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Détail de l'auteur
Auteur Luis San Andrés
Documents disponibles écrits par cet auteur
Affiner la rechercheThermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part I: measurements / Luis San Andrés in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011)
[article]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 10 p.
Titre : Thermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part I: measurements Type de document : texte imprimé Auteurs : Luis San Andrés, Auteur ; Ryu, Keun, Auteur ; Tae Ho Kim, Auteur Année de publication : 2011 Article en page(s) : 10 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Cooling Gas turbines Machine bearings Rotors Shafts Temperature measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Implementation of gas foil bearings (GFBs) into micro gas turbines requires careful thermal management with accurate measurements verifying model predictions. This two-part paper presents test data and analytical results for a test rotor and GFB system operating hot (157°C maximum rotor outer diameter (OD) temperature). Part I details the test rig and measurements of bearing temperatures and rotor dynamic motions obtained in a hollow rotor supported on a pair of second generation GFBs, each consisting of a single top foil (38.14 mm inner diameter) uncoated for high temperature operation and five bump strip support layers. An electric cartridge (maximum of 360°C) loosely installed inside the rotor (1.065 kg, 38.07 mm OD, and 4.8 mm thick) is a heat source warming the rotor-bearing system. While coasting down from 30 krpm to rest, large elapsed times (50–70 s) demonstrate rotor airborne operation, near friction free, and while traversing the system critical speed at ~13 krpm, the rotor peak motion amplitude decreases as the system temperature increases. In tests conducted at a fixed rotor speed of 30 krpm, while the shaft heats, a cooling gas stream of increasing strength is set to manage the temperatures in the bearings and rotor. The effect of the cooling flow, if turbulent in character, is most distinctive at the highest heater temperature. For operation at a lower heater temperature condition, however, the cooling flow stream demonstrates a very limited effectiveness. The measurements demonstrate the reliable performance of the rotor-GFB system when operating hot. The test results, along with full disclosure on the materials and geometry of the test bearings and rotor, serve to benchmark a predictive tool. A companion paper (Part II) compares the measured bearing temperatures and the rotor response amplitudes to predictions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Thermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part I: measurements [texte imprimé] / Luis San Andrés, Auteur ; Ryu, Keun, Auteur ; Tae Ho Kim, Auteur . - 2011 . - 10 p.
Turbines à gaz
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 10 p.
Mots-clés : Cooling Gas turbines Machine bearings Rotors Shafts Temperature measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Implementation of gas foil bearings (GFBs) into micro gas turbines requires careful thermal management with accurate measurements verifying model predictions. This two-part paper presents test data and analytical results for a test rotor and GFB system operating hot (157°C maximum rotor outer diameter (OD) temperature). Part I details the test rig and measurements of bearing temperatures and rotor dynamic motions obtained in a hollow rotor supported on a pair of second generation GFBs, each consisting of a single top foil (38.14 mm inner diameter) uncoated for high temperature operation and five bump strip support layers. An electric cartridge (maximum of 360°C) loosely installed inside the rotor (1.065 kg, 38.07 mm OD, and 4.8 mm thick) is a heat source warming the rotor-bearing system. While coasting down from 30 krpm to rest, large elapsed times (50–70 s) demonstrate rotor airborne operation, near friction free, and while traversing the system critical speed at ~13 krpm, the rotor peak motion amplitude decreases as the system temperature increases. In tests conducted at a fixed rotor speed of 30 krpm, while the shaft heats, a cooling gas stream of increasing strength is set to manage the temperatures in the bearings and rotor. The effect of the cooling flow, if turbulent in character, is most distinctive at the highest heater temperature. For operation at a lower heater temperature condition, however, the cooling flow stream demonstrates a very limited effectiveness. The measurements demonstrate the reliable performance of the rotor-GFB system when operating hot. The test results, along with full disclosure on the materials and geometry of the test bearings and rotor, serve to benchmark a predictive tool. A companion paper (Part II) compares the measured bearing temperatures and the rotor response amplitudes to predictions. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] Thermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part II: predictions versus test data / Luis San Andrés in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 6 (Juin 2011)
[article]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 08 p.
Titre : Thermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part II: predictions versus test data Type de document : texte imprimé Auteurs : Luis San Andrés, Auteur ; Ryu, Keun, Auteur ; Tae Ho Kim, Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Gas turbines Heat transfer Machine bearings Rotors Shafts Thermal expansion Thermal management (packaging) Thermoelasticity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Implementation of gas foil bearings (GFBs) in microgas turbines relies on physics based computational models anchored to test data. This two-part paper presents test data and analytical results for a test rotor and GFB system operating hot. A companion paper (Part I) describes a test rotor-GFB system operating hot to 157°C rotor OD temperature, presents measurements of rotor dynamic response and temperatures in the bearings and rotor, and includes a cooling gas stream condition to manage the system temperatures. The second part briefs on a thermoelastohydrodynamic (TEHD) model for GFBs performance and presents predictions of the thermal energy transport and forced response, static and dynamic, in the tested gas foil bearing system. The model considers the heat flow from the rotor into the bearing cartridges and also the thermal expansion of the shaft and bearing cartridge and shaft centrifugal growth due to rotation. Predictions show that bearings' ID temperatures increase linearly with rotor speed and shaft temperature. Large cooling flow rates, in excess of 100 l/min, reduce significantly the temperatures in the bearings and rotor. Predictions, agreeing well with recorded temperatures given in Part I, also reproduce the radial gradient of temperature between the hot shaft and the bearings ID, largest (37°C/mm) for the strongest cooling stream (150 l/min). The shaft thermal growth, more significant as the temperature grows, reduces the bearings operating clearances and also the minimum film thickness, in particular, at the highest rotor speed (30 krpm). A rotor finite element structural model and GFB force coefficients from the TEHD model are used to predict the test system critical speeds and damping ratios for operation at increasing shaft temperatures. In general, predictions of the rotor imbalance show good agreement with shaft motion measurements acquired during rotor speed coastdown tests. As the shaft temperature increases, the rotor peak motion amplitudes decrease and the system rigid-mode critical speed increases. The computational tool, benchmarked by the measurements, furthers the application of GFBs in high temperature oil-free rotating machinery. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] Thermal management and rotordynamic performance of a hot rotor-gas foil bearings system—Part II: predictions versus test data [texte imprimé] / Luis San Andrés, Auteur ; Ryu, Keun, Auteur ; Tae Ho Kim, Auteur . - 2011 . - 08 p.
Turbines à gaz
Langues : Anglais (eng)
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 6 (Juin 2011) . - 08 p.
Mots-clés : Gas turbines Heat transfer Machine bearings Rotors Shafts Thermal expansion Thermal management (packaging) Thermoelasticity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Implementation of gas foil bearings (GFBs) in microgas turbines relies on physics based computational models anchored to test data. This two-part paper presents test data and analytical results for a test rotor and GFB system operating hot. A companion paper (Part I) describes a test rotor-GFB system operating hot to 157°C rotor OD temperature, presents measurements of rotor dynamic response and temperatures in the bearings and rotor, and includes a cooling gas stream condition to manage the system temperatures. The second part briefs on a thermoelastohydrodynamic (TEHD) model for GFBs performance and presents predictions of the thermal energy transport and forced response, static and dynamic, in the tested gas foil bearing system. The model considers the heat flow from the rotor into the bearing cartridges and also the thermal expansion of the shaft and bearing cartridge and shaft centrifugal growth due to rotation. Predictions show that bearings' ID temperatures increase linearly with rotor speed and shaft temperature. Large cooling flow rates, in excess of 100 l/min, reduce significantly the temperatures in the bearings and rotor. Predictions, agreeing well with recorded temperatures given in Part I, also reproduce the radial gradient of temperature between the hot shaft and the bearings ID, largest (37°C/mm) for the strongest cooling stream (150 l/min). The shaft thermal growth, more significant as the temperature grows, reduces the bearings operating clearances and also the minimum film thickness, in particular, at the highest rotor speed (30 krpm). A rotor finite element structural model and GFB force coefficients from the TEHD model are used to predict the test system critical speeds and damping ratios for operation at increasing shaft temperatures. In general, predictions of the rotor imbalance show good agreement with shaft motion measurements acquired during rotor speed coastdown tests. As the shaft temperature increases, the rotor peak motion amplitudes decrease and the system rigid-mode critical speed increases. The computational tool, benchmarked by the measurements, furthers the application of GFBs in high temperature oil-free rotating machinery. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] 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)
[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 [...] Thermohydrodynamic model predictions and performance measurements of bump-type foil bearing for oil-free turboshaft engines in rotorcraft propulsion systems / Tae Ho Kim in Transactions of the ASME . Journal of tribology, Vol. 132 N° 1 (Janvier 2010)
[article]
in Transactions of the ASME . Journal of tribology > Vol. 132 N° 1 (Janvier 2010) . - 11 p.
Titre : Thermohydrodynamic model predictions and performance measurements of bump-type foil bearing for oil-free turboshaft engines in rotorcraft propulsion systems Type de document : texte imprimé Auteurs : Tae Ho Kim, Auteur ; Luis San Andrés, Auteur Année de publication : 2010 Article en page(s) : 11 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Aerospace components Aerospace propulsion Aircraft testing Convection Cooling Foils Hardening Heat conduction Heating Helicopters Jet engines Machine bearings Maintenance engineering Rotors Shafts Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An engineered thermal management is fundamental to the application of gas foil bearings (GFBs) as turboshaft supports in rotorcraft propulsion systems. The paper presents a model for the thermal energy transport in a rotor-GFB system operating at high temperature with typical inner and/or outer cooling flows. Predicted film temperatures agree with published test data, demonstrating the effectiveness of an outer cooling stream to remove heat and to control the operating temperature. The inner flow stream is not as efficient. The analysis shows paths of thermal energy by conduction and convection to assist in the design and troubleshooting of rotor-GFB systems operating hot. Bearing temperatures and shaft motions measurements are obtained in a test rotor electrically heated to 132°C. In speed-up tests to 26 krpm, the rotor motion amplitude drops suddenly just above the critical speed, thus, evidencing the typical hardening of compliant bearings. At the hottest test condition, since air is more viscous, the rotor peak motion amplitude decreases, not showing a jump. The coastdown tests show the critical speed increases slightly as the temperature increases. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] [article] Thermohydrodynamic model predictions and performance measurements of bump-type foil bearing for oil-free turboshaft engines in rotorcraft propulsion systems [texte imprimé] / Tae Ho Kim, Auteur ; Luis San Andrés, Auteur . - 2010 . - 11 p.
Tribology
Langues : Anglais (eng)
in Transactions of the ASME . Journal of tribology > Vol. 132 N° 1 (Janvier 2010) . - 11 p.
Mots-clés : Aerospace components Aerospace propulsion Aircraft testing Convection Cooling Foils Hardening Heat conduction Heating Helicopters Jet engines Machine bearings Maintenance engineering Rotors Shafts Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An engineered thermal management is fundamental to the application of gas foil bearings (GFBs) as turboshaft supports in rotorcraft propulsion systems. The paper presents a model for the thermal energy transport in a rotor-GFB system operating at high temperature with typical inner and/or outer cooling flows. Predicted film temperatures agree with published test data, demonstrating the effectiveness of an outer cooling stream to remove heat and to control the operating temperature. The inner flow stream is not as efficient. The analysis shows paths of thermal energy by conduction and convection to assist in the design and troubleshooting of rotor-GFB systems operating hot. Bearing temperatures and shaft motions measurements are obtained in a test rotor electrically heated to 132°C. In speed-up tests to 26 krpm, the rotor motion amplitude drops suddenly just above the critical speed, thus, evidencing the typical hardening of compliant bearings. At the hottest test condition, since air is more viscous, the rotor peak motion amplitude decreases, not showing a jump. The coastdown tests show the critical speed increases slightly as the temperature increases. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] Turbocharger nonlinear response with engine-induced excitations / Luis San Andrés in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 3 (Mars 2010)
[article]
in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 3 (Mars 2010) . - 10 p.
Titre : Turbocharger nonlinear response with engine-induced excitations : predictions and test data Type de document : texte imprimé Auteurs : Luis San Andrés, Auteur ; Ash Maruyama, Auteur ; Kostandin Gjika, Auteur Année de publication : 2010 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Compressors Fuel systems Internal combustion engines Machine bearings Shafts Transient response Vehicles Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Turbochargers (TCs) aid to produce smaller and more fuel-efficient passenger vehicle engines with power outputs comparable to those of large displacement engines. This paper presents further progress on the nonlinear dynamic behavior modeling of rotor-radial bearing system by including engine-induced (TC casing) excitations. The application is concerned with a semifloating bearing design commonly used in high speed turbochargers. Predictions from the model are validated against test data collected in an engine-mounted TC unit operating at a top speed of 160 krpm (engine speed=3600 rpm). The bearing model includes noncylindrical lubricant films as in a semifloating-ring bearing with an antirotation button. The nonlinear rotor transient response model presently includes input base motions for the measured TC casing accelerations for increasing engine load conditions. Engines induce TC casing accelerations rich in multiple harmonic frequencies; amplitudes being significant at two and four times the main engine speed. Fast Fourier transfor frequency domain postprocessing of predicted nonlinear TC shaft motions reveals a subsynchronous whirl frequency content in good agreement with test data, in particular, for operation at the highest engine speeds. Predicted total shaft motion is also in good agreement with test data for all engine loads and over the operating TC shaft speed range. The comparisons validate the rotor-bearing model and will aid in reducing product development time and expenditures. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000003 [...] [article] Turbocharger nonlinear response with engine-induced excitations : predictions and test data [texte imprimé] / Luis San Andrés, Auteur ; Ash Maruyama, Auteur ; Kostandin Gjika, 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° 3 (Mars 2010) . - 10 p.
Mots-clés : Compressors Fuel systems Internal combustion engines Machine bearings Shafts Transient response Vehicles Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Turbochargers (TCs) aid to produce smaller and more fuel-efficient passenger vehicle engines with power outputs comparable to those of large displacement engines. This paper presents further progress on the nonlinear dynamic behavior modeling of rotor-radial bearing system by including engine-induced (TC casing) excitations. The application is concerned with a semifloating bearing design commonly used in high speed turbochargers. Predictions from the model are validated against test data collected in an engine-mounted TC unit operating at a top speed of 160 krpm (engine speed=3600 rpm). The bearing model includes noncylindrical lubricant films as in a semifloating-ring bearing with an antirotation button. The nonlinear rotor transient response model presently includes input base motions for the measured TC casing accelerations for increasing engine load conditions. Engines induce TC casing accelerations rich in multiple harmonic frequencies; amplitudes being significant at two and four times the main engine speed. Fast Fourier transfor frequency domain postprocessing of predicted nonlinear TC shaft motions reveals a subsynchronous whirl frequency content in good agreement with test data, in particular, for operation at the highest engine speeds. Predicted total shaft motion is also in good agreement with test data for all engine loads and over the operating TC shaft speed range. The comparisons validate the rotor-bearing model and will aid in reducing product development time and expenditures. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000003 [...]