Title:
Flame stabilization and mixing characteristics in a stagnation point reverse flow combustor

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dc.contributor.advisor Seitzman, Jerry M.
dc.contributor.author Bobba, Mohan Krishna en_US
dc.contributor.committeeMember Filatyev, Sergei
dc.contributor.committeeMember Jagoda, Jechiel I.
dc.contributor.committeeMember Lieuwen, Timothy C.
dc.contributor.committeeMember Shelton, Samuel
dc.contributor.committeeMember Zinn, Ben T.
dc.contributor.department Aerospace Engineering en_US
dc.date.accessioned 2009-01-22T15:41:02Z
dc.date.available 2009-01-22T15:41:02Z
dc.date.issued 2007-10-10 en_US
dc.description.abstract A novel combustor design, referred to as the Stagnation Point Reverse-Flow (SPRF) combustor, was recently developed that is able to operate stably at very lean fuel-air mixtures and with low NOx emissions even when the fuel and air are not premixed before entering the combustor. The primary objective of this work is to elucidate the underlying physics behind the excellent stability and emissions performance of the SPRF combustor. The approach is to experimentally characterize velocities, species mixing, heat release and flame structure in an atmospheric pressure SPRF combustor with the help of various optical diagnostic techniques: OH PLIF, chemiluminescence imaging, PIV and Spontaneous Raman Scattering. Results indicate that the combustor is primarily stabilized in a region downstream of the injector that is characterized by low average velocities and high turbulence levels; this is also the region where most of the heat release occurs. High turbulence levels in the shear layer lead to increased product entrainment levels, elevating the reaction rates and thereby enhancing the combustor stability. The effect of product entrainment on chemical timescales and the flame structure is illustrated with simple reactor models. Although reactants are found to burn in a highly preheated (1300 K) and turbulent environment due to mixing with hot product gases, the residence times are sufficiently long compared to the ignition timescales such that the reactants do not autoignite. Turbulent flame structure analysis indicates that the flame is primarily in the thin reaction zones regime throughout the combustor, and it tends to become more flamelet like with increasing distance from the injector. Fuel-air mixing measurements in case of non-premixed operation indicate that the fuel is shielded from hot products until it is fully mixed with air, providing nearly premixed performance without the safety issues associated with premixing. The reduction in NOx emissions in the SPRF combustor are primarily due to its ability to stably operate under ultra lean (and nearly premixed) condition within the combustor. Further, to extend the usefulness of this combustor configuration to various applications, combustor geometry scaling rules were developed with the help of simplified coaxial and opposed jet models. en_US
dc.description.degree Ph.D. en_US
dc.identifier.uri http://hdl.handle.net/1853/26502
dc.publisher Georgia Institute of Technology en_US
dc.subject Turbulent en_US
dc.subject Reverse flow combustor en_US
dc.subject NOx emissions en_US
dc.subject Stagnation en_US
dc.subject Raman scattering en_US
dc.subject.lcsh Turbulence
dc.subject.lcsh Gas Turbines
dc.subject.lcsh Aircraft gas Turbines
dc.subject.lcsh Gas Turbines Combustion chambers
dc.subject.lcsh Pollution prevention
dc.title Flame stabilization and mixing characteristics in a stagnation point reverse flow combustor en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Seitzman, Jerry M.
local.contributor.corporatename College of Engineering
local.contributor.corporatename Daniel Guggenheim School of Aerospace Engineering
local.relation.ispartofseries Doctor of Philosophy with a Major in Aerospace Engineering
relation.isAdvisorOfPublication a312077b-cd16-4664-ad12-3a719b7f798a
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
relation.isOrgUnitOfPublication a348b767-ea7e-4789-af1f-1f1d5925fb65
relation.isSeriesOfPublication f6a932db-1cde-43b5-bcab-bf573da55ed6
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