Thermoacoustic analysis of lean premixed hydrogen flames in narrow vertical channels

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Show simple item record Veiga López, Fernando Martínez Ruiz, Daniel Kuznetsov, Mike Sánchez-Sanz, Mario 2022-02-17T13:52:03Z 2022-10-01T23:00:05Z 2020-10-15
dc.identifier.bibliographicCitation Fuel, (2020), 278, 118212.
dc.identifier.issn 0016-2361
dc.description.abstract Thermoacoustic instabilities arise for lean hydrogen-air flames propagating in narrow channels. We provide here a detailed experimental analysis of such phenomena in a semi-confined vessel, analyzing the effect of the mixture composition, geometry and gravity on the onset of acoustic-driven flame vibrations. Downward-propagating flames leaner than a critical value vibrate smoothly and transit to the secondary oscillating instability, which develops strong variations of pressure that couple with the propagation dynamics. The transition threshold changes during the propagation along very narrow channels, where heat losses are no longer negligible. The parametric region of equivalence ratio for the secondary thermoacoustic instability diminishes, showing an additional transition for very lean flames. There, the front breaks into several structures and the flame-wave feedback becomes weaker. The influence of gravity is studied by comparing upward and downward propagating flames, where the Rayleigh–Taylor instability arises for sufficiently small values of the Froude number in slow-propagating lean flames. For a constant mixture, buoyancy-driven upward-propagating flames develop less wrinkled fronts than those propagating downwards, and remain unresponsive to acoustic-front interaction. We show here a direct relation between front shape and thermoacoustics. In agreement with previous studies [1], [2], [3], curvature and strain effects on conduction and diffusion characterize the response of the flame to pressure perturbations, with the Markstein number controlling the aforementioned transition. Nevertheless, the theoretical analyses found in the literature can only be used on nearly equidiffusional mixtures, and are not accurate enough to describe the highly diffusive fuel mixtures (i.e. lean hydrogen-air flames) considered in our experiments.
dc.description.sponsorship This work was supported by projects ENE2015-65852-C2-1-R (MINECO/ FEDER, UE), BYNV-ua37crdy (Fundación Iberdrola España) and KIT. The authors want to thank the technical support of ProScience GmbH. in the construction and operation of the experimental setup. D. Martnez-Ruiz would like to acknowledge F. Higuera for fruitful discussions.
dc.format.extent 10
dc.language.iso eng
dc.publisher Elsevier
dc.rights © 2020 Elsevier Ltd. All rights reserved.
dc.rights Atribución-NoComercial-SinDerivadas 3.0 España
dc.subject.other Hydrogen
dc.subject.other Narrow channels
dc.subject.other Markstein number
dc.subject.other Thermoacoustic instabilities
dc.subject.other Gravity
dc.title Thermoacoustic analysis of lean premixed hydrogen flames in narrow vertical channels
dc.type article
dc.description.status Publicado
dc.subject.eciencia Ingeniería Industrial
dc.rights.accessRights openAccess
dc.relation.projectID Gobierno de España. ENE2015-65852-C2-1-R
dc.type.version acceptedVersion
dc.identifier.publicationfirstpage 1
dc.identifier.publicationissue 118212
dc.identifier.publicationlastpage 10
dc.identifier.publicationtitle FUEL
dc.identifier.publicationvolume 278
dc.identifier.uxxi AR/0000027437
dc.contributor.funder Ministerio de Economía y Competitividad (España)
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