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Numerical investigation of wall heat transfer and skin-friction coefficient in reacting turbulent wall-jets
KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.ORCID-id: 0000-0002-5380-0285
KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.ORCID-id: 0000-0002-2711-4687
(Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
Nationell ämneskategori
Annan materialteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-39194OAI: oai:DiVA.org:kth-39194DiVA, id: diva2:439530
Anmärkning
QS 2011Tillgänglig från: 2011-09-08 Skapad: 2011-09-08 Senast uppdaterad: 2023-07-31Bibliografiskt granskad
Ingår i avhandling
1. Fundamental studies of non-premixed combustion in turbulent wall jets using direct numerical simulation
Öppna denna publikation i ny flik eller fönster >>Fundamental studies of non-premixed combustion in turbulent wall jets using direct numerical simulation
2011 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The present thesis deals with the fundamental aspects of turbulent mixingand non-premixed combustion in wall-jet flows. Direct numerical simulations(DNS) of compressible turbulent flows are performed in a wall-jet configura-tion, which has a close resemblance to many industrial combustion applica-tions. The triple ”turbulence-chemistry-wall” interactions are also present inthis flow set-up. These interactions have been addressed by first focusing onturbulent flow effects on the isothermal reaction, including the near-wall issues.Then, by adding heat-release to the simulations, it has been concentrated onheat-release effects on various phenomena that occur in the reacting turbulentwall-jet flow. In the computational domain, fuel and oxidizer enter separatelyin a non-premixed manner and the flow is fully turbulent and subsonic in allsimulations. In the first phase of this study, the case of a turbulent wall-jetincluding an isothermal reaction without heat release is addressed in order toisolate the near-wall effects and the mixing characteristics of the flow and thekey statistics for combustion are studied in the absence of thermal effects. Adeeper insight into three-dimensional mixing and reaction characteristics in aturbulent wall-jet has been gained through investigation of the probability den-sity functions, higher order moments of velocities and reacting scalars and thescalar dissipation rates of different species. In the second phase, DNS of turbu-lent reacting wall-jets including heat release is performed, where a single-stepglobal exothermic reaction with an Arrhenius-type reaction rate is considered.The main target was to identify the heat-release effects on different mixingscales of turbulent wall-jet flow. The scalar dissipation rates, time scale ratios,two-point correlations, one and two-dimensional premultiplied spectra are usedto illustrate the heat release induced modifications. It is observed that heatrelease effects delay the transition process in the chemically reacting cases andenlarge the fluctuation intensities of density and pressure, but have a dampingeffect on all velocity fluctuation intensities. Finer small mixing scales were ob-served in the isothermal simulations and larger vortical structures formed afteradding significant amounts of heat-release. Simulations with different Damk ̈h-  oler numbers, but comparable temperature-rise are performed and the expectedbehavior, a thinner flame with increasing Damk ̈hler number, is observed. Finally, some heat transfer related quantities are examined. The wall heat fluxand the corresponding Nusselt numbers are addressed. The near-wall reactioneffects on the skin friction coefficient are studied and further the reaction char-acteristics are investigated throughout the domain.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2011. s. viii, 44
Serie
Trita-MEK, ISSN 0348-467X ; 2011:09
Nyckelord
Turbulence, non-premixed combustion, global reaction, direct numerical simulation, wall-jet, heat release, mixing scales, heat transfer
Nationell ämneskategori
Annan materialteknik
Identifikatorer
urn:nbn:se:kth:diva-39028 (URN)978-91-7501-089-2 (ISBN)
Presentation
2011-09-28, Sal V2, Teknikringen 76, KTH, Stockholm, 10:15 (Engelska)
Opponent
Handledare
Forskningsfinansiär
Swedish e‐Science Research Center
Anmärkning
QC 20110908Tillgänglig från: 2011-09-08 Skapad: 2011-09-06 Senast uppdaterad: 2023-07-31Bibliografiskt granskad

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Johansson, Arne V.

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Pouransari, ZeinabJohansson, Arne V.
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Linné Flow Center, FLOW
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