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dc.contributor.authorde Oliveira, PM
dc.contributor.authorAllison, Patton
dc.contributor.authorMastorakos, Epaminondas
dc.date.accessioned2018-12-05T00:30:47Z
dc.date.available2018-12-05T00:30:47Z
dc.date.issued2019-01
dc.identifier.issn0010-2180
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/286312
dc.description.abstractThe forced ignition process has a stochastic nature, which can be intensi ed due to turbulence and mixture uctuations. Although fuel droplets represent strong inhomogeneities which are generally detrimental to ignition, the presence of small droplets has been found to enhance ame speeds, decrease minimum ignition energy, and improve the ignitability of overall lean mixtures. In order to understand which factors are conducive to ignition of sprays, a spherically expanding ame is investigated, which is produced by a laser spark in a uniform dispersion of ethanol droplets in turbulent air. The ame is visualised by schlieren and OH*-chemiluminescence for overall equivalence ratios of 0.8 to 2, Sauter mean diameter of approximately 25 m, and u0=SL ranging from 0.9 to 1.3, where u0 and SL denote the rms axial velocity and laminar burning velocity, respectively. The timescales of the spark's effects on the ame are measured, as well as quenching timescales and initial kernel sizes conditional on ignition or failure. Small kernels quenched faster than approximately 0.6 ms, that is, the duration of the ame overdrive, and a minimum kernel radius for ignition of 1mm was observed. The short-mode of ignition failure was suppressed by increasing the laser energy and, consequently, the initial kernel size. Nevertheless, the ignitability of lean mixtures was only e ectively improved through high-energy sparks and partial prevaporisation of the fuel. Virtually all kernels ignited once prevaporisation was increased, and the gas-phase equivalence ratio was approximately 75% of the lower ammability limit, with ignition being limited only by laser breakdown.
dc.description.sponsorshipEuropean Commission Clean Sky project AMEL (641453); Brazilian Space Agency and Brazil's National Council for Scientific and Technological Development
dc.publisherElsevier BV
dc.titleIgnition of uniform droplet-laden weakly turbulent flows following a laser spark
dc.typeArticle
prism.endingPage400
prism.publicationDate2019
prism.publicationNameCombustion and Flame
prism.startingPage387
prism.volume199
dc.identifier.doi10.17863/CAM.33622
dcterms.dateAccepted2018-10-04
rioxxterms.versionofrecord10.1016/j.combustflame.2018.10.009
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserved
rioxxterms.licenseref.startdate2019-01-01
dc.contributor.orcidAllison, Patton [0000-0001-7819-2303]
dc.contributor.orcidMastorakos, Epaminondas [0000-0001-8245-5188]
dc.identifier.eissn1556-2921
rioxxterms.typeJournal Article/Review
pubs.funder-project-idEuropean Commission (641453)
cam.issuedOnline2018-11-12
rioxxterms.freetoread.startdate2019-11-12


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