Hein, Stefan (2014) Linear and nonlinear growth of secondary instabilities of crossflow vortices studied by PSE. Seminar on Math. Dept., Imperial College London, 12. Dec. 2014, London, United Kingdom.
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Kurzfassung
Laminar-turbulent transition in (quasi-) three-dimensional boundary layers dominated by crossflow vortices is studied for the setup of the DLR swept-flat plate experiment. The linear and subsequent nonlinear stages of both the crossflow vortices and their high-frequency secondary instabilities are modelled by nonlinear parabolized stability equations (PSE). In the first part of the talk it is shown that those high-frequency secondary instabilities may develop from the interaction of stationary and low-frequency travelling crossflow vortices, a transition scenario usually more relevant in wind-tunnel experiments. In low-turbulence-level environments like free flight with stationary crossflow vortices being dominant in amplitude the high-frequency secondary instabilities presumably are triggered directly from environmental disturbances via a receptivity mechanism, however. Therefore, in the second part results from a different approach developed recently based on a bi-directional coupling between a secondary instability code and a PSE code are presented. Thereby, the nonlinear development of secondary instabilities including the generation of higher harmonics could be studied up to the stages where the feedback of the finite-amplitude secondary instability modes on the stationary crossflow vortices is no longer negligible and the skin-friction coefficient starts to deviate from that due to the mean flow distortion caused by the stationary crossflow modes alone. The latter could be used as a criterion for imminent laminar-turbulent transition within the saturation region of the stationary crossflow modes which was lacking in a nonlinear PSE analysis of crossflow-dominated transition until now.
elib-URL des Eintrags: | https://elib.dlr.de/93725/ | ||||||||
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Dokumentart: | Konferenzbeitrag (Vortrag) | ||||||||
Titel: | Linear and nonlinear growth of secondary instabilities of crossflow vortices studied by PSE | ||||||||
Autoren: |
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Datum: | 2014 | ||||||||
Referierte Publikation: | Nein | ||||||||
Open Access: | Nein | ||||||||
Gold Open Access: | Nein | ||||||||
In SCOPUS: | Nein | ||||||||
In ISI Web of Science: | Nein | ||||||||
Status: | veröffentlicht | ||||||||
Stichwörter: | laminar-turbulent transition, nonlinear PSE, crossflow vortices, secondary instability | ||||||||
Veranstaltungstitel: | Seminar on Math. Dept., Imperial College London | ||||||||
Veranstaltungsort: | London, United Kingdom | ||||||||
Veranstaltungsart: | Andere | ||||||||
Veranstaltungsdatum: | 12. Dec. 2014 | ||||||||
HGF - Forschungsbereich: | Luftfahrt, Raumfahrt und Verkehr | ||||||||
HGF - Programm: | Luftfahrt | ||||||||
HGF - Programmthema: | Flugzeuge | ||||||||
DLR - Schwerpunkt: | Luftfahrt | ||||||||
DLR - Forschungsgebiet: | L AR - Aircraft Research | ||||||||
DLR - Teilgebiet (Projekt, Vorhaben): | L - Militärische Technologien (alt) | ||||||||
Standort: | Göttingen | ||||||||
Institute & Einrichtungen: | Institut für Aerodynamik und Strömungstechnik > Hochgeschwindigkeitskonfigurationen | ||||||||
Hinterlegt von: | Micknaus, Ilka | ||||||||
Hinterlegt am: | 17 Dez 2014 14:58 | ||||||||
Letzte Änderung: | 19 Dez 2014 12:50 |
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