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dc.contributor.authorRozati, Alien
dc.date.accessioned2014-03-14T20:20:47Zen
dc.date.available2014-03-14T20:20:47Zen
dc.date.issued2007-12-04en
dc.identifier.otheretd-12172007-153840en
dc.identifier.urihttp://hdl.handle.net/10919/30127en
dc.description.abstractThe work presented in this dissertation is the first numerical investigation conducted to study leading edge film cooling with Large Eddy Simulation (LES). A cylindrical leading edge with a flat after-body represents the leading edge, where coolant is injected with a 30Ë compound angle. Three blowing ratios of 0.4, 0.8, and 1.2 are studied. Free-stream Reynolds number is 100,000 and coolant-to-mainstream density ratio is unity. At blowing ratio of 0.4, the effect of coolant inlet condition is investigated. Results show that the fully-turbulent coolant jet increases mixing with the mainstream in the outer shear layer but does not influence the flow dynamics in the turbulent boundary layer at the surface. As a result, the turbulent jet decreases adiabatic effectiveness but does not have a substantial effect on the heat transfer coefficient. At B.R.=0.4, three types of coherent structures are identified which consist of a primary entrainment vortex at the leeward aft-side of the coolant hole, vortex tubes at the windward side of the coolant hole, and hairpin vortices typical of turbulent boundary layers produced by the turbulent interaction of the coolant and mainstream downstream of injection. At B.R. = 0.8 and 1.2, coherent vortex tubes are no longer discernable, whereas the primary vortex structure gains in strength. In all cases, the bulk of the mixing occurs by entrainment which takes place at the leeward aft-side of the coolant jet. This region is characterized by a low pressure core and the primary entrainment vortex. Turbulent shear interaction between coolant jet and mainstream increases substantially with blowing ratio and contributes to the dilution of the coolant jet. As a result of the increased mixing in the shear layer and primary structure, adiabatic effectiveness decreases and heat transfer coefficient increases with increase in blowing ratio. The dissertation also investigates the deposition and erosion of Syngas ash particles in the film cooled leading edge region. Three ash particle sizes of 1, 5, and 10 microns are investigated at all blowing ratios using Lagrangian dynamics. The 1 micron particles with momentum Stokes number St = 0.03 (based on approach velocity and cylinder diameter), show negligible deposition/erosion. The 10 micron particles, on the other hand with a high momentum Stokes number, St = 3, directly impinge and deposit on the surface, with blowing ratio having a minimal effect. The 5 micron particles with St=0.8, show the largest receptivity to coolant flow and blowing ratio. On a mass basis, 90% of deposited mass is from 10 micron particles, with 5 micron particles contributing the other 10%. Overall there is a slight decrease in deposited mass with increase in blowing ratio. About 0.03% of the total incoming particle energy can potentially be transferred as erosive energy to the surface and coolant hole, with contribution coming from only 5 micron particles at B.R.=0.4 and 0.8, and both 5 and 10 micron particles at B.R.=1.2.en
dc.publisherVirginia Techen
dc.relation.haspartRozatiDissertationMEPhD.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectSyngas ash particleen
dc.subjectAdiabatic effectivenessen
dc.subjectLeading edge film coolingen
dc.subjectLarge Eddy Simulationen
dc.subjectErosionen
dc.subjectBlowing ratioen
dc.subjectDepositionen
dc.subjectHeat transfer coefficienten
dc.titleLarge Eddy Simulation of Leading Edge Film Cooling: Flow Physics, Heat Transfer, and Syngas Ash Depositionen
dc.typeDissertationen
dc.contributor.departmentMechanical Engineeringen
dc.description.degreePh. D.en
thesis.degree.namePh. D.en
thesis.degree.leveldoctoralen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.disciplineMechanical Engineeringen
dc.contributor.committeechairTafti, Danesh K.en
dc.contributor.committeememberRagab, Saad A.en
dc.contributor.committeememberPaul, Mark R.en
dc.contributor.committeememberDevenport, William J.en
dc.contributor.committeememberBall, Kenneth S.en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-12172007-153840/en
dc.date.sdate2007-12-17en
dc.date.rdate2007-12-21en
dc.date.adate2007-12-21en


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