010 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cooling  Hydrodynamics  Machine  bearings  Rotors  Shafts  Thermodynamics  Thin  films  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The paper introduces a thermohydrodynamic (THD) model for prediction of gas foil bearing (GFB) performance. The model includes thermal energy transport in the gas film region and with cooling gas streams, inner or outer, as in typical rotor-GFBs systems. The analysis also accounts for material property changes and the bearing components' expansion due to temperature increases and shaft centrifugal growth due to rotational speed. Gas inlet feed characteristics are thoroughly discussed in bearings whose top foil must detach, i.e., not allowing for subambient pressure. Thermal growths determine the actual bearing clearance needed for accurate prediction of GFB forced performance, static and dynamic. Model predictions are benchmarked against published measurements of (metal) temperatures in a GFB operating without a forced cooling gas flow. The tested foil bearing is proprietary; hence, its geometry and material properties are largely unknown. Predictions are obtained for an assumed bearing configuration, with bump-foil geometry and materials taken from prior art and best known practices. The predicted film peak temperature occurs just downstream of the maximum gas pressure. The film temperature is higher at the bearing middle plane than at the foil edges, as the test results also show. The journal speed, rather than the applied static load, influences more the increase in film temperature and with a larger thermal gradient toward the bearing sides. In addition, as in the tests conducted at a constant rotor speed and even for the lowest static load, the gas film temperature increases rapidly due to the absence of a forced cooling air that could carry away the recirculation gas flow and thermal energy drawn by the spinning rotor; predictions are in good agreement with the test data. A comparison of predicted static load parameters to those obtained from an isothermal condition shows the THD model producing a smaller journal eccentricity (larger minimum film thickness) and larger drag torque. An increase in gas temperature is tantamount to an increase in gas viscosity, hence, the noted effect in the foil bearing forced performance. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Thermohydrodynamic analysis of bump type gas foil bearings : a model anchored to test data [texte imprimé] / Luis San Andrés, Auteur ; Tae Ho Kim, 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° 4 (Avril 2010) . - 10 p. Mots-clés : Cooling  Hydrodynamics  Machine  bearings  Rotors  Shafts  Thermodynamics  Thin  films  Turbomachinery Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The paper introduces a thermohydrodynamic (THD) model for prediction of gas foil bearing (GFB) performance. The model includes thermal energy transport in the gas film region and with cooling gas streams, inner or outer, as in typical rotor-GFBs systems. The analysis also accounts for material property changes and the bearing components' expansion due to temperature increases and shaft centrifugal growth due to rotational speed. Gas inlet feed characteristics are thoroughly discussed in bearings whose top foil must detach, i.e., not allowing for subambient pressure. Thermal growths determine the actual bearing clearance needed for accurate prediction of GFB forced performance, static and dynamic. Model predictions are benchmarked against published measurements of (metal) temperatures in a GFB operating without a forced cooling gas flow. The tested foil bearing is proprietary; hence, its geometry and material properties are largely unknown. Predictions are obtained for an assumed bearing configuration, with bump-foil geometry and materials taken from prior art and best known practices. The predicted film peak temperature occurs just downstream of the maximum gas pressure. The film temperature is higher at the bearing middle plane than at the foil edges, as the test results also show. The journal speed, rather than the applied static load, influences more the increase in film temperature and with a larger thermal gradient toward the bearing sides. In addition, as in the tests conducted at a constant rotor speed and even for the lowest static load, the gas film temperature increases rapidly due to the absence of a forced cooling air that could carry away the recirculation gas flow and thermal energy drawn by the spinning rotor; predictions are in good agreement with the test data. A comparison of predicted static load parameters to those obtained from an isothermal condition shows the THD model producing a smaller journal eccentricity (larger minimum film thickness) and larger drag torque. An increase in gas temperature is tantamount to an increase in gas viscosity, hence, the noted effect in the foil bearing forced performance. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Experimental investigation of the effect of biodiesel utilization on lubricating oil degradation and wear of a transportation CIDI engine / Shailendra Sinha in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 09 p. Titre : Experimental investigation of the effect of biodiesel utilization on lubricating oil degradation and wear of a transportation CIDI engine Type de document : texte imprimé Auteurs : Shailendra Sinha, Auteur ; Avinash Kumar Agarwal, Auteur Année de publication : 2010 Article en page(s) : 09 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Biofuel  Engine  cylinders  Internal  combustion  engines  Lubricating  oils  Scanning  electron  microscopy  Wear Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In the present experimental research work, rice-bran oil methyl ester (ROME) is derived through transesterification of rice-bran oil using methanol in the presence of sodium hydroxide catalyst. On the basis of previous research for performance, emission, and combustion characteristics, a 20% (v/v) blend of ROME (B20) was selected as optimum biodiesel blend. This experimental investigation was aimed to investigate the effect of biodiesel on wear of in-cylinder engine components. Endurance tests were conducted on a medium duty direct injection transportation diesel engine with B20. Tests were conducted under predetermined loading cycles in two phases: engine operating on mineral diesel (B00) and engine fueled with B20. After completion of these tests, engines were dismantled for observing the physical condition of various vital engine parts, e.g., piston rings, bearings, cylinder liner, and cylinder head. Physical measurements of these vital parts were also carried out to assess the wear of these parts. The physical wear of various parts except big end bearings (connecting rod bearing bore) were found to be lower in the case of B20 fueled engine. Wear metals in the lubricating oil samples drawn from the engines at regular intervals were investigated. Relatively lower wear concentrations of all wear metals except lead were found in the lubricating oil of B20 fueled engine. To quantify the wear of cylinder liners, surface parameters at different locations in the liner (top dead center, bottom dead center, and midstroke) were measured and compared. A qualitative analysis was also carried out by conducting surface profiles and scanning electron microscopy at the same locations. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Experimental investigation of the effect of biodiesel utilization on lubricating oil degradation and wear of a transportation CIDI engine [texte imprimé] / Shailendra Sinha, Auteur ; Avinash Kumar Agarwal, 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° 4 (Avril 2010) . - 09 p. Mots-clés : Biofuel  Engine  cylinders  Internal  combustion  engines  Lubricating  oils  Scanning  electron  microscopy  Wear Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In the present experimental research work, rice-bran oil methyl ester (ROME) is derived through transesterification of rice-bran oil using methanol in the presence of sodium hydroxide catalyst. On the basis of previous research for performance, emission, and combustion characteristics, a 20% (v/v) blend of ROME (B20) was selected as optimum biodiesel blend. This experimental investigation was aimed to investigate the effect of biodiesel on wear of in-cylinder engine components. Endurance tests were conducted on a medium duty direct injection transportation diesel engine with B20. Tests were conducted under predetermined loading cycles in two phases: engine operating on mineral diesel (B00) and engine fueled with B20. After completion of these tests, engines were dismantled for observing the physical condition of various vital engine parts, e.g., piston rings, bearings, cylinder liner, and cylinder head. Physical measurements of these vital parts were also carried out to assess the wear of these parts. The physical wear of various parts except big end bearings (connecting rod bearing bore) were found to be lower in the case of B20 fueled engine. Wear metals in the lubricating oil samples drawn from the engines at regular intervals were investigated. Relatively lower wear concentrations of all wear metals except lead were found in the lubricating oil of B20 fueled engine. To quantify the wear of cylinder liners, surface parameters at different locations in the liner (top dead center, bottom dead center, and midstroke) were measured and compared. A qualitative analysis was also carried out by conducting surface profiles and scanning electron microscopy at the same locations. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Investigation of nozzle flow and cavitation characteristics in a diesel injector / S. Som in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 12 p. Titre : Investigation of nozzle flow and cavitation characteristics in a diesel injector Type de document : texte imprimé Auteurs : S. Som, Auteur ; S. K. Aggarwal, Auteur ; E. M. El-Hannouny, Auteur Année de publication : 2010 Article en page(s) : 12 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cavitation  Diesel  engines  Mechanical  engineering  computing  Nozzles  Orifices  (mechanical)  Turbulence  Two-phase  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Cavitation and turbulence inside a diesel injector play a critical role in primary spray breakup and development processes. The study of cavitation in realistic injectors is challenging, both theoretically and experimentally, since the associated two-phase flow field is turbulent and highly complex, characterized by large pressure gradients and small orifice geometries. We report herein a computational investigation of the internal nozzle flow and cavitation characteristics in a diesel injector. A mixture based model in FLUENT V6.2 software is employed for simulations. In addition, a new criterion for cavitation inception based on the total stress is implemented, and its effectiveness in predicting cavitation is evaluated. Results indicate that under realistic diesel engine conditions, cavitation patterns inside the orifice are influenced by the new cavitation criterion. Simulations are validated using the available two-phase nozzle flow data and the rate of injection measurements at various injection pressures (800–1600 bar) from the present study. The computational model is then used to characterize the effects of important injector parameters on the internal nozzle flow and cavitation behavior, as well as on flow properties at the nozzle exit. The parameters include injection pressure, needle lift position, and fuel type. The propensity of cavitation for different on-fleet diesel fuels is compared with that for n-dodecane, a diesel fuel surrogate. Results indicate that the cavitation characteristics of n-dodecane are significantly different from those of the other three fuels investigated. The effect of needle movement on cavitation is investigated by performing simulations at different needle lift positions. Cavitation patterns are seen to shift dramatically as the needle lift position is changed during an injection event. The region of significant cavitation shifts from top of the orifice to bottom of the orifice as the needle position is changed from fully open (0.275 mm) to nearly closed (0.1 mm), and this behavior can be attributed to the effect of needle position on flow patterns upstream of the orifice. The results demonstrate the capability of the cavitation model to predict cavitating nozzle flows in realistic diesel injectors and provide boundary conditions, in terms of vapor fraction, velocity, and turbulence parameters at the nozzle exit, which can be coupled with the primary breakup simulation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Investigation of nozzle flow and cavitation characteristics in a diesel injector [texte imprimé] / S. Som, Auteur ; S. K. Aggarwal, Auteur ; E. M. El-Hannouny, Auteur . - 2010 . - 12 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 12 p. Mots-clés : Cavitation  Diesel  engines  Mechanical  engineering  computing  Nozzles  Orifices  (mechanical)  Turbulence  Two-phase  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Cavitation and turbulence inside a diesel injector play a critical role in primary spray breakup and development processes. The study of cavitation in realistic injectors is challenging, both theoretically and experimentally, since the associated two-phase flow field is turbulent and highly complex, characterized by large pressure gradients and small orifice geometries. We report herein a computational investigation of the internal nozzle flow and cavitation characteristics in a diesel injector. A mixture based model in FLUENT V6.2 software is employed for simulations. In addition, a new criterion for cavitation inception based on the total stress is implemented, and its effectiveness in predicting cavitation is evaluated. Results indicate that under realistic diesel engine conditions, cavitation patterns inside the orifice are influenced by the new cavitation criterion. Simulations are validated using the available two-phase nozzle flow data and the rate of injection measurements at various injection pressures (800–1600 bar) from the present study. The computational model is then used to characterize the effects of important injector parameters on the internal nozzle flow and cavitation behavior, as well as on flow properties at the nozzle exit. The parameters include injection pressure, needle lift position, and fuel type. The propensity of cavitation for different on-fleet diesel fuels is compared with that for n-dodecane, a diesel fuel surrogate. Results indicate that the cavitation characteristics of n-dodecane are significantly different from those of the other three fuels investigated. The effect of needle movement on cavitation is investigated by performing simulations at different needle lift positions. Cavitation patterns are seen to shift dramatically as the needle lift position is changed during an injection event. The region of significant cavitation shifts from top of the orifice to bottom of the orifice as the needle position is changed from fully open (0.275 mm) to nearly closed (0.1 mm), and this behavior can be attributed to the effect of needle position on flow patterns upstream of the orifice. The results demonstrate the capability of the cavitation model to predict cavitating nozzle flows in realistic diesel injectors and provide boundary conditions, in terms of vapor fraction, velocity, and turbulence parameters at the nozzle exit, which can be coupled with the primary breakup simulation. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Engine emission modeling using a mixed physics and regression approach / Michael Benz in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 11 p. Titre : Engine emission modeling using a mixed physics and regression approach Type de document : texte imprimé Auteurs : Michael Benz, Auteur ; Christopher H. Onder, Auteur ; Lino Guzzella, Auteur Année de publication : 2010 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air  pollution  control  Artificial  intelligence  Diesel  engines  Engine  cylinders  Fuel  economy  Genetic  algorithms  Neurocontrollers  Regression  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a novel control-oriented model of the raw emissions of diesel engines. An extended quasistationary approach is developed where some engine process variables, such as combustion or cylinder charge characteristics, are used as inputs. These inputs are chosen by a selection algorithm that is based on genetic-programming techniques. Based on the selected inputs, a hybrid symbolic regression algorithm generates the adequate nonlinear structure of the emission model. With this approach, the model identification efforts can be reduced significantly. Although this symbolic regression model requires fewer than eight parameters to be identified, it provides results comparable to those obtained with artificial neural networks. The symbolic regression model is capable of predicting the behavior of the engine in operating points not used for the model parametrization, and it can be adapted easily to other engine classes. Results from experiments under steady-state and transient operating conditions are used to show the accuracy of the presented model. Possible applications of this model are the optimization of the engine system operation strategy and the derivation of virtual sensor designs. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Engine emission modeling using a mixed physics and regression approach [texte imprimé] / Michael Benz, Auteur ; Christopher H. Onder, Auteur ; Lino Guzzella, 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° 4 (Avril 2010) . - 11 p. Mots-clés : Air  pollution  control  Artificial  intelligence  Diesel  engines  Engine  cylinders  Fuel  economy  Genetic  algorithms  Neurocontrollers  Regression  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a novel control-oriented model of the raw emissions of diesel engines. An extended quasistationary approach is developed where some engine process variables, such as combustion or cylinder charge characteristics, are used as inputs. These inputs are chosen by a selection algorithm that is based on genetic-programming techniques. Based on the selected inputs, a hybrid symbolic regression algorithm generates the adequate nonlinear structure of the emission model. With this approach, the model identification efforts can be reduced significantly. Although this symbolic regression model requires fewer than eight parameters to be identified, it provides results comparable to those obtained with artificial neural networks. The symbolic regression model is capable of predicting the behavior of the engine in operating points not used for the model parametrization, and it can be adapted easily to other engine classes. Results from experiments under steady-state and transient operating conditions are used to show the accuracy of the presented model. Possible applications of this model are the optimization of the engine system operation strategy and the derivation of virtual sensor designs. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Ignition delay and combustion characteristics of gaseous fuel jets / Dung Ngoc Nguyen in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 08 p. Titre : Ignition delay and combustion characteristics of gaseous fuel jets Type de document : texte imprimé Auteurs : Dung Ngoc Nguyen, Auteur ; Hiroaki Ishida, Auteur ; Masahiro Shioji, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Ignition  Jet  engines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Gaseous fuels, such as hydrogen and natural gas, are utilized in internal combustion engines for spark-ignition operation. To improve thermal efficiency and to ensure control at good heat-release rates, combustion systems with direct-injection and spontaneous-ignition operation may be preferable. The main objective of this research was to provide fundamental data for the ignition and combustion of hydrogen, natural gas, and methane. Experiments were conducted in a constant-volume combustion vessel to investigate the effects of ambient temperature on ignition delay and combustion characteristics for various injector and ambient conditions. Experimental results showed that all gaseous fuels exhibited similar ignition-delay trends: ignition delay (tau) increased as ambient temperature (Ti) decreased. Among these fuels, hydrogen jets exhibited much shorter tau than natural gas and methane jets at the same Ti and could be ignited at a lower temperature, Ti=780 K. A shorter ignition delay of hydrogen may be attained by controlling the mixture formation by lowering the injection pressure (pj), enlarging the nozzle-hole diameter (dN), increasing the ambient pressure (pi), and increasing the oxygen mole fraction (rO2). In contrast, the methane jet exhibited the longest tau over the whole range of Ti and suffered from misfiring at a higher Ti of 910 K. For natural gas, ignition delay was observed to be shorter than that for methane, owing to a small amount of butane with good ignitability. More specifically, the ignition delay of natural gas differed slightly when dN and pj varied but changed drastically when pi and rO2 decreased. Based on these data, the feasibility of gaseous fuels for compression-ignition engines is discussed from the viewpoint of mixture formation and chemical reaction. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Ignition delay and combustion characteristics of gaseous fuel jets [texte imprimé] / Dung Ngoc Nguyen, Auteur ; Hiroaki Ishida, Auteur ; Masahiro Shioji, 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° 4 (Avril 2010) . - 08 p. Mots-clés : Combustion  Ignition  Jet  engines Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Gaseous fuels, such as hydrogen and natural gas, are utilized in internal combustion engines for spark-ignition operation. To improve thermal efficiency and to ensure control at good heat-release rates, combustion systems with direct-injection and spontaneous-ignition operation may be preferable. The main objective of this research was to provide fundamental data for the ignition and combustion of hydrogen, natural gas, and methane. Experiments were conducted in a constant-volume combustion vessel to investigate the effects of ambient temperature on ignition delay and combustion characteristics for various injector and ambient conditions. Experimental results showed that all gaseous fuels exhibited similar ignition-delay trends: ignition delay (tau) increased as ambient temperature (Ti) decreased. Among these fuels, hydrogen jets exhibited much shorter tau than natural gas and methane jets at the same Ti and could be ignited at a lower temperature, Ti=780 K. A shorter ignition delay of hydrogen may be attained by controlling the mixture formation by lowering the injection pressure (pj), enlarging the nozzle-hole diameter (dN), increasing the ambient pressure (pi), and increasing the oxygen mole fraction (rO2). In contrast, the methane jet exhibited the longest tau over the whole range of Ti and suffered from misfiring at a higher Ti of 910 K. For natural gas, ignition delay was observed to be shorter than that for methane, owing to a small amount of butane with good ignitability. More specifically, the ignition delay of natural gas differed slightly when dN and pj varied but changed drastically when pi and rO2 decreased. Based on these data, the feasibility of gaseous fuels for compression-ignition engines is discussed from the viewpoint of mixture formation and chemical reaction. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Postirradiation testing of high temperature reactor spherical fuel elements under accident conditions / D. Freis in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 06 p. Titre : Postirradiation testing of high temperature reactor spherical fuel elements under accident conditions Type de document : texte imprimé Auteurs : D. Freis, Auteur ; D. Bottomley, Auteur ; J. Ejton, Auteur Année de publication : 2010 Article en page(s) : 06 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Fission  reactor  accidents  Fission  reactor  fuel  Furnaces Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A new furnace for accident condition testing of spherical high temperature reactor fuel elements has been installed and now operates in the hot cells of the Institute for Transuranium Elements (ITU) Karlsruhe. The recent apparatus was constructed on the basis of a former development by Forschungszentrum Jülich (Schenk, Pitzer, and Nabielek, 1988, “Fission Product Release Profiles From Spherical HTR Fuel Elements at Accident Temperatures,” Jülich Report No. 2234), where it was named KüFA, the German acronym for cold finger apparatus. In a preceding publication (Kostecka, Ejton, de Weerd, and Toscano, 2004, “Post-Irradiation Testing of HTR-Fuel Elements Under Accident Conditions, Part 1 and 2,” Second International Topical Meeting on High Temperature Reactor Technology, Beijing, China) the general concept and details of the device were described. The present paper reports on the first operation under hot conditions, and the calibration of the fission gas measurement and of the efficiency of the cold finger, which is used to plate out solid fission products. Finally the results of fission product release and analysis of two heating tests on two fuel elements from the high temperature reactor K6 irradiation experiment (Nabielek, Conrad, Roellig, and Meyers, 1993, “Fuel Irradiation Experiments on HFR-K6 and HFR-B1 With Intermittent Water Vapour Injections,” Technical Committee Meeting on Response of Fuel, Fuel Elements and Gas Cooled Reactor Cores Under Accidental Air or Water Ingress Conditions, Beijing, China, Oct. 25–27) are presented and discussed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Postirradiation testing of high temperature reactor spherical fuel elements under accident conditions [texte imprimé] / D. Freis, Auteur ; D. Bottomley, Auteur ; J. Ejton, 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° 4 (Avril 2010) . - 06 p. Mots-clés : Fission  reactor  accidents  Fission  reactor  fuel  Furnaces Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A new furnace for accident condition testing of spherical high temperature reactor fuel elements has been installed and now operates in the hot cells of the Institute for Transuranium Elements (ITU) Karlsruhe. The recent apparatus was constructed on the basis of a former development by Forschungszentrum Jülich (Schenk, Pitzer, and Nabielek, 1988, “Fission Product Release Profiles From Spherical HTR Fuel Elements at Accident Temperatures,” Jülich Report No. 2234), where it was named KüFA, the German acronym for cold finger apparatus. In a preceding publication (Kostecka, Ejton, de Weerd, and Toscano, 2004, “Post-Irradiation Testing of HTR-Fuel Elements Under Accident Conditions, Part 1 and 2,” Second International Topical Meeting on High Temperature Reactor Technology, Beijing, China) the general concept and details of the device were described. The present paper reports on the first operation under hot conditions, and the calibration of the fission gas measurement and of the efficiency of the cold finger, which is used to plate out solid fission products. Finally the results of fission product release and analysis of two heating tests on two fuel elements from the high temperature reactor K6 irradiation experiment (Nabielek, Conrad, Roellig, and Meyers, 1993, “Fuel Irradiation Experiments on HFR-K6 and HFR-B1 With Intermittent Water Vapour Injections,” Technical Committee Meeting on Response of Fuel, Fuel Elements and Gas Cooled Reactor Cores Under Accidental Air or Water Ingress Conditions, Beijing, China, Oct. 25–27) are presented and discussed. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Integration of nuclear energy into oil sands projects / Ashley E. Finan in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 08 p. Titre : Integration of nuclear energy into oil sands projects Type de document : texte imprimé Auteurs : Ashley E. Finan, Auteur ; Andrew C. Kadak, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air  pollution  control  Fuel  processing  industries  Gas  cooled  reactors  Heavy  water  reactors  Natural  gas  technology  Nuclear  power  Oil  technology  Power  generation  economics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Energy security and greenhouse gas reduction are thought to be two of the most urgent priorities for sustaining and improving the human condition in the near future. Few places pit the two goals so directly in opposition to one another as the Alberta oil sands. Here, Canadian natural gas is burned in massive quantities to extract oil from one of North America's largest native sources of carbon-intensive heavy oil. However, this conflict need not continue. Nonemitting nuclear energy can replace natural gas as a fuel source in an economical and more environmentally sound way. This would allow for the continued extraction of transportation fuels without greenhouse gas emissions, while freeing up the natural gas supply for hydrogen feedstock and other valuable applications. Bitumen production in Alberta expanded dramatically in the past 5 years as the price of oil rose to record levels. This paper explores the feasibility and economics of using nuclear energy to power future oil sands production and upgrading activities, and puts forth several nuclear energy application scenarios for providing steam and electricity to in situ and surface mining operations. This review includes the Enhanced CANDU 6, the Advanced CANDU Reactor, and the pebble bed modular reactor. Based on reasonable projections of available cost information, steam produced using nuclear energy is expected to be less expensive than steam produced by natural gas at current natural gas prices and at prices above $6.50/MMBtu (CAD). For electricity production, nuclear energy becomes competitive with natural gas plants at gas prices of $10–13/MMBtu (CAD). Costs of constructing nuclear plants in Alberta are affected by higher local labor costs, which this paper took into account in making these estimates. Although a more definitive analysis of construction costs and project economics will be required to confirm these findings, there appears to be sufficient merit in the potential economics to support further study. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Integration of nuclear energy into oil sands projects [texte imprimé] / Ashley E. Finan, Auteur ; Andrew C. Kadak, 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° 4 (Avril 2010) . - 08 p. Mots-clés : Air  pollution  control  Fuel  processing  industries  Gas  cooled  reactors  Heavy  water  reactors  Natural  gas  technology  Nuclear  power  Oil  technology  Power  generation  economics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Energy security and greenhouse gas reduction are thought to be two of the most urgent priorities for sustaining and improving the human condition in the near future. Few places pit the two goals so directly in opposition to one another as the Alberta oil sands. Here, Canadian natural gas is burned in massive quantities to extract oil from one of North America's largest native sources of carbon-intensive heavy oil. However, this conflict need not continue. Nonemitting nuclear energy can replace natural gas as a fuel source in an economical and more environmentally sound way. This would allow for the continued extraction of transportation fuels without greenhouse gas emissions, while freeing up the natural gas supply for hydrogen feedstock and other valuable applications. Bitumen production in Alberta expanded dramatically in the past 5 years as the price of oil rose to record levels. This paper explores the feasibility and economics of using nuclear energy to power future oil sands production and upgrading activities, and puts forth several nuclear energy application scenarios for providing steam and electricity to in situ and surface mining operations. This review includes the Enhanced CANDU 6, the Advanced CANDU Reactor, and the pebble bed modular reactor. Based on reasonable projections of available cost information, steam produced using nuclear energy is expected to be less expensive than steam produced by natural gas at current natural gas prices and at prices above $6.50/MMBtu (CAD). For electricity production, nuclear energy becomes competitive with natural gas plants at gas prices of $10–13/MMBtu (CAD). Costs of constructing nuclear plants in Alberta are affected by higher local labor costs, which this paper took into account in making these estimates. Although a more definitive analysis of construction costs and project economics will be required to confirm these findings, there appears to be sufficient merit in the potential economics to support further study. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

An experimental study on air-water two-phase flow patterns in pebble beds / Bai Bofeng in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 05 p. Titre : An experimental study on air-water two-phase flow patterns in pebble beds Type de document : texte imprimé Auteurs : Bai Bofeng, Auteur ; Liu Maolong, Auteur ; Su Wang, Auteur Année de publication : 2010 Article en page(s) : 05 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Fluidised  beds  Two-phase  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An experimental study was conducted on the air-water two-phase flow patterns in the bed of rectangular cross sections containing spheres of regular distribution. Three kinds of glass spheres with different diameters (3 mm, 6 mm, and 8 mm) were used for the establishment of the test section. By means of visual observations of the two-phase flow through the test section, it was discovered that five different flow patterns occurred within the experimental parameter ranges, namely, bubbly flow, bubbly-slug flow, slug flow, slug-annular flow, and annular flow. A correlation for the bubble and slug diameter in the packed beds was proposed, which was an extended expression of the Tung/Dhir model, Jamialahmadi's model, and Schmidt's model. Three correlations were proposed to calculate the void friction of the flow pattern transition in bubble flow, slug flow, and annular flow based on the bubble model in the pore region. The experimental result showed that the modified Tung and Dhir model of the flow pattern transition was in better agreement with the experimental data compared with Tung and Dhir's model. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] An experimental study on air-water two-phase flow patterns in pebble beds [texte imprimé] / Bai Bofeng, Auteur ; Liu Maolong, Auteur ; Su Wang, 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° 4 (Avril 2010) . - 05 p. Mots-clés : Fluidised  beds  Two-phase  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An experimental study was conducted on the air-water two-phase flow patterns in the bed of rectangular cross sections containing spheres of regular distribution. Three kinds of glass spheres with different diameters (3 mm, 6 mm, and 8 mm) were used for the establishment of the test section. By means of visual observations of the two-phase flow through the test section, it was discovered that five different flow patterns occurred within the experimental parameter ranges, namely, bubbly flow, bubbly-slug flow, slug flow, slug-annular flow, and annular flow. A correlation for the bubble and slug diameter in the packed beds was proposed, which was an extended expression of the Tung/Dhir model, Jamialahmadi's model, and Schmidt's model. Three correlations were proposed to calculate the void friction of the flow pattern transition in bubble flow, slug flow, and annular flow based on the bubble model in the pore region. The experimental result showed that the modified Tung and Dhir model of the flow pattern transition was in better agreement with the experimental data compared with Tung and Dhir's model. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

Combustion characteristics of HCCI in motorcycle engine / Yuh-Yih Wu in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 4 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 4 (Avril 2010) . - 04 p. Titre : Combustion characteristics of HCCI in motorcycle engine Type de document : texte imprimé Auteurs : Yuh-Yih Wu, Auteur ; Ching-Tzan Jang, Auteur ; Bo-Liang Chen, Auteur Année de publication : 2010 Article en page(s) : 04 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Combustion  Engines  Internal  combustion  engines  Motorcycles  Petroleum Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Homogeneous charge compression ignition (HCCI) is recognized as an advanced combustion system for internal combustion engines that reduces fuel consumption and exhaust emissions. This work studied a 150 cc air-cooled, four-stroke motorcycle engine employing HCCI combustion. The compression ratio was increased from 10.5 to 12.4 by modifying the cylinder head. Kerosene fuel was used without intake air heating and operated at various excess air ratios (lambda), engine speeds, and exhaust gas recirculation (EGR) rates. Combustion characteristics and emissions on the target engine were measured. It was found that keeping the cylinder head temperature at around 120–130°C is important for conducting a stable experiment. Two-stage ignition was observed from the heat release rate curve, which was calculated from cylinder pressure. Higher lambda or EGR causes lower peak pressure, lower maximum rate of pressure rise (MRPR), and higher emission of CO. However, EGR is better than lambda for decreasing the peak pressure and MRPR without deteriorating the engine output. Advancing the timing of peak pressure causes high peak pressure, and hence increases MRPR. The timing of peak pressure around 10–15 degree of crank angle after top dead center indicates a good appearance for low MRPR. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...] [article] Combustion characteristics of HCCI in motorcycle engine [texte imprimé] / Yuh-Yih Wu, Auteur ; Ching-Tzan Jang, Auteur ; Bo-Liang Chen, 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° 4 (Avril 2010) . - 04 p. Mots-clés : Combustion  Engines  Internal  combustion  engines  Motorcycles  Petroleum Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Homogeneous charge compression ignition (HCCI) is recognized as an advanced combustion system for internal combustion engines that reduces fuel consumption and exhaust emissions. This work studied a 150 cc air-cooled, four-stroke motorcycle engine employing HCCI combustion. The compression ratio was increased from 10.5 to 12.4 by modifying the cylinder head. Kerosene fuel was used without intake air heating and operated at various excess air ratios (lambda), engine speeds, and exhaust gas recirculation (EGR) rates. Combustion characteristics and emissions on the target engine were measured. It was found that keeping the cylinder head temperature at around 120–130°C is important for conducting a stable experiment. Two-stage ignition was observed from the heat release rate curve, which was calculated from cylinder pressure. Higher lambda or EGR causes lower peak pressure, lower maximum rate of pressure rise (MRPR), and higher emission of CO. However, EGR is better than lambda for decreasing the peak pressure and MRPR without deteriorating the engine output. Advancing the timing of peak pressure causes high peak pressure, and hence increases MRPR. The timing of peak pressure around 10–15 degree of crank angle after top dead center indicates a good appearance for low MRPR. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000004 [...]

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