"An Experimental Investigation of Showerhead Film Cooling Performance in a Transonic Vane Cascade at Low Freestream Turbulence"

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dc.contributor.authorBolchoz, Ruford Josephen
dc.contributor.committeechairNg, Wing Faien
dc.contributor.committeememberDiller, Thomas E.en
dc.contributor.committeememberVick, Brian L.en
dc.contributor.departmentMechanical Engineeringen
dc.date.accessioned2014-03-14T20:37:52Zen
dc.date.adate2008-06-17en
dc.date.available2014-03-14T20:37:52Zen
dc.date.issued2008-05-14en
dc.date.rdate2010-11-22en
dc.date.sdate2008-05-21en
dc.description.abstractIn the drive to increase cycle efficiency, gas turbine designers have increased turbine inlet temperatures well beyond the metallurgical limits of engine components. In order to prevent failure and meet life requirements, turbine components must be cooled well below these hot gas temperatures. Film cooling is a widely employed cooling technique whereby air is extracted from the compressor and ejected through holes on the surfaces of hot gas path components. The cool air forms a protective film around the surface of the part. Accurate numerical prediction of film cooling performance is extremely difficult so experiments are required to validate designs and CFD tools. In this study, a first stage turbine vane with five rows of showerhead cooling was instrumented with platinum thin-film gauges to experimentally characterize film cooling performance. The vane was tested in a transonic vane cascade in Virginia Tech's heated, blow-down wind tunnel. Two freestream exit Mach numbers of 0.76 and 1.0—corresponding to exit Reynolds numbers based on vane chord of 1.1x106 and 1.5x106, respectively—were tested at an inlet freestream turbulence intensity of two percent and an integral length scale normalized by vane pitch of 0.05. The showerhead cooling scheme was tested at blowing ratios of 0 (no cooling), 1.5, and 2.0 and a density ratio of 1.35. Midspan Nusselt number and film cooling effectiveness distributions over the surface of the vane are presented. Film cooling was found to augment heat transfer and reduce adiabatic wall temperature downstream of injection. In general, an increase in blowing ratio was shown to increase augmentation and film cooling effectiveness. Increasing Reynolds number was shown to increase heat transfer and reduce effectiveness. Finally, comparing low turbulence measurements (Tu = 2%) to measurements performed at high freestream turbulence (Tu = 16%) by Nasir et al. [13] showed that large-scale high freestream turbulence can reduce heat transfer coefficient downstream of injection.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-05212008-150634en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05212008-150634/en
dc.identifier.urihttp://hdl.handle.net/10919/33075en
dc.publisherVirginia Techen
dc.relation.haspartBolchoz_Thesis.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectcascadeen
dc.subjectHeat--Transmissionen
dc.subjectTurbulenceen
dc.subjectvaneen
dc.subjecttransonicen
dc.subjectturbineen
dc.subjectfilm coolingen
dc.title"An Experimental Investigation of Showerhead Film Cooling Performance in a Transonic Vane Cascade at Low Freestream Turbulence"en
dc.typeThesisen
thesis.degree.disciplineMechanical Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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