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dc.contributor.authorElbaz, Ayman M.
dc.contributor.authorRoberts, William L.
dc.date.accessioned2015-08-03T12:04:07Z
dc.date.available2015-08-03T12:04:07Z
dc.date.issued2014-07
dc.identifier.issn08941777
dc.identifier.doi10.1016/j.expthermflusci.2013.11.011
dc.identifier.urihttp://hdl.handle.net/10754/563009
dc.description.abstractThis paper presents high speed images of OH-PLIF at 10. kHz simultaneously with 2D PIV (particle image velocimetry) measurements collected along the entire length of an inverse diffusion flame with circumferentially arranged methane fuel jets. For a fixed fuel flow rate, the central air jet Re was varied, leading to four air to fuel velocity ratios, namely Vr = 20.7, 29, 37.4 and 49.8. A double flame structure could be observed composed of a lower fuel entrainment region and an upper mixing and intense combustion region. The entrainment region was enveloped by an early OH layer, and then merged through a very thin OH neck to an annular OH layer located at the shear layer of the air jet. The two branches of this annular OH layer broaden as they moved downstream and eventfully merged together. Three types of events were observed common to all flames: breaks, closures and growing kernels. In upstream regions of the flames, the breaks were counterbalanced by flame closures. These breaks in OH signal were found to occur at locations where locally high velocity flows were impinging on the flame. As the Vr increased to 37.4, the OH layers became discontinuous over the downstream region of the flame, and these regions of low or no OH moved upstream. With further increases in Vr, these OH pockets act as flame kernels, growing as they moved downstream, and became the main mechanism for flame re-ignition. Along the flame length, the direction of the two dimensional principle compressive strain rate axis exhibited a preferred orientation of approximately 45° with respect to the flow direction. Moreover, the OH zones were associated with elongated regions of high vorticity. © 2013 Elsevier Inc.
dc.publisherElsevier BV
dc.subjectInverse diffusion flames
dc.subjectPIV measurements
dc.subjectPLIF-OH imaging
dc.titleFlame structure of methane inverse diffusion flame
dc.typeArticle
dc.contributor.departmentClean Combustion Research Center
dc.contributor.departmentMechanical Engineering Program
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.contributor.departmenthigh-pressure combustion (HPC) Research Group
dc.identifier.journalExperimental Thermal and Fluid Science
dc.contributor.institutionMechanical Power Engineering Department, Faculty of Engineering, Helwan University, Cairo 11718, Egypt
kaust.personElbaz, Ayman M.
kaust.personRoberts, William L.


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