An Experimental Study of Turbulent Boundary Layers Subjected to High Free-stream Turbulence Effects

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dc.contributor.authorOrsi Filho, Edgaren
dc.contributor.committeechairSimpson, Roger L.en
dc.contributor.committeememberDevenport, William J.en
dc.contributor.committeememberMarchman, James F. IIIen
dc.contributor.departmentAerospace and Ocean Engineeringen
dc.date.accessioned2014-03-14T20:50:50Zen
dc.date.adate2006-01-06en
dc.date.available2014-03-14T20:50:50Zen
dc.date.issued2005-12-12en
dc.date.rdate2008-01-06en
dc.date.sdate2005-12-27en
dc.description.abstractThe work presented in this thesis was on nominally two-dimensional turbulent boundary layers at zero pressure gradient subjected to high free-stream turbulent intensities of up to 7.9% in preparations for high free-stream turbulence studies on three-dimensional boundary layers, which will be done in the future in the Aerospace and Ocean Engineering Boundary Layer Wind Tunnel at Virginia Tech. The two-dimensional turbulent flow that will impinge three-dimensional bodies needed to be characterized, before the three-dimensional studies can be made. An active turbulence generator designed to create high free-stream turbulence intensities in the wind tunnel was tested and modified in order to obtain the lowest possible mean flow non-uniformities. A seven-hole pressure probe was used to obtain planes of mean velocity measurements. A three-component state of the art laser-Doppler velocimeter (LDV) was used to obtain mean and fluctuating velocities. Previous high free-stream turbulence studies have been reviewed and are discussed, and some of the previously published data of other authors have been corrected. Based on the measurements obtained with the LDV, it was also determined that the semi-log law of the wall is valid for high free-stream turbulence cases, but with different constants than the ones proposed by Coles, where the constants for the high free-stream cases may be dependent on the turbulence intensity. For the first time, the skin friction coefficient (Cf) was deduced from the viscous sublayer. The difference between the U_tau obtained in the viscous sublayer mean velocity profile and the U_tau obtained in the semi-log layer was 1.5%. The skin friction coefficient was determined to increase by 10.5% when the two-dimensional turbulent boundary layer was subjected to high free-stream turbulence effects. Spectral data obtained with the LDV, were compared to the von Kármán model spectrum and to the Pope's model spectrum, where the von Kármán spectrum was proven to fit the spectral data slightly better than the Pope's spectrum. Finally, the Hancock-Bradshaw-Blair parameter obtained for this experiment agreed very well with previously published data.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-12272005-005729en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-12272005-005729/en
dc.identifier.urihttp://hdl.handle.net/10919/36460en
dc.publisherVirginia Techen
dc.relation.haspartEdgarOrsiFilho_Thesis.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectLow Free-stream Turbulenceen
dc.subjectActive Turbulence Generatoren
dc.subjectTurbulent Boundary Layeren
dc.subjectLaser Doppler Velocimetryen
dc.subjectSeven-hole Pressure Probeen
dc.subjectSubsonicen
dc.subjectHigh Free-stream Turbulenceen
dc.titleAn Experimental Study of Turbulent Boundary Layers Subjected to High Free-stream Turbulence Effectsen
dc.typeThesisen
thesis.degree.disciplineAerospace and Ocean Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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