Control of the flow past a sphere in a turbulent boundary layer using O-ring

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dc.contributor.authorOkbaz, Abdulkeri
dc.contributor.authorOzgoren, Muammer
dc.contributor.authorCanpolat, Cetin
dc.contributor.authorSahin, Besir
dc.contributor.authorAkilli, Huseyin
dc.date.accessioned2024-02-23T14:29:24Z
dc.date.available2024-02-23T14:29:24Z
dc.date.issued2022
dc.departmentNEÜen_US
dc.description.abstractThis research work presents an experimental study's outcomes to reveal the impact of an O-ring on the flow control over a sphere placed in a turbulent boundary layer. The investigation is performed quantitatively and qualitatively using particle image velocimetry (PIV) and dye visualization. The sphere model having a diamater of 42.5 mm is located in a turbulent boundary layer flow over a smooth plate for gap ratios of 0 <= G/D <= 1.5 at Reynolds number of 5 x 10(3). Flow characteristics, including patterns of instantaneous vorticity, streaklines, time-averaged streamlines, velocity vectors, velocity fluctuations, Reynolds stress correlations, and turbulence kinetic energy (< TKE >), are compared and discussed for a naked sphere and spheres having O-rings. The boundary layer velocity gradient and proximity of the sphere to the flat plate profoundly influence the flow dynamics. At proximity ratios of G/D=0.1 and 0.25, a wall jet is formed between lower side of the sphere and flat plate, and velocity fluctuations increase in regions close to the wall. At G/D=0.25, the jet flow also induces local flow separations on the flat plate. At higher proximity ratios, the velocity gradient of the boundary layer causes asymmetries in the mean flow characteristics and turbulence values in the wake region. It is observed that the O-ring with various placement angles (theta) on the sphere has a considerable alteration in the flow structure and turbulence statistics on the wake. At lower placement angles, where the O-ring is closer to the forward stagnation point of the sphere, the flow control performance of the O-ring is limited; however, its impact on the flow separation becomes pronounced as it is moved away from the forward stagnation point. At G/D=1.50 for O-ring diameters of 4.7 (2 mm) and 7 (3 mm) percent of the sphere diameter, the-ring exhibits remarkable flow control at theta=50 degrees and theta=55 degrees before laminar flow separation occurrence on the sphere surface, respectively. This conclusion is yielded from narrowed wakes and reductions in turbulence statistics compared to the naked sphere model. The O-ring with a diameter of 3 mm and placement angle of 50 degrees exhibits the most effective flow control. It decreases, in sequence, streamwise velocity fluctuations and length of wake recovery region by 45% and 40%, respectively, which can be evaluated as source of decrement in drag force.en_US
dc.identifier.doi10.12989/was.2022.35.1.001
dc.identifier.endpage20en_US
dc.identifier.issn1226-6116
dc.identifier.issn1598-6225
dc.identifier.issue1en_US
dc.identifier.scopus2-s2.0-85142627566en_US
dc.identifier.scopusqualityQ3en_US
dc.identifier.startpage1en_US
dc.identifier.urihttps://doi.org/10.12989/was.2022.35.1.001
dc.identifier.urihttps://hdl.handle.net/20.500.12452/14676
dc.identifier.volume35en_US
dc.identifier.wosWOS:000879883700001en_US
dc.identifier.wosqualityQ3en_US
dc.indekslendigikaynakWeb of Scienceen_US
dc.indekslendigikaynakScopusen_US
dc.language.isoenen_US
dc.publisherTechno-Pressen_US
dc.relation.ispartofWind And Structuresen_US
dc.relation.publicationcategoryMakale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanıen_US
dc.rightsinfo:eu-repo/semantics/closedAccessen_US
dc.subjectFlow Controlen_US
dc.subjectO-Ringen_US
dc.subjectPiven_US
dc.subjectSphereen_US
dc.subjectTurbulent Boundary Layeren_US
dc.titleControl of the flow past a sphere in a turbulent boundary layer using O-ringen_US
dc.typeArticleen_US

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