Three-dimensional diffusive-thermal instability of flames propagating in a plane Poiseuille flow

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Kelly, Aiden and Rajamanickam, Prabakaran and Daou, Joel and Landel, Julien R. (2024) Three-dimensional diffusive-thermal instability of flames propagating in a plane Poiseuille flow. Proceedings of the Combustion Institute, 40 (1-4). 105258. ISSN 1540-7489 (https://doi.org/10.1016/j.proci.2024.105258)

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Abstract

The three-dimensional diffusive-thermal stability of a two-dimensional flame propagating in a Poiseuille flow is examined. The study explores the effect of three non-dimensional parameters, namely the Lewis number , the Damköhler number , and the flow Peclet number . Wide ranges of the Lewis number and the flow amplitude are covered, as well as conditions corresponding to small-scale narrow ( ≪ 1) to largescale wide ( ≫ 1) channels. The instability experienced by the flame appears as a combination of the traditional diffusive-thermal instability of planar flames and the recently identified instability corresponding to a transition from symmetric to asymmetric flame. The instability regions are identified in the - plane for selected values of by computing the eigenvalues of a linear stability problem. These are complemented by two- and three-dimensional time-dependent simulations describing the full evolution of unstable flames into the non-linear regime. In narrow channels, flames are found to be always symmetric about the mid-plane of the channel. Additionally, in these situations, shear flow-induced Taylor dispersion enhances the cellular instability in < 1 mixtures and suppresses the oscillatory instability in > 1 mixtures. In large-scale channels, however, both the cellular and the oscillatory instabilities are expected to persist. Here, the flame has a stronger propensity to become asymmetric when the mean flow opposes its propagation and when < 1; if the mean flow facilitates the flame propagation, then the flame is likely to remain symmetric about the channel mid-plane. For > 1, both symmetric and asymmetric flames are encountered and are accompanied by temporal oscillations.

ORCID iDs

Kelly, Aiden, Rajamanickam, Prabakaran ORCID logoORCID: https://orcid.org/0000-0003-1240-0362, Daou, Joel and Landel, Julien R.;
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