Further characterization of the disturbance field in a transversely excited swirl-stabilized flame / Jacqueline O'Connor in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 1 (Janvier 2012)  

Public ISBD [article]  inTransactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 1 (Janvier 2012) . - 09 p. Titre : Further characterization of the disturbance field in a transversely excited swirl-stabilized flame Type de document : texte imprimé Auteurs : Jacqueline O'Connor, Auteur ; Tim Lieuwen, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Aircraft Combustion Electric power generation Flames Gas turbines Hydrodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper describes an analysis of the unsteady flow field in swirl flames subjected to transverse acoustic waves. This work is motivated by transverse instabilities in annular gas turbine combustors, which are a continuing challenge for both power generation and aircraft applications. The unsteady flow field that disturbs the flame consists not only of the incident transverse acoustic wave, but also longitudinal acoustic fluctuations and vortical fluctuations associated with underlying hydrodynamic instabilities of the base flow. We show that the acoustic and vortical velocity fluctuations are of comparable magnitude. The superposition of these waves leads to strong interference patterns in the velocity field, a result of the significantly different wave propagation speeds and axial phase dependencies of these two disturbance sources. Vortical fluctuations originate from the convectively unstable shear layers and absolutely unstable swirling jet. We argue that the unsteady shear layer induced fluctuations are the most dynamically significant, as they are the primary source of flame fluctuations. We also suggest that vortical structures associated with vortex breakdown play an important role in controlling the time-averaged features of the central flow and flame spreading angle, but do not play an important role in disturbing the flame at low disturbance amplitudes. This result has important implications not only for our understanding of the velocity disturbance field in the flame region, but also for capturing important physics in future modeling efforts. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000001 [...] [article] Further characterization of the disturbance field in a transversely excited swirl-stabilized flame [texte imprimé] / Jacqueline O'Connor, Auteur ; Tim Lieuwen, Auteur . - 2012 . - 09 p. Génie mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 1 (Janvier 2012) . - 09 p. Mots-clés : Aircraft Combustion Electric power generation Flames Gas turbines Hydrodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper describes an analysis of the unsteady flow field in swirl flames subjected to transverse acoustic waves. This work is motivated by transverse instabilities in annular gas turbine combustors, which are a continuing challenge for both power generation and aircraft applications. The unsteady flow field that disturbs the flame consists not only of the incident transverse acoustic wave, but also longitudinal acoustic fluctuations and vortical fluctuations associated with underlying hydrodynamic instabilities of the base flow. We show that the acoustic and vortical velocity fluctuations are of comparable magnitude. The superposition of these waves leads to strong interference patterns in the velocity field, a result of the significantly different wave propagation speeds and axial phase dependencies of these two disturbance sources. Vortical fluctuations originate from the convectively unstable shear layers and absolutely unstable swirling jet. We argue that the unsteady shear layer induced fluctuations are the most dynamically significant, as they are the primary source of flame fluctuations. We also suggest that vortical structures associated with vortex breakdown play an important role in controlling the time-averaged features of the central flow and flame spreading angle, but do not play an important role in disturbing the flame at low disturbance amplitudes. This result has important implications not only for our understanding of the velocity disturbance field in the flame region, but also for capturing important physics in future modeling efforts. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000001 [...]

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