Untersuchung der Strukturen von künstlich angeregten transitionellen Plattengrenzschichtströmungen mit Hilfe der Stereo und Multiplane Particle Image Velocimetry:

Stereoscopic and Multi-plane PIV measurements on artificially excited transitional boundary layer flows along a flat plate will be presented. The experimental results are focused on the structures of the late stages of K- and Oblique-type transition and on the substructures and the development of a...

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Bibliographische Detailangaben
1. Verfasser: Schröder, Andreas 1968- (VerfasserIn)
Format: Abschlussarbeit Elektronisch E-Book
Sprache:German
Veröffentlicht: Göttingen 2001
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Zusammenfassung:Stereoscopic and Multi-plane PIV measurements on artificially excited transitional boundary layer flows along a flat plate will be presented. The experimental results are focused on the structures of the late stages of K- and Oblique-type transition and on the substructures and the development of a turbulent spot induced by a short locally blown injection of air. Instantaneous velocity fields are examined in order to quantify the local and global dynamics of the structures leading into fully turbulent flow. A statistical analysis of the turbulent spot flow field has been carried out from the measurements consisting of calculations of ensemble averages, rms-fields, Galilean accelerations, probability density functions and space-time-correlations of the velocity fluctuations, the Reynolds stresses of all four quadrants and the y-component of the vorticity. The results of this analysis lead to a model which can describe the interaction of the dominant substructures of the spot and the fluid exchange normal to the wall. The dominant substructures have been identified as relative ordered hairpin-like vortices and wall near streaks. This model enables an explanation for the growth of the spot in both stream-wise and span-wise directions and the self-similar arrowhead shape.
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