Non-normality and internal flame dynamics in premixed flame–acoustic interaction

Show simple item record SUBRAMANIAN, PRIYA SUJITH, RI 2022-07-12T23:25:03Z 2022-07-12T23:25:03Z 2011-05-13
dc.identifier.citation (2011). Journal of Fluid Mechanics, 679, 315-342.
dc.identifier.issn 0022-1120
dc.description.abstract <jats:p>This paper investigates the non-normal nature of premixed flame–acoustic interaction. The thermoacoustic system is modelled using the acoustic equations for momentum and energy, together with the equation for the evolution of the flame front obtained from the kinematic<jats:italic>G</jats:italic>-equation. As the unsteady heat addition acts as a volumetric source, the flame front is modelled as a distribution of monopole sources. Evolutions of the system are characterized with a measure of energy due to fluctuations. In addition to the acoustic energy, the energy due to fluctuations considered in the present paper accounts for the energy of the monopole sources. The linearized operator for this thermoacoustic system is non-normal, leading to non-orthogonality of its eigenvectors. Non-orthogonal eigenvectors can cause transient growth even when all the eigenvectors are decaying. Therefore, classical linear stability theory cannot predict the finite-time transient growth observed in non-normal systems. In the present model, the state space variables include the monopole source strengths in addition to the acoustic variables. Inclusion of these variables in the state space is essential to account for the transient growth due to non-normality. A parametric study of the variation in transient growth due to change in parameters such as flame location and flame angle is performed. In addition to projections along the acoustic variables of velocity and pressure, the optimal initial condition for the self-evolving system has significant projections along the strength of the monopole distribution. Comparison of linear and corresponding nonlinear evolutions highlights the role of transient growth in subcritical transition to instability. The notion of phase between acoustic pressure and heat release rate as an indicator of stability is examined.</jats:p>
dc.language en
dc.publisher Cambridge University Press (CUP)
dc.relation.ispartofseries Journal of Fluid Mechanics
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.
dc.rights This article has been published in a revised form in Journal of Fluid Mechanics This version is free to view and download for private research and study only. Not for re-distribution or re-use. © Cambridge University Press
dc.subject Science & Technology
dc.subject Technology
dc.subject Physical Sciences
dc.subject Mechanics
dc.subject Physics, Fluids & Plasmas
dc.subject Physics
dc.subject aeroacoustics
dc.subject flames
dc.subject reacting flows
dc.subject TRANSIENT
dc.subject SCHEMES
dc.subject GROWTH
dc.subject SOUND
dc.subject 01 Mathematical Sciences
dc.subject 09 Engineering
dc.title Non-normality and internal flame dynamics in premixed flame–acoustic interaction
dc.type Journal Article
dc.identifier.doi 10.1017/jfm.2011.140
pubs.begin-page 315
pubs.volume 679 2022-06-21T04:59:40Z
dc.rights.holder Copyright: Cambridge University Press en
pubs.end-page 342
pubs.publication-status Published
dc.rights.accessrights en
pubs.subtype Article
pubs.subtype Journal
pubs.elements-id 870317 Science Mathematics
dc.identifier.eissn 1469-7645
pubs.record-created-at-source-date 2022-06-21 2011-07-25

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