NASA LogoNTRSNTRS - NASA Technical Reports ServerSearchmore_vertCollectionsAboutNewsHelpLogin Back to ResultsOn the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow ConditionsThe present study, which is the first of a series of investigations dealing with specific issues of low pressure turbine (LPT) boundary layer aerodynamics, is aimed at providing detailed unsteady boundary flow information to understand the underlying physics of the inception, onset, and extent of the separation zone. A detailed experimental study on the behavior of the separation zone on the suction surface of a highly loaded LPT-blade under periodic unsteady wake flow is presented. Experimental investigations were performed at Texas A&M Turbomachinery Performance and Flow Research Laboratory using a large-scale unsteady turbine cascade research facility with an integrated wake generator and test section unit. To account for a high flow deflection of LPT-cascades at design and off-design operating points, the entire wake generator and test section unit including the traversing system is designed to allow a precise angle adjustment of the cascade relative to the incoming flow. This is done by a hydraulic platform, which simultaneously lifts and rotates the wake generator and test section unit. The unit is then attached to the tunnel exit nozzle with an angular accuracy of better than 0.05 , which is measured electronically. Utilizing a Reynolds number of 110,000 based on the blade suction surface length and the exit velocity, one steady and two different unsteady inlet flowconditions with the corresponding passing frequencies, wake velocities and turbulence intensities are investigated using hot-wire anemometry. In addition to the unsteady boundary layer measurements, blade surface pressure measurements were performed at Re=50,000, 75,000, 100,000, and 125,000 at one steady and two periodic unsteady inlet flow conditions. Detailed unsteady boundary layer measurement identifies the onset and extent of the separation zone as well as its behavior under unsteady wake flow. The results presented in ensemble-averaged and contour plot forms contribute to understanding the physics of the separation phenomenon under periodic unsteady wake flow. Several physical mechanisms are discussed.Document ID20030062126Acquisition SourceGlenn Research CenterDocument TypeTechnical Memorandum (TM)AuthorsSchobeiri, Meinhard T.*(Texas A&M Univ. College Station, TX, United States)*Ozturk, Burak*(Texas A&M Univ. College Station, TX, United States)*Ashpis, David E.*(NASA Glenn Research Center Cleveland, OH, United States)*Date AcquiredSeptember 7, 2013Publication DateJune 1, 2003Subject CategoryFluid Mechanics And ThermodynamicsReport/Patent NumberE-13852GT-2003-38917NASA/TM-2003-212290NAS 1.15:212290Meeting InformationMeeting: Turbo Expo 2003Location: Atlanta, GACountry: United StatesStart Date: June 16, 2003End Date: June 19, 2003Sponsors:American Society of Mechanical Engineers,International Gas TurbineFunding Number(s)WBS: WBS 22-708-28-07CONTRACT_GRANT: NCC3-793Distribution LimitsPublicCopyrightWork of the US Gov. Public Use Permitted.Available DownloadsNameType20030062126.pdfSTIcloud_downloadcontent_copyvisibilityRelated RecordsThere are no records associated with this record.visibility_offNo Preview Available
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