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Blade forcing function and aerodynamic work measurements in a high speed centrifugal compressor with inlet distortion / Albert Kammerer in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 9 (Septembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 9 (Septembre 2010) . - 11 p. Titre : Blade forcing function and aerodynamic work measurements in a high speed centrifugal compressor with inlet distortion Type de document : texte imprimé Auteurs : Albert Kammerer, Auteur ; Reza S. Abhari, Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerodynamics  Blades  Calibration  Compressors  Distortion  Impellers  Measurement  uncertainty  Pressure  measurement  Pressure  sensors  Strain  gauges Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Centrifugal compressors operating at varying rotational speeds, such as in helicopters or turbochargers, can experience forced response failure modes. The response of the compressors can be triggered by aerodynamic flow nonuniformities such as with diffuser-impeller interaction or with inlet distortions. The work presented here addresses experimental investigations of forced response in centrifugal compressors with inlet distortions. This research is part of an ongoing effort to develop related experimental techniques and to provide data for validation of computational tools. In this work, measurements of blade surface pressure and aerodynamic work distribution were addressed. A series of pressure sensors were designed and installed on rotating impeller blades and simultaneous measurements with blade-mounted strain gauges were performed under engine representative conditions. To the best knowledge of the authors, this is the first publication, which presents comprehensive experimental unsteady pressure measurements during forced response, for high-speed radial compressors. The experimental data were obtained for both resonance and off-resonance conditions with uniquely tailored inlet distortion. This paper covers aspects relating to the design of fast response pressure sensors and their installation on thin impeller blades. Additionally, sensor properties are outlined with a focus on calibration and measurement uncertainty estimations. The second part of this paper presents unsteady pressure results taken for a number of inlet distortion cases. It will be shown that the intended excitation order due to inlet flow distortion is of comparable magnitude to the second and third harmonics, which are consistently observed in all measurements. Finally, an experimental method will be outlined that enables the measurement of aerodynamic work on the blade surface during resonant crossing. This approach quantifies the energy exchange between the blade and the flow in terms of cyclic work along the blade surface. The phase angle between the unsteady pressure and the blade movement will be shown to determine the direction of energy transfer. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] Blade forcing function and aerodynamic work measurements in a high speed centrifugal compressor with inlet distortion [texte imprimé] / Albert Kammerer, Auteur ; Reza S. Abhari, Auteur . - 2011 . - 11 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 9 (Septembre 2010) . - 11 p. Mots-clés : Aerodynamics  Blades  Calibration  Compressors  Distortion  Impellers  Measurement  uncertainty  Pressure  measurement  Pressure  sensors  Strain  gauges Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Centrifugal compressors operating at varying rotational speeds, such as in helicopters or turbochargers, can experience forced response failure modes. The response of the compressors can be triggered by aerodynamic flow nonuniformities such as with diffuser-impeller interaction or with inlet distortions. The work presented here addresses experimental investigations of forced response in centrifugal compressors with inlet distortions. This research is part of an ongoing effort to develop related experimental techniques and to provide data for validation of computational tools. In this work, measurements of blade surface pressure and aerodynamic work distribution were addressed. A series of pressure sensors were designed and installed on rotating impeller blades and simultaneous measurements with blade-mounted strain gauges were performed under engine representative conditions. To the best knowledge of the authors, this is the first publication, which presents comprehensive experimental unsteady pressure measurements during forced response, for high-speed radial compressors. The experimental data were obtained for both resonance and off-resonance conditions with uniquely tailored inlet distortion. This paper covers aspects relating to the design of fast response pressure sensors and their installation on thin impeller blades. Additionally, sensor properties are outlined with a focus on calibration and measurement uncertainty estimations. The second part of this paper presents unsteady pressure results taken for a number of inlet distortion cases. It will be shown that the intended excitation order due to inlet flow distortion is of comparable magnitude to the second and third harmonics, which are consistently observed in all measurements. Finally, an experimental method will be outlined that enables the measurement of aerodynamic work on the blade surface during resonant crossing. This approach quantifies the energy exchange between the blade and the flow in terms of cyclic work along the blade surface. The phase angle between the unsteady pressure and the blade movement will be shown to determine the direction of energy transfer. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

High temperature fast response aerodynamic probe / Christian Lenherr in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 1 (Janvier 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 1 (Janvier 2011) . - 10 p. Titre : High temperature fast response aerodynamic probe Type de document : texte imprimé Auteurs : Christian Lenherr, Auteur ; Anestis I. Kalfas, Auteur ; Reza S. Abhari, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerodynamics  Gas  turbines  Piezoresistive  devices  Pressure  transducers  Probes  Shafts  Strain  gauges  Strain  sensors  Temperature  sensors Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In order to advance the technology for measurements in higher temperature flows, a novel miniature (diameter 2.5 mm) fast response probe that can be applied in flows with temperatures of up to 533 K (500°F) has been developed. The primary elements of the probe are two piezoresistive pressure transducers that are used to measure the unsteady pressure and unsteady velocity field, as well as the steady temperature. Additional temperature and strain gauge sensors are embedded in the shaft to allow a much higher degree of robustness in the use of this probe. The additional temperature sensor in the shaft is used to monitor and correct the heat flux through the probe shaft, facilitating thermal management of the probe. The strain gauge sensor is used to monitor and control probe shaft vibration. Entirely new packaging technology had to be developed to make possible the use of this probe at such high temperatures. Extensive calibration and thermal cycling of the probe used to bind the accuracy and the robustness of the probe. This novel probe is applied in the one-and-1/2-stage, unshrouded axial turbine at ETH Zurich; this turbine configuration is representative of a high work aero-engine. The flow conditioning stretch upstream of the first stator is equipped with a recently designed hot streak generator. Several parameters of the hot streak, including temperature, radial and circumferential position, and shape and size can be independently controlled. The interactions between the hot streak and the secondary flow present a perfect scenario to verify the probe's capability to measure under real engine conditions. Therefore, measurements with the novel probe have been made in order to prove the principle and to detail the interaction effects with blade row pressure gradients and secondary flows. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] High temperature fast response aerodynamic probe [texte imprimé] / Christian Lenherr, Auteur ; Anestis I. Kalfas, Auteur ; Reza S. Abhari, Auteur . - 2012 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 1 (Janvier 2011) . - 10 p. Mots-clés : Aerodynamics  Gas  turbines  Piezoresistive  devices  Pressure  transducers  Probes  Shafts  Strain  gauges  Strain  sensors  Temperature  sensors Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In order to advance the technology for measurements in higher temperature flows, a novel miniature (diameter 2.5 mm) fast response probe that can be applied in flows with temperatures of up to 533 K (500°F) has been developed. The primary elements of the probe are two piezoresistive pressure transducers that are used to measure the unsteady pressure and unsteady velocity field, as well as the steady temperature. Additional temperature and strain gauge sensors are embedded in the shaft to allow a much higher degree of robustness in the use of this probe. The additional temperature sensor in the shaft is used to monitor and correct the heat flux through the probe shaft, facilitating thermal management of the probe. The strain gauge sensor is used to monitor and control probe shaft vibration. Entirely new packaging technology had to be developed to make possible the use of this probe at such high temperatures. Extensive calibration and thermal cycling of the probe used to bind the accuracy and the robustness of the probe. This novel probe is applied in the one-and-1/2-stage, unshrouded axial turbine at ETH Zurich; this turbine configuration is representative of a high work aero-engine. The flow conditioning stretch upstream of the first stator is equipped with a recently designed hot streak generator. Several parameters of the hot streak, including temperature, radial and circumferential position, and shape and size can be independently controlled. The interactions between the hot streak and the secondary flow present a perfect scenario to verify the probe's capability to measure under real engine conditions. Therefore, measurements with the novel probe have been made in order to prove the principle and to detail the interaction effects with blade row pressure gradients and secondary flows. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]

The cumulative effects of forcing function, damping, and mistuning on blade forced response in a high speed centrifugal compressor with inlet distortion / Albert Kammerer in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 12 (Décembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 12 (Décembre 2010) . - 10 p. Titre : The cumulative effects of forcing function, damping, and mistuning on blade forced response in a high speed centrifugal compressor with inlet distortion Type de document : texte imprimé Auteurs : Albert Kammerer, Auteur ; Reza S. Abhari, Auteur Année de publication : 2011 Article en page(s) : 10 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerodynamics  Blades  Compressors  Confined  flow  Damping  Distortion  Mass  transfer  Vibrations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The vibratory response amplitude of a blade under forced response conditions depends primarily on the aerodynamic excitation amplitude, on damping, and on the effects of mistuning. The work presented here targets to identify the individual contribution of these parameters to the resultant response amplitude depending on the mass flow and the resonance case. For this purpose, measurements were performed of the excitation amplitude, damping, and response amplitude for a high-speed centrifugal compressor. The inlet flow field was intentionally distorted in order to target specific excitation cases of the first main blade mode. For the compressor used, it was found that the overall damping of the first mode could be considered to be constant for any resonance case and mass flow. For this reason, case-to-case variations in the blade-averaged response amplitude were found to depend solely on the aerodynamic excitation amplitude due to inlet flow distortion. Based on an examination of the aerodynamic work distribution during resonance, zones of either excitation or damping work on the blade surface could be successfully identified. This enabled the conclusion to be drawn that energy transfer is a very localized phenomenon and may significantly change as the mass flow is altered, thereby introducing a redistribution of the blade excitation function. The effect of mistuning was shown to alter aerodynamic damping and response amplitude. However, the variation in aerodynamic damping of individual blades was relatively low, thus suggesting that blade-to-blade variation in response amplitude is primarily driven by energy localization in the sense typically experienced with coupled and mistuned structures. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...] [article] The cumulative effects of forcing function, damping, and mistuning on blade forced response in a high speed centrifugal compressor with inlet distortion [texte imprimé] / Albert Kammerer, Auteur ; Reza S. Abhari, Auteur . - 2011 . - 10 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 12 (Décembre 2010) . - 10 p. Mots-clés : Aerodynamics  Blades  Compressors  Confined  flow  Damping  Distortion  Mass  transfer  Vibrations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The vibratory response amplitude of a blade under forced response conditions depends primarily on the aerodynamic excitation amplitude, on damping, and on the effects of mistuning. The work presented here targets to identify the individual contribution of these parameters to the resultant response amplitude depending on the mass flow and the resonance case. For this purpose, measurements were performed of the excitation amplitude, damping, and response amplitude for a high-speed centrifugal compressor. The inlet flow field was intentionally distorted in order to target specific excitation cases of the first main blade mode. For the compressor used, it was found that the overall damping of the first mode could be considered to be constant for any resonance case and mass flow. For this reason, case-to-case variations in the blade-averaged response amplitude were found to depend solely on the aerodynamic excitation amplitude due to inlet flow distortion. Based on an examination of the aerodynamic work distribution during resonance, zones of either excitation or damping work on the blade surface could be successfully identified. This enabled the conclusion to be drawn that energy transfer is a very localized phenomenon and may significantly change as the mass flow is altered, thereby introducing a redistribution of the blade excitation function. The effect of mistuning was shown to alter aerodynamic damping and response amplitude. However, the variation in aerodynamic damping of individual blades was relatively low, thus suggesting that blade-to-blade variation in response amplitude is primarily driven by energy localization in the sense typically experienced with coupled and mistuned structures. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013 [...]