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A computational parametric analysis of the vibration of a three-spool aero-engine under multifrequency unbalance excitation / Pham Minh Hai in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 133 N° 7 (Juillet 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 7 (Juillet 2011) . - 09 p. Titre : A computational parametric analysis of the vibration of a three-spool aero-engine under multifrequency unbalance excitation Type de document : texte imprimé Auteurs : Pham Minh Hai, Auteur ; Philip Bonello, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Turbines à gaz Langues : Anglais (eng) Mots-clés : Aerospace  engines  Damping  Frequency-domain  analysis  Harmonics  Springs  (mechanical)  Time-domain  analysis  Vibrations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The integration of squeeze-film dampers (SFDs) in aero-engine assemblies is a highly cost-effective means of introducing damping in an otherwise lightly damped structure. However, their deployment requires careful unbalance response calculations that take due account of the SFDs' nonlinearity, particularly when they are unsupported by a centralizing spring. Until recently, such calculations were prohibitive due to the large number of assembly modes that typically need to be considered. This problem has been overcome by the authors through the novel impulsive receptance method (IRM) and the receptance harmonic balance method (RHBM), which efficiently solve the nonlinear problem in the time and frequency domains, respectively. These methods have been illustrated on a realistic twin-spool engine and have been shown to be effective for both single frequency unbalance excitation (unbalance on a single rotor) and multifrequency unbalance (MFU) excitation (unbalance on both rotors). In the present paper, the methods are applied to a realistic three-spool engine and the aims are twofold: (i) to present some preliminary results of a parametric study into a three-spool aero-engine assembly and (ii) to propose a technique that makes use of both IRM and RHBM in producing the speed responses under MFU excitation (from all three rotors) with a realistic speed relation between the rotors. The latter technique is necessary since the speed ratio will vary along a realistic speed characteristic and the authors have previously solved the twin-spool MFU problem under a constant speed ratio condition. The approach used here is to approximate the speed characteristic by one in which the speed ratios are ratios of low integers, enabling the use of RHBM to finish off (to steady-state) time-transient solutions obtained through IRM. The parameter study shows that the application of simple bump-spring supports to selected, otherwise unsupported, SFDs along with slight sealing should have a beneficial effect on the dynamic response of aero-engines with heavy rotors. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...] [article] A computational parametric analysis of the vibration of a three-spool aero-engine under multifrequency unbalance excitation [texte imprimé] / Pham Minh Hai, Auteur ; Philip Bonello, Auteur . - 2011 . - 09 p. Turbines à gaz Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 133 N° 7 (Juillet 2011) . - 09 p. Mots-clés : Aerospace  engines  Damping  Frequency-domain  analysis  Harmonics  Springs  (mechanical)  Time-domain  analysis  Vibrations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The integration of squeeze-film dampers (SFDs) in aero-engine assemblies is a highly cost-effective means of introducing damping in an otherwise lightly damped structure. However, their deployment requires careful unbalance response calculations that take due account of the SFDs' nonlinearity, particularly when they are unsupported by a centralizing spring. Until recently, such calculations were prohibitive due to the large number of assembly modes that typically need to be considered. This problem has been overcome by the authors through the novel impulsive receptance method (IRM) and the receptance harmonic balance method (RHBM), which efficiently solve the nonlinear problem in the time and frequency domains, respectively. These methods have been illustrated on a realistic twin-spool engine and have been shown to be effective for both single frequency unbalance excitation (unbalance on a single rotor) and multifrequency unbalance (MFU) excitation (unbalance on both rotors). In the present paper, the methods are applied to a realistic three-spool engine and the aims are twofold: (i) to present some preliminary results of a parametric study into a three-spool aero-engine assembly and (ii) to propose a technique that makes use of both IRM and RHBM in producing the speed responses under MFU excitation (from all three rotors) with a realistic speed relation between the rotors. The latter technique is necessary since the speed ratio will vary along a realistic speed characteristic and the authors have previously solved the twin-spool MFU problem under a constant speed ratio condition. The approach used here is to approximate the speed characteristic by one in which the speed ratios are ratios of low integers, enabling the use of RHBM to finish off (to steady-state) time-transient solutions obtained through IRM. The parameter study shows that the application of simple bump-spring supports to selected, otherwise unsupported, SFDs along with slight sealing should have a beneficial effect on the dynamic response of aero-engines with heavy rotors. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ00013300 [...]

Computational studies of the unbalance response of a whole aero-engine model with squeeze-film bearings / Philip Bonello in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 3 (Mars 2010) . - 07 p. Titre : Computational studies of the unbalance response of a whole aero-engine model with squeeze-film bearings Type de document : texte imprimé Auteurs : Philip Bonello, Auteur ; Pham Minh Hai, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Aerospace  engines  Machine  bearings  Time-domain  analysis  Vibration  control Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The computation of the unbalance vibration response of aero-engine assemblies fitted with nonlinear bearings requires the retention of a very large number of modes for reliable results. This renders most previously proposed nonlinear solvers unsuitable for this application. This paper presents three methods for the efficient solution of the problem. The first method is the recently developed impulsive receptance method (IRM). The second method is a reformulation of the Newmark-beta method. In addition to these two time-domain methods, a whole-engine receptance harmonic balance method (RHBM) is introduced that allows, for the first time, the frequency domain calculation of the periodic vibration response of a real engine. All three methods use modal data calculated from a one-off analysis of the linear part of the engine at zero speed. Simulations on a realistically-sized representative twin-spool engine model with squeeze-film damper bearings provide evidence that the popular Newmark-beta method can be unreliable for large-order nonlinear systems. The excellent correlation between the IRM and RHBM results demonstrates the efficacy of these two complementary tools in the computational analysis of realistic whole-engine models. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000003 [...] [article] Computational studies of the unbalance response of a whole aero-engine model with squeeze-film bearings [texte imprimé] / Philip Bonello, Auteur ; Pham Minh Hai, 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° 3 (Mars 2010) . - 07 p. Mots-clés : Aerospace  engines  Machine  bearings  Time-domain  analysis  Vibration  control Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The computation of the unbalance vibration response of aero-engine assemblies fitted with nonlinear bearings requires the retention of a very large number of modes for reliable results. This renders most previously proposed nonlinear solvers unsuitable for this application. This paper presents three methods for the efficient solution of the problem. The first method is the recently developed impulsive receptance method (IRM). The second method is a reformulation of the Newmark-beta method. In addition to these two time-domain methods, a whole-engine receptance harmonic balance method (RHBM) is introduced that allows, for the first time, the frequency domain calculation of the periodic vibration response of a real engine. All three methods use modal data calculated from a one-off analysis of the linear part of the engine at zero speed. Simulations on a realistically-sized representative twin-spool engine model with squeeze-film damper bearings provide evidence that the popular Newmark-beta method can be unreliable for large-order nonlinear systems. The excellent correlation between the IRM and RHBM results demonstrates the efficacy of these two complementary tools in the computational analysis of realistic whole-engine models. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000003 [...]