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Investigation of shock-induced flow separation over a transonic compressor blade by conditionally averaged PIV and high-speed shadowgraphs

Klinner, Joachim und Hergt, Alexander und Grund, Sebastian und Willert, Christian (2018) Investigation of shock-induced flow separation over a transonic compressor blade by conditionally averaged PIV and high-speed shadowgraphs. 19th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics, 2018-07-16 - 2018-07-19, Lisbon, Portugal.

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Offizielle URL: http://www.lisbon-lasersymposium.org/lxlaser2018

Kurzfassung

The impact of separation control has been investigated in a highly loaded transonic compressor cascade at an inlet Mach number of 1.21 and a chord based Reynolds number of 1.4 x 10^6. Applied control devices are air jet vortex generators (AJVG) and a surface roughness patch. Comparative flows without transition control imply a variation of the upstream turbulence level from 0.5% to 2.5%. Above the suction side, velocities of the unsteady separation region have been captured by particle image velocimetry (PIV). The aerodynamic load alternation due to shock motion results in flexure of the blade surface which have been measured and compensated prior to PIV processing. Single PIV shots indicate shape variations of both the lambda shock system and the associated separation region while the shock foot position is fluctuating within a range of up to 23% of chord. Large sets of statistically independent PIV samples are conditionally averaged upon instantaneous passage shock positions at a resolution of 1% of chord length to quantify the size of flow separation. Large bubble separation occurs if the turbulence of the incoming flow is low. The separation region becomes smaller when AJVGs are applied but still exhibits bubble separation at rear shock positions. The size of the separation region is significantly reduced either if a roughness patch is applied or if the turbulence level of the incoming flow is high. The frequency range of shock motion is analyzed by shock tracking on the basis of high speed shadowgraphs. A Fourier analysis of shock motion in the low frequency range (<1khz) indicates the highest spectral densities for the turbulent case and the lowest densities if roughness patch are applied. Joint probability density distributions of blade displacements and amplitudes of shock movement revealed that upward transverse blade deflections are more frequent at shock positions downstream of the mean shock position while downward deflections are more frequent at frontal shock positions.

elib-URL des Eintrags:https://elib.dlr.de/121148/
Dokumentart:Konferenzbeitrag (Vortrag)
Titel:Investigation of shock-induced flow separation over a transonic compressor blade by conditionally averaged PIV and high-speed shadowgraphs
Autoren:
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID-iDORCID Put Code
Klinner, JoachimJoachim.Klinner (at) dlr.dehttps://orcid.org/0000-0003-2709-9664NICHT SPEZIFIZIERT
Hergt, Alexanderalexander.hergt (at) dlr.dehttps://orcid.org/0009-0008-1643-7326NICHT SPEZIFIZIERT
Grund, Sebastiansebastian.grund (at) dlr.deNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Willert, ChristianChris.Willert (at) dlr.dehttps://orcid.org/0000-0002-1668-0181NICHT SPEZIFIZIERT
Datum:16 Juli 2018
Referierte Publikation:Ja
Open Access:Ja
Gold Open Access:Nein
In SCOPUS:Nein
In ISI Web of Science:Nein
Status:veröffentlicht
Stichwörter:shock-induced separation, bubble separation, conditional average, PIV, transonic buffeting, transition control, SBL, image-based velocimetry, high-speed imaging
Veranstaltungstitel:19th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics
Veranstaltungsort:Lisbon, Portugal
Veranstaltungsart:internationale Konferenz
Veranstaltungsbeginn:16 Juli 2018
Veranstaltungsende:19 Juli 2018
HGF - Forschungsbereich:Luftfahrt, Raumfahrt und Verkehr
HGF - Programm:Luftfahrt
HGF - Programmthema:Antriebssysteme
DLR - Schwerpunkt:Luftfahrt
DLR - Forschungsgebiet:L ER - Engine Research
DLR - Teilgebiet (Projekt, Vorhaben):L - Virtuelles Triebwerk und Validierungsmethoden (alt)
Standort: Köln-Porz
Institute & Einrichtungen:Institut für Antriebstechnik > Triebwerksmesstechnik
Hinterlegt von: Micknaus, Ilka
Hinterlegt am:29 Okt 2018 08:56
Letzte Änderung:24 Apr 2024 20:25

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